ML18095A645

LER 90-037-00 on 901117,plant Vent Radioactive Noble Gas Monitor 1R41C Channel Deenergized & Failed During Investigation of 1R45 Channel Printer Failure Alarm Due to Equipment/Design failure.W/901217 Ltr

ML18095A645
Person / Time
Site:	Salem
Issue date:	12/17/1990
From:	Labruna S, Pollack M Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-037-01, NUDOCS 9012270248
Download: ML18095A645 (5)

Text

. e PS~G Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station.

December 17, 1990 U. S. Nuclear Regulatory Commission Document Control Desk

• Washington, DC 20555

Dear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-70 DOCKET NO. 50-272 UNIT NO. 1 LICENSEE EVENT REPORT 90-037-00 This Licensee Event Report is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR 50.73(a) {2) {iv}. This report is required within thirty (30) days of discovery ..

Sincerely yours,

/5~~

S. LaBruna General Manager -

Salem Operations MJP:pc Distribution The t.nagy. ~jeor)i;::

001??70?4R 901~17

~fiR--Ab5cR 05000272 S PDR

ll!llCfo..*111Jll U.1. NUCLEAll llEOULATOllY C:C...11S!091 f~I APl'llOVED OMe NO. :11ll0-41CM EXl'lllEI: 1/31 . .

LICENSEE EVENT REPORT (LER)

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11 ~ OOCKET NUM9Ell (21 I ,.,.,.e (JI FACILITY NAME Salem Generating Station ~ Unit 1 Io 15 I o IO I o I 21 7 12 1 loF 0 I 4 ESF Signal Actuatl..on; 1R41C Failed .Low Due To Design Concern (Cont. Ventilation Isolation)

EVENT DATE (Ill LER NUMBER (IJ llEl'ORT DA TE (71 OTHEll FACILITIEI INVOLVED 191 l!!ONTH QAV VEAR VEAR tt SE~~i~~~AL ft~~~~ MONTH DAV VEAR FACILITY NAMES DOCKET NUMBER(SI Salem Unit 2 O I 5 I O I O I O I 3 11 P.

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- LICENSEE CONTACT FOR THIS LER 1121 NAME . TELEPHONE NUMBER AREA CODE M. J. Poilack - LER Coordin~tor COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRllED IN THll REPOllT 1131 CAUSE SYSTEM COMPONENT MANUFAC- MANUFAC*

TURER SYSTEM COMPONENT TUR ER I I I I I I I . I I I I I I I I I I I I I I I I I I I I I IUPPLEMENTAL REPORT EXPECTED 1141 MONTH DAV ~AR EXPECTED-

~NO SUBMISSION f YES l/f y11, compl~rr EXPECTED SUBMISSION DATE/

DATE 1151 I I I AISTRACT (Limit to 1400 IPICll, i.*.. 1pproxlm1t1ly fiftHn rlngl**'l'"CO tytHwritton linftJ (111 On 11/17/90, during normal power operation, the Radiation Monitoring Syste~.(RMS) 1R45 RMS ~hannels (medium and high range plant vent noble gas RMS monitors) spiked. high. Subsequently, by design~ - the Plant Vent Radioactive Noble Gas Monitor, 1R41C, channel deenergized and failed low resulting in a Containment Purge/Pressure-Vacuum Relief System (CP/P-VRS)- isolation signal and a closure signal for-the 1WG41 valve*

(Waste Gas Decay Tank Vent Control Valve). After receipt of the CP/P-VRS signal, the signal was reset. All channels returned to normal operation. The CP/P-VRS isolation signal is considered an Engineered Safety Feature (ESF). This event dcctlried during investigation of a 1R45 channel printer failure alarm.* Prior to determining the caus~ of the 1R45 channel spike, a second 1R45 channel spike occurred, on 11/18/90, also resulting in deenergization of the 1R41C-RMS channel with a subsequent CP/P-VRS signal actuation and closure signal for the 1WG41 valve. The root cause of the CP/P-VRS actuation is attributed_to a design/equipment deficiency. Investigation revealed that insulation on several-conductors of a ribbon cable had been damaged. Close inspection reve~led that the wire supplying power to the 1R45 printer controls drawer had been partially severed. The ribbon cable was too

-long and had gotten pinched between the cabinet and the drawer. The wire harnesses (ribbon cables), are not arranged so as to preclude their being pinched between the cabinet and ~he drawer. The damaged section of the subject 1R45 printer ribbon cable was removed and the overall. length of the wire shortene~. The wire harnesses have been supported.

NRC Form :1118 (9-831

.. ~~~~-~~~~-*

LICENSEE EVENT REPORT (LER} TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 90-037-00 2 of 4 PLANT AND SYSTEM IDENTIFICATION:

We~tinghbuse - Pres~urized Water Reactor Energy Industry Identification System (EIIS} codes are identified in the text as fxxl IDENTIFICATION OF OCCURRENCE:

Engineered Safety Feature Actuation: Containment Purge/Pressure-Vacuum Relief System Isolation Due To Equipment/Design Concern Event Dates: 11/17/90 and 11/18/90 Report Date: 12/17/90 This report was initiated by Incident Report Nos.90-877 and 90-880.

