ML20196B346
| ML20196B346 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 02/08/1988 |
| From: | Muller D Office of Nuclear Reactor Regulation |
| To: | Butterfield L COMMONWEALTH EDISON CO. |
| References | |
| TAC-66059, TAC-66060, NUDOCS 8802110177 | |
| Download: ML20196B346 (3) | |
Text
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February 8,1988 DISTRIBUTION:;
Docket File r DCrutchfield NRC & Local PDRs EButcher Docket Nos. 50-373 PDIII-2 r/f JCraig and 50-374 GHolahan JXudrick LLuther RGoel PShemanski OGC-Beth.
ACRS(20)
Edordan Mr. L. D. Butterfield, Jr.
JPartlow PDIII-2 Plant File Nuclear Licensing Manager Comonwealth Edison Company Post Office Box 767 Chicago, Illinois 60690
Dear Mr. Butterfield:
SUBJECT:
RISK BASED EVALUATION OF TECHNICAL SPECIFICATION PROBLEMS AT THE LASALLE COUNTY STATION, EPRI RESEARCH PROJECT 2142-2 TAC NOS. 66059/66060 By letter dated July 10, 1987, Corrrnonwealth Edison submitted a proposed Technical Specification Amendment to allow removal of the main steam line isolation function from Main Steam Tunnel (MST) temperature and differential temperature sensors. The alarm function from the sensors would be retained to provide early indication of potentiel steam leaks.
The analysis used to detemine the effect on plant safety of removing the ambient and differential temperature trips from the Primary Contain-ment Isolation System Group I isolation logic is an EPRI risk-based evaluation.
Even though the EPR: risk analysis concludes that the reliability of the MSIV's to close in response to a steam line break outside the containment is not significantly compromised by removal of the MST temperature trip sensors as part of the trip logic, the regulatory practice is that PRA may be used to supplernent a deteministic analysis; but may not be used as the sole basis for justifying changes. The staff has reviewed this proposed amendment and finds that the risk-based evaluation alone, is not acceptable as the sole basis for approving removal of the MST ambient and differential temperature trips. You should revise your submittal to aadress the Updated Final Safety Analysis Report regulatory requirements and design basis and logic for the leak detection system. The supplemental analysis should focus on the effect on plant safety of removing the ambient and differential trips from the Primary Containment Isolation System Group I isolation logic and any compensatory measures that would be required to support their removal.
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Mr. L. D. Butterfield, Jr. I If there are any questions concerning this information, please contact Paul Shemanski, Project Manager at (301) 492-3017.
Sincerely, Original Signed by/
Daniel R. Muller, Director Project Directorate III-2 Division of Reactor Projects - III, IV, Y and Special Projects cc:
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i Mr. L. D. Butterfield, Jr.
LaSalle County Nuclear Power Station Units 1 and 2 Commonwealth Edison Company CC' John W. McCaffrey Philip P. Steptoe, Esq.
Chief Public Utilities Division Suite 5200 160 North LaSalle Street, Room 900 Three First National Plaza Chicago, Illinois 60602 Chicago, Illinois 60601 Assistant Attorney General 100 West Randolph Street Chicago, Illir.cis 60601 Resident Inspector /LaSalle, NPS U.S. Nuclear Regulatory Commission Rural Route ho 1 P.O. Box 224 Marseilles, Illinois 61341 Chairran LaSalle County Board of Supervisors LaSalle County Courthouse Ottawa, Illinois 61350 Attorney General 500 South 2nd Street Springfield Illinois 62701 Chairnan Illinois Commerce Comission Leland Building 527 East Capitol Avenue Springfield, Illinois 62706 1
Mr. Gary N. Wright, Manager Nuclear Facility Safety 1111nois Department of Nuclear Safety l
1035 Outer Park Drive, 5th Floor t
Springfield, Illinois 62704 Regional Administrator, Region !!!
U.S. Nuclear Regulatory Commission 799 Roosevelt Road 1
Glen Ellyn, Illinois 60137 i
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