"Legal constraints cannot yield even to the noblest of intentions, for judicial visions of the social good will differ from issue to issue and from judge to judge, and will, if allowed to run unchecked, thwart the expression of the democratic will."
How later courts described this case
- "Legal constraints cannot yield even to the noblest of intentions, for judicial visions of the social good will differ from issue to issue and from judge to judge, and will, if allowed to run unchecked, thwart the expression of the democratic will."
Written by the judges who cited it.
The opinion
Opinions of the United
1999 Decisions States Court of Appeals
for the Third Circuit
11-2-1999
In Re: TMI Litigation
Precedential or Non-Precedential:
Docket 96-7623, 96-7624 96-7625
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Recommended Citation
"In Re: TMI Litigation" (1999). 1999 Decisions. Paper 296.
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Volume 1 of 4
Filed November 2, 1999
UNITED STATES COURT OF APPEALS
FOR THE THIRD CIRCUIT
Nos. 96-7623/7624/7625
IN RE: TMI LITIGATION
LORI DOLAN; JOSEPH GAUGHAN; RONALD
WARD; ESTATE OF PEARL HICKERNELL;
KENNETH PUTT; ESTATE OF ETHELDA HILT;
PAULA OBERCASH; JOLENE PETERSON; ESTATE OF
GARY VILLELLA; ESTATE OF LEO BEAM,
Appellants No. 96-7623
IN RE: TMI LITIGATION
ALL PLAINTIFFS EXCEPT LORI DOLAN, JOSEPH
GAUGHAN, RONALD WARD, ESTATE OF PEARL
HICKERNELL, KENNETH PUTT, ESTATE OF ETHELDA
HILT, PAULA OBERCASH, JOLENE PETERSON, ESTATE
OF GARY VILLELLA AND ESTATE OF LEO BEAM,
Appellants No. 96-7624
IN RE: TMI LITIGATION
ALL PLAINTIFFS; ARNOLD LEVIN; LAURENCE
BERMAN; LEE SWARTZ
Appellants No. 96-7625
ON APPEAL FROM THE UNITED STATES DISTRICT
COURT FOR THE MIDDLE DISTRICT OF PENNSYLVANIA
(Civil No. 88-cv-01452)
(District Judge: Honorable Sylvia H. Rambo)
ARGUED: June 27, 1997
Before: GREENBERG and McKEE, Circuit Judges, and
GREENAWAY, District Judge*
(Opinion filed: November 2, 1999)
ARNOLD LEVIN, ESQ.
LAURENCE S. BERMAN, ESQ.
(Argued)
CRAIG D. GINSBURG, ESQ.
Levin, Fishbein, Sedran & Berman
510 Walnut Street, Suite 500
Philadelphia, PA 19106
LEE C. SWARTZ, ESQ.
Hepford, Swartz & Morgan
111 North Front Street
P.O. Box 889
Harrisburg, PA 17108
Attorneys for Appellants in
No. 96-7623/7624/7625
LOU TARASI, ESQ.
Tarasi & Johnson, P.C.
510 Third Avenue
Pittsburgh, PA 15129
Of Counsel for Certain Appellants
Identified in the Entry of Appearance
in Appeal No. 96-7624/7625
_________________________________________________________________
* The Honorable Joseph A. Greenaway, Jr., United States District Court
Judge for the District of New Jersey, sitting by designation.
2
STEPHEN A. SALTZBURG, ESQ.
(Argued)
Howrey Professor of Trial Advocacy,
Litigation and Professional
Responsibility
George Washington Law School
720 20th Street, N.W.
Washington, D.C. 20052
Of Counsel for Appellants in
No. 96-7623/7624/7625
DANIEL J. CAPRA, ESQ.
Reed Professor of Law
Fordham University School of Law
Lincoln Center
140 West 62nd Street
New York, NY 10023
Of Counsel for Certain Appellants
Identified in the Entry of Appearance
in Appeal No. 96-7625
A.H. WILCOX, ESQ. (Argued)
ELLEN K. SCOTT, ESQ. (Argued)
ERIC J. ROTHSCHILD, ESQ.
(Argued)
Pepper, Hamilton & Scheetz, LLP
3000 Two Logan Square
18th and Arch Streets
Philadelphia, PA 19103
LEWIS S. KUNKEL, JR., ESQ.
THOMAS B. SCHMIDT, III, ESQ.
Pepper, Hamilton & Scheetz LLP
200 One Keystone Plaza
North Front & Market Streets
P.O. Box 1181
Harrisburg, PA 17108
Attorneys for Appellees in
Nos. 96-7623/7624/7625
3
REUBEN A. GUTTMAN, ESQ.
Provost & Umphrey
1350 New York Avenue, N.W.
Suite 1040
Washington, D.C. 20005
NED MILTENBERG, ESQ.
Associate General Counsel
Association of Trial Lawyers of
America ("ATLA")
1050 31st Street, N.W.
Washington, D.C. 20007
Amicus Curiae, Association of Trial
Lawyers of America ("ATLA"), in
Support of Appellants
TABLE OF CONTENTS
I. INTRODUCTION 6
II. PROCEDURAL HISTORY 8
III. SCIENTIFIC BACKGROUND 18
A. Overview of Relevant Principles of
Nuclear Physics 18
1. Atomic and Nuclear Structure 18
2. Radioactivity 24
3. Ionizing Radiation 28
4. Radiation Quantities and Units 31
5. Health Effects of Ionizing Radiation 35
i. Deterministic Effects 38
ii. Stochastic Effects 41
6. Radiation in the Environment 44
i. Natural Radiation 44
ii. Man-made Radiation 49
IV. NUCLEAR ENGINEERING 54
A. Nuclear Reaction 54
B. The Operation of Nuclear Power Plant 59
C. Barriers to Release of Radioactive Materials
into the Environment 65
4
V. THE ACCIDENT AND ITS AFTERMATH 66
A. The Accident at TMI-2 66
B. Radioactive Materials Released to the
Environment 70
C. Pathways of Exposure to Radioactive Materia ls 71
VI. LEGAL DISCUSSION 72
A. The Trial Plaintiffs' Appeal 72
1. Background 72
2. Standards Governing the Admissibility of
Scientific Evidence 79
3. Trial Plaintiffs' Dose Exposure Expert
Witnesses 85
i. Ignaz Vergeiner 85
a. Qualifications 85
b. Vergeiner's Opinion. 86
c. Discussion and Conclusions 87
ii. Charles Armentrout and Victor Neuwirth 95
a. Qualifications 95
b. Armentrout's Observations and
Experiences 96
c. Discussion and Conclusion 98
d. Neuwirth's Soil Sample Analyses
and Armentrout's Dose Estimates. 99
e. Discussion and Conclusion 101
iii. James Gunckel 105
a. Qualifications 105
b. Gunckel's Opinion 108
c. Discussion and Conclusions 112
iv. Vladimir Shevchenko 118
a. Qualifications 118
b. Shevchenko's Tree Study 120
c. Discussion and Conclusions 123
d. The Cytogenetic Analysis 126
e. Discussion and Conclusions 130
v. Gennady Kozubov 135
a. Qualifications 135
b. Kozubov's Opinion 135
c. Discussion and Conclusions 137
vi. Olga Tarasenko 139
a. Qualifications 139
b. Tarasenko's Opinion 140
5
c. Discussion and Conclusions 142
vii. Bruce Molholt 145
a. Qualifications 145
b. Molholt's Opinions 146
c. Discussion and Conclusions 149
viii. Sigmund Zakrzewski 155
a. Qualifications 155
b. Zakrzewski's Opinion 158
c. Discussion and Conclusions 159
ix. Theodor Sterling 161
a. Qualifications 161
b. Sterling's Opinion 161
c. Discussion and Conclusions 163
x. Steven Wing 166
a. Qualifications 166
b. Wing's Mortality Study 166
c. Discussion and Conclusions 168
d. Wing's Cancer Incidence Study 170
e. Discussion and Conclusions 173
xi. Douglas Crawford-Brown 173
a. Qualifications 175
b. Crawford-Brown's Opinion 175
c. Discussion and Conclusions 176
4. Effect of the Exclusion of Wing's
Lung Cancer Testimony 179
5. Exclusion of Experts' Submissions
as Untimely 181
6. Conclusion 190
B. The Non-Trial Plaintiffs' Appeal 191
C. The Monetary Sanctions Appeal 200
D. Reassignment Upon Remand 201
VII. CONCLUSION 203
OPINION OF THE COURT
McKEE, Circuit Judge
I. INTRODUCTION
These three appeals arise out of the nuclear reactor
6
accident which occurred on March 28, 1979, at Three Mile
Island in Dauphin County, Pennsylvania.1 Two of the
appeals concern the personal injury claims of more than
2,000 Three Mile Island area residents who allege that they
have developed neoplasms2 as a result of the radiation
released into the environment as a result of the reactor
accident. The first appeal is that of a group of ten trial
plaintiffs who were selected by the parties after the District
Court adopted the plaintiffs' case management order, which
called for a "mini-trial" of the claims of a group of "typical"
plaintiffs (the "Trial Plaintiffs"). The critical issue there is
the trial plaintiffs' ability to demonstrate that they were
exposed to doses of radiation sufficient to cause their
neoplasms. Proof of that causation depended on the
admissibility of the testimony of several experts that the
Trial Plaintiffs retained. These experts attempted to testify
about the amount of radiation released into the
environment by the nuclear reactor accident, and thereby
correlate the plaintiffs' neoplasms to that accident.
Defendants challenged the admissibility of the experts'
testimony and the District Court was therefore required to
hold extensive in limine hearings pursuant to its
"gatekeeping" role under Daubert v. Merrell Dow
Pharmaceuticals, Inc., 509 U.S. 579 (1993). Following those
hearings, the court excluded the overwhelming majority of
the Trial Plaintiffs' proposed expert testimony as to dose
exposure. Following the exclusion of the dose exposure
_________________________________________________________________
1. Sometime prior to argument, the appellees moved to consolidate these
appeals. We denied that request by order dated December 24, 1996. We
did, however, instruct the Clerk to list these three appeals before a
single
merits panel. We now believe that the most expeditious way to dispose
of these appeals is to consolidate them and dispose of them in one
opinion. Therefore, we have entered an order consolidating these three
appeals.
2. A neoplasm is "an abnormal tissue that grows by cellular proliferation
more rapidly than normal and continues to grow after the stimuli that
initiated the new growth cease. N[eoplasm]s show partial or complete
lack of structural organization and functional coordination with the
normal tissue, and usually form a distinct mass of tissue which may be
either benign or malignant." STEDMAN'S MEDICAL DICTIONARY 931 (26th ed.
1995).
7
testimony, the defendants moved for summary judgment
alleging that Trial Plaintiffs could not establish causation
absent the excluded expert testimony regarding dose.
The District Court agreed and held that, as a result of its
rulings under Daubert, Trial Plaintiffs were unable to
connect their neoplasms to the TMI accident. Accordingly,
the court granted summary judgment in favor of defendants
and against the Trial Plaintiffs. In re TMI Litigation
Consolidated Proceedings, 927 F. Supp. 834 (M.D. Pa.
1996). The District Court then reasoned that its Daubert
rulings would be binding on all of the other plaintiffs, i.e.,
the Non-Trial Plaintiffs, if there were evidentiary issues
common to all plaintiffs, Id. at 837. Therefore, the court
therefore extended its Trial Plaintiff summary judgment
decision to the Non-Trial Plaintiffs, and granted summary
judgment to the defendants on all of the claims of the
approximately 2,000 remaining TMI personal injury
plaintiffs. The propriety of that extension is the subject of
the second appeal.
The third and last appeal concerns the propriety of the
District Court's imposition of monetary sanctions against
certain of the plaintiffs' counsel for violations of pre-trial
discovery requirements and orders. The sanctioned counsel
have requested that the TMI personal injury litigation be
reassigned to another trial judge upon remand, if we
reverse the District Court in either or both of thefirst two
appeals.
For the reasons that follow, we will affirm the grant of
summary judgment to the defendants on the claims of the
Trial Plaintiffs (No. 96-7623). We will, however, reverse the
grant of summary judgment to the defendants on the
claims of the Non-Trial Plaintiffs (No. 96-7624), but we will
affirm the imposition of monetary sanctions and deny the
request for reassignment (No. 96-7625).
II. PROCEDURAL HISTORY3
_________________________________________________________________
3. The procedural history of this litigation is almost as complicated as
the scientific principles implicated by the Daubert challenges that we
discuss below. However, an understanding of the procedural history is
necessary to our discussion of the District Court's decision to grant
summary judgment against the Non-Trial Plaintiffs as well as the Trial
Plaintiffs.
8
On March 28, 1979, radioactive materials were released
into the environment as the result of an accident which
occurred at Unit 2 of the Three Mile Island nuclear power
generating station in Dauphin County ("TMI-2"). Three Mile
Island is a small island in the Susquehanna River,
approximately fifteen miles downstream from Harrisburg,
Pennsylvania. Following the accident, thousands of
personal injury and other non-personal injury claims 4 were
filed against the owners and operators of the nuclear facility.5
As noted, more than 2,000 plaintiffs filed claims for
personal injuries6 purportedly caused by exposure to the
radioactive materials released during the accident. Some of
these personal injury claims were originally filed in the
early 1980's in state and federal district courts in
Pennsylvania, New Jersey and Mississippi. The defendants
removed the state court actions to federal district courts in
Pennsylvania and New Jersey, under the authority of the
Price-Anderson Act, Pub.L. No. 85-256, 71 Stat. 576 (1957).7
_________________________________________________________________
4. The defendants have settled non-personal injury claims brought by
individuals, businesses and non-profit organizations within a twenty-five
mile radius of the TMI facility. See Stibitz v. General Public Utility
Corp.,
746 F.2d 993, 995 n.1 (3d Cir. 1984).
5. The defendants are General Public Utilities, Inc., Metropolitan Edison
Co., Jersey Central Power & Light Co., Pennsylvania Electric Co.,
Babcock & Wilcox, Co., McDermott Inc., Raytheon Constructors, Inc.,
and Burns & Roe Enterprises, Inc. They were, at the time of the
accident, either the owners and operators of the facility or companies
which had provided design, engineering and/or maintenance services to
the owners and operators or vendors of equipment or systems installed
in the facility. In re TMI Litigation Cases Consol. II, 940 F.2d 832, 836
(3d Cir. 1991).
6. The personal injury plaintiffs allege that they have developed
radiation
induced neoplasms because of their exposure to ionizing radiation
resulting from the TMI accident.
7. As we noted in In re TMI Litigation Cases Consolidated II, 940 F.2d
832, 837 n.2 (3d Cir. 1991), the Price-Anderson Act was enacted in 1957
as an amendment to the Atomic Energy Act of 1946, Pub.L. No. 79-585,
60 Stat. 755. The Atomic Energy Act was designed to establish an
industry to generate inexpensive electrical power and it envisioned
turning "atomic power into a source of energy" by turning "swords into
plowshares." Pacific Gas & Electric Co. v. State Energy Resources
9
After removal, the District Court for the Middle District of
Pennsylvania ordered, inter alia, that all pending TMI
personal injury cases in the Middle District be
"consolidated for pretrial proceedings only." App. 13097.
The District Court also ordered that the caption of every
subsequent personal injury pleading should be identified as
a personal injury claim. Id.
After we held that the Price-Anderson Act did not create
a cause of action as a federal tort and was not intended to
confer jurisdiction on federal district courts, see Stibitz v.
General Public Utilities Corp., 746 F.2d 993, 997 (3d Cir.
1984) and Kiick v. Metropolitan Edison Co., 784 F.2d 490,
_________________________________________________________________
Conservation & Development Commission, 461 U.S. 190, 193 (1983). The
Atomic Energy Act envisioned the nuclear energy industry as a
government monopoly; however, Congress ultimately decided to permit
the private sector to become involved. See Atomic Energy Act of 1954,
Pub.L. No. 830-703, 68 Stat. 919. The 1954 Act "grew out of Congress'
determination that the national interest would best be served if the
Government encouraged the private sector to become involved in the
development of atomic energy for peaceful purposes under a program of
federal regulation and licensing." Pacific Gas & Electric Co., 461 U.S. at
206-07. Nonetheless, the private sector was wary of the potential
exposure it faced in the event of a nuclear accident because of the
nature of nuclear energy. Thus, while assuring Congress that the risk of
a major nuclear accident was low, "spokesmen for the private sector
informed Congress that they would be forced to withdraw from the field
if their liability were not limited by appropriate legislation." Duke
Power
Co. v. Carolina Environmental Study Group, Inc., 438 U.S. 59, 64 (1978).
In response, Congress enacted the Price-Anderson Act to protect the
public and encourage the development of the atomic energy industry. In
re TMI, 67 F.3d 1103, 1107 (3d Cir. 1995)(citations and internal
quotations omitted), cert. denied, #6D6D 6D# U.S. ___, 116 S. Ct. 1034
(1996).
The Price-Anderson Act limited the "potential civil liability of nuclear
power plant operators and provided federal funds to help pay damages
caused by nuclear accidents." Id. The Act requires nuclear facilities
operators to purchase a specified amount of insurance from private
carriers and further provides for government indemnification above the
insurance amounts to an established aggregate limit on liability. In re
TMI Litigation Cases Consolidated II, 940 F.2d at 837 n.2. The Price-
Anderson Act has been amended three times, most recently in 1988; yet
the goal continues to be "to encourage private sector participation in the
beneficial uses of nuclear materials." Id. at 853.
