ML20045C534

LER 93-008-00:on 930518,identified That Failure of Air Supply to EDG Jacket Cooling Water Temperature Control Valves During Seismic Event Could Cause Overcooling of Edgs. Operability Determination Performed for EDGs.W/930616 Ltr

ML20045C534
Person / Time
Site:	Seabrook
Issue date:	06/16/1993
From:	Feigenbaum T, Peschel J NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO)
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-93-008, LER-93-8, NYN-93086, NUDOCS 9306230255
Download: ML20045C534 (6)

Text

y .. ,

Seab ook NH 03874

= Telephone (603)474-9521 Energy Service Corporation

( Facsimile - (603)474 2987 Ted C. Feigenbaum '

Senior Vice President and Chief NuclearOfficer NYN-93086 June 16,1993 United States Nuclear Regulatory Commission Washington, D.C. 20555 Attention: Document Control Desk

Reference:

(a) Facility Operating License No. NPF-86, Docket No. 50-443

Subject:

Licensee Event Report (LER) 93-08-00: ' Control Air Not Analyzed to Function During Seismic Event" Gentlemen:

Enclosed is Licensee Event Report (LER) No. 93-08-00 for Seabrook Station. This submittal documents an event which was discovered on May 18, 1993. This event is being reported pursuant to 10CFR50.73(a)(2)(ii) and 10CFR50.73(a)(2)(v).

Should you require further information regarding this matter, please contact Mr.

James M. Peschel, Regulatory Compliance Manager at (603) 474-9521 extension 3772.

Very truly yours, ,

Ted C. Feigenbaum TCF:EWM/ tad

Enclosures:

NRC Forms 366/366A 1

220020 l

9306230255 930616 p / )

'S PDR ' ADOCK 05000443 PDR [Lg ij a member of the Northeast Utilities system .f .

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United States Nuclear Regulatory Commission June 16,1993 Attention: Document Control Desk Page two cc: Mr. Thomas T. Martin Regional Administrator United States Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406 Mr. Albert W. De Agazio, Sr. Project Manager Project Directorate I-4 Division of Reactor Projects U.S. Nuclear Regulatory Commission Washington, DC 20555 Mr. Noel Dudley NRC Senior Resident Inspector ,

P.O. Box 1149 Seabrook, NH 03874 INPO Records Center 700 Galleria Parkway Atlanta, G A 30339-5957 l

l i

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y2 NRC FORM 366 U.S. MUCLEAR RLGULA10RY CDPtilSSICJ APPROVED BY OMB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH LICENSEE INENT REPORT (LER) hARD MN E DING B R kS 1 TE 6 THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, (See reverse for required number of digits /charecters for each block) WASHINGTON, DC 20555 0001, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

FAClllIY MAHL (1) D00(ET NUMBER (2) PAGE(3)

Seabrook Station 05000443 1 OF 4 TITLE (4)

Control Air Not Analyzed to Function During Seismic Event EUINT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHEP, FACILITIES ]NVOLVfD (8)

SEQ ENH AL H SION MONTH DAY YEAR YEAR NUMBER NUMBER MONTH DAY YEAR 05000 FAClllIY NAME DOCKET UMBE 05 18 93 93 08 00 06 16 93 CPERATING y lHIS REPORT IS SUBMITTID PtRSUANT TO THE RIQUIREMENTS OF 10 CFR 9: (Check one or more) (11)

MODE (9) 20.402(b) 20.405(c) 50.73(a)(2)(iv) 73.71(b)

POWlJ 20.405(a)(1)(1) 50.36(c)(1) X 50.73(a)(2)(v) 73.71(c) 100 LEVEL (10) 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii) OTHER 20.405(a)(1)(iii) 50.73(a)(2)(1) 50.73(a)(2)(viii)(A) (Specify in tract b ow 20.405(a)(1)(iv) X 50.73(a)(2)(li) 50.73(a)(2)(v111)(B) 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x) NRC Form 366A) t ICENSEE QNTACT IOR lHIS IER (12)

NAME lELEPHONE NUMBER (Include Area Code)

Mr. James M. Peschel, Regulatory Compliance Mgr. (603) 474-9521 Ext. 3772 COMPLE1E ONE ilNE FOR EACH COMPONENT FAltVRE DESCRIBED IN THIS REPORI (13)

CAUSE SYSTEM COMPONENT MANUFACTURER REP A E CAUSE SYSTEM COMPONENT MANUFACTURER 3

SUPPitMf MIAI REPORT EXPECTID (14) EXPECTED MONTH DAY YEAR Y SUBMISSION X (ESIf yes, complete EXPECTED SUBMISSION DATE). NO DATE (15) 07 30 93 ISlRAC1 (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)

North Atlantic Energy Services Corporation (North Atlantic) has identified a condition that is contrary to the design description stated in the Updated Final Safety Analysis Report (UFSAR). Specifically,it has been identified that failure of the air supply to the Emergency Diesel Generators (EDG) jacket cec!ing; water temperature control valves during a seismic event could cause overcooling of the EDGs, which could potentially preclude long term operation of the engines. This is contrary to the UFSAR, which states that the functional performance of the cooling water system is not adversely affected by emironmental occurrences, abnormal operation, accident conditions and loss of power. On May 18,1993, North Atlantic reported this event pursuant to 10CFR50.72(b)(ii) as a condition outside the design basis of the plant.

