05000336/LER-1997-012-02, :on 970410,inadequate DG Start Surveillance Test Was Identified.Caused Because Personnel Was Unaware That Design of Circuitry for DG Ready to Load Annunciator Did Not Adequately Represent Engine Speed.Revised Sps

:on 970410,inadequate DG Start Surveillance Test Was Identified.Caused Because Personnel Was Unaware That Design of Circuitry for DG Ready to Load Annunciator Did Not Adequately Represent Engine Speed.Revised Sps

ML20141C463
Person / Time
Site:	Millstone
Issue date:	05/09/1997
From:	Joshi R NORTHEAST NUCLEAR ENERGY CO.
To:
Shared Package
ML20141C432	List: 05000336/LER-1997-012, Forwards LER 97-012-00 Which Documents an Event That Occurred at Mnps,Unit 2 on 970410.Commitments Made within Ltr,Submitted 05000336/LER-1997-012-02, :on 970410,inadequate DG Start Surveillance Test Was Identified.Caused Because Personnel Was Unaware That Design of Circuitry for DG Ready to Load Annunciator Did Not Adequately Represent Engine Speed.Revised Sps
References
LER-97-012-02, LER-97-12-2, NUDOCS 9705190057
Download: ML20141C463 (3)

LER-1997-012, on 970410,inadequate DG Start Surveillance Test Was Identified.Caused Because Personnel Was Unaware That Design of Circuitry for DG Ready to Load Annunciator Did Not Adequately Represent Engine Speed.Revised Sps

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3361997012R02 - NRC Website

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'NRC FORM 366 U.s. NUCLEAR REGULAToRf Commission APf' ROVED BY OMB NO. 3160-0104 EXPIRES 04/30/98

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LICENSEE EVENT REPORT (LER)

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P AC2JTY NAME (1)

DOCKET NUMBER (2)

PAGE (3)

Millstone Nuclear Power Station Unit 2 05000336 1OF3 l

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Inadequate Diesel Generator Start Surveillance Test 1

EVENT DATE (5)

LER NUMBER (6)

REPORT DATE (7) oTHER FACILITIES lNVoLVED(8)

SEQU AL RE N

MONTH DAY YEAR MONTH DAY YEAR YEAR u

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f 00 05 09 97 012 04 10 97 97 OPERATING THIS REPORT is SUBMITTED PURSUANT To THE REQUIREMENTsoF 10 CFR 5: (Check one or more) (11)

MODE (9)

N 20.2201(b) 20.2203(aH2Hv)

X 50.73(aH2Hi>

50.73(aH2Hviii)

POWER 20.2203(aH1) 20.2203(a)(3Hi) 50.73(aH2Hii) 50.73(aH2)(x)

LEVEL (10) 000 20.2203(aH2Hi) 20.2203(aH3Hn) 50.73(aH2)(iii) 73.71 20.2203(a)(2Hn) 20.2203(aH4) 50.73(aH2)(sv) oTHER r

20.2203(a)(2Hiii) 50.36(cH1) 50.73(aH2Hv) specify in Abstract below 20.2203(aH2)(iv) 50.36(c)(2) 50.73(a)(2)(vii) in NRC Form 366A LICENSEE CONTACT FoR THis LER (12)

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' NAME TELEPHONE NUM8ER Unciude Area Code)

R. G. Joshi, MP2 Nuclear Licensing (860)440-2080 COMPLETE ONE LINE FoR EACH COMPONENT FAILURE DEsCRIBEDIN THIS REPORT (13)

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SYSTEM COMPONE NT M ANUF ACTURE R

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SYSTEM COMPONENT MANUFACTURER pg t

SUPPLEMENTAL REPORT EXPECTED (14)

EXPECTED MONTH DAY YEAR submission X No DATE (15) f as, complete EXPEC TED sUBMISstoN DATE).

ABSTRACT (Limit to 1400 spaces. Lo., approximately 15 single-spaced typewnttenlines) (16)

On April 10,1997, while researching a plant modification, it was discovered that the Emergency Diesel Generator (EDG) operability surveillance tests, which are used to satisfy Surveillance Requirement 4.8.1.1.2.a.2, &

4.81.1.2 c.8 c, inappropriately used the " Diesel Gen Ready to Load

• annunciators as the acceptance criteria to verify

>/= 90% speed. The annunciator is designed to turn on when the diesel generator is at both >/= 97% of Rated Voltage and >/= 90% of Rated Speed. The speed signalis provided by either of two switches which are wired in parallel. One switch, the Speed Switch Transmitter (SST) closes its contact when Diesel Engine Speed is >/= 810 rpm, or >/= 90% of rated speed. The second switch, the Engine Lube Oil Pressure Switch is set to close its contact at.

>/= 13 psi. This pressure may be reached prior to 810 rpm resulting in the " Diesel Gen Ready To Load

• annunciator j

being tumed on before the engine is at 90% of rated speed. This test method would be a non-conservative condition.

The cause of this condition is personnel were unaware that the design of the circuitry for the Diesel Gen Ready To Load annunciator did not adequately represent engine speed.

