05000443/LER-1993-012
| ML20056F785 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 08/26/1993 |
| From: | Feigenbaum T, Peschel J NORTH ATLANTIC ENERGY SERVICE CORP. (NAESCO) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LER-93-012, LER-93-12, NYN-93116, NUDOCS 9308310073 | |
| Download: ML20056F785 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| 4432093012R00 - NRC Website | |
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seae7ox7NH 03874 Telephone (603)474 9521 Energy Service Corporation
( Facsimile (603)474-2987 Ted C. Feigenbaum i Senior Vice President and Chief Nuclear Officer l
NYN- 93116 l i
August 26,1993 United States Nuclear Regulatory Commission Washington, D.C. 20555 f
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Attention: Document Control Desk
Reference:
Facility Operating License No. NPF-86, Docket No. 50-443
Subject:
Licensee Event Report (LER) 93-12-00: " Reactor Trip Due to Electrical Fault in Solid i State Protection System Cabinet" Gentlemen: ,
Enclosed is Licensee Event Report (LER) No. 93-12-00 for Seabrook Station. This submittal f documents an event which was discovered on July 27,1993. This event is being reported pursuant to ;
Should you require further infonnation regarding this matter, please contact Mr. James M. Peschel, Regulatory Compliance Manager at (603) 474-9521 extension 3772.
Very truly yours, J h Ted C. Feigenbaum fr TCF:EWM/act [
Enclosures:
NRC Forms 366/366A f h
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3001;e4J-l) ,
9308310073 930826 IR " !
{DR ADOCK 05000443 PDR 9 i Qi -
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United States Nuclear Regulatory Commission August 26,1993 !
Attention: Document Contml Desk Page two l i
cc: Mr. Thomas T. Martin i Regional Administrator i U.S. Nuclear Regulatory Commission !
Region I l 475 Allendale Road King of Prussia. PA 19406 i Mr. Albert W. De Agazio Sr. Project Manager l Project Directorate 1-4 'j Division of Reactor Projects j U.S. Nuclear Regulatory Commission :
Washington, DC 20555 l i
Mr. Noel Dudley NRC Senior Resident inspector {
P.O. Box 1149 .
Seabrook, Nil 03874 l i
INPO ;
Records Center
- 700 Galleria Parkway l Atlanta, GA 30339-5957
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j NRC FORM 306 U.S. NUCLEAR REGULATORY COMMIS510N AFPROVED BY OMB NO. 3150 0104 (5-92) EXPIRES 5/31/95 ,
. t 4
EST!nATED BURDEN PER RESPONSE TO COMPLY WITH l l
THIS INFORMATION COLLECT]ON REQUEST: 50.0 HRS. i LICENSEE EVENT REPORT (LER)
FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO i i
THE INFORMATION AND RECORDS MANAGEMENT BRANCH (MNBB 7714), U.S. NUCLEAR REGULATORY COMMISSION, !
1 (See reverse for required number of digits / characters for each block) WASHINGTON, DC 20555-0001, AND TO THE PAPERWORK l REDUCTION PROJECT (3150-0104), OFFICE OF !
j MANAGEMENT AND BUDGET, WASHINGTON, DC 20503. l I FAClLlly NAML (1) DOCKET NUMBER (2) PAGE (3) 1 Seabrook Station 05000443 1 OF 3 1 IITLE (4) j Reactor Trip Due to Electrical Fault in Solid State Protection System Cabinet
) EViN1 DATE (5) L E R NUMBE R (6) REPORT DATE (7) OTHER FACILITIES INV01.VID (8) !