10
493 (3d Cir. 1986), the state court actions were remanded,
and the federal court actions were transferred to the
appropriate state courts. The cases originally removed to
the Middle District of Pennsylvania, and those originally
filed in the Middle District, were either remanded or
transferred to the Court of Common Pleas of Dauphin
County. Thereafter, in 1985 and 1986, the bulk of the
personal injury claims which are the subject of this appeal
were filed in the state courts.8
On October 15, 1985, the Dauphin County Common
Pleas Court entered a case management order. In that
order, the Court of Common Pleas ordered that all cases be
consolidated for pretrial purposes, and also required that
all pleadings be captioned to identify which plaintiffs' group
they applied to. That is, all personal injury cases received
from the federal court were consolidated under the caption
"Cases Consolidated I" and the cases filed in state court
after our decision in Stibitz, were consolidated under the
caption "Cases Consolidated II."
In 1988, Congress enacted the Price-Anderson
Amendments Act of 1988, Pub.L. No. 100-408, 102 Stat.
1066. Those amendments to the Price-Anderson Act created
a federal cause of action for "public liability actions"9 and
provided that all such suits arise under the Price-Anderson
Act, 42 U.S.C. S 2014(h). The Act also provided for
consolidation of such actions, including those already filed,
_________________________________________________________________
8. However, personal injury cases continued to befiled after 1986. The
last case filed that is included in these appeals was Kline, et al. v.
General Public Utilities Corp. et al., No. 1:CV 96-451 (M.D. Pa.), and it
was filed on March 15, 1996. However, the latest personal injury case
filed is Tyler et al v. General Public Utilities Corp. et al., No. 1:CV
96-1028
(M.D. Pa.), and it was filed on June 7, 1996. Brief of Appellants in No.
96-7624, at 6 n.8. Apparently, Tyler is not included in this appeal.
9. The Price-Anderson Amendments Act defined a"public liability action"
as "any suit asserting public liability." 42 U.S.C. S 2014(h). "Public
liability" was defined as "any legal liability arising out of or resulting
from a nuclear incident or precautionary evacuation," except for certain
claims covered by workers' compensation, incurred in wartime or that
involve the licensed property where the nuclear incident occurs. 42
U.S.C. S 2104(w).
11
in one federal district court. 42 U.S.C. S 2210(n).10
Following enactment of that Act, the defendants removed all
the pending state actions to the United States District
Court for the Middle District of Pennsylvania.
Thereafter, the District Court for the Middle District of
Pennsylvania conducted a case management conference.
The personal injury cases known as "Cases Consolidated I"
and "Cases Consolidated II" which had been removed from
the Court of Common Pleas of Dauphin County were then
pending in the Middle District along with the companion
actions to the "Cases Consolidated II" which had been filed
by forty-two plaintiffs in Mississippi federal and state court
to take advantage of the more lenient Mississippi statute of
limitations.11 As a result of discussions during the
conference, the District Court entered an order which
required counsel to
meet to streamline the record with an eye toward
reducing the number of duplicative plaintiffs and suits,
assigning fewer case numbers for the various actions,
and deciding which cases needed new complaints to be
filed and which actions do not need answers filed.
Supp. App. at 78. In response to the order, counsel for
plaintiffs and defendants submitted a Stipulation which
provided, inter alia, that the pending TMI personal injury
cases referred to as "Cases Consolidated I" and "Cases
Consolidated II," together with the companion Mississippi
cases, would be consolidated under a single civil action
number "for administrative purposes" (emphasis added).
App. Vol. I, at 440. The Stipulation required that pleadings
dealing with issues common to all plaintiffs, or a legal issue
potentially applicable to all plaintiffs, bear the caption "In
re TMI Consolidated Proceedings" as well as the additional
_________________________________________________________________
10. We subsequently upheld the constitutionality of the retroactive
application of the federal jurisdiction provisions of the Price Anderson
Amendments Act. In re TMI Litigation Cases Consolidated II, 940 F.2d
832 (3d Cir. 1991), cert. denied, 503 U.S. 906 (1992).
11. Counsel for the forty-two plaintiffs concede that they filed suit in
Mississippi to take advantage of Mississippi's six-year statute of
limitations. Pennsylvania had a two-year statute. In re TMI, 67 F.3d
1103, 1105 n.3 (3d Cir. 1995), cert. denied, 516 U.S. 1154 (1996).
12
legend: "This document Relates to: All Plaintiffs." Id. The
Stipulation further required that pleadings dealing with
issues relating to one or more identified plaintiffs be
captioned "In Re TMI Consolidated Proceedings" and
identify lead counsel, the number of plaintiffs represented
by lead counsel and the number of plaintiffs to whom the
pleadings refer. Id. The Stipulation also expressly provided
that
3. Nothing in . . . this Stipulation . . . shal l be deemed
to constitute or affect any waiver of claim, defense or
issue, including but not limited to the statute of
limitations, choice of law and bifurcation or
consolidation for trial of claims, defenses, issues,
parties or proceedings.
Id. The Stipulation was subsequently approved by the
District Court.
Thereafter, in July of 1992, the defendants filed a motion
for summary judgment directed to the forty-two plaintiffs
who had sued in Mississippi state and federal courts.
Defendants alleged that those claims were untimely under
Section 11(b) of the Price-Anderson Amendments Act of
1988, codified at 42 U.S.C. S 2014(hh) (the choice of law
provisions), which provides that "the substantive rules of
decision in [any public liability action] shall be derived from
the law of the State in which the nuclear incident involved
occurs," and under Section 20(b) of that Act, (the effective
date provision), which provides that "the amendments made
by Section 11" of the Act "shall apply to nuclear incidents
occurring before, on, or after the date of the enactment of
this Act." 42 U.S.C. S 2014 note. The District Court ruled
that the Mississippi actions were time-barred, dismissed
the respective claims, and granted summary judgment in
favor of the defendants because it reasoned thatS 20(b),
read in conjunction with S 11, compelled the retroactive
application of Pennsylvania's two-year statute of limitation
to the plaintiffs' claims. In re TMI Cases Consolidated II, No.
88-14532, slip op. at 2-6 (M.D. Pa. Aug. 16, 1993).
On appeal, the Mississippi plaintiffs argued, inter alia,
that retroactive application of the choice of law provision
violated constitutional guarantees of due process. We
13
disagreed, and held that the retroactive application of the
choice of law provision was a rational exercise of Congress'
legislative power. Accordingly, we affirmed the District
Court's grant of summary judgment, and its dismissal of
the claims of the forty-two plaintiffs. In re TMI, 89 F.3d
1106 (3d Cir. 1996), cert. denied, ___ U.S. ___, 117 S. Ct.
739 (1997).
The defendants then moved for summary judgment
against all the TMI plaintiffs, claiming that they had not
breached the duty of care owed to the plaintiffs. The
District Court denied the motion. The court held that state
law on that issue was preempted, and that federal law
determines the standard of care. In re TMI Litigation Cases
Consolidated II, No. 88-1452, slip op. at 36 (M.D. Pa. Feb.
18, 1994). The court also held that federal regulations12 set
the standard of care, and that each plaintiff must prove his
or her individual exposure to radiation in order to establish
causation, but not to establish a breach of the duty of care.
Id. at 30-31. Upon defendants' motion, the District Court
certified the duty of care and causation questions for
interlocutory appeal.13 On that appeal, we held that
plaintiffs must establish that (1) the defendants released
radiation into the environment in excess of the levels
permitted by the federal regulations in effect in 1979; (2)
the plaintiffs were exposed to this radiation, although not
necessarily at the levels prohibited by those regulations; (3)
they have injuries; and (4) radiation was the cause of those
injuries. In re TMI, 67 F.3d 1103, 1119 (3d Cir. 1995), cert.
denied, 516 U.S. 1154 (1996).
After remand, the District Court conducted lengthy in
limine hearings in November of 1995 and in February and
_________________________________________________________________
12. See 10 C.F.R. SS 20.105, 20.106 (1979). These regulations were in
effect at the time of the TMI accident. In re TMI, 67 F.3d 1103, 1108 n.10
(3d Cir. 1996), cert. denied, 516 U.S. 1154 (1996). However, the
regulations have been significantly modified since then. Id. at 1111 n.19.
13. The District Court also certified a question concerning punitive
damages. We held in a separate opinion that punitive damages are
recoverable under the Price-Anderson Amendments Act of 1988 so long
as the money to pay such award does not come from the United States
Treasury. In re TMI, 67 F.3d 1119 (3d Cir. 1995), cert. denied, 517 U.S.
1163 (1996).
14
March of 1996, pursuant to Daubert v. Merrell Dow
Pharmaceuticals, Inc., 509 U.S. 579 (1993). Those hearings
all relate to plaintiffs' radiation dose and medical causation
expert witnesses. In January and April of 1996, the District
Court issued several opinions granting the majority of the
defendants' motions in limine. See In re TMI Cases
Consolidated II, 166 F.R.D. 8 (M.D. Pa. 1996) (granting in
part defendants' motions to exclude plaintiffs' medical
causation experts); Id., 922 F. Supp. 1038 (M.D. Pa.
1996)(same); Id., 922 F. Supp. 997 (M.D. Pa. 1996)
(granting in part defendants' motions to exclude plaintiffs'
radiation dose and medical causation experts); Id., 911 F.
Supp. 775 (M.D. Pa. 1996) (granting in part defendants'
motions to exclude plaintiffs' radiation dose experts); Id.,
910 F. Supp. 200 (M.D. Pa. 1996)(same). Although the
District Court was convinced that the majority of the
plaintiffs' expert witnesses were well-qualified, the court
nonetheless "found many of their opinions to be based on
methodologies that were scientifically unreliable and upon
data that a reasonable expert in the field would not rely
upon." In re TMI Litigation Consolidated Proceedings, 927 F.
Supp. 834, 839 (M.D. Pa. 1996). Accordingly, it ruled that
the much of the expert testimony was inadmissible under
Daubert, and its progeny. In April of 1996, the defendants
filed a motion for summary judgment. They based the
motion upon their contention that the District Court's
Daubert rulings left the plaintiff 's with no admissible
evidence as to the radiation dose levels resulting from the
TMI accident.
A subsidiary issue arose during the summary judgment
proceedings as to whom the summary judgment rulings
would apply. That dispute had its beginnings in June of
1993, when the District Court adopted the plaintiffs'
proposed case management plan which called for an"initial
mini-trial of the claims of twelve `typical' plaintiffs," half
chosen by plaintiffs and half chosen by defendants. App. at
168. Under the plaintiffs' plan (which was adopted by the
District Court), discovery would proceed immediately as to
all issues, including punitive damages and, upon
completion of discovery, "the twelve illustrative Plaintiffs
would then proceed to trial on all their claims." Id.
15
Ultimately, ten test plaintiffs,14 who have been diagnosed
with the listed illnesses, were chosen.15
When the defendants filed their motion for summary
judgment, they captioned it as pertaining to "All Plaintiffs"
and argued that the District Court's summary judgment
motion should be binding on all plaintiffs, not just the ten
trial or test case plaintiffs. The District Court agreed,
stating:
The court finds that resolution of the issue before it
turns on the grounds upon which the court ultimately
grants or denies summary judgment. Defendants are
correct that to the extent the ruling turns on broad
evidentiary issues common to all Plaintiffs, the ruling
will be binding on all Plaintiffs. Likewise, Plaintiffs are
correct that insofar as a ruling is based on a more
narrow, Plaintiff-specific inquiry, the ruling will apply
only to certain Plaintiffs. The court's reading of
documents related to the June 15, 1993 order, in
conjunction with subsequent case management orders
and evidentiary rulings, indicates that discovery and
evidentiary matters were to proceed on an "All
Plaintiffs" basis. A contrary intention or result would
obviate all benefits of having consolidated the many
separate actions. Each Plaintiff 's case depends upon
expert testimony to prove both exposure and medical
causation. Expert discovery is complete, and all expert
reports have been filed. Thus, to the extent that the
expert testimony of record fails to meet the test
_________________________________________________________________
14. As things developed, one of the defendants' test case selections
withdrew from the test group. Consequently, the District Court permitted
defendants to chose one of the parties originally selected by plaintiffs
to
be dismissed from the test case group. In re TMI Litigation Consolidated
Proceedings, 927 F. Supp. 834, 837 n.5 (M.D. Pa. 1996). Thus, the test
case group consisted of ten plaintiffs.
15. Those plaintiffs are: Paula Obercash, acute lymphocytic leukemia;
Gary Villella, chronic myelogenous leukemia; Leo Beam, chronic
myelogenous leukemia; Joseph Gaughan, thyroid cancer; Lori Dolan,
Hurthle cell carcinoma; Jolene Peterson, thyroid adenoma; Richard
Ward, osteogenic carcinoma of the right leg; Pearl Hickernell, breast
cancer; Ethelda Hilt, adenocarcinoma of the ovaries; and Kenneth Putt,
bladder cancer, acoustic neuroma.
16
Plaintiffs' evidentiary burden at this state of the
litigation, it will fail to meet the same burden as to
every Plaintiff. It would be an exercise in futility and a
waste of valuable resources to allow the many separate
actions consolidated under this caption to proceed if it
were clear that the cases could not withstand a motion
for summary judgment. Under such circumstances, the
court's summary judgment ruling will be applicable to
all Plaintiffs.
927 F. Supp. at 838.
The District Court ruled on the merits of the summary
judgment motion that the Trial Plaintiffs had failed to
present either direct or indirect evidence of the doses of
cancer inducing levels of radiation that they were exposed
to. Id. at 870. Accordingly, the court extended its grant of
summary judgment to all of the plaintiffs' cases.
Because the court finds the quantum of evidence on
the issue of dose to be insufficient, and because no
Plaintiff will be able to state a prima facie case without
adequate dose evidence, the instant ruling is binding
on all Plaintiffs.
Id. at 838. Accordingly, the court granted summary
judgment against all of the plaintiffs, both trial and
nontrial.
These appeals followed.
Appeal Number 96-7623 is the appeal of the ten Trial
Plaintiffs. They argue that the District Court improperly
excluded their proffered expert witnesses' testimony on
dose exposure, thereby erroneously subjecting them to
summary judgment. They do not argue that summary
judgment was improper given the District Court's Daubert
rulings. Thus, if we determine that the District Court's
exclusion of their dose exposure testimony was proper, we
must affirm the summary judgment for the defendants
against the trial plaintiffs. Consequently, the primary issue
for our determination in case number 96-7623 is the
propriety of the District Court's exclusion of testimony of
the dose exposure experts. If, however, we decide that the
court improperly excluded some or all of that evidence, we
17
must then decide whether the evidence that was admissible
is sufficient to create a genuine issue of material fact.
Appeal Number 96-7624 is the appeal of all of the TMI
personal injury plaintiffs except the ten Trial Plaintiffs.
Appellants there argue that the District Court improperly
extended its Trial Plaintiffs' summary judgment decision to
them. Appeal Number 96-7625 is the appeal of sanctioned
counsel for the majority of the plaintiffs. Counsel argue that
the District Court's imposition of monetary sanctions
against them for discovery violations was improper. Each
appeal is considered separately.
It is both impractical and unwise to begin our analysis of
the Daubert challenge to the scientific testimony without
first providing a brief discussion of the fundamental
principles of nuclear physics, nuclear engineering, the TMI-
2 accident, ionizing radiation, and the health effects of
ionizing radiation on the human body. These scientific
principles are at the center of the damage that plaintiffs
claim they suffered as a result of the TMI accident and the
District Court's Daubert rulings. Total immersion in the
complexities of these disciplines is neither required, nor
possible. Accordingly, we offer the following overview of the
controlling principles with an awareness that doing so
stretches the boundaries of our institutional competence,
and with a recognition of our need to borrow heavily from
others in academic disciplines far from the familiar confines
of the law.
III. SCIENTIFIC BACKGROUND
A. Overview of Relevant Principles of Nuclear Physics.
1. Atomic and Nuclear Structure.
Plaintiffs alleged that the accident at TMI resulted in a
release of radiation into the atmosphere that caused
changes to the atomic structure of their chromosomes and
resulted in the formation of neoplasms. Their allegations
thus implicate the structure of the atom -- the basic
18
building block of matter -- and the physics of orbiting
electrons.16
The atom consists of a small but massive central nucleus
surrounded by one or more orbital electrons. JOHN R.
LAMARSH, INTRODUCTION TO NUCLEAR ENGINEERING 8 (2d ed.
1983). Orbiting electrons are negatively charged, much
smaller in mass than the neutron, and their distances from
the nucleus are much larger than the radius of the
nucleus. DAVID BODANSKY, NUCLEAR ENERGY: PRINCIPLES, PRACTICES
AND PROSPECTS 346 (1996). The average distance from the
nucleus to the place where the outermost electron is found
provides an approximate measure of atomic size. This
distance is approximately the same for all atoms, except a
few of the lightest atoms, and is about 2 #46# 10 -8 centimeters.17
LAMARSH, at 11.
The nucleus has two constituent parts of approximately
equal mass -- the neutron and the proton.18 BODANSKY, at
346. Each is much more massive than the electron.
LAMARSH, at 6-7. Together, they are called nucleons.
BODANSKY, at 346. The neutron and proton differ in that the
neutron is neutral while the proton has a positive charge
equal in magnitude to the negative charge of the electron.
Id. An atom is neutral or "un-ionized" when the number of
positively charged protons equals the number of negatively
charged electrons. D. J. BENNET, ELEMENTS OF NUCLEAR POWER
1 (2d ed. 1981).19 "Nuclides" are very important to our
_________________________________________________________________
16. As we discuss below, radiation has the potential to fatally interfere
with one of more orbiting electrons.
