ML18096A791

LER 92-011-00:on 920523,control Room Ventilation Automatically Switched from Normal to Accident Mode of Operations for Both Units.Caused by Equipment Failure. Channel C Detector Connector replaced.W/920618 Ltr

ML18096A791
Person / Time
Site:	Salem
Issue date:	06/18/1992
From:	Pollack M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-011, LER-92-11, NUDOCS 9206250363
Download: ML18096A791 (4)

Text

.. . . e CPS~G Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station June 18, 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 92-011-00

'!'his Licensee Event Report is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR 5 o. 7 3 (a) ( 2) *(iv) . This report is required to be *issued within thirty (30) days of *event discovery.

• Sincerely yours,

(

c. A Vondra General Manager -

Salem Operations MJP:pc.

Distribution r:. ._ r, *" r* *;j i'~JlJJ.U_1_

9206250363 920618 PDR ADOCK 05000272 S PDR rG22-

• 95-21"/,OM) 12-89

NRC FORM 366 ' U.S. NUCLEAR REGULATORY COMMISSION (6-891 APPROVED OMB NO. 3150-0104 EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY 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-530). U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3150-01041. OFFICE OF MANAGEMENT AND BUDGET. WASHINGTON. DC 20503.

l FACILITY NAME (1) DOCKET NUMBER (2)

• I PAGE 131 Salem Generating Station - Unit 1 0 I 5 I 0 I 0 I 0 I 2 17 I 2 1 OF 0 I 3 I TITLE f'I

• ESF Sig~al Actuati~n: Control Room Vent. Switch to Erner. Mode Due to RMS Channel Spike.

EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

MONTH DAY YEAR YEAR :ft SE~~~~~~AL tr~~~~~~ MONTH DAY . YEAR FACILITY NAMES DOCKET NUMBER(S) a1s 21 3 9 2 9 12 - a I 111 - a Ia a I*6 1 I a .912 THIS REPORT IS SUBMITTED PURSUANT TO THE R~OUIREMENTS OF 10 CFR §: (Check on* or mor* of tho following} (11 l OPERATING Rr---.~~~~~~~~-r---.~~~~~~~~~"""T"'-_,.~~~~~~~~~"""T"'-_,.~~~~~~~~--1 MODE Cll POWER L~~~L I 0 I 0 I 0 ,_

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20.'°6(1)(1 )(ii 20.'°51*)(1)(11)

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50.73(o)(2)(iv) li0.73(oll2llvl 50.73(a)(2)(viil 73.71(b) 73.71(cl OTHER IStMcify in Abstrocr b1/ow *nd in T_ext. NRC Form lllilllil=

20.'°5(a)(1 )(ill).

• - 50.731oi(2)(1) 50.73(oll2llviil)(Al 366A/

20.'°6(a)(1 )(Iv) 20.'°5(1)(1 )(v)

- 50.73(1)(2)(il) 50.73(o)(2)(ili) 1--

50.73(a)(2)(viil)(Bl 50.73(oll2llxl LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AREA CODE M. J. Pollack - LER Coordinator 0

. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

MANUFAC* MANUFAC*

CAUSE SYSTEM COMPONENT SYSTEM COMPONENT TUR ER 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 SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPECTED n ~NO SUBMISSION DATE 1151 YES (If yos, complot* EXPECTED SUBMISSION DATE}

I I I ABSTRACT (Limit to 1400 spaces, i.e., approximately fifteen single-space typewritten Nnes} (16)

On 5/23/92, Control Room Ventilation automatically switched from normal to accident mode of operation (100% recirculation) for both Salem U-1 and Salem U-2 (by design). This was due to a channel spike initiating an alarm signal on the Control Room Air Intake Radiation Monitoring system (RMS) channel, lRlB. The switching* of the Control*Room Ventilation system to the emergency mode of operation is an Engineered Safety Feature (ESF). The cause of the actuation of.the ESF actuation signal is equipment failure. The lRlB RMS monitor consists of four parallel Geiger-Mueller (GM) tube detectors (LFE Model MD-12C). Investigation identified that the "C" GM tube detector was not fully inserted into its three (3) pin socket connection. lRlB RMS channel spiking was reproduced by vibration of the ventilation duct in which the detector is located.

