ML18096A349

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LER 91-014-00:on 911010,monitor 2R12B Rms Channel Failed Low Resulting in ESF Signal for CP/pressure-vacuum Relief Sys Isolation.Caused by Component Failure.Channel Returned to Svc.Mods Planned to Eliminate Spurious RMS.W/911107 Ltr
ML18096A349
Person / Time
Site: Salem PSEG icon.png
Issue date: 11/07/1991
From: Pollack M, Vondra C
Public Service Enterprise Group
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-91-014-02, LER-91-14-2, NUDOCS 9111210064
Download: ML18096A349 (4)
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Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station November 7, 1991 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Dear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-75 DOCKET NO. 50-311 UNIT NO. 2 LICENSEE EVENT REPORT 91-014-00 This Licensee Event Report is being submitted pursuant to the

~~?uirements of the Code of Federal legulations 10CFR 50.73(a) (2) (iv). This report is required within thirty (30) days of discovery.

S~ly yo:rs, p~ C. 'A. V~ndra General Manag~r -

Salem Operati01is MJP:pc Distribution

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NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (6-89) - 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 (LER) COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT B.RANCH (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.

FACILITY N,<IME (1) DOCKET NUMBER (2) * . I PAGE 131 Salem Generating Station - Unit 2 TITLE (41

!0 I5 I 0 I0 I I ti I 3 11 I 1 11 OF 0 1 3 ESF Signal Actuation: Cont. Ventilation Isolation Due To 2Rl2B RMS Channel Failure EVENT DATE (5) LEA NUMBER (61 REPORT DATE (71. OTHER FACILITIES INVOLVED (Bl MONTH DAY  :;:;:;:::::SEQUENTIAL 1::::::::: REVISION DAY YEAR FACILITY NAMES DOCKET NUMBER(S)

YEAR YEAR  ::::::::::: NUMBER 1::::::::: NUMBER MONTH i 1o 11 o 9 l 911 - o 11 14 - .o o 111 I oI 7 911 THIS REPORT IS SUBMITTED PURSUANT TO THE R~QUIREMENTS OF 10 CFR §: (Check one or more of <he following} (11)

OPERATING l

MODE (9) 20.402(bl 20.406(cl ,_:x 50,73(ol(2l(iv) 73.71(bl 20.406(ol(1 l(il 50.38(c)(11 50.73(ol!21M 73.71 (cl 20.406(ol(1 l(lil 20.405(el(1 )(iii) -- 50.38(c)(2l 60.73(o)(2)(iJ 60,73(o)(21(viil 60,73(oll2Hviiil(Al - OTHER IS~cify in Abstr*ct bdlow 11nd in T11xt, NRC Form 366AI 20.406(0)(1 )(iv) 20.406(el!1 IM 60.73(ol(2lliil 50.73(ol(2) (iiil LICENSEE CONTACT FOR THIS LEA (12)

- 50,73(o)(2l(viiil1Bl 50.73(o)(2l(xl NAME TELEPHONE NUMBER AREA CODE M. J. Pollack - LER Coormiantor 6 I 0 I 9 3 I 3 19 I I 2 10 I 21 2 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE OESCRIBED IN THIS REPORT (13)

MANUFAC* REPORTABLE .,.,.,.,.,.,,,.,. *:-:-:*:*:*:*:*:*:*:*:*:*:*:*:* MANUFAC*

CAUSE SYSTEM COMPONENT TO NPRDS .:.-.:.:.-..,,.,,. ..,.,:.:.:.-... ,,.,._.,.,.,,,.,.,. CAUSE 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 (141 MONTH DAY YEAR EXPECTED

~NO SUBMISSION DATE 1151 j YES (If yes, complete EXPECTED SUBMISSION DATE}

I I I ABSTRACT (Limit to 1400 spaces, i.11** approximately fifteen single-space ryp11written lines) (16)

On October 10, 1991, at 0138 hours0.0016 days <br />0.0383 hours <br />2.281746e-4 weeks <br />5.2509e-5 months <br />, the 2Rl2B (Containment Radioactive Iodine Monitor} Radiation Monitoring System {RMS) channel failed low.

This resulted in an Engineered Safety Feature (ESF) actuation signal for Containment Purge/Pressure-Vacuum ReJief (CP/P-VR) System isolation. The channel was declared inoperable. At the time of the event the CP/P-VR ~ystem valves were closed. The root cause of this event is equipment design~ The detector system used for the Salem Unit 2 RMS channels is manufactured by Victoreen. Periodic problems with this system have been experienced .as indicated in prior LERs (e.g.,

311/90-010-00, and 311/91-007-00). The 2Rl2B detector uses a Victoreen Model 843-34 Scintillator. The Victoreen RMS channels are subject. to voltage transients. An engineering assessment was done to identify possible causes of the momentary channel failure. A functional test was conducted which checked these possible causes. The functional test was successfully completed without identifying a compon~nt failure.

