ML17258A554

Forwards Final Evaluation of SEP Topic III-4.B,turbine Missiles,Incorporating 820208 Comments.Evaluation to Be Basic Input Into Integrated Safety Assessment Unless Changes Identified to Reflect as-built Conditions at Facility

ML17258A554
Person / Time
Site:	Ginna
Issue date:	02/19/1982
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 LSO5-82-02-077, LSO5-82-2-77, NUDOCS 8202230187
Download: ML17258A554 (6)

Text

February 19, 1982 Docket No. 50-244 LS05 O2-077 Mr. John E. Maier, Vice President Electric and Steam Production Rochester Gas 5 Electr ic Corporation 89 East Avenue Rochester, New York 14649 5

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SUBJECT:

SYSTEMATIC EVALUATION PROGRAM TOPIC III-4.B, TURBINE MISSILES - R.E.

GINNA Enclosed is a copy of our final evaluation of Systematic Evaluation Program Topic III-4.B.

This evaluation incorporates comments provided to us by your letter dated February 8, 1982.

This evaluation will be a basic input to the integrated safety assessment for your facility unless you identify changes needed to relect the as-built conditions at your facility.

This topic assessment may be revised in the future if your facility design is changed or if NRC criteria relating to this topic are modified before the integrated assessment is completed.

Sincerely,

Enclosure:

As stated cc w/enclosure:

See next page Dennis M. Crutchfield, Chief Operating Reactors Branch No.

5 Division of Licensing Qao 008 CO/)

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Ginna

'ocket No.

50-244 Rev. 2/8/82 Mr. John E. Maier CC Harry H. Voigt, Esquire

LeBoeuf, Lamb, Leiby and MacRae 1333 New Hampshire Avenue, N.

W.

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 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 Commission Washington, D.

C 20555 Ronald C. Haynes, Regional Administrator Nuclear Regulatory Commission, Region I Office of Inspection and Enforcement 631. Park Avenue King of Prussia, Pennsylvania 19406 Supervisor of the Town of Ontario 107 Ri'dge 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. Richard F. Cole Atomic Safety and Licensing Board U. S. Nuclear Regulatory Commission 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 components important to safety either have adequate protection by means of structural barriers or have an acceptably low proba'bility of damage.

II.

REVIEW CRITERIA

~ 10 CFR 50, Appendix A, GDC 4 RELATED SAFETY TOPICS AND INTERFACES III-4.C, Internally Generated Missiles IV.

REVIEW GUIDELINES Standard Review Plan (SRP) Section 3.5. 1.3, Regulatory Guides (R.G.)

1.115 and 1;117.

V.

EVALUATION 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'Hestinghouse 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) lett'ers to utilities with Westinghouse low pressure turbines requesting information related to this problem.

Both Westinghouse and the NRC staff have been fo'llowing 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 provides an acceptably high degr'ee '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 8I 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).

. RGLE responded to this request-(Reference..2}

and committed.to. the...

.'oui.

criteria.

As a result of this commitment an acceptably high degree of assurance is provided that disc failures at design. speed will not occul.

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 overspeed 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.

This test is only performed during power descent and not repeated during power escalation unless problems

- were encountered.

2.

As turbine is brought'~up to speed, stop and governing valves are "tested" as a normal part of the startup.

Every month except for the last two months of each cycle, while the plant is operating, power is reduced and each stop and'ts two associated gover<<

nor valves are sequentially exercised.

VI.

CONCLUSION, The inspection program committed to by RGEE {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, includin'g 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 The staff concludes, for an interim period until a decision is reached re-garding 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 1.

Letter from D.

M. Crutchfie1d (NRC) to J. Maier (RG&E),

August 28, 1981.

~

2.

Letter from J. Maier (RGKE) to D.

M. Crutchfield (NRC),

September 16, 1981.