ML18046B123
| ML18046B123 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 12/02/1981 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| References | |
| TASK-03-04.B, TASK-3-4.B, TASK-RR LSO5-81-12-005, LSO5-81-12-5, NUDOCS 8112040582 | |
| Download: ML18046B123 (5) | |
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Docket No. 50-255 LS05-8l-12-005 Mr. David P. Hoffman Nuclear Licensing Administrator Consumers Po~~;r Company 1945 W. Parnall Road Jackson, Michigan 49201
Dear Mr. Hoffman:
December 2, 1 981
SUBJECT:
SYSTEMATIC EVALUATION PROGRAM TOPIC III-4.B, TURBINE MISSILES-PALISADES Enclosed is a copy of our evaluation of Systematic Evaluation Program Topic III-4.B.
You are requested to examine the facts upon which the staff has based its evaluation and respond either by confirming that the facts are correct, or by identifying errors and supplying the corrected information.
We encourage you to supply any other material that might affect the staff's evaluation of this topic or b~ significant in the integrated assessment of your facility.
Your response is requested as soon as possible. If no response is received by the time the next phase of the integrated assessment of your facility begins, we will assume that you have no comments or corrections and will consider the topic complete.
Enclosure:
As stated cc w/enc1osure:
See next page
("8112040582 81120~.
I PDR ADOCK 050002551
' p PDR Sincei"e1y, Dennis M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing
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NRG FORM 318 (10-80) NRCM 0240 OFFICIAL RECORD COPY USGPO: 1981-335-960
Mr. David P. Hoffman cc M. I. Miller, Esquire Isham, Lincoln & Beale Suite 4200 One First National Plaza Chicago, Illinois 60670 Mr. Paul A. Perry, Secretary Consumers Power Company 212 West Michigan Avenue Jackson, Michigan 49201 Judd L. Bacon, Esquire Consumers Power Company 212 West Michigan Avenue Jackson, Michigan 49201 Myron M. Cherry, Esquire Suite 4501 One IBM Plaza Chicago, Illinois 60611 Ms. Mary P. Sinclair Great Lakes Energy Alliance 5711 Summerset Drive Midland, Michigan 48640 Kalamazoo Public Library 315 South Rose Street Kalamazoo, Michigan 49006 Township Supervisor Covert Township Route 1, Box 10 Van Buren County, Michigan Office of the Governor (2)
Room l - Capitol Building Lansing, Michigan 48913 William J. Scanlon, Esquire 2034 Pauline Boulevard Ann Arbor, Michigan 48103 Palisades Plant ATTN:
Mr. Robert Montross Plant Manager Covert, Michigan 49043 49043 PALISADES Docket No. 50-255 U. S. Environmental Protection Agency Federal Activities Branch Region V Office ATTN:
EIS COORDINATOR 230 South Dearborn Street Chicago, Illinois 60604 Charles Bechhoefer, Esq., Chairman Atomic Safety and Licensing Board Panel U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Dr. George C. Anderson Department of Oceanography University of Washington Seattle, Washington 98195 Dr. M. Stanley Livingston 1005 Calle Largo Santa Fe, New Mexico 87501 Resident Inspector c/o U. S. NRC Palisades Plant Route 2, P. O. Box 155 Covert, Michigan 49043
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SYSTEMATIC EVALUATION PROGRAM TOPIC III-4.B PALISADES Topic III-4.B TURBINE MISSILES I. INTRODUCTION 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.
I I. REVIEW CRITERIA lD CFR 50, Appendix A, GDC 4 III. RELATED SAFETY TOPICS AND INTERFACES III-4.C Internally Generated Missiles IV. REVIEW GUIDELINES Standard Review Plan (SRP) Section 3.5. l.3, Reg.ulatory Guides (R. G.)
1.115 and 1.117 V. EVALUATION During November 1979, the NRC staff became aware of low pressur~ ~urbine 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.
Both Westinghouse and the NRC staff have been following this problem closely and have developed independent crack growth models.
The findings of multi-plant action, B-46, 11 Turbine Missiles 11, concluded that an inspection schedule based on an approach developed by Westing-house for their turbines provides an acceptably high degree of assurance that discs wi 11 be inspected before cracks can grow to one-ha 1 f of a size that could cause disc failure at speeds up to design speed.
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- "Ii The Consumers Power Company was provided with a safety evaluation report of this approach and was requested to commit to use the four criteria listed on page 3 of the safety evaluation report (Reference 1).
Consumers Power Company responded to this request (Reference 2) and committed to the use of the four criteria.
As a result of this committment, an accep-
~ably high degree of assurrance is provided, which assures that disc fail-ures at design speed will not occur.
As a result of the turbine cracking problem, Westinghouse has revised its probability analysis of damage to safety related structures, systems and components of damage to an acceptable probability.
The analysis includes utilizing the following individual probabilities:
(l) the probability of turbine failure leading to the ejection of turbine missiles due to design speed failures and destructive overspeed failures (pl), (2) the probability of strike (P2) and (3) the probability of damage (P3).
Since the evalua-tion of the latest Westinghouse probability analyses has not been completed by the staff; cri_teria_,considering turbine cracking and the_ impj~_ment_e~_
inservice inspection program; has-not-been established for determining Pl.
The staff, upon completicin of the Westinghouse review, will determine what actions, if any, are required.
The staff determined that the licensee performs a testing program for the overspeed protection system.
Specifically, there are three different tests performed on a routine basis as follows:
At every turbine overhaul and at each refueling outage the following two tests are performed:
l Overspeed protective test - actually overspeed turbine to trip set point to close stop and governing valves.
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As turbine is brought up to speed, stop and governing valves are tested to verify system operability.
Every two weeks, while the plant is operating, power is reduced and ~ath governor and stop valve combination (there are 4) is sequentially exercised.
VI.
CONCLUSION The inspection program committed to by Consumers Power Company (Reference l and 2) provides an acceptably high degree of assurance that turbine discs will not fail at speeds up to design speed.
The testing program of the overspeed protection system, including the stops and control valves at Palisades, provides reasonable assur-rance that the overspeed protection system will remain operable and, thereby, limit the likelihood that overspeed past the design conditions would occur.
The staff concludes, for an interim period until a decision is reached regarding the need for updated probabilitic analysis of the turbine missile hazard, the probability of damage from turbine missiles is acceptably low.
Should further reviews of operating plants and/or additional requirements be deemed necessary, the Palisades plant will be included with that operating plant action.
'REFERENCES
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Letter from D. M. Crutchfield (NRC) to D. P. Hoffman, (CPCo)
August 28, 1981.
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Letter from B. D. Johnson (CPCo) to D. M. Crutchfield, September 29' 1 981.
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