The channel was observed for two (2) weeks, with the output functions blocked, without recurrence of a channel failure. Subsequently, the channel was ret~rned to service. As indicated in LER 311/90-040-00, Engineering has investigated the concerns identified with the Victoreen RMS channels~ Several modifications are planned.to eliminate spurious RMS originated ESF actuation signals. These modifications include installation of an uninterruptable power supply {UPS) for Unit 2 and RMS channel equipment replacements.

NRC Form 365 (6-89)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 91-014-00 *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:

Actuation of an Engineered Safety Feature, Containment Purge Pressure-Vacuum Relief isolation, due to equipment design Event Date:* 10/10/91 Report Date: 11/07/91 This report was initiated by Incident Report No.91-706.

CONDITIONS PRIOR TO OCCURRENCE:

Mode 1 Reactor Power 100% - Unit Load 1160 MWe DESCRIPTION OF OCCURRENCE:

On October 10, 1991, at Ol38 hours, the 2R12B (Containment Radioactive Iodine Monitor} Radiation Monitoring System (RMS} {IL} channel failed low. This resulted in an Engineered Safety Feature {ESF) actuation signal for Containment Purge/Pressure-Vacuum Relief (CP/P-VR} System (BF} isolation. The channel was declared inoperable. At the time of the event the CP/P-VR System valves were closed.

On October 10, 1991, at 0200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br />, the Nuclear Regulatory Commission was notified of the CP/P-VR system actuation signal in accordance with Code of Federal Regulations 10CFR 50.72(b) (2) (ii).

APPARENT CAUSE OF OCCURRENCE:

The root cause of this event is equipment design. The detector system used for the Salem Unit 2 RMS channels is manufactured by Victoreen.-

Periodic problems with this system have been experienced as indicated in prior .LERs (e.g., 311/90-010-00, and 311/91-007-00). The 2R12B detector uses a Victoreen Model 843-34 Scintillator. The Victoreen RMS channels are_ subject to voltage transients.

A functional check of the 2R12B* channel did not reveal any failed components. The channel was observed for two (2) weeks, while its output functions were blocked, with no additional failures. The channel was subsequently returned to service.

ANALYSIS OF OCCURRENCE:

Isolation of the CP/P-VRS is an ESF. It mitigates the release of radioactive material to the environment after a design base accident.

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION

.Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 91-014-00 3 of 3 ANALYSIS OF OCCURRENCE: (cont'd)

The 2R12B RMS channel monitor's the radioactive iodine gas content of the Containment atmosphere. By design, either a "high" alarm signal or a low channel failure will cause automatic isolati-on of the CP/P-VR I

System. At the time of the event, the CP/P-VR valves were closed.

I

,.I Air'samples are pulled from the Containment atmosphere through filter paper which continuously moves past the 2R11A (Containment Radioactive Particulate Monitor) detector. The air sample then passes through a charcoal cartridge (monitored by the 2R12B monitor) and is then mixed into a 'fixed shielded volume where it is viewed by the 2R12A (Containment Radioactive Noble Gas Monitor) monitor. The air sample is then returned to the Containment.

The 2R12A Containment Radioactive Noble Gas monitor is the channel taken credit for by the accident analysis for monitoring Containment airborne *ctivity in order to mitigate the consequences of an accident. The 2R12A monitor has the capability of automatic i~olation of the CP/P-VR System. It remained operable during the course of this event and did not indicate any abnormal Containment airborne activity.

During this event, RCS leakage within Containment did not increase nor was there any indication of increasing Containment activity as

  • indicated by the 2R12B corroborating RMS channels. Therefore, this event did not affect the health or safety of the public. However, due to the automat~c actuation of an ESF system, this event is reportable in accordance with Code of Federal Regulations 10CFR 50.73(a) (2) {iv).

CORRECTIVE ACTION:

An engineering assessment was done to identify possible causes of the momentary channel failure. A functional test was conducted which checked these possible causes. The functional test was successfully completed without identifying a component failure. The channel was observed for two (2) weeks, with the output functions blocked, without recurrence of a channel failure. Subsequently, the channel was returned to service.

As indicated in LER 311/90-040-00, Engineering has investigated the concerns with the Victoreen RMS channels. Several modifications are planned to eliminate spurious RMS originated ESF actuation signals.

These modifications include installation of an uninterruptable power supply (UPS) for Unit 2 and. RMS channel equipment replacements.

_{i(/d General Manager ~

Salem Operations MJP:pc SORC Mtg.91-112

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