05000397/LER-1999-001, :on 990628,ESF Signal Closed All Eight MSIVs While Plant Was Shutdown.Caused by Failure of Relay RPS-RLY-K10D.Subject Relay Was Replaced & Tested on 990630. with
| ML17292B742 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 07/20/1999 |
| From: | Sherman R, Galen Smith WASHINGTON PUBLIC POWER SUPPLY SYSTEM |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GO2-99-135, LER-99-001, NUDOCS 9907270226 | |
| Download: ML17292B742 (8) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 3971999001R00 - NRC Website | |
text
CATEGORY0 REGULATORY INFORMATION DISTRIBUTION SYSTEM (RZDS)
ACCESSION NBR:9907270226 DOC.DATE: 99/07/20 NOTARIZED: NO FACZL:50'-397 WPPSS Nuclear Project, Unit 2, Washington Public POwe AUTH.NAME AUTHOR AFFILIATION, SHERMAN,R.N.
Washington Public Power Supply System SMITH,G.O.
Washington Public Power Supply System RECZP.NAME RECIPIENT AFFILIATION DOCKET 05000397
SUBJECT:
LER 99-001-00:on 990628,ESF signal closed all eight MSZVs while plant was shutdown. Caused by failure of relay RPS-RLY-K10D.Subject relay was replaced
& tested on 990630.
With 990720 ltr.
DISTRIBUTION CODE:
XE22T COPIES RECEIVED:LTR ENCL SIZE:
TITLE: 50.73/50.9 Licensee Event Report (LER), Incident Rpt, etc.
NOTES:
E RECIPIENT ZD CODE/NAME LPD4-2 PD XNTERNALs ACRS NRR/DIPM/ZOLB NRR/DSSA/SPLB RES/DRAA/OERAB EXTERNAL: L ST LOBBY WARD NOAC POORE,W.
NRC PDR COPIES LTTR ENCL 1
1 1
1 1
1 1
1 1-1 1
1 1
1 1
1 RECXPIENT ID CODE/NAME CUSHING, J LE C
E NRR7DRZ P /REXB RES/DET/ERAB RGN4 FXLE 01 LMXTCO MARSHALL NOAC QUEENER,DS NUDOCS FULL TXT COPIES LTTR ENCL 1
1 1
1 1.
1 1
1 1
1 1
1
'1 1
1 0
R D
0 M
NOTE TO ALL "RIDS" RECIPIENTS:
PLEASE HELP US TO REDUCE WASTE ~ TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROL DESK (DCD)
ON EXTENSION 415-2083 FULL TEXT'CONVERSION REQUIRED TOTAL NUMBER OF COPIES REQUXRED:
LTTR 16 ENCL 16
rg
'L
WASHINGTON PUBLIC POWER SUPPLY SYSTEM PO. Box 968
~ Richlanrl, Washington 99352-0968 July 20, 1999 G02-99-135 Docket No. 50-397 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Gentlemen:
Subject:
%NP-2, OPERATING LICENSE NPF-21 LICENSEE EVENTREPORT NO. 99-001-00 Transmitted herewith is Licensee Event Report No. 99-001-00 for WNP-2.
This report is submitted pursuant to 10 CFR 50.73 and discusses the items of reportability, corrective action taken, and action to preclude recurrence.
Should you have any questions or desire additional information pertaining to this report,.please call me or PJ Inserra at (509) 377-4147.
Respectfully, 0 Smith Vice President, Generation MailDrop 927M Attachment cc:
EW Merschoff - NRC MV JS Cushing - NRC NRR INPO Records Center NRC Senior Resident Inspector - 927N (2)
DLWilliams - BPA/1399 PD Robinson - Winston K Strawn 9907270226 990720 PDR ADQCK 05000397 S
FACILITY NAME (1)
WNP-2 DOCKET NUMBER (2) 50-397 PAGE (3) 10F 4
TITLE (4)
Failed Relay Causes ESF Signal to Close All 8 MSXV's While Plant Was Shutdown EVENT DATE (5)
MONTH DAY 06 28 99 1999 LER NUMBER (6)
SEQUENTTAL 001 REPORT DATE (7)
YEAR FACIUTYNAME 1999 FATTY NAME REV.
