[Federal Register Volume 60, Number 36 (Thursday, February 23, 1995)]
[Notices]
[Pages 10122-10123]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-4383]



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NUCLEAR REGULATORY COMMISSION
[Docket Nos. 50-352 and 50-353]


In the Matter of: Philadelphia Electric Company (Limerick 
Generating Station, Units 1 and 2); Exemption

I.

    Philadelphia Electric Company (the licensee), is the holder of 
Facility Operating License Nos. NPF-39 and NPF-85, which authorize 
operation of the Limerick Generating Station (LGS), Units 1 and 2. The 
licenses provide, among other things, that the licensee is subject to 
all rules, regulations, and orders of the Nuclear Regulatory Commission 
(the Commission) now and hereafter in effect. The facilities consist of 
two boiling water reactors located in Montgomery County, Pennsylvania.

II

    Section 50.54(o) of 10 CFR Part 50 requires that primary reactor 
containments for water cooled power reactors be subject to the 
requirements of Appendix J to 10 CFR Part 50. Appendix J contains the 
leakage test requirements, schedules, and acceptance criteria for tests 
of the leak tight integrity of the primary reactor containment and 
systems and components which penetrate the containment. Sections II.H.4 
and III.C.2 of Appendix J to 10 CFR Part 50 require leak rate testing 
of Main Steam Isolation Valves (MSIVs) at the calculated peak 
containment pressure related to the design basis accident, and Section 
III.C.3 requires that the measured leak rates be included in the 
combined local leak rate test results. The proposed deletion of the 
MSIV Leakage Control System (LCS), and proposed use of an alternate 
leakage pathway affects the description of an existing exemption which 
allows the leak rate testing of the MSIVs at a reduced pressure and the 
exclusion of the measured leakage from the combined local leak rate 
test results. The original exemption is contained in the LGS Safety 
Evaluation Report (SER) (NUREG-0991, and its Supplement 3).
    By letter dated December 22, 1994, the licensee requested an 
exemption from the Commission's regulations. The subject exemption is 
from the requirements of 10 CFR Part 50, Appendix J, ``Primary Reactor 
Containment Leakage Testing for Water-Cooled Power Reactors,'' Sections 
II.H.4, III.C.2, and III.C.3, to allow alternative testing pressure and 
leakage limits for the MSIVs and to exclude MSIV leakage from the 
combined local leak rate test results after deletion of the LCS.
    The staff issued for LGS, Units 1 and 2, the current exemption from 
10 CFR Part 50, Appendix J, Sections II.H.4, III.C.2, and III.C.3, 
based on the conclusion that the LGS, Units 1 and 2, MSIV leak testing 
methods were acceptable alternatives to the requirements. This 
conclusion was included in the LGS SER (NUREG-0991, and its Supplement 
3). The SER also described that in the event of a loss-of-coolant-
accident (LOCA), the MSIV LCS will maintain a negative pressure between 
the MSIV and the effluent will be discharged into a volume where it 
will be processed by the standby gas treatment system before being 
released to the environment. The licensee had performed a radiological 
analysis based on an assumed leak rate limit of 11.5 standard cubic 
feet per hour (scfh), and the MSIVs were planned to be periodically 
tested to ensure the validity of the radiological analysis. The staff 
concluded that the current LGS testing procedure, where two valves on 
one steam line are tested simultaneously, between the valves, utilizing 
a reduced test pressure (i.e., half a peak containment pressure of 22 
psig applied between the MSIVs) was acceptable. Also, the staff 
excluded the MSIV test leakage rate from the combined local leak rate 
because the MSIV leakage had been accounted for separately in the 
radiological analysis of the site.
    By letter dated January 14, 1994, the licensee submitted a 
Technical Specifications (TS) amendment request for LGS, Units 1 and 2, 
which supports the planned modification to eliminate the MSIV LCS and 
utilize an alternate leakage pathway (main steam lines and condenser). 
This proposal is based on the Boiling Water Reactor Owners Group 
(BWROG) method summarized in General Electric Report NEDC-31858P, 
Revision 2, ``BWROG Report for increasing MSIV Leakage Rate Limits and 
Elimination of Leakage Control System.'' Therefore, the description of 
the MSIV LCS and the assumed MSIV leak rate are no longer accurate once 
the proposed TS modification is performed and implemented.
    The licensee's January 14, 1994, TS (amendment) request states that 
a plant-specific radiological analysis has been performed in accordance 
with NEDC-31858P, Revision 2, to assess the effects of the proposed 
increase to the allowable MSIV leakage rate in terms of Main Control 
Room (MCR) and off-site doses following a postulated design basis LOCA. 
This analysis utilizes the hold-up volume of the main steam piping and 
condenser as an alternate method for treating MSIV leakage. The 
radiological analysis uses standard conservative assumptions for the 
radiological source term consistent with Regulatory Guide (RG) 1.3, 
``Assumptions Used for Evaluating the Potential Radiological 
Consequences of a Loss-of-Coolant-Accident for Boiling Water 
Reactors,'' Revision 2, dated June 1974. The analysis results 
demonstrate that dose contributions from the proposed MSIV leakage rate 
limit of 100 scfh per MSIV, not to exceed 200 scfh for all four main 
steam lines, and considering the proposed deletion of the MSIV LCS, 
result in an acceptable increase to the LOCA doses previously evaluated 
against the regulatory limits for the off-site doses and MCR doses 
contained in 10 CFR Part 100, and 10 CFR Part 40, Appendix A, General 
Design Criteria (GDC) 19, respectively. The proposed calculated off-
site and MCR doses resulting from a LOCA are the sum of the LOCA doses 
previously evaluated (currently described in the Updated Final Safety 
Analysis Report), and the additional doses calculated using the 
alternate MSIV leakage treatment method. The method of calculating the 
revised doses is conservative, since the LOCA doses 
[[Page 10123]] previously evaluated already include dose contributions 
from MSIV leakage at the maximum leakage rate currently permitted by 
the TS. Appendix 2 of Attachment 3 of the January 14, 1994, submittal 
shows the previously calculated doses and the new calculated doses 
resulting from the proposed changes.
    The staff concluded that the current exemption was acceptable based 
on: The method of MSIV testing (i.e., 22 psig test pressure when 
applied between MSIVs on a single steam line); a radiological analysis 
that assumed a 11.5 scfh MSIV leak rate, and the licensee's commitment 
that the MSIVs would be periodically tested to ensure the validity of 
the radiological analysis (i.e., verify that the MSIV leakage rate 
during testing is accounted for separately in the radiological analysis 
of the site. The proposed changes do not affect the bases for the 
current exemption. The modification and implementing TS change request: 
Will not alter the procedure method of MSIV testing (i.e., test 
pressure will remain at 22 psig when applied between MSIVs) and are 
based on the results of a radiological analysis where the proposed 
leakage rate and the resulting doses are still within regulatory 
limits. Also, the MSIVs will be periodically tested to assure the 
validity of the analysis (i.e., verify that the proposed MSIV leakage 
rate assumed in the radiological analysis is not exceeded per proposed 
TS 3.6.1.2.c), and the MSIV leakage will still be accounted for 
separately in the radiological analysis of the site.
    For the reasons set forth above, the NRC staff concludes that there 
is reasonable assurance that: The current MSIV leak testing method 
(i.e., test pressure of 22 psig when applied between MSIV) is an 
acceptable method; the proposed alternate MSIV leakage pathway (main 
steam lines and condenser), and the calculated doses obtained by 
performing radiological analysis (calculated using an MSIV leakage rate 
limit of 100 scfh per MSIV not to exceed 200 scfh for all four main 
steam lines) are within the limits of 10 CFR Part 100 and GDC 19. The 
staff finds it acceptable to continue to exclude the measured MSIV 
leakage rate from the combined local rate, since the leakage is 
accounted for separately and continues to meet the underlying purpose 
of the rule. Therefore, the staff finds the requested exemption 
presented in the licensee's December 22, 1994, submittal acceptable.

