ML18102B291

LER 96-038-01:on 961210,switchgear Penetration Area Ventilation Could Not Maintain Design Temps.Caused Because Switchgear Penetration Area Ventilation Sys Failure Modes Not Properly Established.Room Temp monitored.W/970509 Ltr

ML18102B291
Person / Time
Site:	Salem
Issue date:	05/09/1997
From:	Garchow D, Bernard Thomas Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-96-038, LER-96-38, LR-N97296, NUDOCS 9705190271
Download: ML18102B291 (5)

Text

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• Public Service Electric and Gas Company P.O, Box 236 Hancocks Bridge, New Jersey 08038-0236 Nuclear Business Unit MAY 0 9 1997 LR-N97296 U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 LER 272/96-038-01 SALEM GENERATING STATION -UNIT 1 FACILITY OPERATING LICENSE NO. DPR-70 DOCKET NO. 50-272 Gentlemen:

This Licensee Event Report (LER) entitled Penetration , Area Ventilation Cannot Maintain Design Temperatures" is being submitted as a Supplement to LER 96-038. This LER is submitted pursuant to the requirements of the Code of Federal Regulations 10CFR50. 73 (a) (2) (ii). Attachment DVH C Distribution LER File 3.7 9705190271 970509 PDR ADOCK 05000272 S PDR General Manager Salem Operations 190005 I llllll lllll lllll llllll llll llllll Ill llll

• es a.Fa c

• 1ne pcwer is in x.lf han._k 95-2168 REV. 6/94 NRCFORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPR:OVED BY OMB NO. 3150-0104 (4-95) EXPIRES 04130/98 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS MANDATORY INFORMATION COLLECTION REQUEST: 50.0 HRS. LICENSEE EVENT REPORT (LER) REPORTED LESSONS LEARNED ARE INCORPORATED INTO THE LICENSING PROCESS AND FED BACK TO INDUSTRY.

FORWARD '. COMMENTS REGARDING BURDEN ESTIMATE TO THE INFORMATION (See reverse for required number of AND RECORDS MANAGEMENT BRANCH (T NUCLEAR REGULATORY COMfllllSSION, WASHINGTON, DC 20 , AND TO digits/characters for each block) THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503. FACILITY NAllE (1) UUCIU:T NUllBER (2) PAGE (3) SALEM GENERATING STATION UNIT 1 05000272 1 OF 4 Penetration Area Ventilation Cannot Maintain Design Temperatures EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8) YEAR I FACILITY NAME DOCKET NUMBER MONTH DAY YEAR SEQUENTIAL I REVISION MONTH DAY YEAR NUMBER NUMBER SALEM UNIT2 05000311 12 10 96 96 038 01 05 97 FACILITY NAME DOCKET NUMBER ----05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check one or more) (11) MODE (9) N 20.2201(b) 20.2203(a)(2)(v)

50. 73(a)(2)(i) 50.73(a)(2)(viii)

POWER 20.2203(a)(1) 20.2203(a)(3)(i) x 50. 73(a)(2)(ii)

50. 73(a)(2)(x)

LEVEL (10) 000 20.2203(a)(2)(i) 20.2203(a)(3)(ii)

50. 73(a)(2)(iii) 73.71 -. 20.2203(a)(2)(ii) 20.2203(a)( 4) 50. 73(a)(2)(iv)

OTHER 20.2203(a)(2)(iii) 50.36(c)(1)

50. 73(a)(2)(v)

Abstract below or in C Form 366A 20.2203(a)(2)(iv) 50.36(c)(2)

50. 73(a)(2)(vii)

LICENSEE CONTACT FOR THIS LER (12) NAME TELEPHONE NUMBER (Include Ar1111 Code) Brian J. Thomas, LER Coordinator 609-339-2022 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13) I REPORTABLE REPORTABLE CAUSE SYSTEM COMPONENT MANUFACTURER TONPRDS I CAUSE SYSTEM COMPONENT MANUFACTURER TONPRDS SUPPLEMENTAL REPORT EXPECTED (14) EXPECTED MONTH DAY YEAR IYES xi NO SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE). DATE(15) ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16) LER 96-038-00 detailed a concern with single failure of the Elecbical Penetration Exhaust Fans. LER 96-038-01 details concerns identified during a revie.v of LER 96-038-00.