17. It is difficult to define the exact size of an atom because the
orbiting
electrons may at times move very far from the nucleus but at other times
pass close to it. LAMARSH, at 7.
18. At one time, it was believed that neutrons and protons were the
fundamental particles of nature. However, it is now understood that they
are not the fundamental particles of nature, but themselves are
composed of more elementary particles called quarks. BODANSKY, at 346.
While knowledge of the existence of quarks and other elementary
particles is crucial to an understanding of the origins of the universe
and
of the ultimate structure of matter, their existence can be ignored in a
discussion of nuclear reactors, radioactivity and nuclear fission. Id.
19. Forces exist in an atom that are critical to atomic structure.
"Coulomb repulsion" is an electrostatic force, governed by Coulomb's
19
discussion. They are differing "species" of atoms whose
nuclei contain particular numbers of protons and neutrons.
LAMARSH, at 8. A nuclide is given the shorthand notation AZ
X, where X is the symbol for the chemical element, Z is the
atomic number and A is the atomic mass number. KNIEF, at
29. In general practice, however, the subscript Z is omitted
_________________________________________________________________
law, which exists between objects that carry the same electrical charge.
BODANSKY, at 349 n.3. The repulsion exists not only on a macroscopic
scale, but also on an atomic scale, BENNET, at 8, and, therefore, it
exists
between the protons in the nucleus because they are positively charged.
Consequently, Coulomb repulsion tends to disrupt (or burst) the
nucleus. Id. The fact that the nucleus of a stable atom is not disrupted
indicates that there is another force which overrides Coulomb repulsion,
and holds the nucleus together. Id. This force, known as the "strong" or
"nuclear force", exists between particles that are incredibly close to
each
other, within about 3 #46# 10-15 meters. The strong force acts with
approximately equal strength between two protons, two neutrons or a
proton and a neutron and binds the nucleus together, so long as the
separation between the particles is less than 3#46# 10-15 meter space in
which the strong force operates to cancel Coulomb repulsive. Id.
Coulomb repulsion is not the only electrostatic force defining atomic
structure. "Coulomb attraction" exists between oppositely charged
particles and this attractive force, operating between the electrically
positive protons and the electrically negative electrons, causes the
electron to orbit around the nucleus of the atom. RONALD ALLEN KNIEF,
NUCLEAR ENGINEERING: THEORY AND TECHNOLOGY OF COMMERCIAL
NUCLEAR POWER
29 (2d ed. 1992).
The chemical properties of an element are determined by the number
of electrons surrounding the nucleus in an un-ionized atom, and the
number of electrons orbiting the atom is equal to the number of protons
in the nucleus. BODANSKY, at 346. That is, a neutral atom has the same
number of protons and electrons, and the number of protons in the
nucleus, (given the symbol "Z"), is the atomic number of a particular
element and identifies it. KNIEF, at 29. Electrons are responsible for the
chemical behavior of the atoms and they identify the chemical elements.
LAMARSH. at 8. Consequently, each element is identified in terms of its
atomic number, Z. BODANSKY, at 346.
The number of neutrons in the nucleus is known as the "neutron
number" and is denoted by the letter "N". L AMARSH, at 8. The sum of the
number of neutrons and protons, i.e., nucleons, in the nucleus is called
the atomic mass number or "mass number", A. Thus, the formula: A =
Z + N. Id.
20
because once the element, X, is given, so is the atomic
number, Z. BODANSKY, at 346. Nuclides whose nuclei contain
the same number of protons, i.e., the same Z, but different
numbers of neutrons, i.e., different N and therefore a
different mass number, A, are called isotopes of the
element. BENNET, at 2. All elements have a number of
isotopes, Id., and they are virtually identical in their
chemical properties to the elements they are isotopes of.
BODANSKY, at 346. However, the masses and other
characteristics of their nuclei are different. BENNET, at 2. An
isotope of an element is given the same shorthand notation
as the nuclide. For example, naturally occurring oxygen,
whose chemical symbol is "O", consists of three isotopes, 16
O, 17O, and 18O. Id. Each has 8 protons and electrons, i.e.,
the same atomic number, Z, but they have 8, 9 and 10
neutrons respectively, i.e., different N (N = A - Z). The nuclei
of a given element can have the same mass number, A, but
have a different atomic number, Z, in which case it is called
an isobar. BODANSKY, at 346.
Though counterintuitive in the extreme, it is nevertheless
a fact of atomic structure that the mass of an atom is less
than the sum of the masses of its constituent parts. BENNET,
at 4; BODANSKY, at 350; KNIEF, at 29; LAMARSH, at 28. The
difference between the mass of the assembled atom and the
sum of the mass of the component atomic parts is known
as the "mass defect". KNIEF, at 29. However, mass is not
really lost in the assembly of an atom from its component
parts. Rather, the mass defect is converted into energy
when the nucleus is formed. Id. The conversion is explained
by the "principle of the equivalence of mass and energy in
which Einstein stated that mass and energy are different
forms of the same fundamental quantity."20 BENNET, at 4.
Therefore, in any reaction where there is a reduction in
mass, the decrease is accompanied by a release of energy.
Id. The energy associated with the mass defect is called
"binding energy" and it represents the total energy that
would be required to disassemble a nucleus into its
constituent neutrons and protons. BODANSKY, at 350.
_________________________________________________________________
20. The equivalence between mass and energy is expressed in Einstein's
famous equation, E = mc2, where E is energy, m is mass and c is the
speed of light. KNIEF, at 28.
21
Binding energy increases in a nucleus as the number of
particles in the nucleus increase. In other words, binding
energy increases with a corresponding increase in atomic
mass number. LAMARSH, at 28. However, the rate of increase
is not uniform. KNIEF, at 30.
The amount of binding energy in a nucleon is important
when determining possible sources of nuclear energy.
LAMARSH, at 28. A nuclei is stable or tightly bound when the
binding energy per nucleon is high. Accordingly, a relatively
large amount of energy must be supplied to break the
stable nuclei apart. Id. When a tightly bound nucleus is
broken apart and two nuclei of intermediate mass are
formed, a relatively large amount of energy is released.
BENNET, at 7. In contrast, nuclei with low binding energy per
nucleon are easily broken apart, and less energy is
released. LAMARSH, at 29.
The now familiar term, "nuclear fission" refers to the
process of causing a tightly bound nucleus to split into two
nuclei of intermediate mass. Id. The process proceeds in the
direction of increased binding energy per nucleon. B ENNET,
at 7. That is, the nuclei of intermediate mass created by the
fission process have greater binding energy than the
original nucleus. LAMARSH, at 30. When the nuclei of
intermediate mass have greater binding energy than the
original nucleus, energy is released during the formation of
the final nuclei. BODANSKY, at 351. This energy that is
released as a result of the fission process is the source of
energy in a nuclear reactor. LAMARSH, at 30. It is what we
commonly refer to as "nuclear energy".
Atoms can exist only in certain states or configurations,
with each state having its own specific energy. B ODANSKY, at
351. The different energy states correspond to different
electron orbits of different radii, LAMARSH, at 15, each with
an energy level equal to the sum of the kinetic and
potential energies of the electron in its orbit. B ODANSKY, at
351. The lowest state of energy is called the "ground state"
and it is the state in which the atom is normally found.
LAMARSH, at 15. However, an electron can, as a result of a
nuclear reaction, jump from its normal orbit to an orbit
that is farther from the nucleus. An increase in energy
corresponds to this "jump", and when an atom has more
22
energy than its ground state it is said to be in an"excited
state". BENNET, at 8. An atom can have a number of excited
states which correspond to the number of jumps the
electron has made. Id. The highest energy state occurs
when the electron is completely removed from the atom.
LAMARSH, at 15. The complete removal of an electron from an
atom is called "ionization" and the resulting atom is said to
be "ionized". Id.
The nucleons in the nuclei also move in orbits; however,
the orbits of nucleons are not as well defined, and are not
as well understood, as the orbits of electrons. L AMARSH, at
16. Like atoms, nuclei normally exist in the ground state.
BENNET, at 8; BODANSKY, at 352. However, nuclei can reach
excited states just as atoms can. BENNET, at 8; BODANSKY, at
352. The process is more complicated in nuclei than in
atoms because excitation of nuclei can result in several
nucleons being raised to excited levels simultaneously.
BENNET, at 8. Although it is not yet possible to account
theoretically for the exact energy levels of nuclei, as it is
possible to do so for atoms. BODANSKY, at 352. It is generally
true that the energies of the excited states and the energies
between states are much greater for nuclei than for atoms.
LAMARSH, at 16. The greater energy results from the greater
forces acting between nucleons. These forces are much
stronger that the forces acting between electrons and the
nucleus. Id.
With a few exceptions, excited states in either atoms or
nuclei exist for only a very short time, about 10 -14 seconds.
BENNET, at 9. Excess energy is quickly emitted and the
system, either atomic or nuclear, decays to states of lower
energy until it ultimately returns to its ground state.
LAMARSH, at 15. The process of going from one state to
another is called a "transition". Id. The energy lost in a
transition is usually carried off by electromagnetic
radiation,21 BENNET, at 9; BODANSKY, at 352, with the lost
_________________________________________________________________
21. Sometimes, however, the energy can be transferred to an electron
through a process known as "internal conversion" which leaves the
nuclide unchanged. At other times, an excited state can decay be
emitting a particle, such as a beta (b) particle or a neutron, thus
changing the atomic number of the nuclide. BODANSKY, at 352 n.8.
23
energy equal to the difference in the energies of the two
states.22 LAMARSH, at 15.
2. Radioactivity.
As suggested by our discussion thus far, nuclei are either
stable or unstable. For all practical purposes, stable nuclei
remain unchanged forever. Unstable nuclei decay
spontaneously into lighter nuclei pursuant to a time scale
that is unique for every element (the "half-life").23 The half-
life for a given element is defined as the time required for
one-half of a given sample of the element to "decay." If the
half-life is greater than some undefined fraction of a
second, the process of decay is called "radioactivity." Half-
lives vary from less than a second to many billions of years.
BODANSKY, at 353. Radioactivity is then, the process by
which unstable nuclei seek stability. KNIEF, at 31.
Frequently, the original unstable nucleus, called the
"parent nucleus", decays to another radioactive nucleus,
called the "daughter nucleus." LAMARSH, at 19. There may be
more than one radioactive daughter nuclei produced until
stability is reached. BENNET, at 11. This process of the
creation and subsequent decay of several daughter nuclei is
referred to as a "decay chain". LAMARSH , at 19.24
_________________________________________________________________
22. The electromagnetic radiation corresponding to an atomic or nuclear
transition is contained in a single discrete packet called a "photon".
BODANSKY, at 352. At one time, light and other forms of electromagnetic
radiation were described as waves. However, it is now known that
electromagnetic radiation behaves at times like a particle. Id. Thus, a
photon is both wave-like and particle-like in character. LAMARSH, at 7.
Visible light is associated with transitions involving the outer electrons
of atoms. X rays correspond to transitions involving the inner electrons
of atoms. Gamma (g) rays correspond to transitions from nuclei.
However, all are photons and there is no difference among them other
than their energy, with visible light having the lowest energy and gamma
(g) rays having the highest energy. In fact, there is really no need to
distinguish between photons from atomic transitions, i.e., x rays, and
photons from nuclear transitions, i.e., g rays. The names date from the
time of their discovery and are probably kept only as a reminder of their
origin. BODANSKY, at 352.
23. Sometimes designated as: "T1/2 ".
24. For example, there are three natural radioactive decay chains whose
parent isotopes have very long-half lives. The three are uranium 238 (T1/2
= 4.51 x 109 years), uranium 235 (T1/2 = 7.1 46 x 108 years), and thorium
232 (T1/2 = 1.41 x 1010 years), and their decay chains contain many
radioactive daughter isotopes leading eventually in each case to a stable
isotope of lead. BENNET, at 18-19.
24
The exact time at which any single nucleus will decay
cannot be determined. KNIEF, at 34. However, the average
behavior of a very large sample of radioactive material can
be described statistically. BENNET, at 15. For a given nuclide,
there is an average time, called the "decay constant", which
characterizes its rate of decay. Id. The decay constant is
defined as the probability per unit of time that a decay will
occur. KNIEF, at 34. The amount of radioactivity present
during a decay is referred to as "activity". F RED A. METTLER,
JR., M.D., AND ARTHUR C. UPTON, M.D., MEDICAL EFFECTS OF
IONIZING RADIATION 7 (2d ed. 1995) (hereinafter "MEDICAL
EFFECTS"). The activity of a given sample is the average
number of disintegrations per unit of time. For a large
sample, the activity is the product of the decay constant
and the number of atoms present. Id. The traditional unit
for measuring radioactivity is the curie (Ci), which is
defined as 3.7 #46# 1010 disintegrations per second.25
A radioactive nuclide is called a "radionuclide." KNIEF, at
32. During the process of radioactive decay, the nucleus
spontaneously emits an alpha (a) particle or a beta (b)
particle. BODANSKY, at 354. The emission of these particles is
often accompanied by the emission of one or more gamma
(g) rays. Id. An alpha (a) particle is a highly stable nucleus
of the isotope helium 4 (4He), consisting of two protons and
two neutrons. LAMARSH, at 20.26 Alpha (a) particles have a
double positive charge and are emitted in a discrete energy
spectrum. Id. They have a low level of energy and, therefore,
are only capable of penetrating matter a small distance.27
Decay by alpha particle emission is rather rare for
nuclides lighter than lead (Pb) which has an atomic number
(Z) of 82. BODANSKY, at 355. However, many of the naturally
_________________________________________________________________
25. The curie, is however, being superseded by a new measuring unit
called the "Becquerel" (Bq), which is defined as one disintegration per
second. BENNET, at 16.
26. Thus, the emission of an alpha (a) particle reduces the atomic
number (Z) of the unstable nuclei by two and the mass number (A) by
four. LAMARSH, at 20.
27. The most energetic of the alpha (a) particles are stopped after
passing through less than 10 centimeters of air or about 0.1 millimeters
of a material such as water. BODANSKY, at 355.
25
occurring radioactive elements with atomic numbers
between 84 (polonium) and 92 (uranium), i.e., the heavier
elements, decay by alpha particle emission. BENNET, at 13.
When these elements decay, the daughter product is closer
to the stability region than the parent. Id. In addition, the
daughter nucleus of these heavier elements is frequently
formed at an excited state of energy so that the excited
nucleus immediately decays further to its ground state by
the emission of gamma (g) radiation. Id. Thus, the decay of
a heavy radioactive isotope by alpha particle emission also
produces gamma (g) radiation. Id.
A beta (b) particle is an electron of nuclear, not orbital,
origin, KNIEF, at 33, but it is identical to the electrons that
orbit the nucleus. BODANSKY, at 355. Because it is an
electron, it has much less mass than an alpha particle. Id.
A neutron that is bound into the nucleus is not stable.
LAMARSH, at 7. During decay, a neutron in the nucleus is
transformed into a proton and an electron and it is this
electron which is emitted as a beta (b) particle. Id.; BENNET,
at 13.
Because beta (b) particle decay has the effect of
transforming one of the neutrons into a proton, the
resulting daughter nucleus has the same mass number (A)
as the parent, but its atomic number (Z) is greater by one.
Id. Moreover, the daughter nucleus may be formed in an
excited state, and decay to its ground state by the emission
of gamma (g) radiation. Id.
In most cases, beta particles are negatively charged and
are more properly designated as b- particles. Positive
electrons, called "positrons" or b+ particles, are emitted from
artificial radionuclides that are produced when positive
particles, such as protons or alpha (a) particles, combine
with a nucleus to form an unstable proton-rich nucleus.
BODANSKY, at 355. These beta particles are very rare in
naturally existing material. Id.
Beta (b) particles do not all have the same energy. BENNET,
at 13. The spectrum of the energy of these particles, ranges
from zero to a fixed maximum or "endpoint energy."
BODANSKY, at 357.28 However, the average energy of beta
_________________________________________________________________
28. The endpoint energy corresponds to the mass difference between the
parent atom and the residual product, as the principle of conservation of
mass plus energy demands. BODANSKY, at 357.
26
particles is about one-third, BENNET, at 13, to one-half,
BODANSKY, at 357, the endpoint energy. The remaining two-
thirds to one-half of maximum possible beta (b ) particle
energy is shared with another particle called the neutrino.29
BENNET, at 13; BODANSKY, at 357. A neutrino is one of
nature's more curious phenomena. It has no charge, and
virtually no mass. KNIEF, at 33. It was once thought to have
no mass; however, it is now believed that the neutrino may
have mass, albeit very small mass. BODANSKY, at 357;
Malcolm W. Browne, Los Alamos Experiment Shows
Neutrino Probably Has Mass, N.Y. Times, May 7, 1996.
Beta (b) particle decay usually occurs when a nuclide has
an excess of neutrons. BENNET, at 13; B ODANSKY, at 358. A
beta particle has greater penetrating ability than an alpha
particle, BENNET, at 21, with average penetration distances
ranging from 0.1 to 1 g/cm2, increasing with increasing
energy. BODANSKY, at 355. A neutrino, however, has great
penetrating power and can pass through very large
amounts of material without stopping. Id. at 358.
As discussed earlier, gamma (g) radiation is
electromagnetic radiation emitted in the form of photons by
nuclei in excited states of energy. Except as noted below,
gamma (g) emission is not a primary process of radioactive
decay. Instead, it follows alpha (a) particle or beta (b)
particle emission. Gamma (g) rays do not have mass or
charge, and they are therefore capable of much greater
penetration of matter than alpha (a) or beta (b) particles.30
BODANSKY, at 355.