III

    Pursuant to 10 CFR 50.12, the Commission may, upon application by 
any interested person or upon its own initiative, grant exemptions from 
the requirements of 10 CFR Part 50 when (1) the exemptions are 
authorized by law, will not present an undue risk to public health and 
safety, and are consistent with the common defense and security; and 
(2) when special circumstances are present. Special circumstances are 
present whenever, according to 10 CFR 50.12(a)(2)(ii), ``Application of 
the regulation in the particular circumstances would not serve the 
underlying purpose of the rule or is not necessary to achieve the 
underlying purpose of the rule * * *,''
    The underlying purpose of the rule is to assure that the total 
valve leakage is within the limits of 10 CFR Part 100 and GDC-19. The 
licensee's analysis has demonstrated that an adequate margin can be 
maintained even if leakage from the MSIV is considered separately and 
subject to a leakage restriction of 100 scfh per MSIV, not to exceed a 
total of 200 scfh for all four main steam lines.

IV

    Accordingly, the Commission has determined that, pursuant to 10 CFR 
Part 50.12, an exemption is authorized by law and will not present an 
undue risk to the public health and safety, and that there are special 
circumstances present, as specified in 10 CFR 50.12(a)(2). An exemption 
is hereby granted from the requirements of Sections II.H.4, III.C.2(a), 
and III.C.3 of Appendix J to 10 CFR Part 50. The exemption allows (1) 
leakage testing of the MSIVs after deletion of the LCS, using a test 
pressure of 22 psig applied between MSIVs and a leakage rate limit of 
100 scfh per MSIV, not to exceed 200 scfh for all main steam lines, and 
(2) exclusion of the measured MSIV leakage rate from the combined local 
leak rate.
    Pursuant to 10 CFR 51.32, the Commission has determined that the 
granting of this exemption will have no significant impact on the 
quality of the human environment (60 FR 7226).
    The exemption is effective upon issuance and will be implemented 
prior to startup of Cycle 4 for LGS, Unit 2, and prior to startup of 
Cycle 7 for LGS, Unit 1.

    Dated at Rockville, Maryland this 16th day of February 1995.

[FR Doc. 95-4383 Filed 2-22-95; 8:45 am]
BILLING CODE 7590-01-M