05000458/LER-1995-001, :on 950125,ESG Actuation Occurred During Performance of Surveillance Test Procedure.Cause Could Not Be Determined.Isolation Had Been Reset & Steam Supply Valve Opened After Event
| ML20083C076 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 05/05/1995 |
| From: | James Fisicaro, Gates T ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LER-95-001, LER-95-1, NUDOCS 9505150098 | |
| Download: ML20083C076 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(x) |
| 4581995001R00 - NRC Website | |
text
Ent:rgy Operatiore, Inc.
River Bend Station 5485 U S Highway 61
= ENTERGY sfr* 2 6n5 (504) 336 4225 FAX (504) 635-5008 JAMES J. FISICARO.
Director -
Nuclear Safety May 5,1995 U.S. Nuclear Regulatory Commission Document Desk Mail Stop P1-37 Control Washington, D.C. 20555
Subject:
River Bend Station - Unit 1 Docket No. 50-458 License No. NPF-47 Licensee Event Report 50-458/95-001-01 File Nos. G9.5, G9.25.1.3 RBF1-95-0115 RBG-41494 Gentlemen:
In accordance with 10CFR50.73, enclosed is the subject report. This revision documents the results of the twt cause investigation conducted by the Significant Event Response Team j
concerning the Engineered Safety Feature (ESF) actuation that occurred on January 25,1995.
Bars in the left margin of the document indicate changes made to the original LER.
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9505150098 950505 PDR ADOCK 05000458 O
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Licensee Event Report 50-458/95-001-01 May 5,1995 RBG-41494 RBF1-95-0115 Page 2 of 2 cc:
U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011 NRC Sr. Resident Inspector P. O. Box 1051 St. Francisville, LA 70775 INPO Records Center 700 Galleria Parkway Atlanta, GA 30339-3064 Mr. C. R. Oberg Public Utility Commission of Texas 7800 Shoal Creek Blvd., St ite 400 North Austin, TX 78757 Louisiana Department of Environmental Quality Radiation Protection Division P.O. Box 82135 13aton Rouge, LA 70884-2135 ATTN: Administrator
NRC FORM 368 U.S. NUCLEAR REGULATONY COMMISSION APPROVED BY OMB NO. 31604104 f5G)
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River Bend Station 05000 458 1 of 4 TITLE (4)
Unintentional Division ' MCIC isoision During Surveillance Testing EVENT DATE (5)
LER huMBER (6)
REPORT DATE (7)
OTHER FACILITIES INVOLVED (8)
MONTH DAY YEAR YEAR SEQUENTIAL REVISION MONTH DAY YEAR F ACILITY NAME DOCKET NUMBER NUMBER NUMBER N/A 05000 F ACILITY NAME DOCKET NUMBER 01 26 95 95 001 01 05 05 95 N/A 05000 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR $ (Check one or more (11)
MODE (9) 1 20.402(b) 20.405(c)
X 50.73(a)(2)(iv) 73.71(b)
POWER 20 405(a)(1)(i) 50.36(c)(1) 50.73(a)(2)(v) 73.71(c)
LEVEL (10) 100 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vii)
OTHER 20.405(a)(1)(iii) 50.73(a)(2)(i) 50.73(a)(2)(viii)(A) gpga,*yg** *ad m 20.405Ia)(1)(tv) 50.73(a)(2)(ii) 50.73(a)(2)(viii)(B) 20.405(a)(1)(v) 50.73(a)(2)(iii) 50.73(a)(2)(x)
LICENSEE CONTACT FOR THIS LER (12) tCME TELEPHONE NUMBER (mcluo. Ar Coo.)
T.W. Gates, Supervisor - Nuclear Licensing 504-381-4866 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
CAUSE
SYSTEM COMPONE NT MANUF ACTUREN R
ABLE
CAUSE
SYSTEM COMPONENT MANUF ACTURER R
ABLE SUPPLEMENTAL REPORT EXPECTED (14)
EXPECTED M NTH DAY YEAR YES X
NO SUBMISSION
<w y... complet. EXPECTED SUBMISSION DATE)
DATE (15)
ABSTRACT tumm 5400.p.c. i...pp<omm.t.iy $s.mai.-.p.c.o typ nit.a im ) tis)
At 1718 on January 25,1995 with the plant at 100 percent power and the unit in Operational Condition 1, an engineered safety feature (ESF) actuation occurred during the performance of a surveillance test procedure.
During continuity measurements on the RCIC system, an isolation signal caused the automatic closure of the RCIC steam supply valve. This report is submitted pursuant to 10CFR50.73(a)(2)(iv) as an ESF r.ctuation.
Although the root cause for this event could not be determined conclusively, the most probable cause was personnel error. Significant management initiatives such as the Human Performance workshops have increased sensitivity to performance errors at River Bend Station by stressing the need for heightened awareness, good teamwork, and questioning attitudes. In addition, the Long Term Performance Improvement Plan (LTPIP) specifically addresses human performance problems and contains initiatives that are presently in progress for improving human performance at River Bend Station.
The isolation was reset and the steam supply valve opened after the event. The STP, including the step which was in progress when the isolation occurred, was completed successfully after the isolation. This event was not safety significant.
