ML13330A260
| ML13330A260 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 03/16/1981 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Dietch R Southern California Edison Co |
| References | |
| TASK-03-04.B, TASK-3-4.B, TASK-RR LSO5-81-03-035, LSO5-81-3-35, NUDOCS 8103230519 | |
| Download: ML13330A260 (6) | |
Text
Docket No. 50-206 LS05-81-03-035 MARCH 1 61981 Mr. R. Dietch, Vice President Nuclear Engineering and Operations Southern California Edison Company 2244 Walnut Grove Avenue Post Office Box 800 Rosemead, California 91770
Dear Mr. Dietch:
SUBJECT:
SAN ONOFRE -
SEP TOPIC III-4.B, TURBINE MISSILES This letter is to advise you that Topic III-4.B, Turbine Missiles has been made generic for reasons given in the enclosure. The previously issued Topic III-4.B assessment for your plant is no longer valid. This is a result of new information issued by Westinghouse as a result of the multi-plant generic cracking problem applicable to all plants with Westinghouse low pressure turbines.
The matter will be handled as part of the solution to this generic problem.
Sincerely, Original signed bWf Dennis I. Crutchfield Dennis M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing
Enclosure:
As stated cc w/enclosure:
See next page 810828 )59 P
- See previous yellow for additional concurrences.
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Docket No. 50-206 Mr. R. Dietch, Vice President Nuclear Engineering and Operations Southern California Edison Company 2244 Walnut Grove Avenue Post Office Box 800 Rosemead, California 91770
Dear Mr. Dietch:
SUBJECT:
SAN ONOFRE - SEP TOPIC III-4.8, TURBINE MISSILES This letter is to advise you that Topic III-4.8, Turbine Missiles has been made generic in the Systematic Evaluation Program (SEP) review of your facility for reasons given in the enclosure. The previously issued Topic III-4.8 assessment for your plant is no longer valid. This is a result of new infor mation issued by Westinghouse as a result of the multi-plant generic cracking problem applicable to all plants with Westinghouse low pressure turbines. The matter will be handled as part of the solution to this generic problem.
Sincerely, Dennis M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing
Enclosure:
As stated cc w/enclosure:
See next page OFFICE SE PB:DL SE:
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0 UNITEDSTATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 March 16, 1981 Docket No. 50-206 LS05-81-03-035 Mr. R. Dietch, Vice President Nuclear-Engineering and Operations Southern California Edison Company 2244 Walnut Grove Avenue Post Office Box 800 Rosemead, California 91770
Dear Mr. Dietch:
SUBJECT:
SAN ONOFRE - SEP TOPIC III-4.B, TURBINE MISSILES This letter is to advise you that Topic III-4.B, Turbine Missiles has been made generic for reasons given in the enclosure. The previously issued Topic III-4.B assessment for your plant is no longer valid. This is a result of new information issued by Westinghouse as a result of the multi-plant generic cracking problem applicable to all plants with Westinghouse low pressure turbines.
The matter will be handled as part of the solution to this generic problem.
Sincerely, Dennis M. Crutchfield, ief Operating Reactors Branch No. 5 Division of Licensing
Enclosure:
As stated cc w/enclosure:
See next page
Mr.
March 16, 1981 cc w/enclosure:
Charles R. Kocher, Assistant Director, Criteria and Standards General Counsel Division Southern California Edison Company Office of Radiation Programs Post Office Box 800 (ANR-460)
Rosemead, California 91770 U. S. Environmental Protection Agency David R. Pigott Washington, D. C. 20460 Samuel B. Casey Chickering & Gregory U. S. Environmental Protection Three Embarcadero Center Agency Twenty-Third Floor Region IX Office San Francisco, California 94111 ATTN:
EIS COORDINATOR 215 Freemont Street,
Jack E. Thomas San Francisco, California 94111 Harry B. Stoehr San Diego Gas & Electric Corrpany P. 0. Box 1831 San Diego, California 92112 Resident Inspector c/o U. S. NRC P. 0.' Box AA Oceanside, California 92054 Mission Viejo Branch Library 24851 Chrisanta Drive Mission Viejo, California 92676 Mayor City of San Clemente San Clemente, California 92672 Chairman Board of Supervisors County of San Diego San Diego, California 92101 California Department of Health ATTN: Chief, Environmental Radiation Control Unit Radiological Health Section 714 P Street, Room 498 Sacramento, California 95814
ENCLOSURE SEP TOPIC III-4.B TURBINE MISSILES The purpose of this topic is to assure that, with respect to potential turbine missiles, all structures, systems and components important to safety either have adequate protection by means of structural barriers or have an acceptably low probability of damage. Regulatory Guide 1.115 and 1.117 and Standard Review Plan (SRP) 3.5.1.3 provide guidance on this subject.
As discussed in SRP 3.5.1.3, it is acceptable to perform a probability analysis of damage to safety related structures, systems and components by potential turbine missiles and compare the calculated probability of damage to an acceptable probability. The analysis includes utilizing the following individual probabilities: (1) the probability of turbine failure leading to the ejection of turbine missiles due to design speed failures and destructive overspeed failures (P1), (2) the probability of strike (P2 ) and (3) the probability of damage (P3 )*, SRP 3.5.1.3 gives acceptable values of P1 based on historical turbine data.
During November 1979, the NRC staff became aware of low pressure turbine disc cracking in Westinghouse turbines at several operating plants.
Additional inspections at other plants possessing Westinghouse turbines also indicated cracking thus implying a generic problem applicable to plants with Westinghouse turbines. Consequently, on February 25, 1980, the NRC issued 50.54(f) letters to utilities with Westinghouse low pressure turbines requesting information related to this problem.
As a result of the turbine cracking problem, Westinghouse is in the process of revising its probability of turbine failure leading to the ejection of turbine missiles (P1 ) and their exit energies. They expect to submit details of these analyses to the Materials Engineering Branch of the NRC staff for review in April 1981.
To more efficiently utilize NRC staff manpower and because the cracking problem is a multi-plant problem generic to all plants with Westinghouse turbines and extending beyond those plants in the Systematic Evaluation Program, we are making generic Topic III-4.B "Turbine Missiles" for those plants possessing Westinghouse low pressure turbines.
-2 The turbine inspection program developed by the Materials Engineering Branch for Westinghouse turbines provides assurance that turbine missile risks will remain acceptably low. The reasoning is discussed in the staff's letter of February 19, 1980 to the Atomic Safety and Licensing Board concerning the North Anna nuclear power station. The staff has developed inspection schedules for those plants with Westinghouse turbines operating with cracks based on the staff's crack growth model.
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