Specifically, during a revie.v of the Switchgear

& Penetration Area Ventlation (SPA V) system performance, PSE&G detennined that the SPAV system may not be able to maintain the minimum design bases temperatures during cold vveather.

Upon receipt of an accident signal, all three of the SPAV system supply fans \NOUld start, and may cause overa>Oling of the area. In addition, during the revie.v of the SPAV system, dampers that are designed to isolate the area upon COi injection for fire suppression, were noted to fall close on a loss of power. Closure of the COi Isolation dampers upon loss of power could cause a loss of ventilation to the switchgear room, and potentially result in the area temperatures exceeding design temperatures.

The cause of this occurrence is that the SPAV system failure modes were not proper1y established and evaluated during the initial plant design. The interim corrective actions are to install temporary modifications to ensure design temperatures can be maintained.

The Switchgear room temperatures are being monitored to ensure that design temperatures are not exceeded.

These interim correclive actions will be in place until permanent oorrective actions are installed.

The SPAV control logic and the COi isolation damper logic will be revised to ensure that area temperatures can be mainta.ined within design limits. This condition is reportable in accordance with 1 O CFR 50. 73(a)(2)QQ(A), any event or condition that resulted in the nuclear power plan+ being operated outside the desigr '1ases. NRC FORM 366 (4-95)

NRC FORM 366A (4-95) U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) 05000272 YEAR I SEQUENTIAL I REVISION 2 NUMBER NUMBER OF SALEM GENERATING STATION UNIT 1 96 --038 --01 TEXT (If more space is required, use additional copies of NRC Form 366A) (17) PLANT AND SYSTEM IDENTIFICATION Westinghouse

-Pressurized Water Reactor Switchgear Ventilation System {VF/-}* DC Power* {EJ/-} Low Voltage Power System {EC/-}

• Energy Industry Identification System (EllS) codes and component function identifier codes appear as (SS/CC) -CONDITIONS PRIOR TO OCCURRENCE At the time of identification, Salem Unit 1 was defueled and Unit 2 was in Mode 5. Post modification was in progress for the Switchgear Penetration Area Ventilation (SPAV) system modification.

' DESCRIPTION OF OCCURRENCE During a design review of the Switchgear Penetration Area Ventilation (SPA V) {VF/-} system performance, PSE&G determined that the potential existed for a single failure of the Electrical Penetration Exhaust Fans {VF/FAN} to place the unit in an unanalyzed condition.

The two Electrical Penetration Exhaust Fans each provide 50 percent of the exhaust flow from the penetration areas. The failure of one fan could result in higher than analyzed temperatures in the Electrical Penetration area, which contains the motor control centers for the three trains of safety-related, motor-operated valves and other Technical Specification required instrumentation.

4 The SPAV system is currently designed to maintain year-round temperatures between 65 and 110 degrees F within the areas served, with outdoor ambient conditions of 0 degrees F winter and 95 degrees F summer, respectively.

The maximum design temperature was recently to 110 degrees from 105 degrees F. The potential for a single failure of the Electrical Penetration Exhaust fan to place the unit in an unanalyzed condition was previously detailed in Revision 0 to LER 96-038. Revision 1 to LER 96-038 will detail two recently identified concerns with the SPAV system: 1) overcooling and 2) overheating on a Miscellaneous Auxiliary Control (MAC) 11 panel failure for Unit 1 or a MAC 21 panel failure for Unit 2. Overcooling Duling Post Modification Testing for recently completed SPAV system modifications and review of the SPAV system performance, PSE&G determined that the SPAV system may not be able to maintain the minimum design temperabJres during cold weather conditions.

Upon receipt of a Safeguards Equipment Cabinet (SEC) signal Q.e., an Engineered Safety Feature start) all three of the SPAV system supply fans would start Wllh all three supply fans running,*

and cold outside air temperabJres, area temperatures could drop below the design minimum temperature of 65 degrees F. NRC FORM 366A (4-95)

NRC FORM 366A (4-95) U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER .NUMBER (6) 05000272 YEAR I SEQUENTIAL I REVISION 3

• NUMBER NUMBER SALEM GENERATING STATION UNIT 1 96 --038 --01 TEXT (If more space is required, use additional copies of NRC Form 366A) (17) DESCRIPTION OF OCCURRENCE (cont'd) Overheating on MAC 11/21 panel failure PAGE (3) OF During the review of the SPAV system, dampers that are designed to isolate upon COiinjection for fire suppression, YJere also noted to fail close on a loss of po.yer. This loss of pcM'er could cause a loss of ventilation, and potentially result in area temperatures exceeding design temperatures.