The root cause of this event is currently under investigation and will be provided to the NRC in a supplemental report. North Atlantic expects to submit this report by July 30,1993.

Immediate corrective actions for this occurrence included a Prelimimtry Operability Determination for the Emergency Diesel Generators. The Operability Determination was supported by a Preliminary Engineering Evaluation which documented the seismic functionality of the diesel air start skid, utilizing available seismic documentation and Engineering judgement. The evaluation concluded that with the use of appropriate operator actions the EDG air start skid will function to support the EDG during a seismic event. Operations Department management has issued a standing operating order discussing the method for restoring power to MCC 511 cud 611, in event that the feeder breakers to the MCC should trip during a seismic event.

NRC FORM 366 (5-92)

/

NRC FORM 356A U.S. NUCLEAR REGULATORY COP 911SS10N APPROVED BY OMB NO. 3150-0104 (5-92) EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REOUEST: 50.0 HRS.

FORWARD COMMENTS REGARDING DURDEN ESTIMATE TO LICENSEE EVENT REPORT (LER) THE INFORMATION AND RECORDS MANAGEMENT BRANCH TEXT CONTINUATION (MNBB 7714 WASHINGTON),20555-0001, OCU.S. AND NUCLEAR TO THEREGULATORY PAPERWORK COMMI REDUCTION PROJECT 3150-0104), OFFICE OF MANAGEMENTANDBUDGET,(WASHINGTON,DC20503.

FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6L PAGE (3)

YEAR SEQUENTIAL REVISION Seabrook Station NUMBER NUMBER 05000443 93 00 2M4 08 TEXT (if more space is required, use additional copies of NRC form 366A) (11)

Description of F. vent North Atlantic has identified a condition that is contrary to the design description stated in the Updated Final Safety Analysis Report (UFSAR). Specifically, it has been identified that failure of the air supply to the Emergency Diesel Generators (EDG) jacket cooling water temperature control valves during a seismic event could cause overcooling of the EDGs, which potentially could preclude long term operation of. the engines. This is contrary to the UFSAR, which states that the functional performance of the cooling water system is not adversely affected by environmental occurrences, abnormal operation, accident conditions and loss of power.

The design basis for the Diesel Generator Cooling Water System as stated in UFSAR Section 9.5.5.1 is not being met as discussed below:

The UFSAR states the following in Section 9.5.5.1 " Design Bases" for the Diesel Generator Cooling Water System:

"The functional performance of the Cooling Water System is not adversely affected by environmental occurrences, abnormal operation, accident conditions, and loss of offsite power."

Additionally, the following statement is made in UFSAR Section 9.5.6.3:

"A loss of air pressure in one of the two redundant supply lines to the engine could affect the supply of 20 psig control air to the diaphragm operated cooling water control valves. Under this condition, the unit will continue to operate but with lower jacket water and air cooler water temperatures since the control valves would go to the full open (maximum cooling) position" The response to NRC Request for Additional Information (RAI) 430.111 which was incorporated in FSAR Amendment 48 (January 1983), stated the following:

"A loss of air pressure in one of the two redundant supply lines to the engine could affect the supply of 20 psig control air to the diaphragm-operated cooling water control valves. Under this condition, the unit will continue to operate, but with lower jacket water and air cooler water temperatures since the control valves would go to the full open (maximum cooling) position. Operation at loads greater than 80% of rated load will minimize the effects of this condition. Redundant alarms are provided to alert the plant operators for appropriate action in the event of low starting air header pressure. Air pressure is also supplied to the backup pumps solenoid valve and the relays associated with cooling water controls. However, loss of control air to any or all of these components will not result in an engine shutdown or degradation of engine performance."

NRC FORM 366A (5-92)

l' NRC F ORM .356A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 I

( 5,-92 ) - EXPIRES 5/31/95 l ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST: ,

50.0 HRS. FORWARD COMMENTS REGARDING 1 LICENSEE EVENT REPORT (LER) BURDEN ESTIMATE TO THE INFORMATION AND l TEXT CONTINUATION RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S.