SEQUENTIAL REVISION FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NUMBER
""" ^ "" 05000
'*C "" " "
07 27 93 93 12 00 08 26 93 O 0
, OPERATING y MMMhNNMNMMWMNMMMh NNNWM
- H0DE (9) ?O.402(b) 20.405(c) X 50.73(a)(2)(iv) 73.71(b)
P04R 20.405(a)(1)( t ) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c) g LEVEL (10) 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii) OTHER I
20.405(a)(1)(iii) 50.73(a)(2)(1) 50. 73(a)(2)(vii i )( A) (Specify in 20.405(a)(1)(iv) 50.73(a)(2)(ii) 50.73(a)(2)(viti)(B) "
[C f 20.405(a)(1)(v) 50.73(a)(2)(iii) 50. 73(a)(2)(x) NRC Form 366A) i
, LICENSEE CONTACT FOR TH15 LER (12) l KAME TELEPHONE NUMBER (Include Area Code)
Mr. James M. Peschel, Regulatory Compliance Manager (603) 474-9521 Ext. 3772 ,
1 i COMPLill ONt ilNE FOR E ACH COMPONINT FAlt VRE DESCRIBED IN THIS REPOR1 (13) I 0 E CAUSE SYSTEM COMP 0hENT MAWUFACTURER CAUSE SYSTEM COMPONENT MANUFACTURER TO 11 JG !! Wl20 Yl.S 11 SN psp (MO NO [
l 11 SN RV 0 68 NO
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) SUPPLEME NTAL RE PORT E XPECTID (14) EXPECTED MONTH DAY YEAR {
4 YES SUBMISSION (If yes, complete EXPECTED SUBMISSION DATE). x NO !
l DATE (15)
- ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16) l 1
On July 27,1993, at 0814 an automatic reactor trip from 100 percent power occurred. This reactor trip was initiated when an i J electrical fault in the Train "A" Solid State Protection System (SSPS)[JG) cabinet resulted in a loss of power to the undervoltage j (UV) coil for the Train "A" reactor trip breaker. The deenerigization of the UV coil caused Reactor Trip Breaker (RTB) "A" to i j open resulting in a reactor trip. Primary plant response was normal with expected Engineered Safety Feature (ESF) actuations l' (Emergency Feedwater Sy stem [BA] actuation on Steam Generator LO-LO level and Feedwater System lSJ] lsolation in response to l the reactor trip). At 0939 EDT on July 27, 1993 North Atlantic made a four-hour notification to the NRC pursuant to -
] 10CFR50.72(bX2Xii) since these events resulted in a Reactor Protection System (RPS) actuation and ESF actuations. ;
1 j There were no adverse safety consequences as a result of this event. Plant equipment functiomd as designed in response to the !
i reactor trip and operator actions were determined to be correct in response to the reactor trip. At no time during the event was ,
j there any adserse impact on the health and safety of plant employees or the public, !
, The root cause for this event was determined to be a faulty lamp test assembly in the logic test panel of the Train A SSPS cabinet, j The lamp test assembly introduced a short from the SSPS auctioneered 48 VDC bus to logic ground when performing a lamp test. l l i j !
Short term corrective actions completed prior to reactor startup included replacing the lamp test socket and test circuit driver card.
Also a visual inspection of the remaining Train A and B SSPS lamp test sockets was performed to verify pin separation. Eong ;
i term corrective actions include performing a failure analysis on the lamp test socket and to evaluate the SSPS test circuit to ,
determine whether the potential for the failure of a single lamp test socket resulting in a reactor trip can be climinated. ;
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i hRC 50W 3e,6 (542) i I i
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NRC FORM 366A U.S. NUCLEAR REGULA1 CRY COM. MISSION APPROVED BY OMB NO. 3150 0104 (5-921 EXPlctES 5/31/95 ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION c0LLECTt0N REQUEST: 50.0 HRS.
FORWARD COMMENTS REGARDING BURDEN ESTIMATE TO LICENSEE EVENT REPORT (LER) lHE INFORMATION AND RECORDS MANAGEMENT BRANCH ,
TEXT CONTINUATION (MNas 7714), U.S. NuCtEAR REGULATORY COMMISSION, WASHINGTON, DC 20555-0001, AND TO THE PAPERWDRK REDUCTION PROJECT t3150-0104), OFFICE OF r MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.
FAClll1Y NAML (1) 00CMT NUMBER (?) llR NUMBER (6) PAGE (3)
TEAR SEQUENTIAL REVIStDN Seabrook Station 05000443 93 0 2 OF 3 12 TLK1 (l1 more spKe 15 required. U5e addiiIandI coptes af h4 t0170 3t:bA) (ll)
Description of Event On July 27,1993, at 0814 an automatic reactor trip from 100 percent power occurred. This reactor trip was initiated when an electrical fault in the Train "A" Solid State Protection System (SSPS)[JG) cabinet resulted in a loss of power to the undervoltage (UV)((27] coil for the Train "A" reactor trip breaker. The deenerigization of the UV coil caused Reactor Trip Breaker (RTB) "A" to opi resulting in a reactor trip.
