[Federal Register Volume 60, Number 47 (Friday, March 10, 1995)]
[Notices]
[Pages 13186-13187]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-5938]



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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-281]


Virginia Electric and Power Company (Surry Power Station Unit No. 
2); Exemption

I

    Virginia Electric and Power Company (the licensee) is the holder of 
Facility Operating License No. DPR-37, which authorizes operation of 
Surry Power Station, Unit 2 (the facility), at a steady-state reactor 
power level not in excess of 2441 megawatts thermal. The facility is a 
pressurized water reactor located at the licensee's site in Surry 
County, Virginia. 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) of the primary containment, at approximately equal intervals 
during each 10-year service period. The third test of each set shall be 
conducted when the plant is shut down for the 10-year inservice 
inspection program.

III

    By letter dated February 14, 1995, the licensee requested temporary 
relief 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 third Type A test by approximately 15 months 
(from the February 1995 refueling outage, to the May 1996 refueling 
outage) and would permit the third Type A test of the second 10-year 
inservice inspection period to not correspond with the end of the 
current American Society of Mechanical Engineers Boiler and Pressure 
Vessel Code (ASME Code) inservice inspection interval.
    The licensee's request cites the special circumstances of 10 CFR 
50.12, paragraph (a)(2)(ii), as the basis for the exemption. The 
licensee points out that 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. 
It has been the experience at Surry Unit 2 during the Type A tests 
conducted from 1985 to date, that the Type A tests have not identified 
any significant sources of leakage in addition to those found by the 
Type B and C tests.
    During operation, the Surry Unit 2 containment is maintained at a 
subatmospheric pressure (approximately 10.0 psia) which provides a good 
indication of the containment integrity. Technical Specifications 
require the containment to be subatmospheric whenever Reactor Coolant 
System temperature and pressure exceeds 350 deg.F and 450 psig, 
respectively. Containment air partial pressure is monitored in the 
control room to ensure Technical Specification compliance. If the 
containment air partial pressure increases above the established 
Technical Specification limit, the unit is required to shut down.

IV

    In the licensee's February 14, 1995, exemption request, the 
licensee stated that special circumstances 50.12(a)(2)(ii) is 
applicable to this situation, i.e., that application of the regulation 
is not necessary to achieve the underlying purpose of the rule.
    Appendix J states that the leakage test requirements provide for 
periodic verification by tests of the leak tight integrity of the 
primary reactor containment. Appendix J further states that the purpose 
of the tests ``is to assure that leakage through the primary reactor 
containment shall not exceed the allowable leakage rate values as 
specified in the Technical Specifications or associated bases''. Thus, 
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 potential leakage pathways through the containment 
boundary are identified within a time span that prevents significant 
degradation from continuing or becoming unknown. [[Page 13187]] 
    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's record of ensuring a leak-tight containment 
has improved markedly since 1985. All ``as-found'' Type A tests since 
1985 have passed and 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 will perform the general containment inspection 
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 Surry Unit 2 containment is of the subatmospheric design. 
During operation, the containment is maintained at a subatmospheric 
pressure (approximately 10 psia) which provides for constant monitoring 
of the containment integrity and further obviates the need for Type A 
testing at this time. If the containment air partial pressure exceeds 
the established Technical Specification limit, the unit must be shut 
down.
    The NRC staff has also made use of 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% 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 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 
1.0L<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 those considerations, it is unlikely 
that an extension of one cycle for the performance of the Appendix J, 
Type A test at Surry, Unit 2, would result in significant degradation 
of the overall containment integrity. As a result, the application of 
the regulation in these particular circumstances is not needed to 
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 schedular extension of one cycle for the 
performance of the Appendix Type A test, provided that the general 
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 11997).
    This Exemption is effective upon issuance and shall expire at the 
completion of the 1996 refueling outage.

    Dated at Rockville, Maryland this 3rd day of March 1995.

    For the Nuclear Regulatory Commission.
Steven A. Varga,
Director, Division of Reactor Projects--I/II, Office of Nuclear Reactor 
Regulation.
[FR Doc. 95-5938 Filed 3-9-95; 8:45 am]
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