Earlier, we noted that excited states in nuclei exist for a
very short time (about 10-14 seconds). Consequently, half-
lives for gamma (g) ray emission are typically very short.
BODANSKY, at 359. However, some nuclei have long-lived
_________________________________________________________________
29. Strictly speaking, the neutrino emitted in b#48# decay is an anti-
neutrino, while the neutrino itself is emitted in b+ decay. When the
distinction between them is not important, they are both referred to as
neutrinos. Again, strictly speaking, the b#48# and neutrino are called
particles, while the b+ and anti-neutrino are called anti-particles.
BODANSKY, at 357.
30. Gamma rays can penetrate to distances ranging from 5 to
20 g/cm2. BODANSKY, at 355.
27
excited states, called "isomeric states", with half-lives
ranging from a fraction of a second to many years. Id. In
fact, in some cases, the excited state is so long that the
nuclei appear semi-stable. LAMARSH, at 21. The decay to a
lower state of energy by gamma (g) ray emission in a nuclei
in an isomeric state is called an "isomeric transition". Id. In
such a case, gamma (g) ray emission appears to be the
primary radioactive process of, rather than incident to,
alpha (a) or beta (b) particle emission. Gamma ray emission
can, however, ultimately be traced back to either initiating
process.31 BODANSKY, at 359.
3. Ionizing Radiation.
The legal dispute before us is rooted in the damage that
purportedly resulted from defendants' release of ionizing
radiation into the atmosphere. There are a number of ways
in which an ion, or charged particle, can interact with an
atom. First, because it is charged, the particle exerts an
electrostatic or "Coulomb force" on the atom's electrons.
The exertion of Coulomb force has various effects upon an
atom. One or more of the electrons may move to an outer
orbit, leaving the atom in an excited state of energy or an
electron may be entirely ejected from the atom. The latter
event results in the formation of an ionized atom. L AMARSH,
at 88. When an atom is ionized, it is split into an ion pair.
The negatively charged electron of this pair is the negative
ion, and the atom minus its negatively charged electron is
the positive ion. BENNET, at 20. This process of ionization
produces ionizing radiation.32 MEDICAL EFFECTS, at 1.
The second possible result is that the charged particle
may penetrate the cloud of orbiting electrons and collide
with the nucleus. After collision, the charged particle is
scattered from the nucleus, and, since momentum and
_________________________________________________________________
31. There is an alternative to gamma (g) ray emission called "internal
conversion", in which the excitation energy is transferred to one of the
inner electrons of the atom. Typically, gamma (g ) ray radiation and
internal conversion are competing processes by which excited nuclei
reach the ground state. BODANSKY, at 359.
32. Ionizing radiation is only a small part of the electromagnetic
spectrum, which includes radio waves, radar, microwaves, ultraviolet
radiation and electric power. MEDICAL EFFECTS, at 1-2.
28
energy are conserved in the collision, the nucleus recoils. If
the charged particle has sufficient mass and energy, the
recoiling nucleus may be ejected from its own electron
cloud and itself become a charged particle. LAMARSH, at 88.
In addition, under certain circumstances, the charged
particle, particularly if it is an alpha (a) particle, may
undergo a nuclear reaction when it collides with the
nucleus. The charged particle may also be accelerated by
the electrostatic or Coulomb field of the electrons or the
nucleus and a photon may be emitted.33 Id.
Whichever of these alternative results occurs, a charged
particle is created. When a charged particle passes through
matter, it excites and ionizes atoms in its path. Id.
However, these charged particles lose energy by virtue of
the electrostatic forces created by their interaction with the
atoms that comprise the matter through which the charged
particles pass. KNIEF, at 70. The electrostatic forces acting
upon the charged particles are proportional to the product
of the charges and inversely proportional to the square of
the distance between them. Thus, the force decreases
rapidly with distance, but becomes negligible only at very
large distances. Id. At any given interval, a charged particle
experiences forces from a very large number of electrons.
The resulting energy losses are well defined for each
charged particle and each material medium. Id. The net
macroscopic effect of charged-particle interactions is
characterized by range and linear energy transfer ("LET").
Id. Range is the average distance traveled by a charged
particle before it completely stops. The LET is the amount
of energy deposited per unit of particle track, which gives
rise to the excitation and ionization. LAMARSH , at 89. The
range and the LET of a specific radiation contribute to the
effect they have on a material, with the range determining
the distance of penetration and the LET determining the
distribution of energy deposited along the path. K NIEF, at
70.
The LET is of particular significance to an inquiry into
the biological effects of radiation. Those effects depend
_________________________________________________________________
33. This latter kind of radiation that is emitted when a charged particle
becomes accelerated, is called "bremsstrahlung". Id. LAMARSH, at 88.
29
upon the extent to which energy is deposited by radiation
as excitation and ionization within a given biological
system. LAMARSH, at 89. The LET increases with the mass
and charge of a moving particle. Id. Consequently, heavy
charged particles, such as alpha (a) particles, are referred
to as high LET radiation. Id.
Charged particles, are referred to as "directly ionizing
radiation" because they are directly responsible for
producing ionization. LAMARSH, at 88; B ENNET, at 20;
BODANSKY, at 354. Uncharged particles, such as gamma (g)
rays, lead to excitation and ionization only after interacting
with matter and producing a charged particle. Accordingly,
uncharged particles are referred to as "indirectly ionizing
radiation." LAMARSH, at 88.
While gamma (g) rays can interact with matter in a
variety of ways, there are, for purposes of our analysis,
three important types of interaction between gamma (g)
radiation and matter -- the "photoelectric effect", "pair
production" and "Compton scattering." BENNET, at 21.
Because very short-range forces govern electromagnetic
mechanisms, a gamma (g) ray must essentially"hit" an
electron for an interaction to occur. KNIEF, at 71. In the
photoelectric effect, which is the most important process at
low gamma (g) ray energies, BENNET, at 199, the gamma (g)
ray interacts with the entire atom, the gamma (g ) ray
disappears and one of the atomic electrons is ejected from
the atom. LAMARSH, at 79. As a result, the energy of the
gamma (g) ray or photon is converted completely to kinetic
energy of an orbital electron. KNIEF, at 71. If the gamma (g)
ray ejects an inner electron, the resulting hole in the
electron cloud is filled by one of the outer electrons.
LAMARSH, at 16, 79. This transition is accompanied either by
the emission of an X ray or by the ejection of another
electron.
Pair production occurs only for high-energy gamma (g)
rays and only in the vicinity of a heavy nucleus. Id. at 80;
BENNET, at 21. The gamma (g) ray is annihilated; and an
electron pair -- a positron and a negatron -- is created.
LAMARSH, at 80. When this occurs the energy of the gamma
(g) ray converted to mass, and kinetic energy of the electron
pair. KNIEF, at 71. Once they are formed, the positron and
30
negatron move around and ultimately lose energy as a
result of collisions with atoms in the surrounding matter.
LAMARSH, at 80. After the positron has slowed to very low
energies, it combines with a negatron, the two disappear
and two photons are produced. LAMARSH, at 80-81. The
photons that are produced are called "annihilation
radiation." Id. at 7.
Compton scattering occurs when the gamma (g) ray
strikes an electron and is scattered. The electron that is
struck in this process recoils and acquires some of the
kinetic energy of the gamma (g) ray, Id. at 81, thus reducing
the energy level of the reaction. KNIEF, at 71. Since the
gamma (g) ray does not disappear as it does during the
photoelectric effect, and is not annihilated as it is in pair
production, the Compton-scattered gamma (g) ray is free to
interact again. LAMARSH, at 82.
Although uncharged particles cause indirect ionizing
radiation, it is nonetheless possible to refer to the LET of
uncharged particles. However, because they have a
relatively low rate of energy loss when compared to the rate
of energy loss of charged particles, gamma rays (g) are
referred to as "low LET radiation." LAMARSH, at 89. The
distinction between high LET radiation and low LET
radiation has important biological consequences. Id. Given
the same dose of radiation, biological damage from high
LET radiation is much greater than damage from low LET
radiation. Id. at 402.
4. Radiation Quantities and Units.
Radiation can be measured by counting the number of
ionized particles it produces as it passes through air.
INTERNATIONAL ADVISORY COMMITTEE, THE INTERNATIONAL CHERNOBYL
PROJECT, TECHNICAL REPORT 20 (1991) (hereinafter "CHERNOBYL
"). Originally, the amount of radiation exposure for X- and
gamma (g) radiations was measured in units of the roentgen
(R), KNIEF, at 72, which is defined as the number of
electrical charges produced in a unit mass of air.
CHERNOBYL, at 20.34 Alternatively, a roentgen can be defined
_________________________________________________________________
34. One roentgen is that quantity of X or gamma (g) radiation which
produces a total charge of one electrostatic unit of either sign in one
cubic centimeter of air at 1 atmosphere at 0o Celsius. LAMARSH, at 400.
31
in terms of the amount of energy released in the production
of ions with a total charge of one electrostatic unit of either
sign. BENNET, at 197.35 Thus, the roentgen is a unit of
exposure in air and not a unit of radiation dose to body
tissue. Moreover, it is not applicable to higher energy X-
rays or to particulate radiations. MEDICAL EFFECTS, at 8.
Consequently, the roentgen is not very useful for comparing
the effects of various radiations on biological systems,
particularly the human body. KNIEF, at 73.
When radiation penetrates material, its energy is
absorbed and released by the constituent atoms of the
material that is penetrated. CHERNOBYL, at 20. The absorbed
energy per unit mass of material is termed the "absorbed
dose." Id.36 Two units are used to measure absorbed dose of
any type of radiation. The original unit of absorbed dose is
the "rad" (radiation absorbed dose) and is defined as 100
ergs of energy per gram of material. LAMARSH, at 401. The
new unit of absorbed dose under the Systeme International
d'Unites ("SI")37 is the gray ("Gy"), which is defined as one
joule of energy absorbed per kilogram of matter. CHERNOBYL,
at 20. Because a rad and a gray are defined in terms of
energy, it is possible to equate rads with grays, with one
gray being equivalent to 100 rads (1Gy = 100 rads), or one
_________________________________________________________________
35. Under this definition, a roentgen is equivalent to depositing about 88
"ergs" in 1 gram of air. KNIEF, at 73. An "erg" is a unit of energy and
one
roentgen under the alternative energy description is energy sufficient to
move the point of a sharpened pencil about 1.5 millimeters across a
piece of paper. Id.
36. Heavy, highly charged particles, such as alpha (a) particles, lose
energy rapidly over distance and, therefore, do not penetrate matter
deeply. For example, alpha (a) particles do not penetrate the layer of
dead cells on the surface of the skin. CHERNOBYL, at 19. Beta (b)
particles,
because of their smaller charge and much smaller mass, are much more
penetrating, BENNET, at 20, and may penetrate up to several centimeters
into the body. CHERNOBYL, at 19. X- and gamma (g) rays have much
greater penetrating power than either alpha (a ) or beta (b) particles,
BENNET, at 20, and they are therefore used for medical diagnostic
purposes. CHERNOBYL, at 19.
37. The SI is a modernized metric system which is becoming the
standard for expressing scientific and technical data. However, much
scientific and technical literature still contains the older, more
customary units. KNIEF, at 671
32
rad equivalent to 10 milligrays (1 rad = 10 mGy). 38 MEDICAL
EFFECTS, at 8.
However, the absorbed dose is not the only factor to be
considered in estimating radiation effects on the human
body. The effects also depend on the LET of the radiation.
KNIEF, at 73; LAMARSH, at 402. Even when the amounts of
energy absorbed are the same, alpha (a) particles are more
damaging to human tissue than gamma (g) radiation
because of the higher LET of alpha (a) radiation. BENNET, at
198. The fact that different types of radiation have different
biological effects for the same absorbed dose is described in
terms of the relative biological effectiveness ("RBE") of the
radiation. LAMARSH, at 402. The RBE depends on the dose,
the dose rate, the physiological condition of the subject,
and various other factors. The RBE is determined through
experimentation. KNIEF, at 73; LAMARSH, at 403. Accordingly,
there is no one RBE for a given type of radiation, and the
unit is used almost exclusively in radiobiology. L AMARSH, at
403.
RBE is, however, used to approximate the quality factor
("Q") of radiation, which is usually the upper limit of RBE
for a specific type of radiation. Id.; K NIEF, at 73. For
example, X-rays and gamma (g) rays have a Q of 1, beta (b)
particles have a Q of 1 to 1.7, depending on their energy,
and alpha (a) particles have a Q of 20. C HERNOBYL, at 20;
KNIEF, at 74. To estimate the effect of a given type of
radiation on body tissue, it is necessary to determine the
dose equivalent. The dose equivalent is arrived at by
multiplying the absorbed dose by the quality factor of the
radiation. The original unit of dose equivalence is the "rem"
(roentgen equivalent man) and is the product of the
absorbed dose in rad and the Q of the particular radiation.
LAMARSH, at 404. Thus, if the radiation is gamma (g)
_________________________________________________________________
38. There is another type of unit which is sometimes used for very high
energy radiation and for particulate radiation. That unit is the "kerma"
(kinetic energy released inmatter) and it is used because it includes not
only the energy deposited in the local area but also the additional energy
deposited as a result of bremsstrahlung. For most purposes, the rad and
the kerma are interchangeable. A major exception is the calculation of
doses for atomic bomb survivors. There, the kerma was higher than the
rad. MEDICAL EFFECTS, at 8.
33
radiation, then an absorbed dose of 1 rad produces a dose
equivalent of 1 rem, and if the radiation is alpha (a) particle
radiation, then an absorbed dose of 1 rad produces a dose
equivalent of 20 rem. The new SI unit of dose equivalence
is the sievert (Sv) and is the product of the absorbed dose
in gray (Gy) and the Q of the radiation. BENNET , at 198.
Since one gray equals 100 rads (1 Gy = 100 rads), then one
sievert equals 100 rem (1 Sv = 100 rem), LAMARSH , at 404,
or one rem equals 10 millisieverts (1 rem = 10 mSv).
MEDICAL EFFECTS, at 8.
The effect of a given dose equivalent varies depending on
the tissue or organ exposed to the radiation. CHERNOBYL, at
20. For example, a given dose of radiation to the hand may
have a different and far less serious effect than the same
dose delivered to a blood-forming organ. Similarly, the
biological effect of a given dose of radiation to a blood-
forming organ will be different from a like exposure to
reproductive tissue. LAMARSH, at 404. However, equal dose
equivalents from different sources of radiation, if delivered
to the same point in the body, should have approximately
the same biological effect. Id. at 403.
The "effective dose" (E), is a unit that is derived from the
equivalent dose in an attempt to indicate the combined
effect of different doses of radiation upon several different
tissues or body parts. CHERNOBYL, at 20. The effective dose
is the product of the equivalent dose in a tissue or organ (T)
multiplied by a factor called the "tissue weighing factor"
(WT), which represents the contribution of that tissue or
organ to the total harm resulting from uniform radiation
exposure to the whole body. Id.39
Each of the preceding units, (i.e., absorbed dose,
equivalent dose and effective dose) relate to the radiation
exposure of an individual. There are, however, units of
exposure for groups of people. They are arrived at by
_________________________________________________________________
39. By way of illustration, the tissue weighing factor for the gonads is
0.20, the tissue weighing factor for red bone marrow is 0.12, and the
tissue weighing factor for the skin and bone surface is 0.01. CHERNOBYL,
at 20. The effective dose is the weighted sum of the equivalent doses in
all the tissues and organs of the body and is a measure of the total risk
from any combination of radiations affecting any organs of the body. Id.
34
multiplying the average dose to the exposed group by the
number of people in the group. CHERNOBYL, at 20-21. The
units are the "collective equivalent dose," which relates to a
specified tissue or organ, and the "collective effective dose,"
which relates to all the people exposed to the radiation. Id.
Both units are expressed in terms of man-rems or man-
sieverts. LAMARSH, at 405, and they represent the total
consequences of the exposure of a population or group.
CHERNOBYL, at 21.
5. Health Effects of Ionizing Radiation.
Soon after the discovery of x-rays and natural
radioactivity, clinical evidence suggested that ionizing
radiation is harmful to human tissue. ANNALS OF THE
INTERNATIONAL COMMISSION ON RADIOLOGICAL PROTECTION, ICRP
PUBLICATION 60, 1990 RECOMMENDATIONS OF THE INTERNATIONAL
COMMISSION ON RADIOLOGICAL P ROTECTION 94 (1990)(hereinafter
"ICRP 60"). The initial evidence was mainly noted from the
effect of ionizing radiation on human skin.40 Id. at 92.
Later, scientists realized that exposing germinal tissue in
plants and animals to ionizing radiation produced effects
not only in the plants and animals that were actually
exposed, but also in subsequent generations of the exposed
plants and animals. Id. Scientific studies and investigations
over the last century, have now given us a wealth of
information about the effects of radiation on humans.41
These studies include extensive in vitro and in vivo animal
experiments, Id., the comprehensive epidemiological studies
of the survivors of the atomic bombings of Hiroshima and
Nagasaki, studies of x-rayed tuberculosis patients; and
studies of people exposed to ionizing radiation during
treatment for ankylosing spondylitis, cervical cancer and
tinea capitis. NATIONAL RESEARCH COUNCIL, COMMITTEE ON THE
BIOLOGICAL EFFECTS OF IONIZING RADIATIONS, HEALTH EFFECTS OF
EXPOSURE TO LOW LEVELSOF IONIZING RADIATION 2(1990)
_________________________________________________________________
40. Ionizing radiation causes nonmalignant skin damage called erythema
or reddening of the skin. LAMARSH, at 409.
