ML20206P280
| ML20206P280 | |
| Person / Time | |
|---|---|
| Site: | Portsmouth Gaseous Diffusion Plant |
| Issue date: | 12/31/1998 |
| From: | Jonathan Brown UNITED STATES ENRICHMENT CORP. (USEC) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GDP-98-2054, NUDOCS 9901110077 | |
| Download: ML20206P280 (4) | |
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s A Global Energy Company December 31,1998 GDP 98-2054 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 Portsmouth Gaseous Diffusion Plant (PORTS)
Docket No. 70-7002 Event Report 98-16 Pursuant to 10 CFR 76.120(c)(2), Enclosure 1 provides a 30-day Event Report for an event involving a failure of an electrical circuit, required by the Safety Analysis Report (SAR) to shutdown an j
operating cell in the X-326 Building at the Portsmouth Gaseous Diffusion Plant.
Should you require additional information regarding this event, please contact Scott Scholl at (740) 897-2373.
Sincerely, I
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. Morris Brown g$p General Manager
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Portsmouth Gaseous Diffusion Plant
Enclosures:
As Stated cc:
NRC Region III OITice NRC Resident inspector-PORTS 9901110077 981231 PDR ADOCK 07007002 C
PDR1 P.O. Box 800. Portsmouth, OH 45661 Telephone 614-897-2255 Fax 614-897-2644 http://www.usec.com Offices in Livermore, CA Paducah, KY Portsmouth, OH Washington, DC
GDP 98-2054 Page1of2 Event Report 98-16 Description of Event On December 1,1998, at approximately 0830 hours0.00961 days <br />0.231 hours <br />0.00137 weeks <br />3.15815e-4 months <br />, while reviewing operating experience item U98059, an electrieal subject matter expert (SME) discovered that an AQ electrical circuit, used to manually shutdown an operating cell on October 7,1998, failed to perform its intended function.
On October 7,1998, at approximately 1305 hours0.0151 days <br />0.363 hours <br />0.00216 weeks <br />4.965525e-4 months <br />, while in standby mode (Mode III), the motor stop pushbutton in the Area Control Room (ACR) was manually actuated to shutdown cell 27-2-11. The actuation of the pushbutton failed to de-energize all of the cell motors as designed. The actuation of the pushbutton only tripped the "A" breaker and did not trip the "B" breaker. The cell motors associated with the "B" breaker remained energized and operational. At approximately 1307 hours0.0151 days <br />0.363 hours <br />0.00216 weeks <br />4.973135e-4 months <br />, operating personnel, using an approved alternate and independent means of disrupting cell power, manually tripped the "B" breaker at the substation. The failed breaker was manufactured by ITE.
The model number of the breaker was L.G.
The manual trip of the "B" breaker at the substation was successful in de-energizing the remaining cell motors. Aner manually tripping the "B" breaker a problem report (PR) was filed. The Plant Shift Superintendent (PSS) who did the initial PR assessment on October 7,1998, incorrectly concluded that this out of service safety system component was not reportable because the PSS considered the cell / equipment motors de-energized and the cell in shutdown mode (Mode VI).
According to the S AR for the Portsmouth Gaseous Diffusion Plant, the pushbuttons in the ACR and Plant Control Facility (PCF) are the means used to manually shutdown cell operation in the event i
of an emergency. The pushbutton when actuated causes the de trip circuit to open the "A" and "B" breakers to de-energize the cell motors. The de control trip circuit and the pushbuttons in the ACR and PCF are part of the Cell Remote Manual Shutdown System. This system is classified as an AQ safety system. This event is reportable in accordance with SAR. Section 6.9 Table 6.9-1, J (1).
Cnuse of Event The direct cause of the failure of the local trip circuit to function on demand was the lack of lubrication on the breaker linkage. The linkage is the mechanism used to initiate the breaker trip sequence. The lubrication applied to the linkage is necessary for the mechanism to operate properly.
The root cause of the niilure of the local trip circuit to function on demand was an inadequate breaker preventive maintenance (PM) procedure. The vendor manual did not describe the type oflubrication to use or the lubrication interval. Consequently, the procedure used to effect PM on ITE breakers did not require maintenance personnel to inspect or lubricate the operating mechanism linkage.
GDP 98-2054 Page 2 of 2 Event Report 98 An Engineering Notice (EN) effective December 22,1998, to June 30,1999, was put in effect to address breakers that need PM prior to procedure revision, PM work performed on ITE type KC and LG breakers in the interim will be accomplished using a maintenance work package. The work package will contain the EN and work instructions to perform lubrication. The EN prescribed the type oflubrication to be used. The work instructions will instruct the maintenance personnel to lubricate the operating mechanism linkage at the required PM frequency.
Corrective Actions 1.
By January 15, 1999, the substation PM procedure will be revised to specify the type lubrication to be used for ITE KC/KG breakers and the interval that the operating mechanism linkage will be lubricated.
Extent of Exposure ofIndividuals to Radiation or Radioactive Materials There were no exposures to individuals from this incident to radiation or radioactive materials.
Lessons Learned from the Event The de control trip circuit and the pushbutton in the ACR are part of the Cell Remote Manual Shutdown System which is described in the Technical Safety Requirement (TSR) as the means to manually shutdown the cell operation from the ACR in case of emergencies. The pushbutton in the ACR when activated should have operated on demand and tripped both breakers. Since this did not occur, credit for manually shutting down the cell using an alternate and independent means cannot be used when determining operability.
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GDP 98-2054
-Page1of1 Event Report 98-06 List of Commitments 1.
By January 15,1999,' the substation PM procedure will be revised to specify the type lubrication to be used for ITE KC/KG breakers and the interval that the operating mechanism linkage will be lubricated.-
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