05000346/FIN-2009005-03
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Finding | |
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| Title | Two Required Trains of CAC Fans Inoperable |
| Description | A self-revealed finding of very low safety significance and associated NCV of Technical Specification (TS) Limiting Condition for Operation 3.6.6, Condition E, was identified for having two required trains of containment air cooler (CAC) fans inoperable for a period longer than allowed by TS. An inadequate design change installed Potter and Brumfield (P&B) rotary relays in the containment air cooling fan circuitry. The use of the P&B relays in this application could cause a failure of the CAC to start in slow speed upon receipt of a valid safety features actuation signal. As an immediate corrective action, the operating CAC fans were shifted from fast-speed alignment to the slow-speed alignment used for accidents, which eliminated the relay issue and allowed them to be declared operable. The P&B relay contacts have since been modified to alter the CAC control circuitry and correct the deficiency. The finding was determined to be more than minor because the finding was similar to IMC 0612, Appendix E, Example 3.a, in that a design modification error was significant enough that the modification required revision or rework to resolve operability concerns. Specifically, the design change that installed the P&B relays in the CAC fan circuitry rendered both trains of containment air cooling inoperable. The finding affected the Barrier Integrity cornerstone since the CACs are designed to limit the pressure and temperature in containment following a design basis loss-of-coolant accident. The finding was determined to be of very low safety significance because the inspectors answered no to all four screening questions under the Containment Barrier column in IMC 0609, Significance Determination Process, Appendix A, Attachment 0609.04, Phase 1 - Initial Screening and Characterization of Findings, Table 4a. The inspectors did not identify a cross-cutting aspect associated with this finding because the concern was not indicative of current plant performance. The inadequate design change to install the P&B relays was implemented in 2001. (Section 1R15 |
| Site: | Davis Besse  |
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| Report | IR 05000346/2009005 Section 1R15 |
| Date counted | Dec 31, 2009 (2009Q4) |
| Type: | NCV: Green |
| cornerstone | Barrier Integrity |
| Identified by: | Self-revealing |
| Inspection Procedure: | IP 71111.15 |
| Inspectors (proximate) | J Rutkowski A Wilson F Mccreesh R Russell J Cameron |
| INPO aspect | |
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Finding - Davis Besse - IR 05000346/2009005 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Davis Besse) @ 2009Q4
Self-Identified List (Davis Besse)
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