[Federal Register Volume 60, Number 93 (Monday, May 15, 1995)]
[Notices]
[Pages 25932-25933]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-11860]



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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-245]


Exemption

    In the Matter of Northeast Nuclear Energy Company (Millstone 
Nuclear Power Station, Unit No. 3).

I

    Northeast Nuclear Energy Company, (NNECO, the licensee) is the 
holder of Facility Operating License No. NPF-49, which authorizes 
operation of Millstone Nuclear Power Station, Unit No. 3 (the 
facility). The license provides, among other things, that Millstone 
Unit 3 is subject to all rules, regulations, and Orders of the U.S. 
Nuclear Regulatory Commission (the Commission or NRC) now or hereafter 
in effect.
    The facility is a pressurized water reactor located at the 
licensee's site in New London County, Connecticut.

II

    Section III.D.1.(a) of Appendix J to 10 CFR part 50 requires the 
performance of three Type A containment integrated leakage rate tests 
(ILRTs), at approximately equal intervals during each 10-year service 
period of the primary containment. The third test of each set shall be 
conducted when the plant is shut down for the 10-year inservice 
inspection of the primary containment.

III

    By letter dated September 28, 1994, as supplemented February 24, 
1995, Northeast Nuclear Energy Company requested exemptions from 10 CFR 
part 50, Appendix J, Section III.D.1.(a) for Millstone Unit 3 (1) to 
eliminate the requirement to perform the third Type A test coincident 
with the 10-year American Society of Mechanical Engineers (ASME) 
inservice inspections, and (2) to extend the 10-year Appendix J test 
until refueling outage 6, a nominal increase of 12 months. These 
exemptions would permit the licensee to perform the third Type A test 
of the first 10-year period during refueling outage 6 scheduled for 
April 1997 rather than during the refueling outage 5.
    The licensee's request cites the special circumstance of 10 CFR 
50.12(a)(2)(ii), as the basis for these exemptions. This special 
circumstance states that the application of the regulation in this 
particular circumstance is not necessary to achieve the underlying 
purpose of the rule.

IV

    Section III.D.1.(a) of Appendix J to 10 CFR part 50 states that a 
set of three Type A leakage rate tests shall be performed at 
approximately equal intervals during each 10-year service period. 
Section III.D.1.(a) also requires that the third Type A test of each 
10-year service period be conducted when the plant is shut down for the 
10-year plant inservice inspections.
    The licensee proposes two exemptions to this section. These 
exemptions would (1) extend the 10-year Appendix J test interval to 
refueling outage 6, a nominal increase of 12 months, and (2) eliminate 
the requirement to perform the third Type A test coincident with the 
10-year ASME inservice inspections.
    The Commission has determined, for the reasons discussed below, 
that pursuant to 10 CFR 50.12(a)(1) this exemption is authorized by 
law, will not present an undue risk to the public health and safety, 
and is consistent with the common defense and security. The Commission 
further determines that special circumstances, as provided in 10 CFR 
50.12(a)(2)(ii), are present justifying the exemption; namely, that 
application of the regulation in the particular circumstances is not 
necessary to achieve the underlying purpose of the rule. The underlying 
purpose of the requirement to perform Type A containment leak rate 
tests at intervals during the 10-year service period is to ensure that 
any leakage through the containment boundary is identified within a 
limited time span that prevents significant degradation from continuing 
or becoming unknown.
    The NRC staff has reviewed the basis and supporting information 
provided by the licensee in the exemption request. The NRC staff notes 
that the licensee has a good record of ensuring a leak-tight 
containment. All Type A tests have passed with significant margin and 
the licensee has noted that the results of the Type A testing have been 
confirmatory of the Type B and C tests which will continue to be 
performed. The licensee has stated to the NRC Project Manager that the 
general containment inspection will be performed during refueling 
outage 5 although it is only required by Appendix J (Section V.A.) to 
be performed in conjunction with Type A tests. The NRC staff considers 
that these inspections, though limited in scope, provide an important 
added level of confidence in the continued integrity of the containment 
boundary.
    The NRC staff has also made use of the information in a draft staff 
report, NUREG-1493 ``Performance-Based Containment Leak-Test Program,'' 
which provides the technical justification for the present Appendix J 
rulemaking results of the effort which includes a 10-year test interval 
for Type A tests. The integrated leakage rate test, [[Page 25933]] or 
Type A test, measures overall containment leakage. However, operating 
experience with all types of containments used in this country 
demonstrates that essentially all containment leakage can be detected 
by local leakage rate tests (Types B and C). According to results given 
in NUREG-1493, out of 180 ILRT reports covering 110 individual reactors 
and approximately 770 years of operating history, only 5 ILRT failures 
were found which local leakage rate testing could not detect. This is 
3% of all failures. This study agrees well with previous NRC staff 
studies which show that Types B and C testing can detect a very large 
percentage of containment leaks. The Millstone Unit 3 experience has 
also been consistent with these results.
    The Nuclear Management and Resources Council (NUMARC), now the 
Nuclear Energy Institute (NEI), collected and provided the NRC staff 
with summaries of data to assist in the Appendix J rulemaking effort. 
NUMARC collected results of 144 ILRTs from 33 units; 23 ILRTs exceeded 
1.0La. Of these, only nine were not due to Type B or C leakage 
penalties. The NEI data also added another perspective. The NEI data 
show that in about one-third of the cases exceeding allowable leakage, 
the as-found leakage was less than 2La; in one case the leakage 
was found to be approximately 2La; in one case the as-found 
leakage was less than 3La; one case approached 10La; and in 
one case the leakage was found to be approximately 21La. For about 
half of the failed ILRTs the as-found leakage was not quantified. These 
data show that, for those ILRTs for which the leakage was quantified, 
the leakage values are small in comparison to the leakage value at 
which the risk to the public starts to increase over the value of risk 
corresponding to La (approximately 200La, as discussed in 
NUREG-1493).
    The licensee also addressed the possible increase in risk due to 
extending this test interval. The licensee concluded that any increase 
in risk would be negligible. This is consistent with independent staff 
studies documented in NUREG-1493.
    Therefore, based on these considerations, it is unlikely that an 
extension of one cycle for the performance of the Appendix J, Type A 
test at Millstone Unit 3 would result in significant degradation of the 
overall containment integrity. Likewise, performance of the third test 
in a refueling outage other than when the plant is shut down for the 
10-year plant inservice inspections has no connection to the detection 
of overall containment degradation. As a result, the application of the 
regulation in these particular circumstances is not necessary to 
achieve the underlying purpose of the rule.
    The preoperational Type A test required by Appendix J was performed 
in July 1985. Millstone Unit 3 started commercial operation on April 
23, 1986. The staff considers this date to also be the start of the 
licensee's first 10-year Type A test period. The extension of the Type 
A test interval for Millstone Unit 3 discussed in this document is 
referenced to this starting date. Based on generic and plant specific 
data, the NRC staff finds the basis for the licensee's proposed 
exemptions to be acceptable.
    Pursuant to 10 CFR 51.32, the Commission has determined that 
granting this Exemption will have no significant impact on the quality 
of the human environment (60 FR 22415).
    This Exemption is effective upon issuance and shall expire at the 
completion of the 1997 refueling outage.

    Dated at Rockville, Maryland, this 8th day of May 1995.

    For the Nuclear Regulatory Commission.
Steven A. Varga,
Director, Division of Reactor Projects--I/II, Office of Nuclear Reactor 
Regulation.
[FR Doc. 95-11860 Filed 5-12-95; 8:45 am]
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