ML17256A558

Forwards Response to 830311 Request for Info Re Mod to Safety Injection Pump 1C Logic.Submittal Consists of Design Criteria & Electrical Schematics

ML17256A558
Person / Time
Site:	Ginna
Issue date:	03/15/1983
From:	Maier J ROCHESTER GAS & ELECTRIC CORP.
To:	Crutchfield D Office of Nuclear Reactor Regulation
References
NUDOCS 8303230232
Download: ML17256A558 (13)

Text

REGULATORY FORMATION DISTRIBUTION S M (RIDS)

AGCESSION NBR:8303230232 DOC ~ DATE: 83/03/15 NOTARIZED:

NO DOCKET FACIL:50 244 Robert Emmet Ginna Nuclear Planti Unit ii Rochester G

05000244 AUTH,NAME AUTHOR AFFILIATION MAIER~J,E ~

Rochester Gas L Electric Corp, REC IP ~ NAME RECIPIENT AFFILIATION CRUTCHFIELDrDo Operating Reactors Branch 5

SUBJECT:

Forwards response to 830311 request for info re mod to. 1C safety injection pump logics Submittal consists of design criteria 8 electrical schematics, DISTRIBUTION CODE; A035S 'OPIES RECEIVED:LTR / ENCL, J SIZE' TITLE:

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ROCHESTER GAS AND ELECTRIC CORPORATION o

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89 EAST AVENUE, ROCHESTER, N.Y. 14649

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'OHN E. gA IER VICE PRESIDENT TELEPHONE AREA COOE TIE 546-2700

, March 15, 1983 Director of Nuclear Reactor Regulation Attention:

Mr. Dennis M. Crutchfield, Chief Operating Reactors Branch No.

5 U.S. Nuclear Regulatory Commission Washington, D.C.

20555 Sub ject:

1C Safety Injection Pump Logic R. E.

Ginna Nuclear Power Plant Docket No. 50-244

Dear Mr. Crutchfield:

Ry letter dated November 22,

1982, we to be made to the 1C Safety Injection Pump to this letter is in response to the March request for additional information on this member of your staff.

identified the modification Logic.

Enclosure A

ll, 1983 telephone

subject, made by a Very truly yours, J

E. Maier Enclosure

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Enclosure A

Desi n Criteria Summar Descri tion of the Desi n The modification as proposed herein affects the Emergency Safety Features Actuation System (ESFAS).

Specifically, the 1C Safety Injection pump control scheme is to be modified so as to a) insure predictable loading of the 1C pump, b) improve availability of the 1C pump in the event of a breaker failure, c) prevent the transfer of a faulted 1C pump motor from its preferred to its alternate source and.d) allow the 871 A&B valves to go full open upon the loss of both 1A 6

1B pump breakers.

The ESFAS System at Ginna Station, consists of control

relays, electro-penumatic timers and a series of electrical and mechanical interlocks on each train.

Xn general, Class 1E equipment is loaded on the safeguards buses at approximately five second intervals.

The only exception is the 1C Safety Injection pump, which is a "swing" pump and may be fed from either breaker 52/SIP1C2 (bus 14, train A).or breaker. 52/SXP1C1 (bus 16, train B).

To prevent closure of both circuit breakers, causing buses 14 and 16 to be paralleled~

a network of interlocks is used.

Presently, these interlocks are configured as discussed in the Ginna Station

FSAR, page 8.2-12a and outlined below.

The first set of interlocks consists of instantaneous

,auxiliary contacts off of time delay relays associated with'he 1C SI&, breakers.

This existing scheme is shown on Figure X.

Normal operation of the 1C SIP system begins with a simultaneous SI signal and normal bus voltage.

The timers on both systems initially

energize, thereby simultaneously deenergizing each

other, which through the interlocks, reenergize once again.

This sequence occurs until such time as one interlock drops out ahead of the other and thus one timer is locked out.

This sequence of instantaneously "picking up" and "dropping out" has the potential of delaying the overall time in which the 1C SI pump finally is placed in service.

In addition, the timing relays can be overstressed.

Because the existing configuration is interlocked ahead of the timing relays it results in the unpredictable loading of the 1C SX pump onto either bus 14 or 16.

An improvement in the performance of the ESFAS system can be accomplished by using "time delayed" contacts as interlocks, that is, output contacts on the time delay relays.

Page 1

Figure II details this modification, which establishes bus 14 as the preferred source for the 1C SI pump and bus 16 as the backup 'source, should bus 14 be out, of service.

The proposed interlocking contacts are time delayed.

That is, they will not open until the relay timers have completed their respective preset delay time. It can be seen that the 1C2 timer is set at 5 seconds while the 1C1 timer is set at 7 seconds.

