ML18096A264

LER 90-020-00:on 900512,containment purge/pressure-vacuum Relief Sys Isolation Signal Received from Radiation Monitoring Sys.Caused by Equipment Design Concerns. Uninterruptible Power Supply installed.W/910912 Ltr

ML18096A264
Person / Time
Site:	Salem
Issue date:	09/12/1991
From:	Pollack M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-020, NUDOCS 9109190272
Download: ML18096A264 (5)

Text

e PS~G Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station September 12, 1991 U. S. Nuclear Regulatory Commission Document Control Oesk Washington, DC 20555

Dear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-75 DOCKET NO. 50-311 UNIT NO. 2 SUPPLEMENTAL LICENSEE EVENT REPORT 90-020-01 This Licensee Event Report supplement is being submitted pursuant to the requirements *of the Code of Federal Regulations 10CFR50.73.

The Corrective Action section has ~een revised. The orignal LER commitment to have additional tagging release administrative

• controls has been removed due to subsequent management review.

Also, other corrective actions have been modified to identify their current status.

Sincerely yours, r;?/Ci9oLJ/"'

C. A. Vondra ~c.-.__,,,

General Manager -

Salem Operations MJP:pc Distribution 9In9190?7~ 910912 tn~* ~66tR osooo311

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95-2189 (10M) 12-Se

NRC FORM366 (6-89)

U.S *. NUCLEAR RE:ULATORV COMMl_SSION - . .. APPROV~O OMS NO. 3150-0104

' * * ..

• EXPIRES: 4/30/92 '

. . *

• TIMATEO BUROEN PER. RESPONSE TO COMPLY WTH THIS'

• , INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARO LICENSEE EVENT . REPORT (LER COMMENTS REGAROING BUROEN ESTIMATE TO THE RECOROS ANO REPORTS MANAGEMENT BRANCH (P-530), U.S. NUCLEAR ,

REGULATORY COMMISSION. WASHINGTON, OC 20555, ANO TO THE PAPERWORK REOUCTION PROJECT (3150-0104), OF.FICE .

OF MANAGEMENT ANO BUOGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2)

• I PAGE 131 Salem Generating Station - Unit 2 TITLE (4)

!o 15 Io Io Io I 31111I1 loF ol ESF Actuatiqn: Containment Vent. Isolation; Equipment Design Concerns EVENT DATE (5) LER N.UMBER (6) REPORT DATE (7) OTHER FACILITIES IN\,fOLVEO (8)

MONTH OAY VEAR VEAR. r:t SE~~~~~~AL J< ~~~~~~ MONTH OAV VEAR FACI LITV NAMES OOCKET NUMBER!S) ols1l2 90 910-ol2lo-:-ol1oj91l2 9j1 o 151010101 I I THIS REPORT IS SUBMITTED PURSUANT TO THE R~QUIREMENTS OF 10 CFR §: (Check on* or more of. the following) (11)

OPERATING MODE (9) 6 .x 73.71(b)

I 20.402(b) 20.405(c) 60.73(1)(2)(iv) 1-~~~~~--'~+---l POWER 20.406(*)(1 )(I)

- 60.3Blcll1)

- 60.73(1)(2)(v)

- 73.71(c)

LEVEL 1101 R1 E 1F 20.40511ll1lliil

- 50.36(c)(2)

- 60.73(1)(2) (vii)

- OTHER ISPtlcify in.Abstroct

......~~~+...-,...,.,... ......~+---l

- - - bfJlow ond in Text. NRC Form 1111111= : : : : :

60.73(1)(2)1il 60.73(1)(2)(vlll)(A) 366A)

- 60.73(1)(2)(ii) 60.73(1)(2) (iii) 60.73(1H2llviii)(B) 60.7311ll2lM LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AREA cooE M. J. Pollack - LER Coordinator 61019 313'191-12101212 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE OESCRIBED IN THIS REPORT (13)

MANUFAC*

CAUSE SYSTEM COMPONENT TURE.R B II L D I El TI V1l 11 I 5 y I I I I I I I I I I I I I I I I I I I I 1*

SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPECTED

~NO SUBMISSION OATE 1151 j YES (If yos, comp/er. EXPECTED SUBMISSION DATE}

I I I ABSTRACT (Limit to 14~0 spactJs. i.e:. tJppfoximately fifteen single-~pace typewritten lines) (1~)

On 5/12/90 at -0640 hours, a Containment Purge/Pressure-Vacuum.Relief System (CP/P-VRS) isolation signal was received from tbe Radiation Monitoring System (RMS). At the time of the event, a Containment Purge was.in progress. The CP/P-VRS isolation valves Glosed as designed. The root cause of CP/P-VRS.isolation has been attributed to equipment design concerns. The Victoreen RMS equipment is susceptible to electrical iransients. At t~e time of the event, *the 2A Vital Bus was being returned to an operable status. During tag release, the No. 21 Station Power Transformer (SPT) output was sensed as an undervoltage condition resulting in the automatic transfer of the 2B and 2C 4KV Vital Busses from No. 21 SPT to No. 22 SPT output. Investigation revealed that operations personnel opened the No. 21 SPT 4KV Potential Transformers (PT) & Primary Fuses drawer which provides infeed breaker contr.ol to the 2A, 2B and 2C Vital Busses. The tagging release did not requir~ the check of this particular drawer. When the Busses.transferr~d SPTs, a momentary loss of power on the bus occurred resulting in CP/P-VRS isolati6n signals. Per Eng., s~~eral RMS system design modifications should eliminate the spurious ESF actuation signals. All Operations Depa~tment shifts have been briefed on thi~ event. Those personnel directly involved with this event have b~en held accountable. The requirements to perform* independent verification of a tagging release, dealing with electrical switching operations, were temporarily expanded.

