ML20079A566
| ML20079A566 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 12/22/1994 |
| From: | Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9501030141 | |
| Download: ML20079A566 (6) | |
Text
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'Ctation support Department.
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Ji PECO ENERGY.
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965 Chesterbrook Boulevard 4
Wayne. PA 19087-5691 10 CFR 50.12(a)
December 22,1994 Docket Nos. 50-352 50-353 i
License Nos. NPF-39 1
NPF-85 I
U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555
SUBJECT:
Umerick Generating Station, Units 1 and 2
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Information Supporting an Exemption to 10 CFR 50, Appendix J Gentlemen:
PECO Energy Company (PECO Energy) is submitting information supporting an Exemption from 10 CFR 50, Appendix J, " Primary Reactor Containment Leakage Testing for Water-Cooled Power Reactors," in accordance with 10 CFR 50.12(a).
By letter dated January 14,1994 PECO Energy requested Technical Specifications (TS) Change Request No. 93-18-0, " Deletion of the Main Steam isolation Valve (MSIV) Leakage Control System,"
for LGS Units 1 and 2.10 CFR 50, Appendix J, Sections ll.H.4 and lil.C.2 require leak rate testing of MSIVs at the calculated peak containment pressure related to the design basis accident, and Section lil.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 and proposed use of an altemate leakage pathway affects the description of an existing exemption which allows the leak rate testing of the MSIVs at a reduced pressure and to exclude the measured leakage from the combined local leak rate test results. The original exemption is contained in the LGS Safety.
Evaluation Report (i.e., NUREG4991, and its supplement 3). Therefore, the information contained in Attachment 1 supports an exemption from 10 CFR 50, Appendix J, Sections ll.H.4, Ill.C.2 and
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lil.C.3.
Information describing that the proposed attemate pathway supports a 10 CFR 50, Appendix J, l
exemption is contained in Attachment 1 to this letter, j
We request that the information supporting an exemption for 10 CFR 50, Appendix J, for LGS, Units I and 2, in accordance with 10 CFR 50.12 be approved, and coincide with the approval of TS l
Change Request No.93-184 prbr to January 20,1995. We also request that the revised exemption become effective within 30 days of issuance for each unit (i.e., January 20,1995 for LGS Unit 2, and j
January 20,1996 for LGS Unit 1)
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9501030141 941222 PDR ADOCK 05000352 I
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i December 22,1994 Page 2 If you have any questions, please do not hesitate to contact us.
Very truly yours, e
e G. A. Hunger, Jr.,
Director - Licensing Section Attachment cc:
T. T. Martin, Administrator, Region I, USNRC (w/ attachment)
N. S. Perry, USNRC Senior Resident inspector, LGS (w/ attachment)
R. R. Janati, PA Bureau of Radiological Protection (w/ attachment).
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ATTACHMENT 1 i
r UMERICK GENERATING STATION UNIT 1 AND UNIT 2 DOCKET Nos.
50-352 50-353 l
UCENSE Nos.
NPF 39
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NPF45 i
"Information Supporting an Exemption to 10 CFR 50 Appendbc J' Supporting Information for Exemption - 3 PAGES i
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- p Page1 PECO Energy Company (PECO Energy), licensee under Faculty Operating License Noe NPF-39 and NPF-85 for Limerick Generating Station (LGS), Units 1 and 2, submits the following information supporting an exemption in accordance with 10 CFR 50.12(a), which allows the leak rate testing of the MSIVs at a reduced pressure and excludes the measured leakage from the combined local leak rate test results.