To correct this deficiency, Surveillance procedures have been revised to venfy engine speed. In the response to NOV 336/96-08-07 (NNECO Commitment No. B16076-2), Millstone Unit No. 2 committed to perform a review of Technical Specification surveillance procedures to ensure compliance with Technical Specification surveillance requirements as part of the Operational Readiness Plan.

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TEXT CONTINUATION FACIUTY NAME m DOCKET LER NUMBER (6)

PAoE (3)

SEQUENTIAL REVISION l

YEAR NUMBER NUMBER 2OF3-i Millstone Nuclear Power Station Unit 2 05000336 97

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00 TEKT rIf more spaceis requwed use additionalcopies of NRC form 366A) l11l

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1.

Description of Event

On April 10,1997, while researching a plant modification, it was discovered that the Emergency Diesel Generator (EDG) [EK) operability surveillance tests, which are used to satisfy Surveillance Requirement 4.8.1.1.2.a.2, &

4.8.1.1.2.c.8.c, inappropriately used the " Diesel Gen Ready to Load" annunciators [lB) as the acceptance criteria j

to venfy >/= 90% engine speed. The annunciator is controlled by the High Speed Relay (HSR) in the EDG output i

circuit breaker logic. The annunciator is designed to turn on when the diesel generator is at both >/= 97% Rated

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Voltage and >/= 90% of Rated Speed (Speed). The HSR is energized by either of two switches which are wired in l

parallel, One switch, the Speed Switch Transmitter (SST), closes its contact when Diesel Engine Speed is >/= 810 t

rpm, or >/= 90% of rated speed. This condition indicates the engine is, in fact, ready to accept load. The second l

switch, the Engine Lube Oil Pressure Switch (OPS), is set to close its contact at >/= 13 psi. However, this pressure may be reached pnor to 810 rpm. Thus, the Surveillance Test Acceptance Criteria, the " Diesel Gen Ready To Load

• annunciator, may be turned on before the engine is at 90% of rated speed. This test method would be a 1

non-conservative condition. At the time of discovery of this condition the unit was defueled.

This event is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B), any operation or condition prohibited by

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I the plant's Technical Specifications.

II.

Cause of Event

l Personnel were unaware that the design of the circuitry for the Diesel Gen Ready To Load annunciator did not adequately represent ogine speed.

Ill. Analysis of Event r

The EDG output breaker circuit has a Ready To Load indicating light in the diesel room and a Diesel Gen Ready To Load annunciator in the control room which indicate the EDG is at 90% of rated speed and 97% of rated voltage. The voltage signal is from the '59' relay (>/= 4035 volts). The speed signal comes from the High Speed Relay (HSR) which is actuated by two switches in parallel. First, the SST contact which closes at >/= 810 rpm.

Second, the OPS contact which closes at >/= 13 psi. When contacts of both the '59' relay and the HSR are closed, the Diesel Ready To Load (DRL) relay picks up and turns on the Ready To Load indicating light and the Diesel Gen Ready To Load annunciator, The existing design is in agreement with the Vendor Technical Manual. The manual discusses the lube oil pressure switch (OPS) with its contact closure at 13 psi increasing. The pressure switch is described as being a redundant device to the 810 rpm speed switch. The engine typically reaches 810 rpm in 8 to 9 seconds from the start signal. During a field test the OPS switch actuated 9 to 10 seconds after the start signal. The time for the engine to develop 13 psi and the response time of the oil pressure switch is difficult to predict since the time will vary with oil temperature Therefore, it is not possible to accurately correlate engine oil pressure to engine speed during an engine start.

Because the actual diesel generator start time is unaffected by the method of surveillance, and recent tests using direct measurement of the output of the SST have confirmed start times of 8 to 9 seconds, well within the Technical Specification requirement of </= 15 seconds, there is no safety significance to this event.

. NRC FC=M 35 % 44 95)

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,U.S, NUCLEAR REGULATORY COMMISSloN 14 @ 5)

UCENSEE EVENT REPORT (LER)

TEXT CONTINUATION

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FACE.lTY NAME (1)

DOCKET LER NUMBER (6)

PAGE (3) l SEQUENTIAL REVISION I

3 YA NUMBER NUMBER 3OF3 l

. Millstone Nuclear Power Station Unit 2 05000336 97

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TEKT (11more space is required. use addrtionalcopies of NRC Form 366A) (11)

IV. Corrective Action

i As a result of this event, the following actions have been, or will be, performed.

t 1.

Surveillance procedures have been revised to verify engine speed.

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2. In the response to NOV 336/96-08-07 (NNECO Commitment No. B16076-2), Millstone Unit No. 2 i

committed to perform a review of Technical Specification surveillance procedures to ensure compliance with Technical Specification surveillance requirements as part of the Operational Readiness Plan.

V.

Additionalinformation

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Similar Events

LER 96-038:

Inadequate Surveillance Test used to verify Emergency Diesel Generator Operability. Reported lL that the setpiont of the voltage relay which indhated >/= 97 percent of rated voltage was miscalibrated.

t Energy Industry identification System (Ells) codes are identified in the text as [XX).

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