05000259/FIN-2009008-03
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Finding | |
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Title | Safety-Related Molded Case Circuit Breakers |
Description | The team indentified an Unresolved Item (URI) regarding safety-related molded-case circuit breakers (MCCBs) in safety-related applications. TVA had not implemented a test program to detect potential deterioration or to assure that all installed safety-related MCCBs would perform satisfactorily in service. TVA procedure 0-TI-395, Breaker Testing and Maintenance Program, required that critical molded case circuit breakers be subject to preventative maintenance (PM) activities. This included, in part, inspection for overheating, mechanical operation, enclosure inspection, overload trip testing, and instantaneous trip testing. The TVA program required that the testing and PM activities be performed every four to six years. UFSAR 8.6.4.1.1 stated, in part, that zero-resistance short circuits at the battery board or any point downstream can be cleared by the breakers operating within their ratings. To ensure this was satisfied by the installed equipment, degradation of breaker performance should have been detectable and acceptably controlled by periodic testing and preventive maintenance. Additionally, UFSAR 8.5.2.11 stated, in part, that the standby AC power system will meet or exceed the requirements of IEEE-308, Criteria for Class 1E Power Systems at Nuclear Generating Stations. This standard recommended that periodic tests be performed at scheduled intervals to detect deterioration of equipment and to demonstrate operability of components that are not exercised during normal operation. Four MCCBs on 250 VDC Battery Board 1 were selected by the team (breakers 607, 705, 712, 715) as part of the inspection sample. No records of PM activities were found on these four MCCBs. While addressing the extent of this condition, TVA identified a total of 622 safety-related MCCBs in both AC and DC applications for which no testing was being performed. As a result of the inspectors observations, TVA initiated PER 209095 and scheduled testing of the 622 safety-related MCCBs that were not being tested in accordance with the TVA PM program. As of December 28, 2009, TVA had successfully tested 30 of the 622 breakers. This represented a small sample of the total breaker population. The inspectors plan to review additional PM test results to determine if this performance deficiency is more than minor. This issue is unresolved pending further inspection to determine the extent of condition and impact of not implementing a test program to assure that all installed safety-related MCCBs would perform satisfactorily. (URI 05000259, 260, 296/2009008- 01, Safety-Related Molded Case Circuit Breakers |
Site: | Browns Ferry ![]() |
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Report | IR 05000259/2009008 Section 1R21 |
Date counted | Dec 31, 2009 (2009Q4) |
Type: | URI: |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.21 |
Inspectors (proximate) | T Ross E Guthrie S Walker M Pribish J Hamman C Kontz C Fletcher P Niebaum R Williams J Eargle L Pressley W Deschaine J Wray L Jarriel C Stancilj Leivor Aiello R Berryman H Campbell C Even R Patterson B Desai J Kent |
INPO aspect | |
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Finding - Browns Ferry - IR 05000259/2009008 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Browns Ferry) @ 2009Q4
Self-Identified List (Browns Ferry)
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