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 Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station 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 September 12, 1991 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 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. MJP:pc Distribution 910912 osooo311 PDR ' ' Sincerely yours, r;?/ Ci9oLJ/"'

C. A. Vondra General Manager -Salem Operations 95-2189 (10M) 12-Se NRC FORM366 (6-89) U.S *. NUCLEAR RE:ULATORV COMMl_SSION

-. ..

OMS NO. 3150-0104

' * * ..

• EXPIRES: 4/30/92 ' . . *

• TIMATEO BUROEN PER. RESPONSE TO COMPLY WTH THIS' LICENSEE EVENT REPORT (LER*, INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARO . 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 o 15 Io Io Io I 31111I1 loF ol TITLE (4) 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 J<

MONTH OAV VEAR FACI LITV NAMES OOCKET NUMBER!S) ols1l2 90 910-ol2lo-:-ol1oj91l2 9j1 o 151010101 I I OPERATING MODE (9) 6 THIS REPORT IS SUBMITTED PURSUANT TO THE OF 10 CFR §: (Check on* or more of. the following)

(11) 20.402(b) 20.405(c) .x 60.73(1)(2)(iv) 60.73(1)(2)(v) 60.73(1)(2) (vii) 60.73(1)(2)(vlll)(A) 60.73(1H2llviii)(B) 60.7311ll2lM 73.71(b) 73.71(c) ---

POWER I 20.406(*)(1

)(I) 60.3Blcll1)

-LEVEL . -1101 R1 E 1F 20.40511ll1lliil

--OTHER ISPtlcify in.Abstroct bfJlow ond in Text. NRC Form 366A) 50.36(c)(2)

......

......

---60.73(1)(2)1il

--60.73(1)(2)(ii)

--60.73(1)(2) (iii) 1111111= ::::::::::

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) CAUSE SYSTEM COMPONENT MANUFAC* TURE.R B II L D I El TI V1l 11 I 5 y I I I I I I I SUPPLEMENTAL REPORT EXPECTED (14) j YES (If yos, comp/er. EXPECTED SUBMISSION DATE} I I I I I I I I I I I I I 1

• EXPECTED SUBMISSION OATE 1151 MONTH DAY YEAR I I I ABSTRACT (Limit to spactJs. i.e:. tJppfoximately fifteen typewritten lines)

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 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 the check of this particular drawer. When the SPTs, a momentary loss of power on the bus occurred resulting in CP/P-VRS isolati6n signals. Per Eng.,

RMS system design modifications should eliminate the spurious ESF actuation signals. All Operations shifts have been briefed on event. Those personnel directly involved with this event have 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 NRC Form 366 (6-89)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station Unit 2 DOCKET NUMBER 5000311 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse

-Pressurized Water Reactor LER NUMBER 90-020-01 PAGE 2 of 4 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 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 ---------------------

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LICENSEE EVENT REPORT (LER) TEXT CONTINuATION Salem Generating Station Unit 2 APPARENT CAUSE OF OCCURRENCE:

DOCKET NUMBER 5000311 (cont'd) LER NUMBER 90-020-01 PAGE 3 of 4 by opening the No. 21 SPT 4KV infeed breakers and closing the No. 22 SPT 4KV infeed 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 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 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 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 lOCFR 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 have been developed.

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

CJ C/ p Cr_.../ General Manager J

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