4 there are six COi Isolation dampers in each unit that are designed to close, to control COi flooding in the event of a fire. The control pcM'erforthese COi Isolation dampers sis supplied by the MAC 11 panel for Unit 1, and the MAC 21 panel for Unit 2. A failure of the MAC 11 panel or the MAC 21 panel 'M>Uld cause the COz Isolation dampers for that unit to close. The clOsing of these COz Isolation dampers 'M>llld interrupt ventilation air flow and could result in the area temperatures exceediilg design temperatures.

CAUSE OF OCCURRENCE The cause of this occurrence is that the SPA V system failure modes were not properly established and evaluated during the initial plant design, and the impact of the damper closure due to loss of power was not considefed.

Damper closure was assessed in terms of supporting the automatic initiation of the C02 suppression system in response to 10 CFR 50 Appendix R concerns.

PRIOR SIMILAR OCCURRENCES LER 272/95-008-00 reported a similar concern of exceeding 105 degrees if only one of the three Electrical Penetration Supply Fans were operable.

This occurrence was caused by the failure of two of the supply fans. LER corrective actions addressed the supply fans and did not address the exhaust fans. In the past two years there were eleven LERs that addressed design deficiencies as the cause. These LERs are 272/95-014-00, 272/95-020-00, 272/95-029-00, 272/96-001-00, 272/96-010-00, 272/96-012-00, 272/96-018-00, 272/96-019-00, 272/96-020-00, 272/96-034-00 and 272/96-037-00.

Corrective actions for these LERs were specific to the particular issue. As stated in the 50.54(f) response, PSE&G has reason.able assurance that Salem stations are being operated in accordance with their design bases NRC FORM 366A (4-95)

• NRC FORM 366A (4-95) U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT (LER) TEXT CONTINUATION FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6) PAGE (3) 05000272 YEAR I SEQUENTIAL I REVISION 4 NUMBER NUMBER OF SALEM GENERATING STATION UNIT 1 96 --038 --01 TEXT (If more space is required, use additional copies of NRC Form 366A) (17) SAFETY CONSEQUENCES AND IMPLICATIONS Overcooling 4 The overcooling of the Switchgear rooms would occur only with extremely low outside air temperatures, and would be a concern with the -"C" 125 Vdc battery room. The "C" 125 Vdc battery room has a non-safety related heater installed.

While the heater could not be relied upon to maintain temperatures above 65 degrees F, the heater would most likely prevent the room from falling below design temperature.

Further, the plant is designed with sufficient redundant DC power sources to safely shutdown with the failure of the "C" 125 Vdc batteries.

In addition, other equipment in the area may be adversely effected.

Overheating on MAC 11/21 Panel failure The maximum room temperature with the C02 Isolation dampers closed has been preliminary determined to exceed 11 O degrees. The maximum room temperature has not been determined, but some safety related equipment may be adversely impacted.

The loss of the MAC 11/21 panel is indicated in the Control Room. The Control Room response includes notifying the fire protection personnel.

To mitigate the elevated room temperatures, the C02 Isolation dampers would have to be opened, or ttie room doors opened. The health and safety of the public was not affected.

CORRECTIVE ACTIONS 1.

• A design review of the SPAV system in response to LER 96-038-00 has been completed.

This review identified the concerns addressed in this LER. 2. A 10CFR50.59 Evaluation was completed to increase the maximum design temperature to 110 degrees. 3. Administrative controls to address removal from service of an Electrical Penetration Exhaust Fan will be implemented prior to Salem Unit 2 entering Mode 4. The outside air intake dampers were modified to enable them to fully close to preclude reducing area temperatures to below acceptable design minimums.

4. A modification to the supply fan start logic, and the outside supply dampers will be implemented to ensure that the minimum design temperature is maintained.

This modification is scheduled to be completed for both Units by May 31, 1997. 5. As an interim corrective action, the Switchgear room temperature is being routinely monitored to ensure that the_ maximum design temperature is not exceeded, and controls are in place to limit temperature increases in the area. 6. As a permanent .corrective action, a modification to the C02 damper logic is scheduled to be completed for both Units Unit by May 31, 1997. NRC FORM 366A (4-95)