[Federal Register Volume 61, Number 21 (Wednesday, January 31, 1996)]
[Notices]
[Pages 3511-3512]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-1868]



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NUCLEAR REGULATORY COMMISSION
[Docket No. 50-352]


Philadelphia Electric Company (Limerick Generating Station, Unit 
1)

Exemption

I

    The Philadelphia Electric Company (the licensee) is the holder of 
Facility Operating License No. NPF-39, which authorizes operation of 
the Limerick Generating Station (LGS), Unit 1. The license provides, 
among other things, that the licensee is subject to all rules, 
regulations, and orders of the Nuclear Regulatory Commission (the 
Commission) now or hereafter in effect.
    The LGS, Unit 1 facility consists of a boiling water reactor, 
located in Chester and Montgomery Counties, Pennsylvania.

II

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

III

    By a June 20, 1995 letter, the licensee requested a one-time 
exemption from the requirement to perform a set of three Type A tests 
at approximately equal intervals during each 10-year service period. 
The requested exemption would permit a one-time interval extension of 
the third Type A test and would permit the third Type A test of the 
first 10-year ISI 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 and to be performed in 
the seventh refueling outage. The proposed action is requested to allow 
the licensee to realize cost savings and reduced worker radiation.
    Subsequent to the licensee's submittal, a rulemaking was completed 
on Appendix J (60 FR 49495, September 26, 1995) which allows the Type A 
test to be performed at intervals up to once every 10 years. However, 
because the licensee's outage is scheduled to begin in January 1996, 
there is insufficient time for the licensee to implement the amended 
rule prior to the start of the outage.
    The licensee was previously granted a similar exemption on February 
16, 1994 (59 FR 9257). This 1994 exemption and the related license 
amendment (Amendment No. 67) allowed the licensee to perform its third 
Type A test during the 10-year plant ISI refueling outage by extending 
the test interval between the second and third test to approximately 65 
months.
    The licensee's request cites the special circumstances of 10 CFR 
50.12, paragraph (a)(2), as the basis for the exemption. The licensee 
also stated 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. Data, 
supplied by the licensee, from the first (August 1989) and second 
(November 1990) ILRTs at LGS, Unit 1, indicate that most of the 
measured leakage is from the containment penetrations and not from the 
containment barrier. The ``as-left'' leakage rate was well below the 10 
CFR Part 50, Appendix J limit. Appendix J requires the leakage rate to 
be less than 75% of La to allow for deterioration in leakage paths 
between tests. The allowable leakage rate, La, is 0.5 wt.%/day. 
Therefore, the established acceptable limit is <0.375 wt.%/day. The as-
left leakage rates for the first two ILRTs were 0.178 and 0.334 wt.%/
day, which are below the acceptable limit. The Type B and C test (Local 
Leakage Rate Test or LLRT) program also provides assurance that 
containment integrity has been maintained. LLRTs demonstrate 
operability of components and penetrations by measuring penetration and 
valve leakage.

IV

    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; 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 rule is to ensure that any potential 
leakage pathways through the containment boundary are identified such 
that leakage will not exceed allowable leakage rate values. The NRC 
staff has reviewed the basis and supporting information provided by the 
licensee in its exemption request. The NRC staff notes that the first 
and second ILRTs of the set of three tests for the first 10-year 
service period were conducted in August 1987 and November 1990. The 
third ILRT will be scheduled for Refueling Outage 7, projected to start 
in April 1998. In a September 29, 1995 phone call, the licensee stated 
to the NRC staff that they 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 regulatory guide (i.e., Regulatory Guide 1.163) 
accompanying Appendix J Option B specifies that the containment 
inspections be performed more often than the Type A tests.
    The NRC staff has also made use of the information supporting the 
revised Appendix J, including NUREG-1493, which provides the technical 
justification for the 10-year test interval for Type A tests. The 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 Type B and C testing. 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 that 
LLRT could not detect. This is 3% of all failures. This study agrees 
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 called 
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 shows that in about one-third of the cases exceeding allowable 
leakage, the as-found leakage was lessthan 2La; in one case the 
leakage was 

[[Page 3512]]
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. KFor about half of 
the failed ILRTs, the as-found leakage was not quantified. These data 
show that, for those ILRTs for which 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). Therefore, based on these considerations, it is unlikely 
that an extension of another cycle for the performance of the Appendix 
J, Type A test at LGS Unit 1 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 
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 schedule extension of an additional one cycle, to 
the seventh refueling outage, for the performance of the Appendix J, 
Type A test, provided the general containment inspection is performed 
in the sixth refueling outage, to be acceptable.
    Pursuant to 10 CFR 51.32, the Commission has determined that 
granting this exemption will have no significant effect on the quality 
of the human environment (60 FR 57604).
    This exemption is effective upon issuance, shall supersede the 
exemption dated February 16, 1994 and shall expire at the completion of 
the 1998 refueling outage.

    Dated at Rockville, Maryland this 25th day of January 1996.

    For the Nuclear Regulatory Commission.
Steven A. Varga,
Director, Division of Reactor Projects--I/II, Office of Nuclear Reactor 
Regulation.
[FR Doc. 96-1868 Filed 1-30-96; 8:45 am]
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