05000456/LER-1993-001, :on 930107,RC Pump Underfrequency Quarterly Surveillance Experienced Trip,Due to Single Failure of Logic Card in B-Train Ssps.Failed Universal Card Sent to Vendor for Detailed Failure Analysis
| ML20127P018 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 01/29/1993 |
| From: | Kofron K, Stogsdill A COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BW-93-0040, BW-93-40, LER-93-001, LER-93-1, NUDOCS 9302010165 | |
| Download: ML20127P018 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(1) 10 CFR 50.73(a)(2)(x) |
| 4561993001R00 - NRC Website | |
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C:mm:nw:alth Edison-Oraldwood Nuclear Power Station Route #1, Box 84 Braceville. Illinois 60407 Telephone 815/453-2801 January 29,1993 BW/93-0040 U. S. Nuclear Regulatory Commission Document Control Desk Washington, D. C. 20555 Gentlemen:
The enclosed voluntary Licensee Event Report from Braldwood Generating Station is being transmitted to you as a 30-day written report.
This report is number 93-001, Docket No. 50-456, d
K. L. Kofr Station Manager Braidwood Station KLK/AJS/dla 728/ZD85G Enc:
Licensee Event Report No. 93 001-00 cc:
NRC Region ill Administrator NRC Resident inspector INPO Record Center CECO Distribution List 290034 9302010165 930129 DR ADOCK 0500 6
e htC FDRO 366 U.S. OCLEAR REGAATORT CtD9tlS$10N APPROVED SY (BW No. 3150-0104
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EXPIRES 5/31/95 ESTIMATED BURDEN PER RE SPONSE TO COMPLT WITN LICENSEE EVENT REPORT (LER)
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THE INFORMAil0N AND RECORDS MANAGEMENT ORANCN (MNS8 7714), U.S. NUCLEAR REGULATORT C0 fells $l0N, (See reverse for required ruber of digits / characters for each block)
WA$NINCION, DC 20555 0001 As IO THE PAPERWDRK REDUCil0N PROJECT (31$0 0104),
0FFICE OF MANACFMFNi AND BUDGET. WASHINGTON, DC 20503.
FACILITT MAK (1)
DOCKET NLseER (2) l.
PME (3)
Braidwood 1 05000456 l
1-OF 5 TITLE (4)
Reoctor Trip Due to Logic Card Falture in Train B Solid State Protection System EVINT DATE (5)
LER Ntsentt (61 RrPopi DATE (7)
OTMrt FACit titr$ INvotyrD (s) 88 MCCIM DAY YEAR YEAR M0hfM CAY YEAR NuwstR NumstR one 05000 FACILIM hAME DOCKE 01 07 93 93 001 00 01 29 93 05 OPERAllNG HMI 15 mlMfD MANT TO IMF HQUlWNM Of 10 CM h (Cuck w or mon) (M) y G DE (9) 20.402(b) 20.405(c)
X 50.73(a)(2)(lv) 73.71(b)
POWER 20.405(a)(1 Hl) 50.36(c)(O 50.73(a)(2)(v) 73.71(c)
LEVEL (10) 20.405(a)(1)(ii) 50.36(c)(2)
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NAME TELEPHONE NUMBER (include Area Code)
A.
Stogsdill, Technical Staff Engineer (815) 458-2801 yT 34 3 C0MPtFIE ONE tlNE FOR T ACH Cf34PONf MI F AllORE DESCR lBlD IN IN1$ RFPORT (13)
CAUSE
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CAUSE
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DATE (15)
A8STRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)
On January 7, 1993 while performing Unit One Reactor Coolant Pump Underfrequency Quarterly Surveillance, Unit one experienced a Reactor Trip.
The failed component was on the A215 Universal Logic card which is the decision maker for the 2 out of 4 logic in the RCP-UF circuit. The'A215 card was replaced and the SSPS Bi-monthly Diagnostics test was reperformed to ensure the replacement card functioned properly and verify the complete SSPS system was operational.
The failed Universal Logic card was sent to the vendor for a detailed failure analysis.
There have been previous occurrences of spurious ESF actuations due to problems in the Train B SSPS circuitry.
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EXPIRES 5/31/95 ElflMATED sVRDEN PER RESPONSE 10 COMPLY WifM TN!$ INFORMA110N COLLEtil0N REQUEST: 50.0 NR$.
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Braidwood 1 vfAR stoutNTIAL REylsl0N 2 OF 5 05000456 93 0
001 --
TEXT (If more gpace is reoutrUse e@tional copies of NRC Form 3Q (IT)
A.
PLANT CONDITIONS PRIOR TO EVENT:
Unit:
Braidwood 1; Event Date:
January 7, 1993; Event Time: 1314
- - Mode:
1 - Power Operation; Rx Power:
100%;
RCS (AB) Temperature / Pressure:
NOT / NOP; B.