On July 27,1993 at approximately 0810 Instrumentation and Control (l&C) technicians began performing IX1680.921, ;
SSPS "A" Train Logic Test. IX 1650.921 is the bimonthly surveillance procedure used to test the actuation logic of the Train A SSPS cabinet. During a lamp test on the logic test panel, early in the proccdure, one lamp was identified as being " burned-out" The lights are tested by depressing the lamp into the socket and verifying a lit condition.
After completing the initial check, the non-functioning lamp was checked a second time to verify that it was a burned ,
out bulb and not a bad connection. The reactor trip occurred an instant after the lamp was depressed a second time. I The response to the reactor trip and the subsequent recovery actions by plant operators were determined to be correct.
Primary plant response was normal with expected Engineered Safety Feature (ESF) actuations (Emergency Feedwater System [BA] actuation on Steam Generator LO-LO level and Feedwater System [SJ) Isolation in response to the i reactor trip). Ilowever, during the secondary plant response approximately six minutes after the reactor trip, the tube side relief valve (1-MVD-V-132) for the 26B feedwater heater ruptured and an upstream small bore pipe failed at an elbow upstream of the valve. This valve failure did not adversely affect the response of the plant to the reactor trip.
The vahe and piping were repaired prior to plant startup. The problem with the valve during a secondary plant transient had been previously identified and a design change is scheduled to be installed during the next refueling ,
outage to resolve the problem.
At 0939 EDT on July 27, 1993 North Atlantic made a four-hour notification to the NRC pursuant to 10CFR50.72(b)(2)(ii) since this event resulted in an RPS and ESF actuations. !
Safety Conscauences !
There were no safety consequences as a result of this event. Plant equipment functioned as designed in response to ;
the reactor trip and operator actions were determined to be correct in response to the reactor trip. At no time during the event was there any adverse impact on the health and safety of plant employees or the public. !
Root Cause The root cause for this event was determined to be a faulty lamp test assembly in the logic test panel of the Train A SSPS cabinet. The lamp test assembly introduced a short from the SSPS auctioneered 48 VDC bus to logic ground when performing a lamp test. The 48 VDC is used as " pull-up" voltage for SSPS contact inputs, including permissive and memory ground inputs. The fault reduced the 48 VDC bus voltage which allowed contact inputs to the universal logic cards to drop out causing a SSPS logic input to be sensed. The voltage drop also affected the output on some t
NRC FORM 366A tS-92)
NRC 70aN 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED SY 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 LI.CENSEE EVENT REPORT (LER) BURDEN ESTIMATE TO THE INFORMATION MD TEXT CONTINUATION RECORDS MANAGEMENT BRANCH (MNB3 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. j FACllllY NAME (1) '- DOCAET NUMBER LER NUMBER (6) PAGE (3)
YEAR SEQUENTIAL REVIS10 Seabrook Station l 05000443 93 00 3 OF 3 12 1 EXT (11 more space is requirea. use a:31ticral coptes of hkl f orm 3bbA) (17)
(Continued) universal circuits causing additional state changes in the system. The fault caused the 48 VDC to RTB "A" UV coil to drop out which in turn opened the breaker tripping the reactor. The UV coil is designed to drop out if it senses a voltage drop for longer than approximately 12 milliseconds.
Corrective Actions Short term corrective actions completed prior to reactor startup included replacing the lamp test socket and the l
semiautomatic tester card. Also a visual inspection of the remaining Train A and B SSPS lamp test sockets was I performed to verify pin separation and proper power output from both power supplies. Long term corrective actions include performing a failure analysis of the lamp test assembly, an evaluation of the SSPS test circuit to determine whether the potential for the failure of a single lamp socket resulting in a reactor trip can be eliminated, an evaluation of procedure IX1680.921 and similar test procedures to determine if the lamp test can be performed after the bypass breakers are closed. and an inspection of similar lamp sockets to determine if there is a generic problem.
Plant Conditions This event took place while the plant was in MODE 1, at 100 percent power, with a Reactor Coolant System [AB]
temperature of 587 degrees Fahrenheit and a pressure of 2235 psig.
Previous Occurrences This is the first event of this type at Seabrook Station.
haC FORM 366A (5-92)
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