05000298/LER-1998-001, :on 980127,discovered That Closing SGTS Unit Crosstie Valve During Performance of Certain Surveillance Test Procedures Renders Both Trains Inoperable.Caused by Failure to Recognize.Procedures Revised
| ML20203G737 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 02/26/1998 |
| From: | Dewhirst L, Peckham M NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LER-98-001, LER-98-1, NLS980033, NUDOCS 9803030056 | |
| Download: ML20203G737 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(1) |
| 2981998001R00 - NRC Website | |
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COOPER NUCLE AR 6T ATION P.O. BOX 98, BROWNVLLE. NEBRASMA 68W1 Nebraska Public Power District
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.m NLS980033 February 26,1998 1
1 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 Gentlemen:
Subject:
Licensee Event Report No. 1998-001 Cooper Nuclear Station, NRC Docket 50-298, DPR-46 The subject Licensee Event Report is forwarded as an enclosure to this letter.
Sincerely, I
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[ t-M.1. Peckham Plant Manager
/lrd Enclosure ec: Regional Administrator USNRC - Region IV Senior Project Manager USNRC - NRR Project Directorate IV-1
/f Senior Resident inspector USNRC NPG Distribution f1 INPO Records Center W. Turnbull MidAmerica Energy 9803030056 900226 PDR ADOCK 05000298
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NRC FdRM 366 U.S. NUCLEAR REIULATO2Y COMMISSION APPROVED BY OMB NO. 3150-0104 4499 EXPIRES 04130/9B ISTWATED $URDEN PIR RtSPONSE TO COMPLY WITH TMit MAND ATORV INFORM AT10h COLLtCT104 R10015160 0 HRS REPORTED LE$3DNS Lt ARNED ARE INCORPOR Af(D INT:
LICENSEE EVENT REPORT (LER)
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FAcarry NAME m oocaET NudR m eAoE 13:
COOPER NUCLEAR STATION 05000298 1OF3 Tif Lt 141 Technical Specification Violation Due to Failure To Address Equipment lnoperability During Surveillance Testing EVENT DATH is)
LER NUMarR (6)
REPORT DATE (7)
OTHER FACILITIES INPOLVED fB)
F Acm NAME oocxET NUMBER SEQUENTIAL REVISION MONTH DAY YEAR YEAR MONTH DAY YEAR NUMBER NUMBER F ActLrty NAME DOCKET NUMBER 01 27 1998 1998 001 00 02 26 1998 05000 OPERATINO C'"
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N MODE (9) 20.2201(b) 20.22031aH2Hv)
X 50.73(aH2)(l) 50.73(aH2Hviii)
POWER 20 2203f ait11 20 2203f alf3Hi) 50 73f aH2)fii) 50 73f a)(211x1 100 LEVEL (10) 20.2203(aH2)(i) 20.2203(aH3Hii) 50.73(aH2Hiii) 73.71 20 2203f aH2)fiii 20 2203fnH4) 50 73(alf 2Hiv)
OTHER 20.2203(aH2Hiiil 50.36(c)(1) 50.73(aH2Hv) specify in Abstract below 20.2203(aH2Hivl 50.36(cH2) 50.73(aH2Hviil LICENSEE CONTACT FOR THIS LEF f12)
NAME TELEPHONE NUMBER (include Area codel Linda R. Dewhirst, Licensing Engineer (402) 825 5009 COMPLETF ONE LINE FOR EACH COMPONENT FAILURE DEfCRiarfiiN "HIS REPORT (13)
- - CAUSE SYSTEM COMPONENT MANUFACTURER
CAUSE
SYSTEM COMPONENT MANUFACTURER SUPP FM8NTAL REPORT EXPECTED (14)
MONN DAY MAR EXPECTED YES SuBMisSloN Of yes, complete EXPECTED SUOMISSION DATE).
X NO DATE (15)
ABSTRACT ! Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) (16)
On January 27,1998, it was discovered that closing the Standby Gas Treatment (SGT) system unit crosstie valve during performance of certain surveillance test procedures renders both trains inoperable.
This procedural step led to an inadvertent violation of Technical Specifications due to the failure to recognize the vulnerability of SGT operability under the particular surveillance test conditions, immediate actions taken included placing the surveillance procedures involving the closure of the crosstle valve on administrative hold, and revising a system operating procedure which operates the crosstie valve to include a caution statement indicating both SGT trains are inoperable unless one train is isolated (non-f unctional). The surveillance test procedures will be revised such that testing is performed when the SGT system is not required to be operable OR allow testing without closing the crosstie valve. A sampling of surveillance test procedures with similar test conditions will also be reviewed to determine if actions taken ouring testing adversely affects operable equipment.
NRC r0RM 3681499
- U.S. fdVCLEAR REGULATORY COMMISSION I4 951 LICENSEE EVENT REPORT (LER)
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TEXT CONTINUATION FACitt'Y N AME fil DOCKET
.ER NUMBER f 61 PAGE (3)
YtAR SEQUENTIAL REVISION COOPER NUCLEAR STATION 05000298 2
OF 3
1998 - 001 --
00 TEXT (11rnore space is required, use additional copies of NRC form 366A) (11)
PLANT STATUS At the time of the event, the plant was at full power, steady state operation.