1he No. 21 SPT 4KV PT & Primary Fuses drawer labeling was expand~d.

NRC Form 366 (6-89)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 90-020-01 2 of 4 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse - Pressurized Water Reactor Energy Industry Identification System (EIIS) codes are identif1ed in the text as (xxJ IDENTIFICATION OF OCCURRENCE:

Engineered Safety Feature Actuation: Containment Purge/Pressure-Vacuum Relief System Isolation Due To Equipment/Design Concerns Event Date: 5/12/90 Report Date: 9/12/91 This report was initiated by Incident Report No.90-311.

CONDITIONS PRIOR TO OCCURRENCE:

Mode 6 (Refueling)

DESCRIPTION OF OCCURRENCE:

On May 12, 1990 at 0640 hours0.00741 days <br />0.178 hours <br />0.00106 weeks <br />2.4352e-4 months <br />, a Containment Purge/Pressure-Vacuum Relief System (CP/P-VRS) {BF) isolation signal was received from the Radiation Monitoring System (RMS} (ILJ. At the time of the event, a Containment Purge was in progress. The CP/P-VRS isolation valves closed as designed.

Since CP/P-VRS isolation is an Engineered Safety Feature (ESF), the Nuclear Regulatory Commission was notified of this event in accordance with Code of Federal Regulations 10CFR 50.72(b) (2) (ii).

APPARENT CAUSE OF OCCURRENCE:

The root cause of the actuation of CP/P-VRS has been attributed to design/equipment concerns. As addressed by prior LERs, the Victoreen RMS equipment is susceptible to electrical transients (reference LERs 311/90-009-00 and 311/90-001-00).

At the time of the event, the 2A Vital Bus was being returned to an operable status. The ~ssociated tags were being released. It had been inoperable in support of outage activities. During the tagging release, the No. 21 Station Power Transformer (SPT) output was sensed as an undervoltage condition resulting in the automatic transfer of the 2B and 2C 4KV Vital Busses from No. 21 SPT to No. 22 SPT output.

Investigations revealed that the undervoltage condition occurred as a result of operations personnel opening the No. 21 SPT 4KV Potential Transformers (PT} & Primary Fuses drawer. When opening the drawer, the PT primary connections are disconnected from the No. 21 SPT 4 KV output resulting in a loss of secondary PT voltage to the 70%

undervoltage relays. The undervoltage relays initiated the transfer

LICENSEE EVENT REPORT (LER) TEXT CONTINuATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 90-020-01 3 of 4 APPARENT CAUSE OF OCCURRENCE: (cont'd) by opening the No. 21 SPT 4KV infeed breakers and closing the No. 22 SPT 4KV infeed bre~kers.

The drawer is located in the 2A Vital Bus* switchgear cubicles and is labeled "NO. 21 STA. PWR. TRANS. 4KV PT'S & PRIMARY FUSES" and "CAUTION DO NOT OPEN WHILE IN SERVICE". The operator opened the drawer to check the status of the PT fuses that he thought were only associated with the out of service 2A Vital Bus. However, this drawer provides inf~ed b~eaker control to the 2A, 2B and 2C Vital Busses. The tagging release* did not require the check of this particular drawer.*

When the Vital Busses transferred SPTs,. a momentary loss of power on the bus occurred. This is due to the design that the closed SPT

• infeea breaker must open prior to closure of the alternate SPT infeed breaker.* Conservatively, RMS channel protection functions are designed to actuate upon loss of power. Subsequently, the RMS channels, which -provide CP/P-VRS isolation signals, actuated.

ANALYSIS OFOCCURRENCE:

The CP/P-VRS isolation signal was not identified to a specific.

channel. With a momentary loss of AC power, the RMS output relays will deenergize in the "fail safe" condition (i.e., ESF actuati~n)~

When power is restored the output relays will return to normal operation.

• Several channels can cause CP/P-VRS isolation including: 1) 2Rl1A -

Containment Radioactive Particulate Monitor; 2) 2R12A - Containment Radioactive Noble Gas Monitor; 3) 2R12B - Containment Radioactive Iodine Monitor; and 4) 2R41C - Plant Vent Radioactive Noble Gas Monitor.*

As previously discussed, actuation of CP/P-VRS was the result of a loss of power conditiont not the result of high ac~ivity~ Due to the actuation of CP/P-VRS, chemistry sampling of the plant vent was completed. Results indicated no significant release of radioactive material. 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 311/90-009-00, Engineering has investigated the concerns with the Unit 2 RMS channels. It is anticipated that severa+ system design modifications will eliminate the spurious ESF actuation signals. These modifications include installation of an uninterruptable power supply (UPS) and RMS channel equipment replacements. Plans for completion of these modificat~ons have been developed.

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 2 5000311 90-020-01 4 of 4 CORRECTIVE ACTION: (cont'd)

All Operations Department shifts have been briefed on this event.

The need to maintain "attention to detail", to ensure compliance with the requirements of ~ job, wa~ stressed~

Those personnel directly involved with this event have .been heid accountable.

Due to the unique configuration of the electrical systems during the outage; the requirements to perform independent verification of a tagging release dea'ling with electrical switching operations were temporarily expanded. This change may be used in the future as conditions warrant.

The No. 21 SPT 4KV PT &: Primary Fuses drawer labeling was expanded to identify that the drawer provides infeed breaker control to the 2A, 2B and 2C Vital Busses.

rJ/Of?oL,yfi,~*

C/ p General Manager

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Salem Operations MJP:pc SORC Mtg.* 91-093