ML18096A808

LER 92-013-00:on 920602,two ESF Actuation Signals Initiated from Radiation Monitoring Sys Causing Alarm.Cause Attributed to an Electrical Fault in Sys.Both Channels Returned to Service After Resetting Alarm functions.W/920702 Ltr

ML18096A808
Person / Time
Site:	Salem
Issue date:	07/02/1992
From:	Pollack M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-013, LER-92-13, NUDOCS 9207070382
Download: ML18096A808 (4)

Text

OPS~G Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey,08038 Salem Generating Station July 2, 1992

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 92-013-00 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 to be issued within

• thirty (30) days of event discovery.

Since ely yours,

c. A Vondra General Manager -

Salem Operations MJP:pc Distribution Thi:: (,*,pr.nv PP.onl8 ri::,,a."2.

,

9207070382 920702 PDR ADOCK 05000272 95-2189 (10M) 12-89 S . PDR

NRC FORM366 U.S. NUCLEAR REGULATORY COMMISSION 16-891 APPROVED OMB NO. 3150-0104 EKPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE* TO COMPLV WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD LICENSEE EVENT REPORT CLER) COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH (P-6301. U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON. DC 20555. AND TO .

THE PAPERWORK REDUCTION PROJECT (3150-01041. OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON. DC 20S03.

I FACILITY NAME 111 DOCKET NUMBER 121 I PAii!: 131 Salem Generatina Station - Unit 1 . o 1s101010121112l1loF 013 TITLE l'I 2 Enqineered Safety Feature actuation siqnals initiated from the Radiation Monitoring Syst.

EVENT DATE 151 LER NUMBER Ill REPORT DATE (71 OTHER FACILITIES INVOLVED Ill MONTH DAY VEAR YEAR mr SE~~~~~~AL {? :~~~~ MONTH DAY YEAR FACILITY NAMES . DOCKET NUMBERISI 016012 929l2-ol1b-olo*oh cl2912 01s1010101 I I OPERATING THll REPORT IS SUBMITTED PURSUANT TO THE R~OUIREMENTI OF 10 CFR §: (Chtck on1 or mor1 (!f th* fo/lowinlJ} 1111

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.__ ll0.7311112ll*lllllAI l50.731*112ll*llillBI ll0.731*11211*1 366AI LICENSEE CONTACT FOR THIS LER 1121 NAME TELEPHONE NUMBER AREA CODE M i >>~11~~~ ~* T.~~ Coordinator 6 1019 313191-12!01212 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 1131 MANUFAC* MANUFAC*

CAUSE SYSTEM COMPONENT TUR ER . TURER 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 SUPPLEMENTAL REPORT EKPECTED 1141 MONTH DAY VEAR rx, EXPECTED n YES (If y1r. comol1t1 EXPECTED SUBMISSION DATE} N.0 SUBMISSION DATE 1151 I I I ABSTRACT (Limir ro 1400 *J>>C**. i.*.. *pprOllim*t.ly fift11n 1inglt1*l1Jac* ty~w;itr.n /in**} (111 on 6/2/92, at 0043 hours4.976852e-4 days <br />0.0119 hours <br />7.109788e-5 weeks <br />1.63615e-5 months <br />, the iRlA Control Room General Area Monitor and the lRllA Containment Particulate Radiation Monitoring System (RMS)

Monitor channels spiked into alarm*. The lRlA channel spike caused control.Room Ventilation to switch to the emergency mode of operation in both Units (by design) and the lRllA channel spike caused Containment Purge/Pressure-Vacuum Relief System isolation (both are ESF signals). At the time of the lRlA and lRllA RMS channel spikes a design change was being incorporated*to the lA Vital Instrument Inverter and the inverter was aligned to support preventive maintenance. The cause of this event is attributed to an electrical perturbation on the lA 115 VAC system.

Investigation to date has not identified the cause of the perturbation.

The following tests did not reveal any anomalies; 1) inverter fan a~sembly testing and 2) ESF manual safety injection testing where lA Vital Bus loads were shed and sequenced on. The lRllA and lRlA RMS channels were returned to service following resetting of their alarm interlock functions. Investigation of the electrical perturbation is continuing.

