05000331/LER-1980-055-01, /01T-0:on 801110,main Steam Relief Valve Stuck Open Resulting in Rx Scram.Caused by Wiring Error During 1980 Design Change Work & Inadequate post-installation Testing.Error Corrected & Test Procedure Revised
| ML112410804 | |
| Person / Time | |
|---|---|
| Site: | Duane Arnold  |
| Issue date: | 11/24/1980 |
| From: | Tooker D IES Utilities, (Formerly Iowa Electric Light & Power Co) |
| To: | NRC/OI/RGN-III/FO |
| Shared Package | |
| ML112410805 | List: |
| References | |
| LER-80-055-01T, LER-80-55-1T, NUDOCS 8012020495 | |
| Download: ML112410804 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| 3311980055R01 - NRC Website | |
text
REGULIATORY
- RMATION DISTRIBUTION SYSf (RIDS)
ACCESSION NBR:8012020495 DOC.DATE: 80/11/24 NOTARIZED: NO DOCKET #
FACIL:50-331 Duane Arnold Energy Center, Iowa Electric Light & Po,w 05000331 AUTH.NAME AUTHOR AFFILI.ATIUN TO0KER,DW, Iowa Electric Light & Power Co.
RECIPNAME' RECIPIE+TlAFFILIATION Region 3, Chicago, Office of the Director SUBJECT: LER 80-055/01T-0:on 801110,main steam relief valve stuck open resulting iniRx scramCaused by wiring error during 1980 design change work & inadequate post-installation testing.E!rror corrected & test procedure revised.
DISTRIBUTION CODE,: A002 TITLE: Incident Reports COPIES RECEIVED:LTR 4 ENCLi SIZE:
NOTES:
RECIPIENT ID CODE/NAME.
ACTION:
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6o 61 OCXET NUMSSIA 6a 69 EVENT OATE 74 75 REPORT OATS 60 EVENT OSCRIPTION ANO PAqRABL= CONSECUENCES 1On Nov. 10 during plant start-up, a main steam relief valve stuck open (which resulted in a Rx. scram. During the transient, the Rx. vessel wate lr level dropped below the Lo level trip setpoint. Operator follow-up act Lions revealed the channel A side of the containment Group 3 isolation 1had not tripped as it should have. Group 3 valves include the containmen It purge and vent valves. The B side corresponding valves isolated. The plant was placed in cold shutdown for investigation and relief VLV. work 90 ge worK during 1980 refueling outage ting to identify the problem. The oup 3, side A logic isolation. The olation verified to operate properly sed. No similar reports submitted.
mE-1oo4OF OISCOVERY OtSCOVSAY OESCR1FTIO4 LA J10(Oerator Observation 45 4
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DUANE ARNOLD ENERGY CENTER Iowa Electric Light and Power Company Licensee Event Report -
Supplemental Data Docket No. 050-0331 Licensee Event Report Date:
11-24-80 Reportable Occurrence No:
80-055
EVENT DESCRIPTION
At 1613 hours0.0187 days <br />0.448 hours <br />0.00267 weeks <br />6.137465e-4 months <br /> on November 10, 1980 during a normal plant startup, a main steam rel ief valve stuck open which resulted in reactor depressurization and an automatic scram (see Licensee Event Report No.80-054).
During the transient, the reactor vessel water level dropped to 7.5 inches below instrument zero.
This is below the trip setpoint on reactor vessel water low level (12 inches above instrument zero) which shouldhave resulted in a Group 3 isolation of the containment.
Investigation revealed that te Group 3 Isolation Channel "A" side logic had not tripped as it should have.
The Group 3 isolation valves include containment purge and vent valves.
The Group 3 Isolation Channel "B" side logic had tripped properly and the corresponding valves isolated.
The "B" side trip resulted in isolation of all containment purge and vent lines by closure of an isolation valve on each line redundant to the "A" side valve that failed to close.
The reactor was placed in a cold shutdown condition to further investigate the cause of the Group 3, Channel "A" side failure and to replace/repair themain steam relief yalye.
CAUSE DESCRIPTION:
The problem was traced to a wiring error apparently made during design change work during the 1980 refueling outage. A wire was terminated at the wrong location on a terminal strip which effectively bypassed the low water level Group 3, Channel "A" logic isolation. The valves in the Group 3 Channel "A" logic isolation would have isolated properly on either of the other Group 3 isolation parameters (high drywell pressure or reactor building ventilation exhaust or refueling floor high/low radiation).
Further investigation revealed that the low water level Group 3 "A" logic isolation wiring problem could not have been identified by the post-installation testing or subsequently by the existing surveillance testing program.
CORRECTIVE ACTION
The wiring error was corrected and the Group 3 Channel "A" logic isolation verified to operate properly. Further, a special task force was established at 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> on November 12, 1980 to study all of the design change work scheduled/implemented since the beginning of the 1980 refueling outage. The emphasis of the review was placed on the post installation testing program and plant system operability surveillance testing program adequacy. In several instances, the post installation testing was re vised and reperformed and testing procedures were revised as deemed necessary to adequately ensure the proper operation of plant electrical systems/components.
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DUANE ARNOLD ENERGY CENTER Iowa Electric Light and Power Company Licensee Event Report -
Supplemental Data Docket No. 050-0331 Licensee Event Report Date: 11-24-80 Reportable Occurrence No: 80-055 CORRECTIVE ACTION CONTINUED:
Also an administrative Hold was placed on plant restart until the review work was completed and any necessary corrective actions/retest work completed. At 2000 hours0.0231 days <br />0.556 hours <br />0.00331 weeks <br />7.61e-4 months <br /> on November 14, 1980 the task force review work was complete, all corrective actions had been completed, the administrative Hold was lifted, and the plant was readied for normal start-up.
In order to.prevent recurrence of this problem, a detailed review of the design change procedure and post-installation testing requirements adequacy is presently being conducted at DAEC. As an interim corrective measure an Administrative design change implementation stop work order has been issued until a determination has been made that design change reviews, work controls, and retest control mechanisms are adequate.
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