41. One commentator has noted that "more than 80,000 studies have
been reported in the scientific literature, indicating that radiation
effects
have been studied far more thoroughly than other environmental
impacts." KNIEF, at 77.
35
(hereinafter "BEIR V"). These studies have allowed science
to "narrow the range of uncertainties in human
radiobiology." CHERNOBYL, at 37.
As noted earlier, an atom is ionized when an electron is
ejected from its orbit and expelled from the atom. As
ionizing radiation passes through human tissue, it can
transfer its energy along the tracks of the charged particles
to the atoms and molecules of the tissue and ionize the
atoms and molecules of that tissue. CHERNOBYL , at 37.
There are two mechanisms by which ionizing radiation
can alter human cells. LAMARSH, at 409. First, the ionization
can directly alter biological structures by the disruption or
breakage of molecules. Id.; ICRP 60, at 96. Second,
biological structures can be altered indirectly by chemical
changes set in motion by the transfers of energy to the
medium as the ions pass through the molecular structure
of human tissue. ICRP 60, at 96. Most of this energy
transfer takes place in the water of our cells simply because
water is the major component of the human body. 42 MEDICAL
EFFECTS, at 13; BEIR V, at 12. When an ionizing particle
passes through a water molecule, it may ionize it and
produce an ionized water molecule, H2O+, and an electron.
The electron can be trapped and produce a hydrated
electron, eaq. BEIR V, at 12. However, the ionized water
molecule, H2O+, reacts with another water molecule to
produce a free radical called the "hydroxyl radical, OH." Id.43
This particular free-radical is very reactive because it has
an unpaired electron and seeks to pair its electron in order
to stabilize itself. BEIR V, at 13. At high initial
concentrations, back reactions occur which produce
hydrogen molecules, hydrogen peroxide and water. Id.
However, the water molecule is not always ionized in this
process. It can also simply become excited and break up
into the hydrogen radical, H., and the hydroxyl radical,
OH.. Id.
The result of this chemical process is the formation of the
_________________________________________________________________
42. Human cells are made up of 70% water. MEDICAL EFFECTS, at 13.
43. A free radical is an atom or molecule that has a single unpaired
electron. MEDICAL EFFECTS, at 13.
36
three highly reactive species: the hydrated or aqueous
electron, eaq, the hydroxyl radical, OH., and the hydrogen
radical, H.. Id. All three are highly reactive and can damage
the molecular structure of human cells. Id. Free radicals
are produced almost immediately after an energy transfer.44
They move rapidly in the medium, can travel some distance
from the site of the original event that creates them, and
they can cause chemical changes in the medium. Id.
However, even though free radicals are highly reactive and
potentially very dangerous to the structure of cells in
human tissue most recombine to form oxygen and water in
about 10-5 seconds without causing any injury. MEDICAL
EFFECTS, at 13.
Ionization radiation can damage cells whether the
radiation results directly from the electrons set in motion or
indirectly by the chemical production of free radicals.
CHERNOBYL, at 37. A great deal of evidence suggests that
DNA is the principal target in an irradiated cell, and is the
most critical site for lethal damage. ICRP 60, at 96; BEIR V,
at 13. DNA is believed to be the "critical cellular component
injured," as low doses of radiation. MEDICAL EFFECTS, at 16.
The random character of energy absorption events caused
by ionizing radiation can damage vital parts of DNA in
several ways including single-strand or double-strand
breaks in the DNA molecule. ICRP, at 96. However, it has
been postulated that the majority of DNA strand breaks are
not due to the direct effects of ionizing radiation, but rather
are caused by the hydroxyl radical. MEDICAL EFFECTS, at 14;
see also BEIR V, at 14. Irradiation can also cause a
number of recombinational changes to cells. ICRP 60, at
96.
Not all irradiation-caused damage to DNA is harmful.
Cells have evolved complex repair systems and when a
single-strand break occurs, it is quite possible that the site
of the damage can be identified and the break very quickly
repaired. Id.; CHERNOBYL, at 38. In such a case, the DNA
structure is returned to its original form, and there is no
long term cellular consequence. ICRP 60, at 96. For
example, if ionizing radiation affects a single protein within
_________________________________________________________________
44. A They are created in about 10-12 seconds. BEIR V, at 13.
37
a cell, the cell can simply produce a new protein and there
is no functional change. CHERNOBYL at 37. Alternatively, the
repair may not return to DNA to its original form, but DNA
integrity may be retained. Id.
While it is possible for double strand breaks in DNA to be
repaired, the consequences of a double strand break are
very serious. ICRP 60, at 96. Chromosomal aberrations are
a result of DNA that is damaged by irradiation. These
aberrations can be measured quantitatively as a function of
absorbed dose. Id. at 97. The outcome could be cell
reproductive death, misrepair reflected in a mutation or
extensive gene deletion. Id. at 96.
If cellular damage is not repaired, it may prevent the cell
from surviving or reproducing, or it may result in a viable
but modified cell. CHERNOBYL, at 38. The two outcomes have
severe, and different, implications for the human body,
leading to either "deterministic" or "stochastic" effects. Id.
Deterministic effects are entirely predictable and their
severity is an inevitable consequence of a given dose.
LAMARSH, at 409. Stochastic effects are those that occur at
random, i.e., they are of an aleatory or statistical nature.
CHERNOBYL, at 38. Thus, stochastic effects are those whose
probability of occurrence, as opposed to severity, is
determined by dose. LAMARSH, at 409.
i. Deterministic Effects.
Deterministic effects result when an organism can no
longer compensate for the extent of dead cells by
proliferating viable cells. ICRP 60, at 99. Cell death or cell
killing is the main process involved in deterministic effects.
Id. Unless the dose is very high, most types of cells are not
immediately killed, but continue to function until they
attempt to divide. Id. The attempt to divide will fail,
probably because of severe chromosome damage, and the
cell will die.45 Id. Cell death usually becomes apparent
within a few hours or days after irradiation. Id. at 97.
_________________________________________________________________
45. Although individual cell death in a tissue is stochastic, the total
effect of the death of a high number of cells in a tissue is
deterministic.
ICRP 60, at 99; CHERNOBYL, at 38.
38
Cell death is not always life threatening because most
body organs and tissues are unaffected by the loss of even
a substantial number of cells. CHERNOBYL, at 38. It is only
when a tissue or organ absorbs a certain threshold dose
high enough to kill or impair the reproduction of a
significant fraction of vital cells within the tissue or organ
that there is a clinically detectable impairment of function.
ICRP 60, at 99. If enough cells are killed, the function of
the tissue or organ is impaired. Id. at 97. In extreme cases
the organism dies. Id. The severity of the effect is dependent
on the dose. Id. Thus, the likelihood of a deterministic effect
is zero at a dose lower than some threshold, but the
likelihood increases to certainty above such a threshold
dose, with the severity of the harm increasing with dose.
CHERNOBYL, at 38-39.
Cells that divide rapidly are very sensitive to radiation
and it is in these cells that the damage from radiation
appears to be the greatest. KNIEF, at 75. Such cells include
lymphocytes, immature bone marrow cells and intestinal
epithelium. Slightly less sensitive cells include those of the
lens of the eye and the linings of the stomach, esophagus,
mouth and skin. Cells of intermediate sensitivity include
those of the liver, kidneys, lungs, thyroid andfibrous
tissue. Cells that divide slowly or not at all are the least
sensitive to radiation. CHERNOBYL, at 39. These include
mature red blood cells, muscle connective tissue as well as
bone, cartilage and nervous tissue. Id. Thus, if a person
receives a whole body absorbed dose of 1 Gy or 100 rad,
generally only those cells with very high sensitivity would
be killed. However, as the whole body absorbed dose is
increased, additional cells and organs could die and
thereby alter the person's clinical presentation. Id.
Obviously, if exposure to ionizing radiation results in
damage to vital organs or tissues, it may well be fatal. Id.
The likelihood of a deterministic effect is practically zero
for absorbed doses below 1 Gy or 100 rad. Above that
absorbed dose level, deterministic effects occur. Some
examples of deterministic effects are erythema, bone
39
marrow depression, radiation cataracts, sterility, and acute
radiation syndrome. Id.; MEDICAL EFFECTS, at 280.46
Clinically significant bone marrow depression has a
threshold for acute absorbed doses of about 0.5 Gy or 50
rad and for protracted exposure over many years of about
0.4 Gy or 40 rad per year. CHERNOBYL, at 39. Absent
appropriate medical care, bone marrow depression will
result in half of the people in a heterogeneous population
who are acutely exposed to a dose of about 3 to 5 Gy or
300 to 500 rad.47 Id. The threshold for opacities significant
enough to cause vision impairment (which occurs after
some delay) appears to be in the range of 2 to 10 Gy or 200
to 1000 rad for an acute exposure to x-rays or gamma (g)
rays. The threshold for chronic exposure over many years
is thought to be about 0.15 Gy or 15 rad per year. Id.
Death is almost certainly the deterministic effect for an
individual exposed to a whole body dose of about 6 Gy or
600 rad or higher over a short period. Id. A 3 Gy or 300 rad
dose would be lethal for half of an irradiated population
who receive little or no medical care, the so called"median
lethal dose". Id. However, it has been postulated that for
people in good health who receive very intensive medical
treatment, the median lethal dose may be from 5 Gy or 500
rad to as high as 9 Gy or 900 rad. Id.
_________________________________________________________________
46. The threshold for temporary sterility in men for a single absorbed
dose to the testis is about 0.15 Gy or 15 rad and the threshold under
conditions of prolonged exposure is about 0.4 Gy or 40 rad. CHERNOBYL,
at 39. The threshold for permanent sterility is 3.5 to 6 Gy or 350 to 600
rad for acute exposure and 2 Gy or 200 rad for prolonged exposure. Id.
The threshold for permanent sterility in women is an acute absorbed
dose between 2.5 to 6 Gy or 250 to 600 rad or a protracted dose over
many years of about 0.22 Gy or 22 rad. Id.
47. The estimate of the number of people who would die within a certain
number of days without medical attention following a significant whole
body absorbed dose is called the "lethal dose estimate" and, in this
example, would be expressed as "LD50/60", meaning "Lethal Dose for
50% of the population within 60 days without medical attention." KNIEF,
at 76.
40
ii. Stochastic Effects.
Stochastic effects are those which result when an
irradiated cell is modified rather than killed. C HERNOBYL, at
39. Even at very low doses it is possible that ionizing
radiation may deposit sufficient energy into a cell to modify
it. ICRP 60, at 98. Thus, there is a finite possibility for the
occurrence of a stochastic event even at very small doses.
Id. Consequently, it is assumed that there is no threshold
for the initiation of a stochastic event. Id. , at 98; MEDICAL
EFFECTS, at 73. Put another way, it is believed that
stochastic effects can occur even at the lowest doses and,
therefore, the possibility of a stochastic effect has to be
taken into account at all doses. ICRP 60, at 67. The
probability that cancer will result from radiation increases
proportionally with dose. ICRP 60, at 69. CHERNOBYL, at 40.
However, it is currently believed that there is no threshold
dose below which the probability of cancer induction is
zero. ICRP 60, at 69; CHERNOBYL, at 40. It is presumed that
any transformed cell can become cancerous and become a
malignant tumor. CHERNOBYL, at 40.
There are two generally recognized types of stochastic
events. The first can occur in somatic cells and may result
in the induction of cancer in the exposed person. The
second can occur in cells of the germinal tissue and may
result in hereditary disorders in the descendants of the
irradiated.48 CHERNOBYL, at 39-40; ICRP 60, at 69, 106-07.
However, even though hereditary stochastic effects have
been demonstrated on highly irradiated mice, CHERNOBYL, at
42, hereditary stochastic effects have not yet been clearly
demonstrated in humans. BEIR V, at 4. Thus, any such
effects are based on extrapolation from mice to humans.49
_________________________________________________________________
48. "There are approximately 4 #46# 1013 cells in the average adult
person.
. . . [and they] are divided into two broad classes: somatic cells and
germ
cells. Almost all of the cells in the body are somatic cells. These are
the
cells that make up the organs, tissues, and other body structures. The
germ cells, which are also called "gametes", function only in
reproduction." LAMARSH, at 406.
49. Such extrapolation has led to the estimate that at least 1 Gy or 100
rad of low-dose, low LET radiation is necessary to have any hereditary
stochastic effect on humans. BEIR V, at 4.
41
Genetic studies of the almost 15,000 children of the
survivors of the atomic bombing in Japan have not yielded
evidence of a statistically significant increase in severe
hereditary effects. CHERNOBYL, at 42; BEIR V, at 4. Of
course, the difficulties encountered in studying the
probability of hereditary effects are formidable and include
the need to monitor very large numbers of people in
irradiated and controlled populations. The difficulty is
increased because hereditary effects caused by radiation
may be indistinguishable from hereditary disease due to
other causes. CHERNOBYL, at 42.
It is cancer induction -- the first stochastic event -- that
it as issue here. The cell modification caused by ionizing
radiation is presumably the result of specific molecular
DNA changes by a process known as "neoplastic
transformation." It is assumed that there is no threshold for
the induction of the molecular changes at the DNA site.
ICRP 60, at 97, 107. The potential for unlimited cellular
proliferation characteristically results from molecular
changes. Id., at 107. Nevertheless, this change alone does
not result in a malignant transformation because other
changes occur in a malignant transformation. Id.
Carcinogenesis is currently believed to be a multistep
process requiring two or more intracellular events to
transform a normal cell into a cancer cell. BEIR V, at 135.
The changes that occur are believed to proceed
sequentially. ICRP 60, at 97. The initial events in the
production of a cell or cells with the potential to develop
into a cancer are known as "initiation". Id. The initiated cell
or cells must undergo further changes, usually after a long
time and possibly after stimulation by a promoting
substance or catalyst, before becoming a cell with
malignant potential. Id. Thereafter, the division and
multiplication of such cells gives rise to an occult tumor in
the "progression" stage. Id. at 97-98. "Progression" refers to
the proliferation of a subpopulation of cells within a tumor.
BEIR V, at 137. This subpopulation expands and overgrows
the less aggressive cells. Id. The carcinogenic process,
includes the growth of a primary cancer to a detectable size
(e. g., about 1 cm in diameter and containing billions of
cells). In humans it can take many years for such a tumor
to spread to other tissues. ICRP 60, at 98.
42
The period between exposure to radiation and possible
detection of a resulting cancer is called the "latency period".
Id. at 107. By way of example, the median latency period
for induced leukemia may be about 8 years. The latency
period for many induced solid tumors, such as tumors of
the breast or lung. Id. The "minimum latency period" is the
shortest time in which a specified radiation-induced tumor
is believed to occur after exposure. Id. It is about two years
for acute myeloid leukemia, and between 5 and 10 years for
other types of cancers. Id.
Significantly, the severity of a cancer does not depend on
the level of the dose that triggered it. ICRP 60, at 60;
CHERNOBYL, at 40. The mathematical model used to describe
radiation induced cancer is the "linear risk model". BEIR V,
at 4; CHERNOBYL, at 40. It is expressed as y = ax, where y is
the incidence of excess cancer, a is a constant, and x is the
dose. MEDICAL EFFECTS, at 81. The linear risk model posits
that each time energy is deposited in a cell or tissue, there
is a probability of the induction of cancer. Id. Thus, the
effect of each small dose is additive, and therefore
spreading a given dose out over time does not reduce the
ultimate risk. Id.
Although there is scientific consensus that ionizing
radiation can cause cancer, ionizing radiation, is not
currently known to leave a tell-tale marker in those cells
which subsequently become malignant. NATIONAL COUNCIL ON
RADIATION PROTECTION AND MEASUREMENTS, NCRP STATEMENT NO.
7, THE PROBABILITY THAT A PARTICULAR MALIGNANCY MAY HAVE
BEEN CAUSED BY A SPECIFIED IRRADIATION 1 (1992) (hereinafter
"NCRP 7"). Medical examinations and laboratory tests can
determine the type and extent of a cancer, suggest an
optimal treatment, and provide a likely prognosis, but they
rarely (if ever) provide definite information as to its cause.
Id. Consequently, medical evaluation, by itself, can neither
prove nor disprove that a specific malignancy was caused
by a specific radiation exposure. Id. Therefore, the primary
basis to link specific cancers with specific radiation
exposures is data that has been collected regarding the
increased frequency of malignancies following exposure to
ionizing radiation. Id. In other words, causation can only be
established (if at all) from epidemiological studies of
43
populations exposed to ionizing radiation. Id.; LAMARSH, at
413.
However, the task of establishing causation is greatly
complicated by the reality that a given percentage of a
defined population will contract cancer even absent any
exposure to ionizing radiation. In industrialized countries
where the life expectancy averages about 70 years, about
30% of the population will develop cancer and about 20%
of the population will die of cancer. CHERNOBYL , at 42. It is
estimated that if 100,000 persons with an age and sex
distribution typical of the United States are exposed to a
whole body dose of 0.1 Sv and are followed over their
lifetimes, between 770-810 people would develop fatal
cancers in excess of the normal incidence. BEIR V, at 6.
6. Radiation in the Environment.
The inquiry into cause is further complicated by the fact
that radiation is a "constituent element" of our
environment, and mankind has been exposed to it since
our first appearance on this planet. CHERNOBYL , at 23.
Obviously, natural environmental radiation has been, and
continues to be, augmented by man-made radiation.
Consequently, "the radiation environment of today differs
from that of yesterday, and it will continue to be
transformed in the future." Id. The total average annual
dose, from both natural radiation and man-made radiation,
is 3.6 mSv or 360 mrem. BEIR V, at 18.
i. Natural Radiation.