DESCRIPTION OF EVENT
There were no systems or components inoperable at the beginning of the event which contributed to the severity of the event.
Prior to the event, a pre-job briefing was conducted between the Unit Nuclear Station Operator (NSO) and an extra NSO assigned to perform the Control Room functions associated with the test.
On January 7, 1993 while performing Technical Surveillance 1BWVS 3.1.1-6 (Unit One Reactor Coolant Pump Underfrequency Quarterly Surveillance),
Unit One-experienced a Reactor Trip.
The Reactor Coolant Pump Underfrequency Surveillance (RCP-UF) performs verification of the Trip Actuating Device Operational Test of the RCP bus Underfrequency input to the Solid State Protection System ~(SSPS).
The RCP Underfrequency Reactor Trip Coincidence logic is 2 out of 4 buses with permissive P-7.
Each RCP bus contains an A-Train and B-Train UF Relay.
Testing is performed on'each relay independently with verification of control room annunciation and reset.
This sequence is repeated for all four of the RCP buses in 1BwVS 3.1.1-6.
On the day of the event, the RCP-UF Surveillance was being performed by three Technical Staff Engineers and supported by a Nuclear Station Operator.
Two engineers were performing the relay actuations in the 6.9KV Switchgear Room and the third engineer and NSOLwere at the~ Main control Board to verify and acknowledge alarms generated, along-with-the underfrequency bistables associated with each 6.9 KV bus.
Communications were maintained throughout the testing via sound powered headsets.- Testing was completed satisfactorily on bus 156 and 157 relays.
Testing was then completed satisfactorily on bus 158_A-Train relay.
At 1314, upon actuation of bus 158 B-Train relay, a trip signal was generated resulting in a Reactor Trip and a trip of all four RCP's.
Procedure IBwEP-0, Unit One Reactor Trip / Safety Injection, was entered.
The relay was reset and surveillance stopped.
Operations immediately proceeded to stabilize the plant and re-start the 1D RCP on bus 159.
As the unit was being stabilized, Tech Staff and Operations dnpar_trents_. began an investigation _to_ find the IDDt_Cause_of the event.
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LICENSEE EVENT REPORT (LER) 7:"NF0nES" A7 TEN 0sSI cE e ANs TEXT CONTINUATION (n=8a m4), u.s. NuCitAt REaulAt0er Conniss10N, WA$N!NC10N, DC 20$55 0001, AND 10 iME PAPERWORK REDUCTION PROJECT (3150 0104),
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FACILITT MAmf (1)
DoctTT Ntsett (?)
LFR taseER (6?
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Braidwood 1 YEAR SEQUENTIAL REVISION 05000456 93 0
3 OF 5
-- 0 01 --
TEXT (If more_ space is re M eed. Use e # tional copies of het Form 366A) (17)
After intial interviews with partTcipants and a thorough review of the circuit, surveillance, and sequence of events recorder, it appeared there had been a logic f ailure and not a personnel error.
After the plant was stablized in Mode 3, RCP-UF Surveillance was reperformed in an effort to recreate the failure and collect more data.
The surveillance was performed satisfactorily, which indicated an intermittent logic problem.
At this time a task force was established to develop a troubleshooting plan.
Technical Staff Engineers developed a three part action plan consisting of UF relays, control room annunciation and SSPS troubleshooting.
Each part of the plan was assigned to independent teams with expertise in that area of concern.
The teams then expanded and detailed their portion of the action plan to ensure effective isolation of the logic failure.
This plan was then reviewed and approved by Station upper management and offsite consultants.
Once approved, the. troubleshooting plans were implemented.
Team 1 comprised of Tech Staff Engineers and OAD Engineers conducted a complete investigation of all equipment in the 6.9KV Switchgear room, concentrating on the UF relays.
Inspection and check-out of relays associated with buses 156, 157, 158, and 159 found no failed or questionable equipment.
Further review of the circuit and documentation from the event verified that the failure was not in the individual relays or breakers.
Team 2 comprised of Tech Staff Engineers investigated-possible failures-in the annunciator system.
Inspection and check-out from IPA 30J (annunciator input panel) to the Control Room annunciator windows and audible alarms found no failed components.
The sequence of events recorder also performed without failure under test conditions.
This area was proven not to be an adverse factor in the event.
A third team consisting of Tech Staff Engineers conducted an investigation in an effort to isolate the failure in B-Train Solid State Protection System (SSPS).
This team predicted a specific test failure in 1BwoS 3.1.1-21 (SSPS bi-monthly diagnostics test) which would verify the suspect logic card.
