[Federal Register Volume 60, Number 84 (Tuesday, May 2, 1995)]
[Notices]
[Pages 21557-21558]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-10729]



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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-410]


Niagara Mohawk Power Corp. (Nine Mile Point Nuclear Station Unit 
2); Exemption

I

    Niagara Mohawk Power Corporation (NMPC or the licensee) is the 
holder of Facility Operating License No. NPF-69, which authorizes 
operation of Nine Mile Point Nuclear Station Unit 2 (the facility/
NMP2), at a steady-state reactor power level not in excess of 3323 
megawatts thermal. The facility is a boiling water reactor located at 
the licensee's site in Oswego County, New York. The license provides 
among other things, that it is subject to all rules, regulations, and 
Orders of the U.S. Nuclear Regulatory Commission (the Commission or 
NRC) now or hereafter in effect.

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 shutdown for the 10-year inservice 
inspection of the primary containment.

III

    By letter dated March 9, 1995, NMPC requested temporary relief for 
NMP2 from the requirement to perform a set of three Type A tests at 
approximately equal intervals during each 10-year service period of the 
primary containment. The requested exemption would permit a one-time 
interval extension of the second Type A test by approximately 18 months 
(from the April 1995 refueling outage, to the late 1996 refueling 
outage).
    The licensee's request cites the special circumstances of 10 CFR 
50.12, paragraph (a)(2)(ii), as the basis for the exemption. The 
existing Type B and C testing programs are not being modified by this 
request and will continue to effectively detect containment leakage 
caused by the degradation of active containment isolation components as 
well as containment penetrations. The licensee has analyzed the results 
of the previous Type A tests performed at NMP2. Two Type A tests 
(including the preoperational test) have been conducted from 1986 to 
date with no failures. Therefore, application of the regulation in the 
particular circumstances 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.
    The licensee proposes an exemption to this section which would 
provide a one-time interval extension for the second Type A test by 
approximately 18 months. 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 approximately equal intervals during the 
10-year service period, is to ensure that any potential leakage 
pathways through the containment boundary are identified within a 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 has noted 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 stated in its submittal that a visual internal 
and external inspection of the mechanical and structural integrity of 
the containment shell is completed during every refueling outage. The 
NRC staff considers these inspections 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, which provides the technical justification for the 
present Appendix J rulemaking effort which also includes a 10-year test 
interval for Type A tests. The integrated leakage rate test, 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 (Type 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 
percent of all failures. This study agrees well with previous NRC staff 
studies which show that Type B and C testing can detect a very large 
percentage of containment leaks. The NMP2 experience has also been 
consistent with these results as previously noted.
    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.OL<INF>a. 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 2L<INF>a; in one case the leakage 
was found to be approximately 2L<INF>a; in one case the as-found 
leakage was less than 3L<INF>a; one case approached 10L<INF>a; and in 
one case the leakage was found to be approximately 21L<INF>a. 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 L<INF>a (approximately 200L<INF>a, as discussed 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 NMP2 would result in significant degradation of the 
overall containment integrity. As a result, the application of the 
regulation in these particular circumstances is not necessary to 
[[Page 21558]] achieve the underlying purpose of the rule.
    Based on generic and plant specific data, the NRC staff finds the 
basis for the licensee's proposed exemption to allow a one-time 
exemption to permit a scheduler extension for NMP2 of one cycle for the 
performance of the Appendix J, Type A test, provided that the visual 
containment inspection is performed, to be acceptable.
    Pursuant to 10 CFR 51.32, the Commission has determined that 
granting this Exemption will not have a significant impact on the 
environment (60 FR 17374).
    This Exemption is effective upon issuance and shall expire at the 
completion of the late 1996 refueling outage.

    Dated at Rockville, Maryland, this 24th day of April 1995.

    For the Nuclear Regulatory Commission.
Steven A. Varga,
Director, Division of Reactor Projects--I/II, Office of Nuclear Reactor 
Regulation.
[FR Doc. 95-10729 Filed 5-1-95; 8:45 am]
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