There are two major sources of natural radiation. These
are cosmic radiation and terrestrial radiation. L AMARSH, at
427. Cosmic radiation is highly energetic radiation that
bombards the earth from outer space. Terrestrial radiation
originates in radionuclides found in the earth and in our
own bodies. Id. Together, cosmic and terrestrial radiation
deliver the highest radiation dose that people normally
receive.50 CHERNOBYL, at 23.
_________________________________________________________________
50. The average annual dose of natural radiation is 2.4 millisieverts
(mSv) or 240 millirems (mrems). Natural background radiation levels
vary widely throughout the world. The dose of 2.4 mSv or 240 mrems is
44
Cosmic radiation consists primarily of a highly-energetic
mixture of protons (about 87%), alpha (a) particles (about
11 percent), and a trace of heavier nuclei (about 1%) and
electrons (about 1%). LAMARSH, at 427. However, the
atmosphere acts as a shield, greatly weakening cosmic rays
before they reach earth. MEDICAL EFFECTS, at 32. About 26
cosmogenic radionuclides have been identified. They are
produced by the action of cosmic radiation. LAMARSH, at 429.
However, of the 26, only tritium (3H)51, beryllium-7 (7Be),
sodium-22 (22Na) and carbon-14 (14C), contribute
appreciably to irradiation, MEDICAL EFFECTS, at 32, and only
carbon-14 (14C), is responsible for significant radiation
doses. LAMARSH, at 429. Fortunately, carbon-14 is a
relatively short-lived radionuclide.52 It primarily results from
the atmospheric interaction of thermalized cosmic ray
neutrons and nitrogen. Id. The concentration of 14C is about
the same in all living species, i.e., 7.5 picocuries per gram
of carbon. Id. Because approximately 18% by weight of the
human body is carbon, 14C contributes an estimated
annual dose of 0.007 mSv or 0.7 mrems. Id.
The average dose of cosmic radiation at or near sea level
is 0.37 mSv per year or 37 mrems per year. Id.; CHERNOBYL,
at 23. However, the dose rate increases with altitude,
doubling about every 1500 meters. CHERNOBYL, at 23.
Consequently, people living at high altitudes53 may have an
average annual dose level reaching 1 mSV or 100 mrems.
Id.
Terrestrial radiation accounts for as much as 85% of the
_________________________________________________________________
a world-wide average. However, it has been estimated that the average
annual dose in the United States from natural background radiation is
higher, around 3 mSv or 300 mrems, because of a reevaluation of the
quantities and effects of radon gas. KNIEF, at 88. For a brief discussion
of radon gas, see below.
51. Tritium is a radioactive isotope of hydrogen. There is another isotope
of hydrogen call deuterium (2H) or heavy hydrogen. Deuterium is not
radioactive. LAMARSH, at 8; MEDICAL EFFECTS, at 391, 396.
52. T1/2 = 5730 years.
53. For example, Denver, Colorado or Bogota, Colombia. CHERNOBYL, at
23.
45
total average annual dose of natural radiation, i.e., a little
over 2.0 mSv or 200 mrems annually Id. There are
approximately 340 naturally-occurring nuclides on earth,
and of these, about 70 are radioactive. LAMARSH , at 429.
They are called primordial radionuclides because they have
existed in the earth's crust since the earth was formed. Id.
Those now present on earth have half-lives comparable to
the age of the universe. MEDICAL EFFECTS, at 33. Accordingly,
primordial radionuclides with half-lives of less than about
108 years can no longer be detected. Id. Primordial
radionuclides with half-lives of more than 1010 years have
decayed very little up to now. Id.
Primordial radionuclides produce secondary
radionuclides through the process of radioactive decay.
There are three distinct chains of primordial radionuclides:
(1) the uranium series, which originates with 238U; (2) the
thorium series which originates with 232 Th; and (3) the
actinium series, which originates with 235 U. Together, the
parent of each chain and its respective daughter products
contribute significantly to terrestrial irradiation. Id.
Uranium is found in various quantities in most rocks and
soils, and it is the main source of radiation exposure to
people out-of-doors. CHERNOBYL, at 23. The uranium isotopes
are alpha (a) particle emitters and, therefore, they do not
contribute to gamma (g) ray exposure.54 MEDICAL EFFECTS, at
33. Since uranium isotopes are generally present in low
concentrations, they do not contribute significantly to the
internal alpha (a) ray dose delivered to humans. Id.
However, since these isotopes are found in soil and
fertilizers, they migrate into our food chain, and therefore,
into our tissue. Id. at 35.
Another significant source of terrestrial radiation
exposure is radium-226 (226Ra)-- an isotope which
originates in the uranium series -- and its daughter
_________________________________________________________________
54. Naturally occurring uranium consists of threeisotopes, 234U, 235U
and 238U. Uranium-238, the parent of the uranium series is the most
abundant isotope, present in the amount of 99.28%, and it is in
equilibrium with 234U, which is present in the amount of 0.0058%.
Uranium-235, present in the amount of 0.71%, is the parent of the
actinium series. MEDICAL EFFECTS , at 33.
46
products. Radium-226, with a half-life of 1622 years, is an
alpha (a) emitter and is present in all rocks, soils and
water. Id. Radium is chemically similar to calcium and it
passes through the food chain into humans because plants
absorb it from the soil.55 The annual dose attributable to
the intake of 226Ra is 7 microsieverts (Sv) or 0.7 mrem. Id.
at 36.
Approximately 95% of the world's people live in areas
where the annual average dose from outdoor external
radiation sources is about 0.4 mSv or 40 mrems.
CHERNOBYL, at 24. However, there are areas in the world
where people are exposed to very high levels of terrestrial
radiation. For example, thorium-rich monozite sands in
certain areas of Brazil and India also have exceptionally
high levels of irradiation. LAMARSH, at 429.56
Radium-226 is also an important source of terrestrial
radiation exposure because it decays to radon-222 (222Rn),
a noble gas radionuclide with a half-life of 3.8 days that
emits alpha (a) particles and contributes to gamma (g)
radiation through its gamma-emitting descendants. Id.
Radon is an odorless, colorless, nonreactive gas that poses
no significant biological threat. Id. Alpha (a) particles
emitted by radon outside the body do not penetrate skin.
Id. However, the daughter elements formed as radon decays
can be a significant source of natural irradiation and
potential biological damage. CHERNOBYL, at 24. Once inhaled,
the radon daughters may be deposited in the tracheo-
bronchial tree. Id. Some of the radon daughters -- the
polonium isotopes, 218 (radon A) and 214 (radon C 1) --
emit alpha (a) particles. 218Po (radon A) provides the major
alpha (a) particle dose to the tracheo-bronchial tree, and it
therefore poses an increased risk of lung cancer. C HERNOBYL,
at 24.
_________________________________________________________________
55. In the human body, 70% to 90% of radium is found in bone. MEDICAL
EFFECTS, at 35.
56. Similarly, in Guarapari, Meaipe and Pocos de Caldas in Brazil,
exposure dose rates can be 100 times the norm, and in the coastal areas
of Kerala and Tamil Nadu in India, exposure rates can be 1000 times
higher than the norm. CHERNOBYL, at 24.
47
Because it is a noble gas, radon diffuses from its point of
origin. LAMARSH, at 430. Moreover, because it is the
immediate daughter product of the decay of radium-226 (226
Ra), it can be present in radium-bearing rocks, soils and
home construction materials. Id at 429-30. Radon enters
buildings primarily through the underlying and
surrounding soils and, secondarily from building materials,
outdoor air, tap water and natural gas. CHERNOBYL, at 24.
Since concentration increases in enclosed spaces, radon
concentration is much higher indoors than outdoors.
MEDICAL EFFECTS, at 37-38. Radon is the largest contributor
to terrestrial radiation because people spend most of their
time indoors.57 Levels of radon in the air vary from place to
place, season to season, day to day and hour to hour. Id.
Both lead-210 (210Pb) and polonium-210 (210Po), which, as
noted above, are decay products of radon-222 (222Rn), are
introduced into the human body through inhalation as well
as through the food chain. LAMARSH, at 429-30. 222Rn is a
noble gas and therefore, tends to diffuse into the
atmosphere where it can travel large distances before
decaying into 210Pb. Id. at 430. 210Pb is not inert and
attaches to dust and moisture particles in the atmosphere
soon after it is formed. Consequently, it can be inhaled
directly into the body or fall onto leafy vegetables or pasture
grasses from where it can enter the food chain. Id. at 430,
433. Lead-210 does not lead to significant internal
radiation doses because it is a rather weak beta (b) particle
emitter. However, its daughter product, 210Po, is a powerful,
highly-energetic alpha (a) particle emitter and it provides
very significant doses of radiation. Id. at 431.
Because both radionuclides can enter the body through
ingestion, internal radiation exposure is influenced by
dietary patterns. CHERNOBYL, at 24. For example, both
radionuclides are present in seafood thus, in countries
such as Japan, where seafood is a dietary staple, annual
intakes of both radionuclides are significantly higher than
in countries where seafood is not a staple. Id. Both
_________________________________________________________________
57. It is responsible for more than half of the natural radiation we are
exposed to, i.e., 1.3 mSv per year or 130 mrems per year. CHERNOBYL, at
24.
48
radionuclides concentrate in lichens. Accordingly, people in
the extreme northern hemisphere who eat the meat of
animals that graze on lichens (caribou and reindeer) have
levels about ten times higher than the norm. Id. Both 210Pb
and 210Po are found on broadleaf tobacco plants, Id. at 433.
Both of these radionuclides have also been detected in
commercial tobacco products and in cigarette smoke.
CHERNOBYL, at 24.
There is a dispute within the scientific community as to
whether background radiation produces stochastic effects.
The International Commission on Radiological Protection
assumes that stochastic effects may be induced by natural
radiation and man-made radiation. ICRP 60, at 93. It has
been inferred that about 3% of cancer deaths each year in
the United States are attributable to background radiation,
with 1.5 to 2% due to natural radiation, 0.5% to medical
uses and 1% or less to occupational sources. See Luis
Felipe Fajardo, Ionizing Radiation and Neoplasia, in NEW
CONCEPTS IN NEOPLASIA AS APPLIED TO DIAGNOSTIC PATHOLOGY 99
(Cecilia M. Fenoglio-Preiser, Ronald S. Weinstein and
Nathan Kaufman, eds., 1986). However, it has also been
reported that natural background has not yet been proven
to be cancer inducing, and, some scientists claim that
natural background radiation does not cause cancer. Id.
ii. Man made Radiation.
Here, of course, we are most directly concerned with
radiation from the nuclear power plant at TMI. It is
undisputed that the production of electricity by nuclear
power can add to the radioactivity in our environment.
Irradiation occurs in the production of electricity, and in all
stages of the fuel cycle, i.e., mining, fuel fabrication,
transportation, reactor operation and reprocessing
CHERNOBYL, at 26-27. However, under normal
circumstances, and without considering the effect of
nuclear power plant accidents, the overall impact of nuclear
power generation on the total population is reported to be
very small. MEDICAL EFFECTS, at 45.
There are three major sources of man-made radiation
other than nuclear power plants. These are: industrial
processes other than nuclear power generation that also
49
use radionuclides, medical irradiation, and nuclear
weapons testing. CHERNOBYL, at 24.
Medical irradiation is generally divided into three
categories: (1) diagnostic x-ray examinations; (2) the use of
radiopharmaceuticals in nuclear medicine; (3) therapeutic
applications of radiation. MEDICAL E FFECTS, at 47.58
Nuclear weapons testing occurs either above ground
("atmospheric testing"), or underground.59 Radionuclides
released in atmospheric testing can enter the body directly
or be deposited on the earth's surface from whence they
may later be absorbed via the food chain, or be absorbed
through by way of external radiation. MEDICAL EFFECTS, at
44.
Generally, estimates of human exposure to fallout are
more concerned with atmospheric (and more particularly
stratospheric), fallout than with local or tropospheric fallout
because radionuclides in the stratosphere result in fallout
worldwide. Id. In fact, stratospheric particulate fallout
accounts for most of mankind's worldwide exposure to
fission products. Id. Fallout consists of numerous
radioactive byproducts of atomic reactions. However, only
four of these have half-lives of sufficient length to be of
significant concern to present and future populations: 14C,
with a half-life of 5730 years; 137Cs and 90Sr, both with a
half-life of 30 years; and 3H, with a half-life of 12 years.
CHERNOBYL, at 25. 14C provides almost two-thirds of the dose
exposure because of the relatively short half-lives of the
other three radionuclides. Id. The average annual dose to
individuals from atmospheric testing is 0.01 mSv or 1
_________________________________________________________________
58. The average annual dose due to medical irradiation is between 0.4
and 1 mSv or 40 to 100 mrems. CHERNOBYL, at 47. Of the three categories
of medical irradiation, diagnostic x-ray examinations account for almost
95% of the total dose received. Id.
59. Atmospheric testing began in 1945. From then until 1980 there were
more than 400 nuclear weapons tested in the atmosphere. CHERNOBYL, at
25. In 1963, the United States, the United Kingdom, and the former
USSR entered into the Partial Test Ban Treaty, and undertook to cease
atmospheric testing. However, France and China continued atmospheric
testing. Id. All of the atmospheric tests released significant amounts of
radioactive material into the environment. CHERNOBYL, at 47.
50
mrems. Id. There have been approximately 1300
underground nuclear weapons tests. MEDICAL EFFECTS, at 44.
However, a well-contained underground explosion delivers
little, if any, radionuclides to the environment, except for
occasional venting. Id.
Industrial processes, such as electricity production,
mining, and the use of certain building materials and
fertilizers produce above average concentrations of natural
radionuclides. CHERNOBYL, at 25. Coal contains more
radionuclides than other fossil fuels and burning coal
produces a large amount of particulate emissions. M EDICAL
EFFECTS, at 39. Other sources of industrial irradiation
include certain consumer products, such as luminous
timepieces, electronic and electrical devices, video display
terminals, antistatic devices, and smoke detectors. MEDICAL
EFFECTS, at 42. However, tobacco products probably
contribute the greatest radiation dose of all consumer
products. Id. at 43. It has been postulated that the
radionuclides 210Pb and 210Po are responsible for the high
incidence of lung cancer in smokers. BEIR V, at 19;
LAMARSH, at 433.
It is generally conceded that atmospheric weapons testing
has contributed more to man-made radiation than nuclear
power plants. Id. at 45. On average, the annual dose from
all facets of the nuclear fuel cycle is less than 0.1% of that
from natural radiation, CHERNOBYL, at 26, or less than 10
mSv or 1 mrem a year. KNIEF, at 88. In fact, it has been
postulated that atmospheric releases of radionuclides from
fossil fuel plants, especially coal plants without scrubber
systems, may be greater than the releases of radionuclides
from nuclear power plants. MEDICAL E FFECTS, at 45.
Nevertheless, it is beyond dispute that nuclear power
plants in general, and nuclear accidents in particular, can
release harmful radioactivity into the environment.
Irradiation occurs not only in the production of electricity
but in all stages of the fuel cycle, i.e., mining, fuel
fabrication, transportation, reactor operation and
reprocessing CHERNOBYL, at 26-27.60
_________________________________________________________________
60. Under normal circumstances, and without considering the effect of
nuclear power plant accidents, the overall impact of nuclear power
generation on the total population is reported to be very small. MEDICAL
EFFECTS, at 45.
51
61. Charged particles and gamma (g) rays can also induce fission, but
they are not significant for our purposes because neutron induced
fission is the basis of commercial nuclear power, KNIEF, at 41, and it is
that fission that occurred at TMI.
Accordingly, before proceeding with our discussion of the
District Court's application of Daubert to the expert
testimony that was offered to prove that TMI-2 released
radiation that caused the Trial Plaintiffs' neoplasms we will
briefly discuss the operation of a nuclear power plant in an
effort to better determine if Trial Plaintiffs proffered
sufficient evidence to connect their injuries to the nuclear
reactions that took place inside the nuclear generator at
TMI-2. For purposes of assessing the Daubert challenges to
the experts in this case, we will limit our discussion of
nuclear fission to reactions initiated by neutrons.61
52
Volume 2 of 4
Filed November 2, 1999
UNITED STATES COURT OF APPEALS
FOR THE THIRD CIRCUIT
Nos. 96-7623/7624/7625
IN RE: TMI LITIGATION
LORI DOLAN; JOSEPH GAUGHAN; RONALD
WARD; ESTATE OF PEARL HICKERNELL;
KENNETH PUTT; ESTATE OF ETHELDA HILT;
PAULA OBERCASH; JOLENE PETERSON; ESTATE OF
GARY VILLELLA; ESTATE OF LEO BEAM,
Appellants No. 96-7623
IN RE: TMI LITIGATION
ALL PLAINTIFFS EXCEPT LORI DOLAN, JOSEPH
GAUGHAN, RONALD WARD, ESTATE OF PEARL
HICKERNELL, KENNETH PUTT, ESTATE OF ETHELDA
HILT, PAULA OBERCASH, JOLENE PETERSON, ESTATE
OF GARY VILLELLA AND ESTATE OF LEO BEAM,
Appellants No. 96-7624
IN RE: TMI LITIGATION
ALL PLAINTIFFS; ARNOLD LEVIN; LAURENCE
BERMAN; LEE SWARTZ
Appellants No. 96-7625
ON APPEAL FROM THE UNITED STATES DISTRICT
COURT FOR THE MIDDLE DISTRICT OF PENNSYLVANIA
(Civil No. 88-cv-01452)
(District Judge: Honorable Sylvia H. Rambo)
ARGUED: June 27, 1997
Before: GREENBERG and McKEE, Circuit Judges, and
GREENAWAY, District Judge*
(Opinion filed: November 2, 1999)
IV. NUCLEAR ENGINEERING
A. Nuclear Reaction.62
The bulk of electricity generated in the United States is
the result of thermal energy (i.e., heat) produced in either
fossil-fueled boilers or nuclear power plants. ANTHONY V.
