ML17258A390

Forwards Evaluation of SEP Topic III-4.B, Turbine Missiles, & Requests Review for Accuracy as Soon as Possible

ML17258A390
Person / Time
Site:	Ginna
Issue date:	12/18/1981
From:	Crutchfield D Office of Nuclear Reactor Regulation
To:	Maier J ROCHESTER GAS & ELECTRIC CORP.
References
TASK-03-04.B, TASK-3-4.B, TASK-RR LSO5-81-061, LSO5-81-61, NUDOCS 8112240103
Download: ML17258A390 (6)

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December 18, 1981 Docket Ho. 50-244 LS05 12-061 Mr. John E. Maier, Vice President Electric and Steam Production f Rochester Gas 8I Electric Corporation 89 East Avenue Rochester, New York

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SUBJECT:

SYSTBlATIC EVALUATION PROGRAM TOPIC III-4.B, TURBINE I'IISSILES - R. E.

GINNA 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 informaoo tion.

Ite encourage you to supply any other material Chht might affect the staff's evaluation of this topic or be 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.

Sincerely,

Enclosure:

As stated cc w/enclosure:

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Mr. John E. Maier CC Harry H. Voigt, Esquire LeBoeufLamb, Leiby and MacRae 1333 New Hampshire Avenue, N.

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Suite 1100 Washington D. C.

20036 Mr. Michael Slade 12 Trailwood Circle Rochester, New York 14618 Ezra Bialik Assistant Attorney General Environmental Protection Bureau New York State Department of Law 2 World Trade Center New York, New York 10047 Resident Inspector R. E. Ginna Plant c/o U. S.

NRC 1503 Lake Road Ontario New York 14519 Director, Bureau of Nuclear Operations State of New York Energy Office Agency Building 2 Empire State Plaza Albany, New York 12223 Rochester Public Library.

115 South Avenue Rochester, New York 14604 Supervisor of the Town of Ontario 107 Ridge Road West

Ontario, New York 14519 Dr.

Emmeth A. Luebke Atomic Safety and Licensing Board U. S..Nuclear Regulatory Commission Washington, D. C.

20555 Dr.'ichard F. Cole Atomic Safety and Licensing Board U. S. Nuclear Regulatory Comaission Washington, D. C.

20555 U. S. Environmental Protection Agency Region II Office ATTN:

Regional Radiation Representative 26 Federal Plaza New York New York 10007 Herbert Grossman, Esq.,

Chairman Atomic Safety and Licensing Board U. S. Nuclear Regulatory Comnission Washington, D. C.

20555

SYSTEMATIC EVALUATION PROGRAM TOPIC III-4.B GINNA TOPIC:

III-4.B, TURBINE MISSILES INTRODUCTION

.The purpose of this topic is to assure that, with respect to potential turbine missiles, all structures, systems and compo'nents important to safety either have adequate protection by means of structural barriers or have an acceptably low probability of damage.

REVIEW CRITERIA 10 CFR 50, Appendix A, GDC 4 RELATED SAFETY TOPICS AND INTERFACES IV.

III-4.C, Internally Generated Missiles REVIEW GUIDELINES Standard Review Plan (SRP) Section 3.5. l. 3, Regulatory Guides (R.G.)

1.115 and 1.117.

V, EVALUATION During November 1979, the NRC staff became aware of'ow pressure turbine disc cracking in Westinghouse turbines't 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, "Turbine Missiles," concluded that an inspection schedule based on an approach developed by Westing-house for their turbine p'rovides an acceptably high degree of assurance that discs will be inspected before cracks can grow to one-half of a size that could cause disc failure at speeds up to design

'speed, The Rochester Gas 5 Electric Company (RGSE) 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).

RG&E responded to this request (Reference

2) and,committed to the.

four criteria.

As a result of this commitment an acceptably high degree of assurance is provided that disc failures 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:

(1) the probability of turbine failure leading to the ejection of turbine missiles due to design speed failures and destructive over speed failures (Pl),

(2) the probability of strike (P2) and (3) the probability of damage P3).

Since the evaluation of the latest Westinghouse probability analyses has not been completed by the staff, criteria, considering turbine cracking and the implemented inservice inspection

program, have not been established for determining Pl.

The staff, upon comple-tion 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.

2.

As turbine is brought up to speed, stop and governing valves are tested to verify system operability.

Every'onth except for the last two months of each cycle, while the plant is operating, power is reduced and each governor arid stop valve combination (there are 4) is sequentially exercised.

VI, CONCLUSION The inspection program committed to by RGRE (Reference 1

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 Ginna provides reasonable assurance that the overspeed protection system will remain operable and, thereby, limit the likelihood that overspeed past the design conditions would occur.

I The staff concludes, for an interim period until a decision is reached regarding the need for updated probabilistic 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 Ginna plant will be included with that operating plant action.

VII.

REFERENCES

~ l.

Letter from D.

M. Crutchfield (NRC) to J. Maier (RGSE),

August 28, 1981.

2.

Letter from J. Maier (RGEE) to D.

M. Crutchfield (NRC),

September 16, 1981.