NUMBER 20 00 07 OTHFR FACILITIES INVOLVED (8)
OPERATING HODE THIS REPORT IS SUBHITTED PURSUANT TO THE REQUIREMENTS OF 10 CPR 5:
(Check one or sore)
(11)
POWER LEVEL 20A02(b) 20AOSa 1
20A05(a)(1) 00 20.
s 1
6 20.
a 1
20.
a 1
20AOS(c) 5036 c 1
50.36(c)(2) 50.73 a 50.73 a i
x 50.73(a)(2)(iy) 50.73 a v
50.73(a)(2)(vll) 50.
s I
A 50.
a I
50.73 a 73.71(b) 73.71 c OTHER NAME R.N. Sherman, Licensing Engineer LICENSEE CONTACT FOR THIS LER (12)
TELEPHONE NUMBER (Irc)ude Area Code)
(509) 377%616 COMPLETE ONE LINE FOR EACH CCMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
CAUSE
X JC RLY G080 COMPONENT MAMJFAcnATER REPORTABLE TO EPIX NO kg/i '"'
CAUSE
g:;P~g MANUFACTURER REPORTABLE TO EPIX SUPPLEMENTAL REPORT EXPECTED (14 )
YES
(@yea, comp(eted EXPECTED SUNOSSION DATE).
X NO EXPECTED On June 28, 1999 at approximately 1244 hours0.0144 days <br />0.346 hours <br />0.00206 weeks <br />4.73342e-4 months <br /> the plant was in Mode 4 during a fuel savings dispatch.
The reactor vessel head was in place and the head bolts properly tensioned.
Allcontrol rods were verified to be full in and no core alterations were in progress.
The A-Train of the Residual Heat Removal System was in service and performing the shutdown cooling function.
The Emergency Core Cooling System equipment that is required by technical specifications for Mode 4 operation was operable. A surveillance of the main turbine throttle valve position switches was in progress.
The Nuclear Steam Supply Shutoff System (NSSSS) generated an unexpected Main Steam Isolation Valve (MSIV) closure signal, and all eight MSIV's and the inboard main steam line drain valve closed.
Surveillance testing of the main turbine throttle valve position switches was stopped.
An Incident Review Board was formed to investigate the event.
The resident NRC inspector was notified and the NRC was notified of the unexpected Engineered Safety Feature (ESF) actuation via the Emergency Notification System.
The cause of this event was the failure of Reactor Protection System relay RPS-RLY-K10D, in that contacts opened due to vibration from an adjacent relay under test.
This generated a half MSIV closure signal.
The other half isolation signal was generated, as
- expected, by the main turbine throttle valve position switch surveillance.
There were no personnel errors or procedural deficiencies that contributed to this event.
Relay, RPS-RLY-K10D, was replaced and tested on June 30, 1999.
In addition, testing of the turbine throttle valves was completed on July 1, 1999, and did not cause an MSIV closure signal. There were no safety consequences associated with this event.
This event is being reported per the requirement of 10CFR50.73(a)(2)(iv) as an event or condition that resulted in an automatic actuation of an Engineered Safety Feature.
The ESF automatic actuation was not from a valid NSSSS actuation signal.
However, the actuation occurred while the isolation s stem was in service.
LICENSEE EVENT REPORT (LER)
Failed Rela Causes E$F Si to Close All8 MSIV's While Plant Was Shutdown fACILITYNAME (I)
DOCKET NUMBER (2)
LER NUMBER {6)
SEQUENTIAL NUMBER REVISION NUNB6R PAGE
{3)
WNP-2 50-397 99 001 00 2
OF 4
TEXT (Ifmore space is required, Use addNonal copies of NRC Form 366A) (17j Event Descri tion On June 28, 1999 at approximately 1244 hours0.0144 days <br />0.346 hours <br />0.00206 weeks <br />4.73342e-4 months <br /> the plant was in Mode 4 during a fuel savings dispatch.
The reactor vessel head was in place and the head bolts properly tensioned.
Allcontrol rods were verified to be full in and no core alteiations were in progress.
The A-Train ofthe Residual Heat Removal (RHR) System was in service and performing the shutdown cooling function. The Emergency Core Cooling System (ECCS) equipment that is required by technical specifications for Mode 4 operation was operable. A surveillance ofthe main turbine throttle valve position switches was in progress.
The Nuclear Steam Supply Shutoff System (NSSSS) generated an unexpected Main Steam Isolation Valve (MSIV) [SB, ISV]
closure signal, and all eight MSIV's and the inboard main steam line drain valve closed.
The resident NRC inspector was notified and the NRC Operations Center was notified ofthe unexpected Engineered Safety Feature (ESF) actuation via the Emergency Notification System (ENS).
&e notification Event Number is 35877.
The ENS notification cited 10CFR50.72(b)(2)(ii), ESF actuation.
Immediate Corrective Action
Surveillance testing ofthe main turbine throttle valve position switches was stopped.
An Incident Review Board (IRB) was formed and the event was investigated.