NERO, JR., A GUIDEBOOKTO NUCLEAR REACTORS 3 (1979).
Nuclear power plants generate energy through nuclear
fission. Id. Nuclear fission provides nearly one hundred
million times as much energy as the burning of one carbon
atom of fossil fuel. KNIEF, at 4. Fission therefore has obvious
advantages over fossil-fuel based energy production. It has
been estimated that the complete fission of just one pound
of uranium would release approximately the same amount
of energy as the combustion of 6,000 barrels of oil or 1,000
tons of high-quality coal. NERO, at 4. However, the major
disadvantage of the fission process is now painfully
obvious. It requires mankind to harness and control one of
the most awesome physical powers in the universe. In
addition, potentially deadly radioactive materials are
produced in the process. KNIEF, at 4
Neutron interactions with nuclei are possible because the
absence of a charge allows a neutron to approach a nucleus
without repulsion from an opposing force. BENNETT, at 23.
The important reactions occur at relatively low energies and
include "elastic scattering", "inelastic scattering", "neutron
capture" and fission. BODANSKY at 46. Chance determines
_________________________________________________________________
* The Honorable Joseph A. Greenaway, Jr., United States District Court
Judge for the District of New Jersey, sitting by designation.
62. The general term "nuclear reaction" describes any of a wide number
of interactions involving nuclei. BODANSKY, at 46.
54
which of these reactions occur for a given neutron. Id. at
48.
In elastic scattering, a neutron and nucleus collide
without any change in the structure of the target nucleus.
Id. It is, therefore, like "the collision of two billiard balls of
unequal mass." BENNET, at 23. Although the structure of the
nucleus is unchanged in elastic scattering, the laws of
motion cause the neutron to change direction and speed
and the nucleus recoils. BODANSKY, at 47. The total kinetic
energy of the system is unchanged, but some of the
neutron's energy is transferred to the target nucleus. Id.
Elastic scattering can occur with any target nucleus, but in
nuclear reactors it is most significant when the target
nucleus is relatively light, and the loss of kinetic energy is,
therefore, relatively large. Id. In that scenario, elastic
scattering effectively reduces the energy of the neutrons
without depleting their number.
Inelastic scattering differs from elastic scattering because
the target nucleus is left in an excited state. Id. The target
nucleus decays, usually quickly, to the ground state with
the emission of gamma (g) rays. The total kinetic energy of
the neutron and the target nucleus after the scattering is
less than that of the neutron before the scattering, with the
difference equaling the energy of the gamma (g ) rays. Id. An
important characteristic of inelastic scattering is that
neutrons lose on average much more energy per collision
than they do in elastic scattering. BENNET, at 28.
In neutron capture, which occurs in the first stage of
many reactions, the neutron combines with the target
nucleus to form an excited compound nucleus. BODANSKY, at
47. The term "neutron capture" is usually restricted to
cases where the excited compound nucleus decays by the
emission of gamma rays.63 Id. The number of gamma rays
emitted in the de-excitation varies. Id.
Neutron capture can occur for almost any target nucleus
and it plays two general roles in nuclear reactors. First, it
_________________________________________________________________
63. An example is: formation: n + 238U fi 239U*
de-excitation: 239U* fi 239U + g's
BODANSKY, at 47.
55
consumes neutrons that might otherwise initiatefission.
Second, it transforms nuclei produced in fission into other
nuclei. Id. Further, as will be discussed below, the reaction
is significant because it is the first step in the production
of plutonium-239 in reactors. Id.
As noted earlier, a nuclear reactor produces energy from
fission. However, fission is possible for only a very few
target nuclei, the most important being isotopes of uranium
and plutonium. Id. at 48. If an appreciablefission yield is
produced by neutron incidents upon a target nucleus, that
nuclear species is termed fissile. Id. at 61. In a typical
fission reaction, the excited compound nucleus divides into
two fragments plus several neutrons.64 Id. at 48. The energy
released in fission comes from the large kinetic energy of
the fission fragments. Id. An averagefission event produces
nearly 200 million electron volts of energy (200 MeV). KNIEF,
at 45. In contrast, approximately 2-3 electron volts (eV) of
energy is released for each carbon atom burned with
oxygen. Id. Neutrons produced by the fission event have an
average energy of 2 million electron volts (2 MeV). BENNET,
at 55. The fission fragments come to rest within about 10-3
centimeters of the fission site so that all of their energy is
converted into heat. LAMARSH, at 76. It is important to
remember that he fission products are all radioactive.
BENNET, at 30. The formation of eachfission product is
followed by a series of beta decays that continues with
successive emission of b- particles until a stable isobar is
reached. BODANSKY, at 48. In addition, gamma rays are
emitted in the de-excitation of the fission fragments,
assuming they are formed in excited states, as well as in
the de-excitation of the products of the successive b-
decays. Id..
_________________________________________________________________
64. A typical fission reaction illustrated for a 235U target is of the
general
form:
n + 235U fi236U* fi144Ba + 89Kr +
3n.
The products in this example are barium 144 (atomic number Z = 56),
krypton 89 (Z=36), and 3 neutrons. BODANSKY, at 48. Many other
outcomes are also possible, always subject to the condition that the
sums of the atomic numbers of the products are the same as those of
the initial system. Id. Both the 144Ba and 89Kr nuclei areradioactive. Id.
56
The release of significant amounts of energy fromfission
requires a chain reaction. Id. at 69. Fission forms the
backbone of the required chain reaction. NERO , at 5. Earlier,
it was noted that neutrons produced by fission in the
uranium fuel have an average energy of 2 MeV. However,
fission in uranium will not result in a chain reaction if the
neutrons interact at energies close to those in which they
were emitted. BODANSKY, at 73. Consequently, it is necessary
to reduce the energy of the neutrons from this average
energy region to a more favorable region below 1 electron
volt (eV) by elastic collisions with the nuclei of a moderator.
Id. Commonly used moderators are hydrogen in water,
deuterium in heavy water or carbon in graphite. Id. at 74.
After a sufficient number of elastic collisions with the
moderator, the neutrons have reached a low or "thermal
energy" and a chain reaction can occur. NERO , at 7.
A chain reaction is sustained by the emission of low
energy neutrons from fissioning nuclei. BODANSKY, at 50. A
nuclear reactor such as TMI-2 is "merely" the system in
which a controlled chain reaction takes place. LAMARSH, at
103. In order for a self-sustaining chain reaction to occur,
at least one of the neutrons produced in one fission event
must cause a second fission event from which one neutron
causes a third fission event, and so on. Id. at 102. Each
such generation must have more fission events than the
preceding one if a continuing and useful chain reaction is
to occur. BODANSKY, at 69.65 The condition for establishing a
chain reaction is commonly expressed as the "achievement
of criticality". Id. "Criticality" is described quantitatively in
terms of the multiplication factor, denoted by the symbol k,
LAMARSH, at 102, or the criticality factor, BODANSKY, at 69,
which is defined as the ratio of the number offissions (or
fission neutrons) in one generation divided by the number
of fissions (or fission neutrons) in the preceding generation.
_________________________________________________________________
65. The average number of neutrons emitted infission is crucial for
establishing the practicality of a chain reaction. Id. at 64. The number
of neutrons varies from event to event, ranging from 0 to about 6. Id.
Generally 2 or 3 neutrons are emitted per event. Id. The excess is
necessary because some neutrons will be lost to capture reactions and
other neutrons will leave the region where the chain reaction is to be
established. Id.
57
LAMARSH, at 102. A system is critical if k equals 1. Id. If k is
greater than 1, the system is "supercritical," "and a
divergent chain reaction exists in which the neutron
density and fission rate increase, possibly at an explosive
rate as in an atomic bomb." BENNET, at 54. If k is less than
1, the system is "subcritical" and the chain reaction
decreases and eventually stops. Id
In a nuclear reactor, the operator can vary the value of k
by varying the rate at which neutrons are produced within
the reactor with the rate at which they are absorbed or
disappear.66 LAMARSH, at 103. To increase the power being
produced by the reactor, the operator increases k to a value
greater than 1 so that the reactor becomes supercritical. Id.
When the desired level has been reached, the operator
adjusts k to one so that the reactor is critical and
maintains the desired level. Id. To reduce power or shut the
reactor down, the operator reduces k to less than 1, making
the reactor subcritical. Id.
Earlier, we noted that neutron capture wastes neutrons
if we consider only fission. However, neutron capture plays
an important role in reactors because through it
nonfissionable nuclei become fissile. BODANSKY, at 61, 78.
Neutron capture in thorium-232 (232Th) and uranium-238
(238U) leads, with interveningb- decays, to the production of
the fissile nuclei uranium-233 (233U) and plutonium-239
(239Pu). Id. at 61. Therefore, 232 Th and 238U are termed
fertile. Id. Where uranium is used as the fuel, plutonium-
239 (239Pu) is ultimately produced by the capture of
neutrons in fertile uranium-238 (238U). The 239Pu can be
used for the production of atomic weapons or in other
reactors. BODANSKY, at 78. It also contributes fissile material
which is consumed in the reactor before the fuel is
removed, supplementing the original fissile 235U in the fresh
fuel. Id. Essentially, through neutron capture, the fertile
nuclei become fissile nuclei enabling the nuclear reaction to
continue in the reactor.
_________________________________________________________________
66. Nuclear bombs and explosives cannot be controlled in this way and
therefore are not called reactors. LAMARSH, at 103.
58
B. The Operation of Nuclear Power Plant.67
At its most elementary level, a nuclear reactor is a
deceptively simple apparatus. Simply put, a nuclear power
plant produces heat energy that is converted to steam in a
boiler. Affidavit of John A. Daniel at P 17. The steam is
used to turn a turbine, which is connected to, and turns an
electrical generator that produces electrical power. Id. The
apparent simplicity of this basic operation is made even
more deceptive when one considers the awesome power of
the forces at work within nuclear reactors such as TMI-2.
However, beyond this elementary level, a nuclear power
plant is an extraordinarily complex system. The heat energy
is produced in a vessel called a "reactor," because it
contains the nuclear reactions. Id. The reactor vessel is a
steel pressure vessel with walls that are 8-1/2 inches thick,
surrounded by a concrete and steel shield over 8 feet thick.
Id. at 23.
The TMI-2 nuclear reactor at issue here was a standard
Babcock & Wilcox pressurized water reactor ("PWR").68 It
_________________________________________________________________
67. The following description is taken, for the most part, from two
sources -- the affidavit of a defense expert witness and a report
commissioned by the Nuclear Regulatory Commission. We rely on these
sources because appellants have not provided us with any evidence of
the workings of a nuclear power plant, and because the basic operation
of a nuclear power plant is not in dispute. See 927 F. Supp. at 846. The
affidavit is of John A. Daniel, a nuclear engineer who is currently a
consultant to the nuclear power industry, and can be found in the
Consolidated Appendix at 14759-14889. The government report is
MITCHELL ROGOVIN, NUCLEAR REGULATORY COMMISSION INQUIRY GROUP,
NUREG/CR-1250, TMI REPORT TO THE COMMISSIONERS AND TO THE PUBLIC AT
10-13 (1980).
68. The physical plant of a PWR nuclear power plant consists of a
reactor building, a turbine building, an auxiliary building, a fuel
handling building and a control and service building. Daniel Aff. at P 23.
The reactor vessel, pressurizer, associated piping, reactor coolant pumps
and steam generators are collectively referred to as the "reactor coolant
system" and are located in the reactor building. Id. The reactor building
is actually a large pressure vessel designed to withstand the pressure
increase which would result if there was a rupture in reactor coolant
piping. Id. at P 24. During the plant's operation, the reactor building is
kept air tight and access to the building is through personnel air locks,
similar to those used on spacecraft. Id.
59
used uranium dioxide (U02) as a fuel. Id. at PP 17, 18; J. A.
Daniel, Noble Gas Transport During the TMI-2 Accident
(1993) 87. The UO2 is formed into ceramic pellets, each of
which is about one-half inch in diameter. Daniel Aff. at
P 17. Fuel pellets are stacked into metal rods called "fuel
pins", which are arranged into square "fuel assemblies." Id.
The fuel assemblies are approximately twelve feet high,
contained in the reactor, and are collectively referred to as
the "reactor core". Id. The fuel assemblies contain several
control rods with instruments, some of which monitor the
reactor, and others which speed up or slow down the
reaction. Id. These control rods, contain materials with
large thermal neutron absorption capacities. BODANSKY, at
80. The rods are either inserted or withdrawn to maintain
the appropriate level of criticality, (where k equals 1), and
enable the reactor to operate at steady power for long
periods of time. BENNET, at 107-08. The reactor contains
water some of which serves to cool the reactor during the
nuclear reaction, and some of which is heated to steam by
the chain reaction. The fuel rods containing the uranium
fuel are sheathed in rods that prevent the fuel pellets from
coming into direct contact with the water in the reactor
core and are called the fuel cladding. MITCHELL ROGOVIN,
NUCLEAR REGULATORY COMMISSION INQUIRY GROUP, NUREG/CR-
1250, TMI REPORT TO THE COMMISSIONERS AND TO THE PUBLIC 10
(1980)(hereinafter "NUREG/CR-1250"). Daniel Aff. at P 17.
The nuclear reaction in the core is generated by a
neutron source which emits neutrons in a manner designed
_________________________________________________________________
The turbine, condenser and electrical generator are housed in a
concrete and steel building called the "turbine building". Id. at P 23.
The
auxiliary building contains the auxiliary systems used to process and
maintain the chemical and radiological purity of the reactor coolant. Id.
The fuel handling building houses the storage facilities for new and used
fuel. Id. After it is removed from the reactor core, the used fuel is
stored
underwater in the "spent fuel pool." Id. The auxiliary and fuel handling
buildings have redundant air filtration units which are designed to
remove filterable radioactive particles before being discharged to the
environment. Id. The plant operations personnel monitor and maintain
control of the various plant systems from a central control room located
in the control and service building. Id.
60
to initiate a chain reaction. Most fission products are solid
at fuel temperature, but some are gases. Id. at P 18. Some
of the fission products, especially the noble gases krypton
and xenon, migrate to the edge of the fuel pellet and collect
in the space between the fuel and the cladding. Since some
of the fission products may escape from the cladding into
the water in the reactor, the reactors are designed to
contain cooling water within its own closed loop. Id.
In a PWR of the TMI-2 type, there are three cooling
systems. Daniel Aff. at P 19. A PWR coolant system69 is a
circuit or closed loop of distilled water with a small amount
of boric acid. NUREG/CR-1250 at 10. The primary circuit,
called the "primary coolant" or "reactor coolant", circulates
water through the reactor core. Daniel Aff. at P 19. During
normal reactor operation, the water in the primary coolant
is kept at an average temperature of 575o F and pressures
high enough, (around 2200 pounds per square inch), to
keep the water from boiling to steam. NUREG/CR-1250 at
10. The water in the primary coolant circulates and
recirculates through this loop. Id. While it is circulating and
recirculating, the primary coolant water picks up heat from
the fission reaction in the reactor core and carries the heat
from the core through two "hot leg" pipes to two steam
generators. Daniel Aff. at P 19; NUREG/CR-1250 at 10. The
steam generators are tanks, approximately 35 feet tall, in
which the primary coolant water passes through a large
number of narrow tubes that transfer heat to water
contained in another, separate circuit, called the
"secondary circuit" or "feedwater loop." Daniel Aff. at P 19;
NUREG/CR-1250 at 10. The water in the secondary circuit,
called "feedwater," is maintained at a lower pressure than
the water in the primary coolant circuit, Daniel Aff. at P 19,
allowing the feedwater to boil to steam. Id.; NUREG/CR-
1250 at 10. The steam in the secondary circuit is called the
"main steam system". Daniel Aff. at P 19.
The primary coolant water, having lost some of its heat in
the secondary circuit, is then returned to the reactor core
through four pipes, known as "cold legs." NUREG/CR-1250
_________________________________________________________________
69. There are two virtually identical coolant loops in the TMI-2 reactor,
called the "A" and "B" loops. NUREG/CR-1250 at 11.
61
at 11. Once the primary coolant water is returned to the
reactor core, it is heated once again by the nuclear
reaction, and the cycle repeats. Id. The primary coolant
water is kept moving at high speed in the primary circuit by
four reactor coolant pumps -- enormous devices each of
which requires enough electricity for its own operation to
light a small town. Id.
At a point between the reactor and the steam generator,
there is a pipe leading to the bottom of a large vessel or
tank called a "pressurizer". NUREG/CR-1250 at 11. During
normal operation, coolant water does not circulate back
and forth through this pipe. Id. The pressurizer is normally
kept a bit more than half full of coolant water. Above the
water is a cushion, or "bubble," of steam. Id.; Daniel Aff. at
P 20. The pressurizer is a means of keeping the pressure in
the reactor coolant system relatively constant, to prevent
the reactor coolant water from boiling. NUREG/CR-1250 at
11. The steam cushion at the top of the pressurizer can be
made larger or smaller by slight heating or cooling of the
pressurizer water just beneath it. Id. When the bubble
temperature and pressure are increased, the bubble tends
to push water from the pressurizer out into the primary
reactor coolant loop, thereby increasing pressure in the
loop. Id. When the temperature and pressure in the
pressurizer are lowered, steam condenses and the bubble
shrinks. Id. Consequently, water tends to come from the
reactor coolant loop into the pressurizer, and the overall
system pressure is lowered. Id.