CONDITIONS PRIOR TO OCCURRENCE:

Mode 1 Reactor Power 100% Unit Load 1145 MWe DESCRIPTION OF OCCURRENCE:

On November 17, 1990 at 0445 hours0.00515 days <br />0.124 hours <br />7.357804e-4 weeks <br />1.693225e-4 months <br />, during normal power operation, the Radiation Monitoring System (RMS} (ILi 1R4S RMS channels (medium and high range plant vent noble gas RMS monitors} spiked high.

Subsequently, by design, the Plant Vent Radioactive Noble. Gas Monitor, 1R41C, channel deenergized and failed low result1ng in a Containment Purge/Pressure-Vacuum Relief System (CP/P-VRS) {BF) isolation signal and a closure signal for the 1WG41 valve (Waste Gas Decay Tank Vent Control Valve). After receipt of the CP/P-VRS signal, the signal was reset. All channels returned to normal operation.

This event occurred during investigation of a 1R45 channel printer failure alarm.

The CP/P-VRS isolation signal is considered an Engineered Safety Feature (ESF). Subsequently, at 0631 hours0.0073 days <br />0.175 hours <br />0.00104 weeks <br />2.400955e-4 months <br /> on November 17, 1990, the Nuclear Regulatory Commission was notified of the automatic actuation of CP/P-VRS as required by Code of Federal Regulations 10CFR 50.72{b} (2} (ii).

Prior to determining the cause of the 1R45 channel spike, a second 1R45 channel spike occurred, on November 18, 1990 at 1625 hours0.0188 days <br />0.451 hours <br />0.00269 weeks <br />6.183125e-4 months <br />, also resulting in deenergization of the 1R41C RMS channel with a subsequent CP/P-VRS signal actuation and 1WG41 valve closure signal.

The NRC was notified of this second actuation at 1706 hours0.0197 days <br />0.474 hours <br />0.00282 weeks <br />6.49133e-4 months <br /> on November 18, 1990 in accordance with Code of Federal Regulations_

10CFR 50.72(b} (2} (ii). This second actuation occurred during a required 1R45 channel check, prior to the discovery of the root cause of the first event.

I LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER . LER NUMBER PAGE Unit 1 5000272 90-037-00 3 of 4 APPARENT CAUSE OF OCCURRENCE:

.The root cause of the CP/.P-VRS actuation is attribut.ed to a**

design/equipment deficiency. -Investigation revealed that insulation.

on several conductors of*a ribbon cable had been damaged. Close irispection rev~aled that the wire supplying power to the 1R45 printer controls drawer had been partially sever~d. The ribbon cable was too long and had gotten pinched between the cabinet and the drawer.

The, wire harnesses (ribbon cables), located behind the 1R45 controls drawer are not arranged so as to preclude their being pinched between the cabinet and the drawer. The, drawer must be routinely slid out*in order to access a controls~key pad (in su~port of ch~nnel checks).

Therefore, when the drawer was moved, the wire shorted to ground resulting in the 1R45 channel spike. Both £SF.actuations occurred during drawer movement.

The physical location of the ribbon cable, in the back of the drawer, is such.that it cannot be easily observed.

ANALYSIS OF OCCURRENCE:

Tsola.tion of the CP /P-VRS is part of the design Engineered Safety

.~eatures (ESFs). It.mitigates the release of excessive quantiti~s of.

radioactive material to the environment after a design base accident.

The 1R45B ch~nnel is interlocked-with the 1R41 detectors and sample pump causing them to deenergize upon reaching the high radiation level setpoint. This is designed to protect the 1R41 channel detectors. With the dete~tors deenergized, a CP/P-VRS isolation signal is generated, by design.

1 The 1R41C 6hannel mo~itors the plant vent effluent releases for.

radioactive noble gas via representative sampling. The ESF actuation feature of CP/P-VRS isolation, associated with this channel, is of conservative design. It is redundant to the 1R12A channel. In addition to its ESF function, the channel isolates the 1WG41 valve (Waste Gas Decay.Tank Vent Control Valve). During the 1R41C CP/P-VRS isolation signal events, the 1Rl2A monitor remained operable.

At the time of these events, neither containment purge, containment pressure/vacuum reli'ef or waste gas decay tank release was in

• progress. The associated valves with these functions were in the closed position during both.*events.

The 1R45B and C channel detectors are Eberline SA~14 and SA-15 (respectively) energy compensated GM tubes.

The inadvertent actuation of the CP/P-VRS isolation signal was caused by an equipment/design concern, not high activity. Therefore, this.

event did not affect the health or safety of the public. However, due to the actuati6n of an ESF function, this event is reportabl~ in accordance with Code of Federal Regulations 10CFR 50.73(a) (2) (iv).

I LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 90-037-00 4 of 4 ANALYSIS OF OCCURRENCE: (cont'd)

On March l, 1990 this same event occurred on the Salem Unit 2 2R45 printer (reference LER 311/90-011-00). The Unit 2 2R45 channel printer is the same printer used by the 1R45 channel. As a result of the Unit 2 event, the printer quarterly preventive maintenance requirements (for both Units) were modified to include inspection of the printer wiring. The last Unit 1 printer inspection was completed in October 1990. No wiring concerns were noted as a result of that inspection.

CORRECTIVE ACTION:

The damaged section of the subje~t 1R45 printer ribbon cable was removed and the overall length of the wire shortened. The wire harnesses (for the Salem Unit 1 and Salem Unit 2 R45 channel printers) have been supported to prevent them from being pinched between the drawer and the cabinet.

General Manager -.

Salem Operations MJP:pc SORC Mtg.90-160