Consequently, the time delayed contacts on the 1C2 timers will deenergize the 1C1 timer in 5 seconds, thus making bus 14 the preferred source for the 1C SI pump motor.

The USNRC staff has evaluated this proposed change. and in their Safety Evaluation Report (NUREG 0916) have endorsed this approach of eliminating the uncertainty associated with the 1C pump loading.

I As discussed, the existing scheme loads the 1C pump on the bus whose timer happens to pick up first. If an undervoltage condition occurs, the 1C pump can swing

. over to.the opposite train.

However, if full bus voltage exists but the breaker fails to "close in", due to a tripper bar adjustment problem or some other mechanical

problem, then the 1C pump function is lost.

Figure II represents part of the proposed modification which will allow the 1C pump motor to swing to bus 16, should the 1C2 breaker fail to close on bus 14 after a total delay time of 37 seconds.

'This transfer will not however be allowed if an electrical fault occurs on the 1C motor.

This transfer scheme will not subject both trains to a common electrical fault.

This is an NRC requirement and must be included in this modification.

The proposed modification to the ESFAS system utilizes a spare TD relay on the A Train Sequencer.

The new relay (2-1C2X) will be energized through a "b" contact off of the SIP breaker on bus 14 (52/SIP1C2) coincident with an alarm switch off of the same breaker.

'I

',I I The new timing relay will be set at 30 seconds and it follows the 2/SIP 1C2 timer until it times out and causes the 1C2 breaker to close.

If this breaker fails to close within the 30 second period, then the 2-1C2X Page 2

will energize and drop out the 2-SIPlC2 timer and al low the 2-SIP1C1 timer to pick up and seven seconds

later, the 1C pump will be automatically loaded on bus 16.

The 37 second time delay comes about. by using the spare 30 second timer on the A train plus the 7 seconds delay associated with the 1C1 breaker TD relay.

Since a

single 1C breaker failure is the only postulated failure that must be considered and it is assumed that both the 1A and 1B SI pumps are operational, the total accumulated time delay of 37 seconds is consistent with the Ginna Station FSAR.

In addition to modifications to the interlocks, the control scheme for the valves associated with the 1C pump requires evaluation.

In the event that either the 1A or 1B SI pump breakers fail to close after an SI signal is received, then the 871 A or B valves are automatically aligned so that the 1C pump functionally replaces the lost SI pump.

However, in the event, that both the 1A and 1B SI pump breakers electrically fail to close after an SI, the 871 A

& B valves will automatically go closed, isolating the 1C pump.

The proposed modification will provide valve control logic consisting of an auxiliary relay that energizes only when both the SIP1A and 1B breakers fail to close.

This relay will block the auto closure of both 871A 6

B valves.

This logic is only formed during SI.

The auxiliary relay, once energized, will prevent the 871 A6B valves from going closed.

(Note:

871 A&B are normally "opened").

Figure III outlines the proposed scheme.

Functions The functions of the proposed change to the electrical interlocks (i.e.

change from instantaneous to time delay contacts) is to assure that the 1C SIP will be supplied.from Bus 14 and if Bus 14 undervoltage

occurs, to swing over to Bus 16.)

The function of the additional timer and control changes is to allow the 1C pump to transfer to Bus 16 if the 1C breaker on Bus 14 fails to close due to

~an electrical or mechanical failure of the 1C2 breaker with the exception of an over current condition due to a fault on the 1C pump.

Should a fault occur.on the 1C motor Page 3

it. will trip out after attempting to close'on to bus 14.

This condition will be detected and the 1C motor will not be transfers'ed to bus 16.

This will preclude subjecting both safety trains to a common fault.

In addition, the 480 volt class IE system has been evaluated to ensure that a fault on the 1C pump motor will not result in a detectable undervoltage on bus 14 and initiate a transfer.

This evaluation has been reviewed and accepted by the USNRC staff reviewers and is referenced in section 2.3.

The functions of proposed control scheme on the 871 ASB valves is to allow these valves to open on the loss of both the 1A and 1B safety injection pump and the successful closure of either 1C1 or 1C2 breakers.

Performance Re uirements The time delayed interlocking contacts shall be set for 5 seconds on train A and 7 seconds on train B consistent with the Ginna Station FSAR.

The time delay required for developing the control scheme that will allow the 1C pump motor to swing over to Bus 16 on the failure of the 1C2 breaker (other than undervoltage) must be set to operate at 30 seconds so that the 1C motor is not loaded onto the diesel along with another 1E motor.

The auxiliary relay required to form the logic that willjallow the.'871 A and B valves to go open on con-current loss of the 1A and 1B Safety Injection pump motors shall be instantaneous and not time delayed.

Control All. proposed changes and modifications shall be auto-

matic, and no manual control will be included.

Modes of 0 eration The normal mode of these control schemes to operate will be to automatically form the required logic.

This logic will however be verified by test.

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