Nebraska Public Power District, Cooper Nuclear Station; Environmental Assessment and Finding of No Significant Impact

NUCLEAR REGULATORY COMMISSION

[Docket No. 50-298]

Nebraska Public Power District, Cooper Nuclear Station;

Environmental Assessment and Finding of No Significant Impact

The U.S. Nuclear Regulatory Commission (the Commission) is

considering the issuance of an exemption from certain requirements of

its regulations to Facility Operating License Number DPR-46. This

license was issued to the Nebraska Public Power District (the licensee)

for operation of the Cooper Nuclear Station (CNS) located in Nemaha

County, Nebraska.

Environmental Assessment

Identification of the Proposed Action

The licensee requested, in its application dated May 13, 1994, an

exemption from the pressure test requirements of Section III.D.2(b)(ii)

of Appendix J, ``Primary Reactor Containment Leakage Testing For Water-

Cooled Power Reactors,'' to 10 CFR Part 50 (Appendix J to 10 CFR Part

50). The staff discussed the details of the proposed exemption with the

licensee in a telephone conference call on September 28, 1995. The

proposed exemption would allow the licensee to leak test the personnel

air lock at CNS at a test pressure less than Pa, (the calculated

peak containment internal pressure resulting from the containment

design basis accident), under certain conditions. The reduced pressure

test of the air lock would be conducted as the first of two tests

during a restart from refueling or cold shutdown, prior to entry into

an operational mode requiring containment leaktight integrity by the

CNS Technical Specifications (TSs). As stated in CNS TS 4.7.A.2.f.5,

for periodic leakage testing of the personnel air lock, Pa is 58

psig and the reduced test pressure is 3 psig.

This leakage test is part of the Type B tests required by Appendix

J to 10 CFR Part 50 to verify containment integrity. Because an air

lock allows entry into the containment and is part of the containment

pressure boundary, excessive leakage through the air lock could

compromise containment integrity. The air lock consists of an inner and

outer door and the leakage test is performed by pressurizing the space

between the doors.

[[Page 57251]]

The Need for the Proposed Action

Section III.D.2 of Appendix J to 10 CFR Part 50 specifies the

required periodic retest schedule for Type B tests, including testing

of air locks. Pursuant to Section III.D.2(b)(ii), licensees are

required to leakage test air locks, opened during periods when

containment integrity is not required by the TSs, at the end of such

periods. This section applies to testing of air locks during restart

from refueling or cold shutdown because the CNS TSs do not require

containment integrity for either of these operational modes. This

section states that the air lock test shall be performed at a pressure

that is not less than Pa.

The proposed exemption is concerned with Section III.D.2(b)(ii);

however, there are two other sections in Appendix J which have

requirements on testing air locks. Section III.D.2(b)(i) requires an

air lock test every 6 months at a test pressure of Pa and, as

relevant here, Section III.D.2(b)(iii) requires a test every 3 days

when the air lock is used during a period when containment integrity is

required by the TSs. The latter section requires the test pressure to

be Pa, or the test pressure specified in the TSs, which for CNS is

stipulated as 3 psig in TS 4.7.A.2.f.5.

The licensee stated in its application that it currently tests the

personnel air lock twice during the restart of the plant for power

operation from refueling or cold shutdown: (1) Prior to the reactor

being taken critical, or the reactor water temperature being above

100 deg.C (212 deg.F), and (2) after the last entry into containment

for leak inspection during restart. The time between the two tests is

about 24 to 48 hours, and the second test is at low reactor power prior

to entry into the run mode, the full power mode of operation.

The first test is in accordance with Section III.D.2(b)(ii) and is

performed at the conclusion of the period when containment integrity is

not required by the TSs. This test is conducted prior to entry into an

operational mode requiring containment integrity. The second test is in

accordance with Section III.D.2(b)(iii) and is performed at 3-day

intervals while the air lock is being used when containment integrity

is required. As stated above, in accordance with this section, the

second test could be conducted at a test pressure of 3 psig at CNS

because this pressure is stated in TS 4.7.A.2.f.5. However, because the

licensee also performs the second test to meet the 6-month interval

requirement in Section III.D.2(b)(i), the second test is conducted at

Pa. If this second test is not necessary to satisfy the 6-month

interval test requirement, there is no requirement that the licensee

conduct it at Pa.

When no maintenance or repairs have been performed on the air lock

that could affect its sealing capability and the periodic 6-month test

at Pa has been performed successfully, opening of the air lock

during a plant shutdown or refueling outage is not a reason to expect

it to leak in excess of the requirements. When the air lock is tested

at a pressure less than Pa in preparation for restart from

refueling or cold shutdown, under such conditions, and the air lock has

been successfully tested at Pa within the previous six months,

containment integrity is assured. If, however, maintenance or repairs

have been performed on the air lock affecting its sealing capability

since the last 6-month test, the first test prior to entering a

condition which requires containment integrity must meet the test

pressure requirements of Section III.D.2(b)(ii) and be conducted at a

test pressure not less than Pa.

