[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]
BILLING CODE 7590-01-M
