ML19350B745
| ML19350B745 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 03/16/1981 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Counsil W CONNECTICUT YANKEE ATOMIC POWER CO. |
| References | |
| TASK-03-04.B, TASK-3-4.B, TASK-RR LSO5-81-03-038, LSO5-81-3-38, NUDOCS 8103230607 | |
| Download: ML19350B745 (4) | |
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March 16, 1981 Docket No. 50-213 LSoS-81-03-038 Mr. W. G. Counsil, Vice President Nuclear Engineering and Operations Connecticut Yankee Atomic Pcwer Co.
Post Office Box 270 Hartford, Connecticut 06101
Dear Mr. Counsil:
SUBJECT:
HADDAM NECK - SEP TOPIC III-4.8, 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.
This matter will be handled as part of the solution to the culti-plant generic cracking problem applicable to all plants with Westinghouse low pressure turbines.
Sincerely, o
Dennts. Crutchfield, Ch ' f Operating Reactors Branch No. 5 Division of Licensing
Enclosure:
As stated cc w/ enclosure:
See next page SGol
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Mr. W. G. Counsil March 16, 1981 cc w/ enclosure:
Day, Berry & Howard U. S. Environmental Protection Counselors at Law Agency One Constitution Plaza Region 1 Office Hartford, Connecticut 06103 ATTN: EIS C0ORDINATOR JFK Federal Building Superintendent Boston, Massachusetts 02203 Haddam Neck Plant RFD #1 Resident Inspector Post Office Box 127E Haddam Neck Nuclear Power Station East Hampton, Connecticut 06424 c/o U. S. NRC East Haddam Post Office Mr. James R. Himmelwright East Haddam, Connecticut 06423 Northeast Utilities Service Company P. O. Box 270 Hartford, Connecticut 06101 Russell Library 119 Broad Street Middletown, Connecticut 06457 Board of Selectmen Town Hall Haddam, Connecticut 06103 Connecticut Energy Agency ATTN: Assistant Director Research and Policy Development Department of Planning and Energy. Policy 20 Grand Street Hartford, Connecticut 06106 Director, Criteria and-Standards Division Office of Radiation Prograns (ANR-460)
U. S. Environmental Protection
.Agenqr Washington, D. C.
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=9 ENCLOSURE
,SEP TOPIC 111-4.8 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 orcbability 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 (P ) and (3) the prebability of damage (P ).
SRP 3.5.1.3 2
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 (P ) and their exit energies. They 1
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.
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_. 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 Atcmic Safety and Licensing Board concerning tne t; orth 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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