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River Bend Station 05000 458 95-001 01 2OF4 TEKT (W more space a requed, une additener ccpes of NRc Farm 300m17)
REPORTED CONDITION At 1718 on 25 January,1995 with the plant at 100 percent power and the unit in Operational Condition 1, an engineered safety feature (ESF) actuation, the automatic closure of the RCIC steam supply valve, occurred during the performance of surveillance test procedure STP-207-5253, "RCIC/RHR System Isolation, RHR Equipment Area Ambient Temperature High Channel Calibration, Logic System Functional Testing." The ESF function of the containment isolation valve involved in the event provides for the mitigation of a break in the RCIC steam supply header. Specific and dedicated sensors and logic are provided to sense flow and/or temperature conditions that would be indicative of a break in the RCIC steam supply header. It is this circuitry that had its logic unintentionally satisfied during the performance of this STP and the unplanned full actuation of this ESF function occurred during this event. This report is therefore submitted pursuant to 10CFR50.73(a)(2)(iv) as an ESF actuation.
INVESTIGATION i
While performing the 18 month Logic System Functional Test for the circuitry from the RHR Equipment Area Ambient Temperature High temperature switch to the RCIC relay contacts and wiring in 1H13*P642, Division II J
Leak Detection Cabinet, an isolation of the Division II RCIC inboard steam supply isolation valve 1E5 l'MOVF063 occurred. Instrumentation and Controls technicians were performing a continuity check in the RCIC isolation logic when the isolation occurred.
After the isclation the Technician removed the multimeter test leads from the pancl; therefore, the position of the leads at the time of the isolation could not be determined. When interviewed, the technicians involved expressed that, to the best of their knowledge, the Surveillance Test Procedure was followed as written.
A Significant Event Response Team was formed to perform a detailed investigation and Root Cause determination. During their research, possible failure modes for this type ofisolation were analyzed. Through extensive investigative analysis and troubleshooting, the following possible failure modes were eliminated: cable fault, grounded terminal, procedure error, and antenna coupling / induced voltage (EMI). By eliminating the other potential causes, the SERT determined that technician error was the most probable root cause for this event.
The SERT concluded that no operability questions exist for this system.
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River Bend Station 05000-458 95-001-01 3OF4 ROOT CAUSE While the root cause for this event cannot be conclusively determined, the Significant Event Response Team investigating the isolation determined that the most probable root cause was technician error during performance of the Surveillance Test Procedure.
Kepner-Tregoe techniques and fault tree analysis were used to analyze and eliminate all possible causal factors.
The potential causal factors identified by the Significant Event Response Team were a cable fault, a grounded terminal, procedure error, antenna coupling / induced voltage (EMI), and technician error (an incorrectly landed lead). The surveillance test procedure was reviewed in detail following the event. The SERT concluded that the i
procedure, if performed correctly could not have caused the isolation. On the basis of the results of exhaustive troubleshooting efrorts combined with problem analysis techniques, the SERT determined that a cable fault, a grounded terminal and antenna coupling / induced voltage (EMI) were not credible failure modes for the unanticipated isolation. Afler exhausting all other possible causal factors for this event, the SERT concluded that technician error was the most plausible explanation for the RCIC isolation.
CORRECTIVE ACTIONS
Initial corrective actions taken in response to this event were that the RCIC system was restored to its normal i
status and the STP which caused the isolation was successfully performed subsequent to the event. A comparison of the panel circuitry to the connection diagrams and schematics was performed, and no discrepancies were noted. Also, voltage readings were taken at various points in the circuitry to verify proper operation. In addition, a Significant Event Response Team was formed to coordinate troubleshooting, investigate the root cause, and formulate corrective actions.
In addition, Surveillance Test Procedures which perform Logic System Functional testing on the isolation portion of the RCIC system were reviewed for possible procedure improvements. This review found that the tests could be significantly improved by eliminating unnecessary and redundant portions of the tests and by changing the methods used for verifying proper circuit operation. The SERT identified Surveillance Test Procedures for the RCIC isolation logic that should be reviewed for potential optimization. These Surveillance Test Procedures will be reviewed with revisions performed as necessary. In addition, the Long Term Performance Improvement Plan, using the guidance of the Procedure Upgrade Project, is currently improving the overall quality of procedures at River Bend Station in the area of human factors.
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River Bend Station 05000-458 95-001-01 4OF4 Training will be provided to Operations, I&C, and Electrical Maintenance personnel on the need to preserve the status of equipment after an ESF actuation or similar type event. The trr aing will stress the importance of Icaving test equipment and initiation signals as they were prior to the isolation so that the root cause for the event can more easily be determined. The training will also stress that this policy should never take precedence over plant and personnel safety.
Significant and comprehensive initiatives have been implemented in accordance with the RBS Long Term Performance improvement Plan (LTPIP) in the area of Human Performance. Especially pertinent to this event are the following initiatives:
- 1. Improve S.T.A.R. program implementation.
- 2. Reduce the number of problems resulting from human performance issues.
- 3. Establish a site-wide accountability program.
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- 4. Perform an analysis of the key work processes with the greatest impact on human performance.
SAFETY ASSESSMENI Afler the isolation, STP-207-5253 was reperformed and successfully completed. Since the RCIC isolation safety function occurred as designed, and no abnormalities were discovered, the RCIC isolation activation instrumentation was declared to be operable. Based on these investigations, this event was not safety significant.