Criticality Accident Requirements

NUCLEAR REGULATORY COMMISSION

10 CFR Parts 50 and 70

RIN 3150-AF87

Criticality Accident Requirements

AGENCY: Nuclear Regulatory Commission.

ACTION: Proposed rule.

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SUMMARY: The Nuclear Regulatory Commission (NRC) is amending its

regulations to provide light-water nuclear power reactor licensees with

greater flexibility in meeting the requirement that licensees

authorized to possess more than a small amount of special nuclear

material (SNM) maintain a criticality monitoring system in each area

where the material is handled, used, or stored. This action is taken as

a result of the experience gained in processing and evaluating a number

of exemption requests from power reactor licensees and NRC's safety

assessments in response to these requests that concluded that the

likelihood of criticality was negligible.

DATES: Comments on the proposed rule must be received on or before

January 2, 1998.

ADDRESSES: Mail comments to: Secretary, U.S. Nuclear Regulatory

Commission, Washington, DC 20555-0001, Attention: Rulemaking and

Adjudication Staff. Hand deliver comments to 11555 Rockville Pike,

Maryland, between 7:45 am and 4:15 pm on Federal workdays.

Copies of any comments received may be examined at the NRC Public

Document Room, 2120 L Street NW. (Lower Level), Washington, DC.

For information on submitting comments electronically, see the

discussion under Electronic Access in the Supplementary Information

section.

FOR FURTHER INFORMATION CONTACT: Stan Turel, Office of Nuclear

Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC

20555-0001, telephone (301) 415-6234, e-mail [email protected].

SUPPLEMENTARY INFORMATION: For additional information see the Direct

Final Rule published in the rules section of this Federal Register.

Procedural Background

Supplementary Information

section.

FOR FURTHER INFORMATION CONTACT: Stan Turel, Office of Nuclear

Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC

20555-0001, telephone (301) 415-6234, e-mail [email protected].

SUPPLEMENTARY INFORMATION: For additional information see the Direct

Final Rule published in the rules section of this Federal Register.

Procedural Background

Because NRC considers this action noncontroversial and routine, we

are publishing this proposed rule concurrently as a direct final rule.

The direct final rule will become effective on February 17, 1998.

However, if the NRC receives significant adverse comments on the direct

final rule by January 2, 1998, then the NRC will publish a document

that withdraws the direct final rule. If the direct final rule is

withdrawn, the NRC will address in a Final Rule the comments received

in response to the proposed revisions in a subsequent final rule.

Absent significant modifications to the proposed revisions requiring

republication, the NRC will not initiate a second comment period for

this action in the event the direct final rule is withdrawn.

Electronic Access

You may also provide comments via the NRC's interactive rulemaking

web site through the NRC home page (http://www.nrc.gov). This site

provides the availability to upload comments as files (any format), if

your web browser supports that function. For information about the

interactive rulemaking site, contact Ms. Carol Gallagher, (301) 415-

6215; e-mail [email protected].

List of Subjects

10 CFR Part 50

Antitrust, Classified information, Criminal penalties, Fire

prevention, Intergovernmental relations, Nuclear power plants and

reactors, Radiation protection, Reactor siting criteria, Reporting and

recordkeeping requirements.

10 CFR Part 70

ormation about the

interactive rulemaking site, contact Ms. Carol Gallagher, (301) 415-

6215; e-mail [email protected].

List of Subjects

10 CFR Part 50

Antitrust, Classified information, Criminal penalties, Fire

prevention, Intergovernmental relations, Nuclear power plants and

reactors, Radiation protection, Reactor siting criteria, Reporting and

recordkeeping requirements.

10 CFR Part 70

Criminal penalties, Hazardous materials transportation, Material

control and accounting, Nuclear materials, Packaging and containers,

Radiation protection, Reporting and recordkeeping requirements,

Scientific equipment, Security measures, Special nuclear material.

For the reasons set out in the preamble and under the authority of

the Atomic Energy Act of 1954, as amended, the Energy Reorganization

Act of 1974, as amended, the National Environmental Policy Act of 1969,

as amended, and 5 U.S.C. 553, the NRC is considering adopting the

following amendments to 10 CFR Parts 50 and 70.

PART 50--DOMESTIC LICENSING OF PRODUCTION AND UTILIZATION

FACILITIES

1. The authority citation for 10 CFR Part 50 continues to read as

follows:

Authority: Secs. 102, 103, 104, 105, 161, 182, 183, 186, 189, 68

Stat. 936, 937, 938, 948, 953, 954, 955, 956, as amended, sec. 234,

83 Stat. 444, as amended (42 U.S.C. 2132, 2133, 2134, 2135, 2201,

2232, 2233, 2236, 2239, 2282); secs. 201, as amended, 202, 206, 88

Stat. 1242, as amended 1244, 1246, (42 U.S.C. 5841, 5842, 5846).

Section 50.7 also issued under Pub. L. 95-601, sec. 10, 92 Stat.

2951, as amended by Pub. L. 102-486, sec. 2902, 106 Stat. 3123, (42

U.S.C. 5851). Sections 50.10 also issued under secs. 101, 185, 68

Stat. 936, 955, as amended (42 U.S.C. 2131, 2235); sec. 102, Pub. L.

91-190, 83 Stat. 853 (42 U.S.C. 4332). Sections 50.13, 50.54(dd),

and 50.103 also issued under sec. 108, 68 Stat. 939, as amended (42

U.S.C. 2138). Sections 50.23, 50.35, 50.55, and 50.56 also issued

under sec. 185, 68 Stat. 955 (42 U.S.C. 2235)

f Licenses and Construction Permits'' to

read as follows:

Sec. 50.68 Criticality accident requirements.