NRC Form 366 (6-891

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER *PAGE Unit 1 5000272 92-013-00 2 of 3 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse Pressurized Water Reactor Energy Industry Identification System (EIIS) codes are identified in the text as {xx}

IDENTIFICATION OF OCCURRENCE:

2 Engineered Safety Feature actuation signals initiated from the Radiation Monitoring System Event Dates: 6/02/92

.Report Date: 7/02/92 This report was initiated by Incident Report No.92-353.

CONDITIONS PRIOR TO OCCURRENCE:

Mode 6 (Refueling) 10th Refueling Outage in progress DESCRIPTION OF OCCURRENCE:

On June 2, 1992, at 0043 hours4.976852e-4 days <br />0.0119 hours <br />7.109788e-5 weeks <br />1.63615e-5 months <br />, the lRlA Control Room General Area Monitor .and *the 1R11A Containment Par.ticulate Radiation Monitoring System (RMS) Monitor channels {IL} spiked into alarm. The lRlA channel spike caused Control Room Ventilation to switch to the Emergency Mode of Operation in both Units (by design) and the 1Rl1A channel spike caused a Containment Purge/Pressure-Vacuum Relief*

(CP/P-VR) System {BF} isolation signal. *

. In addition to the RMS channel spikes., other equipment. fed by the 1A Vital Instrument Bus experienced electrical perturbation (e.g.,

failure of the Hydrogen Analyzer.).

The 1R1A and 1Rl1A RMS channel spikes occurred while a design change was being incorporated to the lA Vital Instrument Inverter and the inverter was aligned to support preventive maintenance .. The AC line regulator was deenergized and the inverter was manually selected to supply power to the lA Vital Instrument Bus.,

During the design change, it was required to remove the AC line regulator cooling fan fuses to allow fan alarm relay replacement.

When the first fan fuse was removed, the technician observed an audible change in the inverter's background noise. This noise change is related to an increase/decrease in the inverter load or 'input AC voltage changes. Concurrently, the Control Rooin operators observed RMS channel spiking (including the 1R1A* and 1RllA channels) and

• numerous overhead alarms. The affected equipment is powered.from lA

. Vital Instrument *Bus.

• LICENSEE EVENT REPORT *(LER) TEXT CONTINUATION

• Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 . 5000272 92-013-00 3 of 3 DESCRIPTION OF OCCURRENCE: (cont'd)

The containment ventilation isolation valves were open at* the time of this event; i.e., Containment Purge was in progress. The valves closed per design upon RMS actuation. Also, the equipment required to change state, as a result of the lRlA actuation, responded per design.

Control Room ventilation switching to its emergency mode of operation and CP/P-VR System isolation are Engineered Safety Features (ESFs).

Therefore, the Nuclear Regulatory Commission (NRC) was notified of these actuation signals in accordance with Code of Federal Regulations 10CFR 50.72(b) (2) (ii). on June 2, 1992, at 0209 hours0.00242 days <br />0.0581 hours <br />3.455688e-4 weeks <br />7.95245e-5 months <br />.

APPARENT CAUSE OF OCCURRENCE:

The cause of this event is attributed to an electrical perturbation on the lA 115 VAC system. Investigation to date has not identified the cause of the perturbation. The following tests did not reveal any anomalies: 1) inverter fan assembly testing and 2) ESF manual safety injection testing where lA Vital Bus loads were shed and sequenced on.

• 1 i

ANALYSIS OF OCCURRENCE: I I

Isolation of the CP/P-VR System is an ESF. It mitigates the release of radioactive material to the environment after a design basis accident. Switching of the Control Room ventilation to the accident mode of operation (100% recirculation) is also an ESF. .It allows continued Control Room habitability during post~lated accidents.

The two (2) ESF actuations did not result from an increase in Containment particulate activity or Control Room ventilation duct radiation levels. This event did not affect the health or safety of the public;* however,-it is reportable to the NRC in accordance with Code of Federal Regulations 10CFR 50.73(a) (2) (iv).

CORRECTIVE ACTION:

The lRllA and lRlA RMS channels were returned to service following resetting of their alarm interlock functions. Also, the other affected equipment were returned to service.

Investigation of the electrical perturbation is continuing.

The lA Vital Instrument Bus was found.to have functioned as designed. No MJP:pc SORC Mtg.92-072