EVENT DESCRIPTION
On January 27,1998, during the review of several Standby Gas Treatment (SGT) system (Ells Code: BH]
procedures for implomontation of Improved Technical Specifications (ITS), it was discovered that surveillance test procedures inadvertently led to a violation of Technical Specifications. The surveillance test procedures include steps for closing the SGT system crosstie valve (Ells Code: V], necessary to provide removal of decay heat generated in the charcoal and High Efficiency Particulate Air (HEPA) filters (Ells Code: FLT) resulting from the retention of fission products following a Design Basis Accident loss of Coolant Accident (DBA LOCA). When the crosstie valve is closed and both SGT system trains are functional, the decay heat removal function is impaired; thus rendering both SGT system trains inoperable. Technical Specifications (TS) require that upon discovery that both trains are inoperable, the plant must be placed in a condition where the SGT system is not required (i.e., cold shutdown). The TS Limiting Condition of Operation (LCO) provides no time requirements for achieving cold shutdown under these circumstances (both SGT trains inoperable). Thus, TS 1.0.J (ITS LCO 3.0.3) must be invoked which applies in cases wnere an LCO cannot be satisfied because of circumstances in excess of those addressed in the specification which requires that the facility be placed in HOT SHUTDOWN within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
Once it was discovered that the closure of the crosstie valve rendered both trains inoperable, a review of past performances of the surveillance procedures was performed. The results indicated that surveillance testing had been conducted routinely (at a frequency of approximately once per cycle) at power. Though the surveillance test procedures are sufficient for their intended purpose (acceptable results have been demonstrated), they do not adequately address the impact to SGT operability anct the plant conditions required to perform testing.
The surveillance procedures involving the c;osure of the crosstie valve were immediately placed on administrative hold. One system operating procedure was identified as operating the crosstie valvo, and it was immediately revised to include a caution statement that closing the crosstie valve renders both SGT trains inoperable unless one train is isolated (non functional).
BASIS FOR REPORT Performance of the subject surveillance procedures at power results in a violation of TS, therefore this event is being reported as a violation of Technical Specifications under 10 CFR 50.73(a)(2)(1)(B).
CAUSE
The cause of this event is a f ailure to recognize the vulnerability of both trains of the SGT system being inoperable when the crosstie valve is closed under the conditions of the surveillance test (unit is at power, both trains are f unctional).
A contributing factor is an incorrect description of the decay heat removal function in the Updated Safety Analysis Report (USAR).
MC FORM 366A 14 951 J
NZC F6;M 366A U.S. NUCLEAR REGULATORY COMMISSION 1499 LICENSEE EVENT REPORT (LER)
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TEXT CONTINUATION FACILITY NAME i11 DOCKET
.ER NUMBER f 61 PAoEf3)
YEAR SE0VENTIAL REVISION COOPER NUCLEAR STATION 05000298 3
OF 3
1998 - 001 --
00 TEXT (11anore space is required. use additio.1al copies of NRC form 366Al 111)
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SAFETY SIGNIFICANCE
This event had potential significance. In the event of a DBA LOCA, both trains are automatically started and, upon verification that both subsystems are operating and reactor building pressure is less than or equal to minus 0.25 inches water gage, the redundant train is shut down to a standby condition. The potential exists that without decay heat removal, the filters in SGT unit which is shut down would reach ignition temperatures, which could also affect the operability of the in-service unit. However, there is a low probability that the event would actually occur. A probabilistic safety analysis (PSA) was performed which addresses the probability of a DBA LOCA occurring at the ssmo time the surveillance test was being performed and the cro.;stie valve was closed. The probability was calculated as 3.4 x 10E-9; the threshold for significant safety evolutions is core damage probability greater than 1 x 10E 6. Thus, based on a probabilistic comparison, this event does not pose a significant safety risk. Note also that the condition with the crosstie valve closed only existed for a short period of time while the surveillance was being performed. Following the completion of the surveillan :e, the procedures provide inctructions to open the crosstie valve to its throttled position.
The significance of this event is further mitigated by the f act that there is a dependence on SGT run time and time to ignition temperature due to the decay heat of fission products deposited on the charcoal filters following a DBA LOCA. An engineering evaluation demonstrates that with the crosstie valve closed, the charcoal filter in the non-operating train could reach ignition temperature in approximately 3.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />; however this is based on the assumption that the train had been operating for ten days following the event.
CORRECTIVE ACTIONS
The surveillance test procedures will be revised such that testing is performed when the SGT system is not required to be operable OR conduct testing without closing the crosstie valve.
A sampling of surveillance test procedures with similar test conditions will be reviewed to determine if actions taken during testing adversely affects operable equipment.
The USAR will be updated to correctly describe the decay heat removal function of the crosstie valve.
PREVIOUS EVENTS The following are events with similar circumstances:
LER 1995-014, " Procedural Error That Could Result in Compromising Secondary.ontainment Integrity During Accident Conditions" LER 1997-007-00, " Opening of a Torus to Drywell Vacuum Breaker" we row nui499 l
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ATTACHMENT 3 LIST OF NRC COMMITMENTS l
Correspondence No: NLS990033 The following table identifies those actions committed to by the District in this document.
Any other actions discussed in the submittal represent intended or planned actions by the District.
They are described to the NRC for the NRC's information and are not regulatory commitments.
Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.
COMMITTED DATE
COMMITMENT
OR OUTAGE Update the USAR to clearly define the safety function of the SGT system crosstie valve.
N/A Review a sampling of surveillance test procedures with similar test conditions to determine if actions taken N/A during testino adversely affects operable equipment.
Revise SGT surveillance procedures such that testing is to be performed when the SGT system is not quired to be operable OR allow testing without the clos 1..J the N/A crosstie valve, s
l PROCEDURE NUMBER 0.42 l
REVISION NUMBER 5 l
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