(a) Each holder of a construction permit or operating license for a

nuclear power reactor issued under this part, or a combined license for

a nuclear power reactor issued under part 52 of this chapter shall

comply with either 10 CFR 70.24 of this chapter or requirements in

paragraph (b).

(b) Each licensee shall comply with the following requirements in

lieu of maintaining a monitoring system capable of detecting a

criticality as described in 10 CFR 70.24:

(1) Plant procedures may not permit handling and transportation at

any one time of more fuel assemblies than have been determined to be

safely subcritical under the most adverse moderation conditions

feasible by unborated water.

(2) The estimated ratio of neutron production to neutron absorption

and leakage (k-effective) of the fresh fuel in the fresh fuel storage

racks shall be calculated assuming the racks are loaded with fuel of

the maximum permissible U-235 enrichment and flooded with pure water

and must not exceed 0.95, at a 95 percent probability, 95 percent

confidence level.

(3) If optimum moderation of fresh fuel in the fresh fuel storage

racks occurs when the racks are assumed to be loaded with fuel of the

maximum permissible U-235 enrichment and filled with low-density

hydrogenous fluid, the k-effective corresponding to this optimum

moderation must not exceed 0.98, at a 95 percent probability, 95

percent confidence level.

bility, 95 percent

confidence level.

(3) If optimum moderation of fresh fuel in the fresh fuel storage

racks occurs when the racks are assumed to be loaded with fuel of the

maximum permissible U-235 enrichment and filled with low-density

hydrogenous fluid, the k-effective corresponding to this optimum

moderation must not exceed 0.98, at a 95 percent probability, 95

percent confidence level.

(4) If no credit for soluble boron is taken, the k-effective of the

spent fuel storage racks loaded with fuel of the maximum permissible U-

235 enrichment must not exceed 0.95, at a 95 percent probability, 95

percent confidence level, if flooded with pure water. If credit is

taken for soluble boron, the k-effective of the spent fuel storage

racks loaded with fuel of the maximum permissible U-235 enrichment must

not exceed 0.95, at a 95 percent probability, 95 percent confidence

level, if flooded with borated water, and the k-effective must remain

below 1.0 (subcritical), at a 95 percent probability, 95 percent

confidence level, if flooded with pure water.

(5) The quantity of SNM, other than nuclear fuel stored on site, is

less than the quantity necessary for a critical mass.

(6) Radiation monitors, as required by GDC 63, are provided in

storage and associated handling areas when fuel is present to detect

excessive radiation levels and to initiate appropriate safety actions.

(7) The maximum nominal U-235 enrichment of the fresh fuel

assemblies is limited to no greater than five (5.0) percent by weight.

PART 70--DOMESTIC LICENSING OF SPECIAL NUCLEAR MATERIAL

1. The authority citation for 10 CFR Part 70 continues to read as

follows:

and associated handling areas when fuel is present to detect

excessive radiation levels and to initiate appropriate safety actions.

(7) The maximum nominal U-235 enrichment of the fresh fuel

assemblies is limited to no greater than five (5.0) percent by weight.

PART 70--DOMESTIC LICENSING OF SPECIAL NUCLEAR MATERIAL

1. The authority citation for 10 CFR Part 70 continues to read as

follows:

Authority: Secs. 51, 53, 161, 182, 183, 68 Stat. 929, 930, 948,

953, 954, as amended, sec. 234, 83 Stat. 444, as amended, sec. 1701,

106 Stat. 2951, 2952, 2953 (42 U.S.C. 2071, 2073, 2201, 2232, 2233,

2282, 2297f); secs. 201, as amended, 202, 204, 206, 88 Stat. 1242,

as amended, 1244, 1245, 1246, (42 U.S.C. 5841, 5842, 5845, 5846).

Sections 70.1(c) and 70.20a(b) also issued under secs. 135, 141,

Pub. L. 97-425, 96 Stat. 2232, 2241 (42 U.S.C. 10155, 10161).

Section 70.7 also issued under Pub. L. 95-601, sec. 10, 92 Stat.

2951 (42 U.S.C. 5851). Section 70.21(g) also issued under sec. 122,

68 Stat. 939 (42 U.S.C. 2152). Section 70.31 also issued under sec.

57d, Pub. L. 93-377, 88 Stat. 475 (42 U.S.C. 2077). Sections 70.36

and 70.44 also issued under sec. 184, 68 Stat. 954, as amended (42

U.S.C. 2234).

Section 70.61 also issued under secs. 186, 187, 68 Stat. 955 (42

U.S.C. 2236, 2237). Section 70.62 also issued under sec. 108, 68

Stat. 939, as amended (42 U.S.C. 2138).

2. In Sec. 70.24, paragraph (d) is revised to read as follows:

Sec. 70.24 Criticality accident requirements.

* * * * *

2077). Sections 70.36

and 70.44 also issued under sec. 184, 68 Stat. 954, as amended (42

U.S.C. 2234).

Section 70.61 also issued under secs. 186, 187, 68 Stat. 955 (42

U.S.C. 2236, 2237). Section 70.62 also issued under sec. 108, 68

Stat. 939, as amended (42 U.S.C. 2138).

2. In Sec. 70.24, paragraph (d) is revised to read as follows:

Sec. 70.24 Criticality accident requirements.

* * * * *

(d) The requirements in paragraph (a) through (c) of this section

do not apply to holders of a construction permit or operating license

for a nuclear power reactor issued pursuant to part 50 of this chapter,

or combined licenses issued under part 52 of this chapter, if the

holders comply with the requirements of paragraph (b) of 10 CFR 50.68

of this chapter.

Dated at Rockville, Maryland this 14th day of November, 1997.

For the Nuclear Regulatory Commission.

L. Joseph Callan,

Executive Director for Operations.

[FR Doc. 97-31732 Filed 12-2-97; 8:45 am]

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