The GM tubes hang. from the top of the duct. They are inserted in Crouse Hinds strain relief connectors. The rubber* *grommet inside the connector had embrittled due to age. Duct vibration had caused the detector pins to slip out of their'sockets. The channel "C" detector connector grommet was replaced and the,detector reinserted into the socket. The other lRlB RMS channel detectors were verified to be correctly connected; however, they too had aged connector grommets. Upon receipt of new grommets, they too will be replaced. The preventive maintenance program for RMS channels using LFE MD-12C detectors will be revised. Other RMS channels which use LFE MD-12C detectors will be inspected and aged parts will be replaced as required.

N RC Form 366 (6-89)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-011-00 2 of 3 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse - Pressurized Water Reactor Energy Industry Identification System (EIIS) codes are identif i,ed in the text as {xx}

IDENTIFICATION OF OCCURRENCE:

Engineered Safety Feature Signal Actuation: Control Room Ventilation switch to emergency mode due to lRlB channel spike Discovery Date: 5/23/92 Report Date: 6/18/92 This report was initiated by Incident Report No.92-313.

CONDITIONS PRIOR TO OCCURRENCE:

Reactor defueled - 10th Refueling outage in progress DESCRIPTION OF OCCURRENCE:

On May 23, 1992, at 1614 hours0.0187 days <br />0.448 hours <br />0.00267 weeks <br />6.14127e-4 months <br />, Control Room Ventilation automatically switched from normal to accident mode of operation (100% recirculation) for both Salem Unit 1 and Salem Unit 2 (by design) . This was due to a channel spike initiating an alarm signal on the Control Room Air Intake Radiation Monitoring System (RMS) {IL}

channel, lRlB *.

The switching of the Control Room Ventilation system to the emergency mode of operation is an Engineered Safety Feature -(ESF). - Therefore, on May 23, 1992, at 1732 hours0.02 days <br />0.481 hours <br />0.00286 weeks <br />6.59026e-4 months <br />, the Nuclear Regulatory Commission (NRC) was notified of the ESF actuation in accordance with the Code of Federal Regulations iOCFR 50.72(b) (2) (ii).

APPARENT CAUSE OF OCCURRENCE:

The cause of the actuation of the ESF actuation signal is equipment failure.

The 1R1B RMS monitor consists of four parallel Geiger-Mueller (GM)

_tube detectors (LFE Model MD-12C). Investigation identified that the "C" GM tube detector was-not fully inserted into its three (3) pin socket connection. lRlB RMS channel spiking was reproduced by vibration of the ventilation duct in which the detector is located.

The GM tubes hang from the top of the duct. They* are inserted in Crouse Hinds strain relief connectors. Investigation indicated that the rubber grommet insid~ the connector had embrittled due to age.

Over time, duct vibration had caused the detector pins to slip out of

- their sockets.

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating station DOCKET NUMBER LER NUMBER PAGE Unit 1 . 5000272 92-011-00 *3 of 3 ANALYSIS OF OCCURRENCE:

The lRlB channel continuously monitors air from the HVAC intake duct into the Unit 1 Control Room. If any of the four (4) GM tubes reaches the alarm setpoint the monitor actuates an alarm initiating closure of the duct intake valve to prevent contaminated air from entering the control room.

The lRlA channel (Control Room General Area Monitor) did not indicate an increase in Control Room radiation levels during this event. This channel. has the same automatic isolation function as the lRlB channel.

This event was not the result of high activity*; therefore, the health and safety of the public was not affected. However_, since Control Room ventilation system switching to the accident mode of operation is an ESF actuation, this event is reportable to the NRC in accordance with Code of Federal Regulations 10CFR 50.73(a) (2) (iv).

CORRECTIVE ACTION:

The lRlB RMS channel-"C" detector connector grommet was replaced and the detector reinserted into its connector socket.

• The other lRlB RMS channel detectors were verified to be correctly connected; however, they too had aged grommets in their connectors.

Upon receipt of new grommets, they too will be replaced.

The preventive maintenance program for RMS channels using LFE MD-12C detectors will be revised to require periodic connector parts replacement.

Other RMS channels which* use LFE MD-12C detectors will be inspected and aged parts will be replaced as required.

~

General Manager -

Salem Operations MJP:pc SORC Mtg.92-067