ML17257A508

Forwards Request for Addl Info Re Underfrequency Setpoint Reduction.Answers Should Be Submitted W/Revised Analysis Justifying Setpoint Reduction & Specifically Analyzing Rate of Frequency Decay

ML17257A508
Person / Time
Site:	Ginna
Issue date:	07/23/1981
From:	Crutchfield D Office of Nuclear Reactor Regulation
To:	Maier J ROCHESTER GAS & ELECTRIC CORP.
References
LSO5-81-07-078, LSO5-81-7-78, NUDOCS 8107300246
Download: ML17257A508 (6)

Text

Docket No. 50-244 LS05-81-07-078 July 23, 1981 Mr. John E. Maier Vice President Electric and Steam Production Rochester Gas and Electric Corporation 89 East Avenue Rochester, New York 14649

Dear Mr. Maier:

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SUBJECT:

REDUCTION OF UNDERFREQUENCY SCRAM SETPOINT - GINNA PLANT On July 20, 1981, members of the NRC staff discussed, by telephone, the above subject with members of your staff.

The request for underfrequency setpoint reduction for the R.

E. Ginna Nuclear Power Plant was submitted by your letter dated November 8, 1976.

During the discussion of July 20, the NRC staff raised several questions that are documented in the enclosure to this letter.

We are aware of your intention to submit, later this year, a revised analysis justifying the setpoint reduction and specifically analyzing the rate of frequency decay.

We, therefore, request that the answers to these questions be included as part of that submittal.

Sincerely,

Enclosure:

As stated cc w/enclosure:

See next page 8107300246 810723 PDR ADOCK 05000244 P

PDR g De nis M. Cr tchfield, Chief Operating Reactors Branch tI'5 ivision of Licensing OFFICEP SURNAME/

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Mr. John E. Maier July 23, 1981 cc w/enclosure:

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 Jeffrey Cohen New York State Energy Office Swan Street Building Core 1, Second Floor Empire State Plaza

Albany, New York 12223 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 Resident Inspector R. E. Ginna Plant c/o U. S.

NRC 1503 Lake Road

Ontario, New York 14519 Mr. Thomas B. Cochran Natural Resources Defense Council, Inc.

1725 I Street, N. W.

Suite 600 Washington, D. C.

20006 U. S. Environmental Protection Agency Region II Office ATTN:

E IS COORDINATOR 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 Dr. Richard F. Cole Atomic Safety and Licensing Board U. S. Nuclear Regulatory Commission Washington, D. C.

20555 Dr.

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

20555

4

ENCLOSURE OFFICE OF NUCLEAR REACTOR REGULATION RE VEST FOR ADDITIONAL INFORMATION UNDERFRE UENCY TRIP SETPOINT ROCHESTER GAS AND ELECTRIC CORPORATION R.

E.

GINNA NUCLEAR POWER PLANT DOCKET NO. 50-244 1.

Provide the basis for the 0.9 second delay from the underfrequency trip to the beginning of rod motion into the core.

This is probably a plant specific delay and varies from 0.5 seconds to 1.0 second.

Is the 0.9 second delay a T/S item?

2.

Provide the basis for using a constant sensor relay delay of 35 cycles in your analysis.

Actual contact closure will occur at some frequency below the trip frequency depending on the frequency decay rate.

For

example, the greater the rate of change of frequency the greater the frequency below trip frequency at relay contact closure.

3.

How does the underfrequency trip proposed for Ginna affect the turbine generator, since only one relay from the bus trips the'generator, the

reactor, and the reactor coolant pumps?

Will this change to the trip feature adversely affect the turbine generator?

4.

Will not adjusting the sensor relay delay prevent the unnecessary frequency decay trips - as well as or better than lowering the trip frequency?

5.

Discuss the reasons for the requested decrease in trip setpoint from the point of view of Ginna safety and reliability.

What effect will the change have on the Northeast Power Coordinating Council grid?

6.

The DNBR analysis should be performed for the fuel presently in the core, because the minimum DNBR is a function of fuel type as well as frequency decay rate.

Therefore, provide assurance that a

DNBR analysis, including the proposed

'underfrequency trip, exists for the present fuel.

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7.

Below what frequency decay rate will the pump coastdown be faster than the grid frequency decay rate?

Is it always conservative to assume no RCP breakers open?

8.

Is it always conservative to assume pumo speed is directly proportional to frequency decay (no slip)?

9.

Prpvide assurance that the frequency measurement error is less than 0.15 Hz for the relays to be used at Ginna.

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