Discussion and Justification For Exemption Request LGS Unit 1 and 2 received an exemption from 10 CFR 50, Appendix J. Sections ll.H.4, Ill.C.2, and Ill.C.3 based on the NRC conclusion that the LGS MSIV leak testing methods were acceptable attematives to the requirements. This conclusion was included in the LGS Safety Evaluation Report (SER) (i.e., NUREG-0991, and its supplement 3). In addition to the LGS leak testing program the SER described that in the event of a LOCA, the MSIV Leakage Control System wRl maintain a negative pressure between the MSIVs, and the j
effluent wNI be discharged into a volume where it wRI be processed by the standby gas treatment system before being released to the environs. Furthermore, the SER described that a radiological analysis including this potential source of containment atmosphere leakage was performed. The analysis was based on an assumed leak rate limit for a main steam line through the MSIVs of 11.5 standard cubic feet per hour (scfh),
l and the MSIVs were planned to be periodically tested to ensure the validity of the radiological analysis. The NRC 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 the peak containment pressure or 22 psig applied between the MSIVs) was acceptable, and excluding the MSIV test leakage rate from the combined local leak rate was acceptable because the MSIV leakage had been accounted for separately in l
the radiological analysis of the site.
By letter dated January 14,1994 PECO Energy submitted Technical Specifications (TS) Change Request i
No. 93-18-0, " Deletion of the Main Steam Isolation Valve (MSIV) Leakage Control System," for LGS Units 1 and 2, which supports the planned modification to eliminate the MSIV Leakage Control System and utilze an alternate leakage pathway. This proposal is based on the Bouing Water Reactor Owner's 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 Leakage Control System and the assumed MSIV leak rate wNl no longer be accurate once the proposed modification is performed and implementing TS change is approved.
As stated in the January 14,1994, TS Change Request, 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 utHizes the hold-up volumes of the main steam piping and condenser as an attemate 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-Cooling Accident for Boning Water Reactors," Revision 2, datsd June 1974. The analysis results demonstrates that dose contributions from the proposed MSIV leakage rate limit of 100 sofh per steam line, not to exceed 200 scfh for all four main steam lines, along with the proposed deletion of the MSIV Leakage Control System, 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 100, and 10 CFR 50, Appendix A, General Design Criteria (GDC) i 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 attemate MSIV leakage treatment method. This method of calculating the revised doses is highly conservative since the LOCA doses previously evaluated already include dose contributions from MSIV leakage at the maximum leakage rate currently permitted by TS.
Appendix 2 of Attachment 3 of the January 14,1994, submittal shows the previously calculated doses and
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Page 2 the new calculated doses resulting from the proposed changes.
Based upon the description contained in a September 14,1984, PECO exemption letter, the SER and supplement 3 to the SER, the NRC concluded 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); that a radiological analysis was performed, assuming a 11.5 scfh MSIV leak rate, and the MSIVs would be periodically tested to ensure validity of the radiological analysis (i.e., verify that the MSIV leakage rate assumed in the radiological analysis is not exceeded per TS 3.6.1.2.c.); and a MSIV leakage rate measured during testing is accounted for separately in the radiological analysis of the site. The proposed changes do not affect the current exemption in so much that the modification and implementing TS change: will not alter the procedure method of MSIV testing (i.e., test pressure will remain at 22 poig when applied between MSIVs); is based on the results of a radiological analysis, where the proposed leakage rate is assumed, and the resulting doses are silll within regulatory limits, and 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 d the site.
The NRC may, upon application, grant exemptions from the requirements d 10 CFR 50, where special circumstances are present. 10 CFR 50.12(a)(2)(ii) states the NRC may grant exemptions from the requirements of 10 CFR 50 whenever 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.
PECO Energy has concluded that: the current MSIV leak rate testing method (i.e. test pressure of 22 psig when applied between MSIVs) is an acceptable method; the proposed attemate MSIV leakage pathway, and the calculated doses obtained by performing a radiological analysis, which assumed MSIV leakage rate limit.
of 100 scfh per steam line, not to exceed a total of 200 scfh for all four main steam lines, are within the limits of 10 CFR 100 and GDC 19; it is acceptable to continue to exclude the measured MSIV leakage rate from the combined local leak rate, since the leakage is accounted for separately and continues to meet the underlying purpose of the rule.