A relief valve, referred to as a "power-operated relief
valve" ("PORV"), is located in a pipe leading out of the top
of the pressurizer, at the top of the space normally
occupied by the steam bubble. Daniel Aff. at P 21,
NUREG/CR-1250 at 11. The PORV is designed to open
automatically when the system begins to overpressurize.
NUREG/CR-1250 at 11. Theoretically, if the pressure in the
coolant system rises very abruptly, the PORV will open,
some of the steam will rush out to a drain tank, thus
shrinking the bubble, more water will move up into the
pressurizer from the primary coolant loop, and system
pressure will decrease. Id.; Daniel Aff. at P 21. A rupture
disk is provided on the drain tank to relieve pressure if the
62
drain tank becomes too full. Daniel Aff. at P 21. When the
system pressure is back to normal, the PORV is supposed
to close automatically. NUREG/CR-1250 at 11. If the PORV
fails to close, there is a backup, called a "block valve".
Daniel Aff. at P 21. There are two other safety valves in
addition to the PORV. NUREG/CR-1250 at 11; Daniel Aff.
at P 21.
The heart of the secondary circuit or feedwater loop is the
steam generator. NUREG/CR-1250 at 11. After the water in
the secondary circuit is heated to steam by the hot water
from the primary coolant system, the steam moves through
the secondary circuit or feedwater loop to a steam turbine
which turns the power generator that produces the
electricity. NUREG/CR-1250 at 11. The steam then passes
through a condenser, where it is cooled and condensed into
water once again and recycled through the steam
generators. Id. at 11-12. The pipe line returning the water
from the condenser to the steam generator also contains
the condensate polishers or "demineralizers". Id. at 12. The
demineralizers are basically water softeners, that use ion
exchange resins to purify the feedwater. Id.
The condenser itself is cooled by water from the third
circuit, i.e., the cooling towers, Id. at 12; Daniel Aff. at P 19,
which are the familiar landmarks of nuclear plants. The
water in the condenser circuit, having been warmed in the
process of condensing steam back into water, is pumped up
to the cooling towers. NUREG/CR-1250 at 12. The
condenser water is thus cooled by exposure to the
atmosphere as it tumbles down a steep run of steps and
then is pumped back into the condensers. Id. The escaping
water vapor is the plume or cloud which can often be seen
coming out of the cooling tower. Id.70
_________________________________________________________________
70. During this process, chemicals may be added to the reactor coolant
to fine tune the nuclear reaction in the reactor core, and to remove any
impurities that may have collected in the coolant. Daniel Aff. at P 22.
During power operations, a small flow of reactor coolant is bled off from
the reactor coolant system and passed through a series of filters and
demineralizers. Id. If additional water is needed in the reactor coolant
system, it is added from water stored in tanks located in an auxiliary
building. Id. The system that collects water from the reactor coolant
system and adds water to the reactor coolant system is called the
"makeup and purification system". Id. Any gases collected from the
reactor coolant system are collected in waste gas decay tanks. Id.
63
In addition to the systems peculiar to a PWR, the TMI-2
reactor had a general safety system common to all reactors
called the "emergency core cooling system" ("ECCS"), which
is designed to supply cooling water to the hot reactor core
if there is a loss of water due to a break in the reactor
coolant system. NUREG/CR-1250 at 12. If the break is
small, the leakage flowing from the break may not be
significant and the system's internal pressure will stay
high, making it difficult for the ECCS to pump water in. Id.
Consequently, the plant has high pressure injection ("HPI")
pumps to deliver water from a large borated water storage
tank ("BWST"). Id. However, the HPI pumps are not able to
deliver enough water if the break is large. Id. Therefore, the
system has a set of low pressure injection ("LPI") pumps
that can deliver water to the core rapidly when a large pipe
break has caused the system's internal pressure to drop.
Id. The LPI pumps also draw water from the BWST. Id.
The LPI pumps also have another purpose. When a
reactor is shut down, the radioactive waste in the fuel
continues to produce a considerable, but diminishing,
amount of decay heat for days following shutdown. This
heat must be removed if the core is to be kept from melting.
Id. Even after the reactor is shut down, the accumulated
fission products continue to decay and release energy
within the reactor. LAMARSH, at 350. This fission product
decay is called "decay heat". Id. A method for handling the
decay heat and for cooling the reactor core after shutdown
must be provided or the temperature of the fuel may rise to
a point where the fuel's integrity is compromised and
fission products are released. Id.
After shutdown, the reactor is first cooled by the
continued normal operation of the steam generators until
the reactor coolant system is cooled to a temperature of
about 300$F and an internal system pressure below 400
psi. NUREG/CR-1250, at 12. Then, valves are opened to let
one of the LPI pumps circulate coolant through the reactor
core and out to a special heat exchanger to bring the
system temperature down to about 120#DE#-140#DE#F. Id.71
_________________________________________________________________
71. The LPI system is called the "decay heat removal system" when it
performs this function. NUREG/CR-1250 at 12.
64
Finally, there is an ECCS system called the "coreflood
tanks." These are two tanks almost completelyfilled with
water under a medium-pressure of about 600 psi. Id. They
stand above the reactor and a check valve prevents the
higher reactor core system pressure from driving more
water into them. Id. If a large pipe break occurs, it takes a
few minutes for the HPI and LPI pumps to deliver cooling
water to the core. Id. Therefore, the coreflood tanks are
designed to drop their thousands of gallons of water to cool
the core until the HPI and LPI pumps deliver cooling water.
Id.
C. Barriers to Release of Radioactive Materials into
the Environment.
A nuclear reactor must obviously have barriers designed
to prevent the fission products from entering the working
areas of the reactor or escaping into the environment.
NUREG/CR-1250 at 342. The first such barrier is the
ceramic fuel matrix in which the fission products are
produced. Id. The uranium dioxide (UO2) used in the TMI-2
reactor is a ceramic fuel which has microscopic boundaries
("grain boundaries") between the molecules. Daniel, Noble
Gas Transport at 87. These boundaries serve as
microscopic roadways for certain fission products to travel
out of the fuel. Id. Thus, some of the elements that are
volatile or gaseous at the operating temperature of the fuel
are able to migrate through the ceramic fuel. NUREG/CR-
1250 at 342. However, the majority of the fission products
that are produced are either trapped or chemically bound.
Id.
The second barrier to the release of fission products is
the fuel cladding. The UO2 ceramic pellets are sealed in the
fuel rods to prevent the fuel pellets from directly contacting
the water in the reactor core. There is a small gap between
the fuel and the fuel cladding. Noble gases such as krypton
and xenon, and other volatile nuclides are contained in that
gas. However, if a defect or rupture develops in the fuel
cladding, volatile fission products can be released into the
coolant. Id. at 343. At the time of the TMI-2 accident, the
Nuclear Regulatory Commission generally allowed operation
65
of a reactor with up to 1% of the fuel having a defect in its
cladding.72 Id.
The third barrier is the reactor coolant. Many of the
volatile fission products, the radioiodines and
radiohalogens, are soluble in the coolant in "ionic"
(electrically charged) form. Id. at 343. These materials can
be removed by demineralizers, such as those in the makeup
and purification system of the reactor, or they may remain
dissolved in the coolant. Id. The majority of these
radionuclides are contained in the primary coolant system,
Id., and are soluble in the coolant. Id. Their solubility
decreases and they tend to precipitate or "plate out" as the
pH of the primary coolant is increased. Id. The noble gas
radionuclides, kryptons and xenons, have very low
solubility in the coolant, particularly in the presence of
other gases such as hydrogen, and they evolve into a gas or
vapor phase above the coolant or wherever the coolant is
depressurized. Id.
The fourth barrier is the reactor pressure vessel and the
piping of the primary coolant system, which are made of
heavy walled steel. Id. The fifth barrier is the containment
building itself. It is designed to withstand
overpressurization and external impacts and contain or
delay fission product releases during an accident. Id.
V. THE ACCIDENT AND ITS AFTERMATH
A. The Accident at TMI-2.73
_________________________________________________________________
72. Even in the absence of defective fuel elements, a small background
concentration of fission products exists in the primary coolant system,
because of the fissioning of trace quantities of uranium ("tramp
uranium") in or on the fuel cladding material. NUREG/CR-1250 at 342.
73. Although the defendants have previously conceded that radioactivity
was released into the environment as a result of the TMI-2 accident, see
67 F.3d at 1119, there is apparently some dispute about the "specific
operation of the TMI-2 PWR during the accident. . . ." 927 F. SUPP. at
846. Our description of the accident is taken from defense exhibits.
Plaintiffs have not offered an explanation of how the accident occurred,
and have focused instead on the biological damage they allege it caused.
66
What has been described as the "[n]ation's worst nuclear
accident"74 began at about 4:00 a.m. on Wednesday, March
28, 1979, The Comptroller General Report to the Congress,
Three Mile Island: The Most Studied Nuclear Accident in
History 1 (1980). Ironically, the "nation's worst nuclear
accident" grew out of a minor malfunction, or transient that
occurred in the nonnuclear part of the system. NUREG/CR-
1250 at 3. For some reason, several feedwater pumps, 75
that normally drew heat from the PWR's cooling water,
shut-off automatically.76 Id. at 310. The system was
designed so that when the feedwater pumps tripped, the
main turbine and electrical generator also tripped. Id. Thus,
by design, the turbine and generator tripped approximately
one second later. Id. Three seconds after the turbine
tripped, the pressure in the reactor coolant system
increased to a level that caused the PORV to open in order
_________________________________________________________________
Nevertheless, a basic understanding of the defendant's theory of how the
accident occurred provides helpful background to a Daubert analysis of
the disputed expert testimony plaintiffs attempted to offer. It is in this
context only that we set forth a description of the accident. We caution,
however, that the description we set forth is intended only for the
limited
purpose of framing our Daubert discussion. It is not intended to suggest
the appropriate resolution of any factual dispute that may linger as to
the precise manner in which the numerous controls all failed at TMI.
74. Prior to the TMI-2 accident, there were "major" reactor accidents at
the National Reactor Testing Laboratory in Idaho in 1955 and 1961, at
the Fermi Reactor in Detroit, Michigan in 1966 and at Browns Ferry 1
in Alabama in 1975. BODANSKY, at 212-13. Major accidents outside of the
United States occurred at Chalk River, Canada in 1952, Windscale,
England in 1957, Lucens, Switzerland in 1969 and, perhaps the most
famous of all reactor accidents, at Chernobyl, in Ukraine about 30 miles
south of the border with Belarus, (both of which were then part of the
former USSR) in 1986. Id.
75. Neither the condensate nor the feedwater systems are unique to
nuclear power plants. Both systems are similar to those used in fossil-
fuel plants. NUREG/CR-1250 at 310.
76. The exact reason why the water pumps tripped has not been
determined. NUREG/CR-1250 at 311. However, it has been postulated
that the operations of a condensate polisher in the auxiliary building was
implicated in the tripping of a condensate pump which in turn caused
the tripping of the main feedwater pumps. NUREG/CR-1250 at 310-311.
67
to release the pressure. Id. When the PORV opened, the
fission process in the reactor core automatically shut down.
Id. Consequently, the heat generation in the reactor core
dropped to decay heat levels. J. A. Daniel, Noble Gas
Transport at 5.
However, the PORV did not close as it should have when
the system pressure was reduced to acceptable levels.
Instead, it remained open for approximately 2 hours.
Comptroller General Report ("CGR") at 2. Unfortunately, the
personnel operating Unit 2 did not realize that the PORV
had not closed. They believed that it had automatically
closed when the system was depressurized. Id. ;
NUREG/CR-1250 at 324. Because the PORV remained
open, reactor coolant water flowed from the reactor coolant
system into the reactor coolant drain tank, which is
designed to collect reactor coolant that is released from the
reactor coolant system through the PORV during power
operation. Daniel, Noble Gas Transport at 6. The continued
flow of reactor coolant water into the reactor coolant drain
tank caused a safety valve to lift on the drain tank and a
drain tank rupture disk to burst. Id. This rupture disk
burst allowed the reactor coolant water to be discharged
directly into the reactor building, which overfilled along
with its sump pumps. Id. The reactor building sump pumps
were on automatic and aligned with the auxiliary building
sump tank. Id. at 31. When the reactor building sump
pumps overfilled, some coolant water was transferred to the
aligned auxiliary building sump tank. Id. For some reason,
there was no rupture disk on the sump tank and reactor
coolant water was discharged directly into the auxiliary
building. Id. at 31; CGR at 2. The contaminated coolant
water continued to flow from the reactor building into the
auxiliary building for several days. CGR at 2. Estimates of
the amount of radioactive water discharged into the reactor
and auxiliary buildings range from 700,000 gallons,
Nuclear Energy Institute, The TMI 2 Accident: Its Impact, Its
Lessons, http://www.nei.org/pressrm/facts/TMI-2.htm>,
to 5,000,000 gallons. NUREG/CR-1250 at 339.
Approximately 2 minutes into the accident, the
emergency core cooling system ("ECCS") began pumping
water into the reactor core. CGR at 2. However, operations
68
personnel, still believing that the PORV had closed, and
therefore unaware that reactor coolant water was escaping
from the reactor coolant system, turned off most of the
water flowing to the core through the ECCS. Id. They did so
believing that they were preventing the reactor system from
becoming filled with water -- a condition they were required
to prevent. Id.
However, there was not enough coolant water being
circulated through the reactor coolant system to cool the
reactor core because reactor coolant water was being
discharged into the reactor building. Consequently, the core
reaction was producing more heat than the coolant system
was removing, and the core began to heat up. Daniel, Noble
Gas Transport at 6. The loss of reactor coolant water
allowed the reactor core to become uncovered. Id. Within
three hours of the beginning of the accident, as much as
two-thirds of the twelve-foot high core was uncovered.
Temperatures reached as high as 3500 to 4000 degrees
Fahrenheit or more in parts of the core during its
maximum exposure. THE REPORT OF THE PRESIDENT'S COMMISSION
ON THE ACCIDENT AT THREE MILE ISLAND, THE NEED FOR CHANGE:
THE LEGACY OF TMI 100 (1979) (THE KEMMENY REPORT).
About 2-1/2 hours into the accident, some of the fuel
rods in the reactor cracked, releasing xenon and other
fission product gases, which had accumulated in the fuel
rod gap between the fuel and the cladding, into the coolant
water. Daniel Aff. at P 28. Over the next few hours, more
fuel rods cracked, releasing radioactive iodine and cesium
into the primary coolant water as well as additional noble
gases. Id.
A series of events then unfolded involving various
reactions, valves and controls. The end result was that,
nearly 10 hours into the accident, there was a sudden
spike of pressure and temperature in the reactor building.
Id. at 329. Initially, the spike was dismissed as some type
of instrument malfunction. Id. at 330. However, operations
personnel learned on March 29th that the spike was
caused by the explosion of hydrogen gas in the reactor
building. Id. at 329; CGR at 2. Fears of another hydrogen
explosion developed when a hydrogen gas bubble was later
found in the reactor system. CGR at 2; NUREG/CR-1250 at
69
336, 338. Presumably, there was a concern that another
hydrogen explosion would damage the reactor vessel,
leading to further releases of radioactive material.
NUREG/CR-1250 at 338. However, the fears about another
hydrogen explosion were later learned to be unfounded. Id.;
CGR at 2.
During the last days of March and the first week of April,
operations personnel began to regain control and contain
the radioactive releases caused by the accident. See
NUREG/CR-1250 at 334-39. However, it was not until the
afternoon of April 27, 1979 that stable conditions were
finally established in TMI-2. Id. at 339.
B. Radioactive Materials Released to the
Environment.
The parties generally agree that the radioactivefission
products released to the environment as a result of the
accident escaped from the damaged fuel and were
transported in the coolant through the letdown line into the
auxiliary building. NUREG/CR-1250 at 343; Daniel, Noble
Gas Transport at 33 ("The major pathway forfission
product transport to the auxiliary building was through the
letdown piping of the makeup and purification system.");
Daniel Aff. at P 22. Once in the auxiliary building, the
radioactive fission products were released into the
environment through the building's ventilation system.77
NUREG/CR-1250 at 343; Daniel, Noble Gas Transport at
60. Because of the volatility of noble gases and
_________________________________________________________________
77. TMI-2 also contained a treatment system, called the "liquid radwaste
treatment system", which was designed to collect, process, monitor and
recycle or dispose of radioactive liquid wastes prior to discharge to the
environment. After the system processed the liquid radwaste, it was
discharged into the Susquehanna River. However, because the primary
coolant water flowed into the auxiliary building during the accident, the
liquid radwaste treatment system was overwhelmed and radioactive
materials were released to the Susquehanna River. The Nuclear
Regulatory Commission's Special Inquiry Group concluded that the
quantity of radioactive materials contained in the liquid released into
the
Susquehanna River was not significant. NUREG/CR-1250, at 347-51.
None of the plaintiffs here claim harm as a result of the releases of
liquid
radwaste into the river.
70
radioiodines, those elements were the primary
radionuclides available for release from the auxiliary
building. NUREG/CR-1250 at 343. Two krypton isotopes,
87 and 85, were not released in significant quantities
because of the short half-life of 87Kr and because of the
small amount of 85Kr in the reactor core. Id. Nonetheless,
despite the various filters, radioiodines were released.78
After the first day, the quantities of 88Kr and 135Xe were
reduced by radioactive decay. Id. All of the 133I contained in
the coolant w
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