05000311/LER-1990-027

LER 90-027-00:on 900628,determined That ESF Signal Actuation 2R41C Channel Failed Low Due to 2R45 Interlock.Caused by Design/Equipment Concerns.Engineering Investigated Concerns & Uninterruptable Power Sys installed.W/900717 Ltr

ML20055G611
Person / Time
Site:	Salem
Issue date:	07/17/1990
From:	Miller L, Pollack M Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-027, LER-90-27, NUDOCS 9007230371
Download: ML20055G611 (4)

LER-2090-027,

Event date:
Report date:
3112090027R00 - NRC Website

text

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O PSEG Public Servico Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station -

July [17, 1990 o

U; S. Nuclear-Regulatory Commission Document' Control-Desk.

Washington,'DC. 20555

Dear Sir:

SALEN GENERATING. STATION LICENSE NO. DPR-75 iDOCKET NO. 50-311

. UNIT No. 2-LICENSEE EVENT-REPORT 90-027-00 4 --

=This Licensee Event Raport 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.

1 Sincerely yours, N

L. K. Miller.

General Manager -

[M w Salem Operations MJP:pc Distribution 9007230371 900717 PDR ADOCK0500ggi s

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a.. - , ., - , ,o.c On June 28, 1990 at 1320 hours0.0153 days <br />0.367 hours <br />0.00218 weeks <br />5.0226e-4 months <br />, with the Unit in Mode 3, the Radiation Monitoring System (RMS) 2R45 RMS channels (medium and high range Plant Vent nobleLgas RMS monitors) spiked high.- Subsequently, by design, zthe Plant Vent Radioactive Noble Gas Monitor, 2R41C,_ channel

~deenergized.and failed low resulting in a Containment 1 Purge / Pressure-Vacuum Relief System (CP/P-VRS) isolation signal and a closure signal for the 2WG41 valve (Waste Gas Decay Tank Vent Control ,

Valve). The CP/P-VRS isolation signal is considered an Engineered l~ Safety Feature (ESF). The root cause of the CP/P-VRS actuation is L attributed to design / equipment conc' erns. As indicated in prior LERs (e.g., 311/90-019-00), the Salem Unit 2 RMS is prone to voltage transients. Investzgation of this event did not identify any-specific equipment / component failure. Since the event, the R45 channels have been operating satisfactorily. Therefore, the 2R45 channel spike has p been attributed to a voltage transient. As indicated in LER ,

L 311/90-019-00, Engineering has investigated the concerns with the Unit 2'RMS channels. It is anticipated that several system design l l nodifications will eliminate the spurious ESF actuation signals. One 4 l of these design modifications is the installation of an

.uninterruptable power supply (UPS), which will be completed by February 1991. The plans for completion of these modifications are included in the current PSE&G Living Engineering Plan for the RMS system.

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4 kICENSEE EVENT REPORT (LER) TEXT CONTINUATION Sal'an Generating Station DOCKET NUMBER LER NUMBER PAGE

. Unit 2 5000311 90-027-00 2 of 3 _

PLANT AND SYSTEM IDENTIFICATION:

Westinghouse - Pressurized Water Reactor Energy Industry Identification System (EIIS) codes are identified in the text as (xxl IDENTIFICATION OF OCCURRENCE 1 Engineered Safety Feature Actuation: Containment Purge / Pressure-Vacuum Relief System Isolation Due To Equipment / Design Concerns Event Date: 6/28/90 Repor t Date: 7/17/90 This report was initiated by Incident Report No. 50-443.

CONDITIONS PRIOR TO OCCURRENCE:

Mode 3 (Hot Standby)

DESCRIPTION OF OCCURRENCE:

On June 28, 1990 at 1320 hours0.0153 days <br />0.367 hours <br />0.00218 weeks <br />5.0226e-4 months <br />, with the Unit in Mode 3, the Radiation Monitoring System (RMS) IIL) 2R45 RMS channels (medium and high range Plant Vent noble gas RMS monitors) spiked high. Subsequently, by design, the Plant Vent Radioactive Noble Gas Monitor, 2R41C, channel deenergized and failed low resulting in a Containment Purge / Pressure-Vacuum Relief System (CP/P-VRS) IBFI isolation signal and a closure signal for the 2WG41 valve (Waste Gas Decay Tank Vent Control Valve).

The CP/P-VRS isolation signal is considered an Engineered Safety Feature (ESF). Subsequently, at 1440 hours0.0167 days <br />0.4 hours <br />0.00238 weeks <br />5.4792e-4 months <br /> on June 28, 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) .

APPARENT CAUSE OF OCCURREN_C_E_:_

The root cause of the CP/P-VRS actuation is attributed to design / equipment concerns. As indicated in prior LERs (e.g.,

311/90-019-00), the Salem Unit 2 RMS is prone to voltage transients.

Investigation of this event did not identify any specific equipment / component failure. Since the event, the R45 channels have been operating satisfactorily. Therefore, the 2R45 channel spike has beer attributed to a voltage transient.

ANALYSIS OF OCCURRENCE:

Isolation of the CP/P-VRS is part of the design Engineered Safety Features (ESPs). It mitigates the release of excessive quantities of

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,. L7CENSEE EVENT REPORT (LER) TEXT CONTINUATION 831'em Generating Station DOCKET NUMBER LER NUMBER- PAGE

' Unit 2 5000311 90-027-00 3 of 3

' ANALYSIS OF OCCURRENCE: (cont'dl radioactive material to the environment after a design base accident.-

The 2R45B channel is interlocked with the 2R41' detectors and sample pump.to cause them to deenergize upon reaching the high radiation

. level'setpoint. This is designed to protect the 2R41 channel detectors. When the detectors are deenergized, a CP/P-VRS isolation >

signal is generated as per conservative design.

1 The 2R41C channel monitor's 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 2R12A channel. In:

addition to its ESF function, the channel will cause the isolation of the 2WG41 valve-(Waste Gas Decay Tank Vent Control Valve). During. 1 i the 2R41C CP/P-VRS isolation signa) events, the_2R12A monitor l- remained operable.

l-l At the time of this event, neither Containment Purge, Containment Pressure / Vacuum Relief or Waste Gas Decay Tank release was in progress. The associated valves with these functions were in the l closed position.

The-2R45B 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, nor the result of high activity. 3

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

CORRECTIVE ACTION:

As indicated'in LER 311/90-019-00, Engineering has investigated the concerns with the Unit 2 RMS channels. It.is anticipated that L several system design modifications will eliminate the spurious ESF.

L actuation signals. One of these design modifications is the.

installation'of an uninterruptable power supply (UPS), which will be.

L completed by February 1991. The plans for completion of these modifications are included in the current PSE&G Living Engineering Plan for the RMS system. ,

N General Manager - 4 Salem Operations MJP:pc SORCLMtg.90-088

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