In testing the air lock at reduced pressure, a strongback

(structural bracing) would not have to be installed on the inner air

lock door. During the test, the space between the inner and outer doors

is pressurized. The strongback is needed when the test pressure is

Pa because the pressure exerted on the inner door during the test

is in a direction opposite to the pressure on the inner door during an

accident, and Pa is sufficiently high to damage the inner door

during the test without the strongback. The reduced pressure test would

be conducted at 3 psig, and the strongback would not be needed to

protect the inner door during the test.

Installing a strongback, performing the test, and removing the

strongback requires several hours during which access through the air

lock is prohibited. The strongback is attached to the door inside

containment where personnel would be exposed to radiation inside

containment. The reduced pressure test could be conducted without the

strongback and, thus, in a shorter time with less occupational exposure

to CNS personnel involved with the test. Because the second test is

conducted at Pa, not performing the first test at Pa will

reduce the number of such tests using strongbacks and, therefore, will

reduce the time involved in performing the tests and the magnitude of

occupational exposure at CNS.

The licensee is, therefore, proposing to conduct the first test

during restart at a test pressure of 3 psig, which is less than

Pa, which is not presently allowed by Section III.D.2(b)(ii). The

air lock leakage measured for the reduced test pressure would be

extrapolated to a value consistent with Pa, then that value would

be compared to the acceptance criteria in Appendix J for Type B tests

to confirm that containment integrity is verified. If containment

integrity is verified, the measured air lock leakage is considered

acceptable.

Environmental Impacts of the Proposed Action

The Commission has completed its evaluation of the licensee's

request. The proposed exemption does not change the number of air lock

tests to verify containment integrity upon plant restart, the manner in

which the second test is conducted, the time when the tests would be

conducted, nor the acceptance criteria for the tests. Thus, the

assurance of containment integrity would be maintained at a level

consistent with current Appendix J requirements. The proposed exemption

would also not change other requirements in Appendix J for periodic

testing of the air lock at Pa, and would not change the existing

CNS safety limits, safety settings, power operations, or effluent

limits. The proposed exemption would effectively replace the test

pressure requirement in Section III.D.2(b)(ii) with that in Section

III.D.2(b)(iii), in that the latter section allows for reduced pressure

testing of air locks in accordance with plant TSs.

The change will not increase the probability or consequences of

accidents, no changes are being made in the types of any effluents that

may be released offsite, and there is no significant increase in the

allowable individual or cumulative occupational radiation exposure.

Accordingly, the Commission concludes that there are no significant

radiological environmental impacts associated with the proposed action.

With regard to potential nonradiological impacts, the proposed

action does involve features located entirely within the restricted

area as defined in 10 CFR Part 20. It does not affect nonradiological

plant effluents and has no other environmental impact. Accordingly, the

Commission concludes that there are no significant nonradiological

environmental impacts associated with the proposed action.

Alternatives to the Proposed Action

Since the Commission has concluded that there is no measurable

environmental impact associated with the proposed action, any

alternatives with equal or greater environmental impact need not be

evaluated. As an alternative to the proposed action, the staff

considered denial of the requested

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exemption. Denial of the application would result in no change in

current environmental impacts. The environmental impacts of the

proposed action and the alternative action are similar, but the

proposed action would reduce occupational exposure at CNS.

Alternative Use of Resources

This action does not involve the use of any resources not

previously considered in the Final Environmental Statement for the

Cooper Nuclear Station, dated February 1973.

Agencies and Persons Consulted

In accordance with its stated policy, on October 19, 1995, the

staff consulted with the Nebraska State official, Ms. Julia Schmidt,

Division of Radiological Health, Nebraska Department of Health,

regarding the environmental impact of the proposed action. The State

official had no comments.

Finding of No Significant Impact

Based upon the environmental assessment, the Commission concludes

that the proposed action will not have a significant effect on the

quality of the human environment. Accordingly, the Commission has

determined not to prepare an environmental impact statement for the

proposed action.

For further details with respect to this action, see the licensee's

request for an exemption dated May 13, 1994, which is available for

public inspection at the Commission's Public Document Room, The Gelman

Building, 2120 L Street, NW, Washington, DC, and at the local public

document room located at the Auburn Public Library, 118 15th Street,

Auburn, Nebraska 68305.

Dated at Rockville, Maryland, this 6th day of November 1995.

For the Nuclear Regulatory Commission.

James R. Hall,

Senior Project Manager, Project Directorate IV-1, Division of Reactor

Projects III/IV, Office of Nuclear Reactor Regulation.

[FR Doc. 95-28028 Filed 11-13-95; 8:45 am]

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