Informatinn Sunnartina an Environmeihi Assessment i
With respect to the subject exemption for LGS, Unit 1 and 2, the following information is provided to support an Environmental Assessment.
Identification of Proposed Action The proposed action is to maintain the current exemption from 10 CFR 50, Appendix J, Sections li.H.4 and Ill.C.2, which exempts LGS from the requirement to perform MSIV leak rate testing at the calculated peak containment pressure related to the design basis accident, and Section Ill.C.3 requiring that the MSIV measured leak rates be included in the combined local leak rate test results. PECO Energy is proposing to re-apply for the exemption based on a proposed change to the current exemption description; specifically, the elimination of the MSIV leakage Control System, use d the attemate leakage treatment method, and increasing the assumed MSIV leakage rate from 11.5 scfh to 100 scfh per steam line, not to exceed a total of 200 scfh for all four main steam lines. The proposed exemption will maintain the leak rate testing of the MSIVs at a reduced pressure (i.e.,22 psig when applied between valves) and will continue to exclude the measured leakage from the combined local leak rate test results.
The Need for the Proposed Action The original exemption d 10 CFR 50, Appendix J, Sections ll.H.4 and Ill.C.2, which require leak rate testing of MSIVs at the peak calculated containment pressure related to the design basis accident, was
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rarWad and is proposed to ba retained since the design of the MSIVs is such that testing in the reverse direction tends to uneemt the valve, resulting in a meaningless test. The results of such a test would not serve the underfying purpose of the rule. The current LGS MSIV leak rate test mWhod is adarFa, and maintaining this method (i.e.,22 pelg when applied betwoon valves) wil ensure the results of future MSIV f
tests wil be evaluated on a simber basis. The total observed leakage resulting from a leakage test where two MSIVs on one steam line are tested simultaneously, between the valves, utlizing a reduced test pressure wil continue to be conservatively assigned to the penetration.
The original exemption of 10 CFR 50, Appendix J, Section Ill.C.3, which requires that the measured MSIV leak rates be included in the combined local leak rate test results, was requested and is prapnaart to be retained. This leakage rate wil continue to be accounted for separately in the radiological site analysis, and therefore, the exemption meets the underlying purpose of the rule.
j Environmentalimpacts of the Proposed Action f
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The existing exemption is proposed to be retained, and is justified, since the prnpr=ad changes l
would not result in a significant increase to the LOCA doses previously evaluated against the off-site and I
Main Corf.rol Room dose limits contained in 10 CFR 100 and 10 CFR 50, Appendix A General Design Criteria 19, respectively. As described in the preceding " Justification For Exemption," the method d calculating the revised doses is highly conservative, and the doses resulting from a postulated design basis l
LOCA are below regulatory limits.
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Alternative to the N-:-g-:::1 Action l
Since we have concluded that there is no significant environmental impact associated with the requested exemption, any attematives would have either no or greater environmental impact.
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The principal attemative would be to deny the requestad exemption which would require the f
performance of a 10 CFR 50, Appendix J, MSIV leak rate test at peak calculated containment pressure and as described in the preceding "Need forThe Proposed Action,' the results of such a test on the LGS design, would not serve the underlying purpose of the rule. Since the MSIV test leakage rate is accounted for l
separately in the radiological site analysis, the exemption meets the underlying purpose of the rule and no other altemative is necessary. In addition, this exemption is included as part of Standard Technical Specifications (NUREG 0123) and is consistent with regulatory practices.
Alternative Use of Resources This proposed exemption does not Irwolve the use of any resources not previously considered in connection with the Nuclear Regulatory Commission's Final Environmental Statement dated. AprI 1984, related to the operation of the Limerick Generating Station, Unit 1 and Unit 2.
j information Supporting a Finding of No Significant impact f
We have concluded, based on the preceding environmental assessment, that the proposed action f
wHI not have a significant effect on the quality of the human environment; therefore, an environmental impact statement for the requested exemption would not be required.
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