ML17244A437

in Response to 781129 Ltr,Concludes Containment Ventilation Circuitry & Procedures Re Use Are Adequate

ML17244A437
Person / Time
Site:	Ginna
Issue date:	03/30/1979
From:	White L ROCHESTER GAS & ELECTRIC CORP.
To:	Ziemann D Office of Nuclear Reactor Regulation
References
TASK-06-04, TASK-6-4, TASK-RR NUDOCS 7904060227
Download: ML17244A437 (8)

Text

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REGUL TORY INFORMATION DISTR'IBU N SYSTFM (RIDS)

ACCESSION NBR:7904060227 DOC ~ DATEc 79/03/30 NOTARIZED: NO DOCKET' FACIL:50'44 ROBERT EMMET GINNA NUCLEAR PLANT E UNIT 1g ROCHESTER G 05000240 AUTH'AME AUTHOR AFFILIATION WHITED L' D ~ ROCHESTER GAS 8 ELECTRIC RECIPIENT AFFILIATION CORP'KC IP ~ NAME

'ZIEMANNED ~ L ~ OPERATING REACTORS BRANCH 2

SUBJECT:

IN RESPONSKA TO 781128 LTRgCONCLUDES CONTAINMENT VENTILATION CIRCUITRY 5 PROCEDURES RE USE ARE CODE: A030S TITLE!

COPIES RECEIVED:LTR CONTAINMENT PURGING.

ADEQUATE'ISTRIBUTION

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SIZE:

D ALE->5<,E4 NOTES:

RECIPIENT COPIES REC IP IENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL; ACTION! 05 BC.op.g g.

INTERNAl: 0 REG FILE. 1 02 NRC PDR 1 1 2 TA/EDO 1 15 CORE PKRF BR 1 16 AD 'SYS/PROJ 1 17 ENGR BR 1 18 REAC SFTY BR 1 19 PLANT SYS BR 1 20 EEB 1 21 EFLT TRT SYS 1 22 BRINKMAN 1

?3 C GRIMES 1 24 E REEVES 1 EXTERNALS 03 LPDR 1 04 NSIC, 25 ACRS 16 16 0

'OTAL NUMBKR OF COPIES REQUIRED'TTR 00 ENCL,

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raft IISIII ROCHESTER GAS AND ELECTRIC CORPORATION o 89 EAST AVENUE, ROCHESTER, N.Y. 14649 LEON D. WHITE. JR. TELEPHONE VICE PRESIDENT ARK* CODE TIS 546.2700 March 30, 1979 Director of Nuclear Reactor Regulation Attention: Mr. Dennis L. Ziemann, Chief Operating Reactors Branch No. 2 U. S. Nuclear Regulatory Commission Washington, D.C. 20555 b

Subject:

Review of Safety Actuation Circuits With Overrides R.E. Ginna Nuclear Power Plant Docket No. 50-244

Dear Mr. Ziemann:

Your letter of November 29, 1978 requested that we perform a review of all safety actuation signal circuits which incorporate Ou'r letter of February 16, 1979 pro-manual override features.

vided the results of that review. The purpose of this letter is to supplement and amplify the information on the containment ventilation isolation circuitry which has previously been pre-sented.

The containment ventilation isolation circuitry and the reset function were described in our previous letter. The isola-tion signal is generated either by safety injection (SI) or high containment radiation alarm on containment radiation monitors.

Once a signal is generated, the isolation function is locked in and can only be cleared through use of the reset function, even if the initiating signal has been cleared. Further, once a high radiation signal is generated, the signal itself is locked in and must be cleared. This is not cleared by the containment ventila-tion isolation reset.

As stated in our previous letter the reset function is not annunciated. However, the signals that generate a containment ventilation isolation signal are annunciated. The position of the purge valves is indicated by lights on the control board.

Hence, a combination of an isolation signal (annunciated) and a lack of a close'ight for the respective valve is positive indica-tion'the reset function has been actuated.

The reset switch is a key lock switch and its use is covered by strict administrative controls. Situations in which it might QO>

be required are as follows. If a spurious S.I. or high radiation signal were to generate an isolation signal, it would be necessary

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ROCHESTER GAS AND ELECTRIC CORP. SHEET NO.

March 30, 1979 Mr. D.L. Ziemann, Chief to use the switch to clear the isolation signal. Before using the reset, however, the plant operator would clear the spurious signal. Thus, when the reset was employed, it would momentarily block the signals but following release would not. block subsequent signals. Procedural precautions alert the operator to the fact that the spurious signal should be cleared prior to using the reset. Strict control of the key for the reset under the Shift Foreman ensures that proper procedures are followed inasmuch as no single operator error can result in improper use of the reset.

function.

A second situation involving the use of the reset key switch is following the monthly test of the containment ventilation isolation circuitry. In this test, a simulated signal is input into the circuitry. Following completion of the test, the test signal is removed and cleared. Only after this is accomplished is the isolation signal cleared, again under strict administrative controls including decisions by two operators.

A third circumstance which could involve use of the key switch is an actual high radiation signal which isolates contain-ment when purging is desired. Purging could be accomplished by use of the reset function thereby overriding the high radiation signal, however, this is not permitted without a 'detailed evalua-tion. In addition, to the best of our knowledge, this has never occurred in nearly ten years of plant, operation. The practice, enforced by procedure, in this case is to attempt to clear the high radiation signal in case it. is a spurious signal. If it is not a spurious signal, the set point of the monitor would be evaluat.ed and raised, while ensuring that all regulatory require-ments for release concentrations (e.g., 10 CFR Part 20 limits) are met. This would permit the high radiation signal to be cleared. Once the high radiation signal were cleared, the ventila-tion isolation signal could be cleared by momentary use of the reset key switch. Plant procedures for this situation, will explicitly provide information as to the function of the reset function and the need to thoroughly understand and evaluate the situation at hand before using the reset. Again, it has never been necessary, to the best of our knowledge, to use the reset to override an isolation signal in our nearly ten years of plant operation.

Finally, it may be necessary to use the reset function in order to purge containment to limit. hydrogen buildup in containment following a design basis loss of coolant accident (LOCA). Follow-ing a LOCA, both a high radiation and SI signal will exist. If, based on hydrogen sampling of the containment atmosphere, necessary to purge, the plant operator is provided detailed it is precautions on use of the reset. He is directed to place all valve position controllers in the close position so that no valve will open on initiation of the reset. Then the operator actuates

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ROCHESTER GAS AND ELECTRIC CORP. SHEET NO.

DATE March 30, 1979 To Mr. D.L. Z iemann, Chief the reset. Finally, he initiates containment purge. It should be noted that purging to control the post-accident, hydrogen concentration is not necessary until at least several days after the event.

In conclusion the Ginna containment ventilation isolation circuitry and procedures regarding its use are adequate. This is based on the detailed procedural controls which have been imple-mented, the physical control of the reset key switch which involves at least two operators to use, and ten years of successful plant operation.

Very truly yours, Leon D. White, LDW:np

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