Further Evaluation The IRB determined that during the surveillance test ofthe 04 Turbine Throttle Valve, the valve position relay, RPS-RLY-K10H [JC, RLYj was energized as a result ofthe II4 Turbine 'Ilmottle Valve being opened.
This condition was expected and provides one-half of the NSSSS logic needed to generate a signal for closure of the MSIV's. In addition, the IRB determined the contacts ofthe valve position relay for the 83 Turbine Throttle Valve, RPS-RLY-K10D [JC, RLY], opened due to vibration from the operation of relay RPS-RLY-K10H.
This was not anticipated and provided one-half of the NSSSS logic needed to generate a signal for closure of the MSIV's.
The two NSSSS channel signals, together, were sufficient to generate the MSIVclosure signal, which caused the eight MSIV's and the inboard main steam line drain valve to close.
The bvo relays involved in this event, RPS-RLY-K10H and RPS-RLY-K10D are physically adjacent to one another.
This event is being reported per the requirement of 10CFR50.73(a)(2)(iv) as an event or condition that resulted in an automatic actuation of an Engineered Safety Feature.
The ESF automatic actuation was not from a valid NSSSS actuation signal.
However, the actuation occurred while the isolation system was in service.
0 LICENSEE EVENT REPORT (LER)
Failed Rela Causes ESF Si to Close All8 MSIV's While Plant Was Shutdown DocKET NUMBER I E)
FACILITY NAME I I )
LER NUMBER Is)
SEQUENTIAL NUMBER asvrsroN NUNBER PAGE I3)
WNP-2 50- 3 97 99 001 00 3
OF 4
TEXT (Ifmore space Is required, use addit)or)al copies of NRC Form 366A) (1 T)
The followinginformation regarding this event is provided to enhance the Significance Determination Process:
I.
2.
3.
Both trains ofEmergency AC power were operable and capable ofperforming their intended safety function.
The High Pressure Core Spray System was operable and capable ofperforming its intended safety function.
The A Train ofthe Residual Heat Removal System was in service performing the Shutdown Cooling function and the B train was operable and capable ofperforming its intended safety function.
Allcontrol rods were verified fullin and no core alterations were in progress.
The event described above did not involve a loss ofintended safety function. In addition, the event described above did not involve an event or condition that alone could have prevented the fulfillment of any safety functions described in 10CFR50.73(a)(2)(v).
Root Cause The cause ofthis event was the failure of relay RPS-RLY-KIOD, in that contacts opened due to vibration &om an adjacent relay under test.
This generated an MSIV closure signal.
This conclusion is supported by physical evidence obtained by plant test equipment.
There were no personnel errors or procedural deficiencies that contributed to this event.
The investigation regarding the cause of the relay to fail when it was subject to vibration is ongoing.
The prelinunary examination did not identify evidence of materials degradation that could have contributed to intermittent opening of contacts 11-12.
Metallic and non-metallic parts appear to be in good condition. The momentary opening of the contact is believed to be the result ofinsufficient contact wipe, which made the 11-12 contact shock sensitive in the dewnergized state.
The calibration sheet for the relay, dated February 9, 1994, has been reviewed and indicates the wipe and gap settings were acceptable.
Atest ofthe relay indicates the normally closed wipe for the 11-12 and the 9-10 contacts is unacceptable.
At this time there is no explanation for the reduction in contact wipe from the 1994 information. Additional examiiiation ofthe fingers and spring force measurements are underway.
Further Corrective Action Relay, RPS-RLY-KIOD, was replaced and tested on June 30, 1999.
In addition, testing of the turbine throttle valves was competed on July 1, 1999, and did not cause an MS1V isolation signal to be generated.
Assessment ofSafe Cons uences There were no safety consequences associated with this event.
The closure ofthe MSIV's while in Mode 4, did not impact plant safety because reactor coolant system temperature was limited to less than 200'.
The control rods were fully inserted at the time of the MSIV closure.
The Emergency Core Cooling Systems that are required by tcchnical specifications were operable and capable of performing their intended safety functions.
The A-Train of the RHR system was operating and performing the shutdown cooling function. This event did not represent a threat to the health and safety ofthe public or plant personnel.
LICENSEE EVENT REPORT (LER)
Failed Rela Causes FSF Si to Close All8 MSIV's While Plant Was Shutdown FACILITY HAHE (I )
DOCKET HVHBER (2)
LER HUHBER (6)
SEQUENTIAL NUHBER RINISION NUNSSE PAGE I3)
WNP-2 50-397 99 001 00 4
oF 4
TEXT(lfmore space is required, use addiUonal copies of NRC Form 366A) (17)
Similar Events
No previous similar events were identi6ed where all eight MSIV's were closed due to failed relay.