PNO-IV-89-031, on 890427,CRD 3 Failed to Insert on Scram During Performance of Weekly Partial Insertion Scram Tests. Troubleshooting Confirmed That CRD Brake Deenergized & That Rod Out Limit Cleared.Licensee Plans to Replace CRDs 3 & 7

PNO-IV-89-031:on 890427,CRD 3 Failed to Insert on Scram During Performance of Weekly Partial Insertion Scram Tests. Troubleshooting Confirmed That CRD Brake Deenergized & That Rod Out Limit Cleared.Licensee Plans to Replace CRDs 3 & 7

ML20245F688
Person / Time
Site:	Fort Saint Vrain
Issue date:	04/28/1989
From:	Westerman T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
References
PNO-IV-89-031, PNO-IV-89-31, NUDOCS 8905020464
Download: ML20245F688 (2)

, April 28, 1989 l 'PRELIIgNARYNOTIFICATIONOFEVENTORUNUSUALOCCURRENCE--PN0-IV-89-31 This prelimirfary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by the Region IV staff on this date.

FACILITY: Fort St. Vrgin- Licensee Emergency Classification:

(DN: 50-267) Notification of Um sual Event

= Alert Site Area Emergency General Emergency X Not Applicable

SUBJECT:

UNPLANNEO SHUTDOWN DUE TO IN0PERABLE CONTROL R0D During performance of the weekly partial insertion scram tests on April 27, 1989, control rod drive (CRD) #3 failed to insert on scram. Troubleshooting confirmed that the CRD brake did de-energize and that the rod out limit did clear, but that the rod pair only moved in approximately 0.6 inches. There are two control rods associated with each CRD. CRD #3 was found to be drivable, but was not scrammable.

The licensee declared CRD #3 inoperable and commenced a reactor shutdown in accordance with TS LC0 3.1.1 at 1:36 a.m. (MDT) on April 23, 1989. All control rods were fully inserted at 6:45 a.m. (MDT). The licensee reported this event to the NRC under 10 CFR 50.72(L)(1)(1)(A). The resident inspector was onsite.

The licensee plans to replace CRD #3 and CRD #7 which had been operating with higher than normal temperatures. The replacement outage should take 7 to 10 days. The resident inspectors will continue to monitor the licensee's actions.

Fort St. Vrain is a high temperature gas cooled reactor (HTGR).

Neither the licensee nor the NRC plans to issue a press release.

The state of Colorado has been informed by the region of the reactor shutdcwn.

Region IV received notification of this occurrence from HQ duty officer at 8:37 p.m. (CDT). Region IV has informed the NRR project manager, the regional public affuirs officer, and the regional state liaison officer.

This information has been confirmed with a licensee representative.

CONTACT: T. F. Westerman, FTS 728-8145 RIV:SC:PSB D:DRQ RA U" l TFWesterman;op LJCal ran RDMartin [

t/ /eF/89 Y /M/89 /2/ / 69 A 8905020464 890428

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PDR I&E PNO-IV-89-031 PNU

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