Upon performance of the bi-monthly test, the expected failure was documented on the procedure and on test monitoring equipment.
The failed component was on the A215 Universal Logic Card which is the decision maker for the 2 out of 4 logic in the RCP-UF circuit The A215 card was replaced and IBwos 3.1.1-21 was reperformed to ensure the replacement card functioned properly and verify the complete SSPS system was operational.
Additional SSPS troubleshooting was completed during this evolution to expose any other degraded or questionable components which could have CDntributed to the eyant, Manual logic input tu tina from the SSPS j
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LICENBEE EVENT REPORT (LER)
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Braidwood 1 YEAR sEauENilAt aEVISION 05000456-
- - 4 OF 5 93 o-001 --
TEXT 11f more sonee is reautred use eMitional copies of NRC Form 366A) (IT) local test panel was conducted to validate test results'from the bi-monthly test.
Input testing from individual RCP relays to the Control Room verified the complete logic circuit.
Inspections were performed'on the SSPS Input Bays, Logic Bay-backplane wiring, and-termipoints to. find damaged or questionable components.
The RCP UF surveillance was reperformed to satisfy Technical Specification surveillance requirements.
These actions verified the single failure found in the SSPS bi-monthly test and-completed the troubleshooting action plan.
B.
CAUSE OF THE EVENT
As outlined above, the root cause of this event was a single failure of a logic card in the B-Train SSPS and there were no other contributing factors.
D.
SAFETY ANALYSIS
This event'had no effect on the safety of the plant or the public.
The SSPS actuations that were generated were neither desired.nor required and were-inappropriate for the existing plant conditions.
The' -
redundant A train of SSPS was operable and available to initiate the necessary ESF actuations had a valid need occurred.
Additionally,-it has been concluded that the problems with the train B SSPS processing circuitry would not have precluded its initiation of the appropriate-ESF actuations had a valid need occurred.
Under the. worst case condition of.a valid situation occurring requiring any or all of-the ESF actuation functions-of SSPS there would still be no effect as this is enveloped in Section 7 of the Updated Final Safety' Analysis Report.- The redundancy and physical train separation of the SSPS provide for initiation and actuation of adequate components to perform all required safety functions from a single train of SSPS combined with its associated train of operable output components.
The A train of SSPS, including all associated A train components, was operable and available throughout the event.
E.
CORRECTIVE ACTIONS
The failed Universal Logic card was sent to the vendor for a detailed failure analysis.
Successful performance of 1BWVS 3.1.1-6 and 1BwOS 3.1.1-21 has proven operability of the RCP UF logic and of B-Train SSPS as a whole.
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EXPIRES 5/31/95 estimated BURDEN PER RESPONSE TO COMPLT WifN INis IkFORMAll0N COLLEC110N REQUEST: 50.0 NRs.
LICENSEE EVENT REPORT (LER)
$""17,o[$8 'o"^n"gE00s Y "GE S "^b A S AN ANA TEXT CONTINUATION (nNos n14), u.s. NUCLEAR mECULATORY COMM!sst(M.
WASHINGTON, DC 20555 0001, AND 10 THE PAPERWORK REDUC 110N PROJECT (3150 0104),
OFFICE Of MAhACEMNT AND BUDGET, WASHINGTON, DC 20503.
FACILlif NAM (1)
DoctIT maats (2) tra utsatt (6?
PAE (3)
Braidwood 1 YEAR SEQUENTIAL REvlsION 05000456 5 OF 5 93 oo
-- 0 01 --
TEXT (If more space is reostred, use additional cooles of hRC f orm 366A) (IT)
F.
PREVIOUS OCCURRENCES
There have been' previous occurrences of spurious ESF actuations due to problems in the Train B SSPS circuitry.
The previous corrective actions addressed'the root and contributing causes.
There is no:
indication of an adverse trend.
DVR 20-1-90-039 / LER 90-018; SPURIOUS TRAIN.B SOLID STATE PROTECTION SYSTEM ACTUATIONS DUE TO COMPONENT FAILURE, PERSONNEL ERROR, AND COMPONENT INTERFACE DESIGN DEFICIENCY - 2 REACTOR TRIPS, 2 SAFETY INJECTIONS - cause was attributed to output function of Train B SSPS.
LER 1-92-013; INADVERTANT SAFETY INJECTION ON 1B TRAIN WHILE PERFORMING 1BWOS 3.1.1-21
- - The root cause of the event was a spurious train B SSPS safety injection signal on main steam line' low pressure due to unknown reason.
G.
COMPONENT FAILURE DATA
MANUFACTURER b'OMENCLATURE MFG PART NUMBER WESTINGHOUSE A215 - Universal 6056D21G01 Logic Card u: ec: nu n.m