NUCLEAR REGULATORY COMMISSION WASHINGTON, DC 20555 0001 AND TO TdE PAPERWORK REDUCTION PROJECT (3150-0104), OFFICE OF l MANAGEMENT AND BUDGET. WASHINGTON, DC '

20503.

FACILITY NAME (1) DOCKET NUMBER LER NUMBER (6) PAGE (3)

YEAR SEQUENIIAL REVISIO Seabrook Station 05000443 93 00 3 OF 4 8

TEXT (11 more space is required, use additional copies of NRC form 366A) (17)

Contrary to the above statements in the UFSAR, the EDG .aanufacturer (Colt Industries) has determined that with the control valves in their maximum cooling positions, the relatively rapid cooling of the jacket water could cause engine damage to the cylinder liner / jacket, piston scuffing or piston seizure due to non-uniform component thermal expansion. On May 18,1993, North Atlantic reported this event pursuant to 10CFR50.72(b)(ii) as a condition outside the design basis of the plant.

The conditions which can result in EDG overcooling are described below. Each EDG is equipped with an independent starting and control air system. The starting air system consists of an air start compressor, air receivers and associated piping. The EDG air start compressors are relied upon to re-charge the air receivers to provide the required starting air and sufficient control air for long term operation. The air-start compressors are highly reliable units. However, they are not currently described in the UFSAR as being qualified to withstand a design basis seismic event and they are powered from seismic Motor Control Centers (MCCs) which supply non-nuclear safety loads. The event most likely to cause both EDG air start compressors to simultaneously malfunction is a design basis seismic event. The design basis assumes that all non-nuclear safety loads fait during the design basis seismic event causing the MCCs (511 and 611) feeder breakers to open. If the design basis seismic event were to adversely affect the air start compressors or their MCCs, the receivers would slowly biced down over a period of 7-15 hours resulting in the jacket cooling water system temperature control valves going to their maximum cooling position.

Safety Conscouences There were no adve'rse safety consequences as a result of the event. An evaluation performed by North Atlantic determined that EDG would continue to provide power during a seismic event.

Adverse safety consequences could have resulted during EDG operation if the compressors were unavailable to recharge the receivers. This could have resulted in the receivers slowly bleeding down if compensatory actions were not taken by the operators. This alarm would alert operators of the degrading condition of the receiver tanks. It is reasonable to expect that the operators would take compensatory actions to restore power to the air compressor when the starting air receivers reached the low and the low-low starting air pressure setpoints, alarming locally and in the main control room. The potentirl safety implications of this scenario are addressed below.

Potential Safety Imolications A potential failure mode for a single train of emergency power existed that was previously unrecognized within the UFSAR and plant operating procedures. Since the need for control air to maintain long term operation of the EDG was not recognized, identification of the starting air compressor and its appurtenances as critical components required for diesel operability was not made. Therefore, a compressor could have been taken out of service without full recognition of the potential safety implications, i

I j

" TETURM .%6A ( 5-W)

NRC FORM.366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 (5 92)' EXPIRES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST:

50.0 HRS. FORWARD COMMENTS REGARDING LICENSEE EVENT RE*.:f)RT (LER) BURDEN ESTIMATE TO THE INFORMATION AND TEXT CONTINUATION RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S.

NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001 AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104). OFFICE OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER LER NUMBER (6) PAGE (3)

YEAR SEQUENTIAL REVIS10 Seabrook Station 05000443 93 00 4 OF 4 8

TEXT (11 more space is required, use additional copies of KRC Form 366A) (17)

Root Cause The root cause of this event is currently under investigation and will be provided to the NRC in a supplemental report. North Atlantic expects to submit this report by July 30,1993.

Corrective Actions 3

Immediate corrective actions for this occurrence included a Preliminary Operability Determination for the Enc q :ncy Diesel Generators which was supported by a Preliminary Engineering Evaluation This evaluation docuanented the sei- f unctionality of the diesel air start skid, utilizing available seismic documentation and Engineering judgement.

Operations Department management has issued a standing operating order describing the method for restoring power to MCC 511 and MCC 611, in event that the feeder breakers to the MCCs should trip during a seismic event. This guidance has been incorporated into EDG local alarm response procedures. This will provide procedural guidance for restoring power to these MCCs upon receipt of the air receiver low pressure alarm.

North Atlantic will address long term corrective actions to prevent reoccurrence of this type event in a supplemental report which is expected to be submitted by July 30,1993.

Previous Occurrences North Atlantic will report any previous occurrences related to this event in its supplemental report which is expected to be submitted by July 30,1993. At the time of discovery of this event, the plant was in MODE 1, 100% power.

hilc F0iiM 366F( 5-92)

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