05000382/FIN-2012007-01
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Finding | |
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Title | Failure to Adequately Evaluate the Impact of Fire Damage on the Dry Cooling Tower Fans |
Description | The team identified a Green non-cited violation of License Condition 2.C.9 and Appendix R,Section III.G for the failure to adequately evaluate the impact of fire damage on the dry cooling tower fans. Specifically, the failure to adequately evaluate fire damage to the dry cooling tower fans did not ensure one train remained available to achieve and maintain hot shutdown conditions from the alternate shutdown panel. The licensee documented this deficiency in Condition Report 2012-00837. The approved fire protection program provided alternative shutdown capability to allow safe shutdown of the plant for a fire requiring an evacuation of the control room. The licensee protected Train B components; consequently, the post-fire safe shutdown analysis assumed Train A equipment would be unavailable. The licensee used Procedure OP-901-502, Evacuation of Control Room and Subsequent Plant Shutdown, Revision 21, to implement the control room evacuation resulting from a fire in the control room. While evaluating circuit protection schemes used for post-fire safe shutdown components, the team identified that the licensee did not adequately evaluate the impact of fire damage on the dry cooling tower fans. The team evaluated circuit protection methods used by the licensee to protect post-fire safe shutdown components needed to achieve hot shutdown during the control room evacuation. The licensee protected post-fire safe shutdown components required to achieve hot shutdown by using either back-up fuses or current limiting resistors in their circuits. Both circuit protection methods ensure post-fire safe shutdown components would continue to function and be available upon transfer from the control room to the alternate shutdown panel. The first circuit protection method consists of two fuses, one normal and one back-up. The normal fuse would open and protect the circuit if fire damage caused excessive current. Procedure OP-901-502 directed the operators to place the fuse transfer switches for various components required for hot shutdown to the back-up position. This action places the backup fuse and circuitry for hot shutdown post-fire safe shutdown components in service at the alternative shutdown panel. The second circuit protection method used a current limiting resistor in the circuit such that it reduced peaking currents resulting from a fault, which prevented the currents from exceeding the rating for the fuses. Since the fuses were protected, the circuit remained available and capable of powering the applicable post-fire safe shutdown components necessary to achieve hot shutdown. From review of circuit drawings, the team determined that the licensee did not protect the 15 Train B dry cooling tower fan circuits against fire damage using either circuit protection method. Each dry cooling tower train includes five groups of three fans. The team determined the post-fire safe shutdown analysis had incorrectly assumed that a single spurious operation caused by a fire in the control room would actuate a single group of three dry cooling tower fans. The team independently walked down the control room and circuit layout for the dry cooling tower fans. The team determined that a fire in Control Panel 33 would affect all 15 dry cooling tower fans as a result of fire damage and did not require any spurious circuit actuations. Since a single control panel fire could render all the dry cooling tower fans inoperable, the licensee implemented an hourly fire watch as a compensatory measure in the control room. The licensee documented this deficiency in Condition Report 2012-00837. The failure to adequately evaluate the impact of fire damage on the dry cooling tower fans was a performance deficiency. The performance deficiency was more than minor because it was associated with the protection against external events (fire) attribute of the Mitigating Systems Cornerstone and it adversely affected the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. The team evaluated this deficiency using Inspection Manual Chapter 0609, Appendix F, Fire Protection Significance Determination Process. The performance deficiency affected the fire protection defense-in depth strategies involving post-fire safe shutdown systems. Since this finding involved a control room abandonment issue, a senior reactor analyst performed a Phase 3 significance determination (refer to Attachment B). The senior reactor analyst determined this finding had very low risk significance based upon a bounding analysis (Green). The dominant core damage sequences involved a fire initiating event, failure of both the component cooling water and auxiliary component cooling water systems, as well as an independent failure of the turbine driven auxiliary feedwater pump. Equipment that helped to mitigate the significance included the unaffected offsite power system, the viable steam generators and the safety related auxiliary feedwater system. Because the original failure to evaluate the impact of fire damage on the dry cooling tower fans had occurred longer than three years prior to this inspection, this finding did not reflect current licensee performance. License Condition 2.C.9 states EOI shall implement and maintain in effect all provisions of the approved fire protection program as described in the Final Safety Analysis Report for the facility and as approved in the Safety Evaluation Report through Supplement 9. Final Safety Evaluation Report, Section 9.5.1.3.1, Detailed Comparison to Appendix A to Branch Technical Position APCSB 9.5-1, Revision 0, Item C specifies that quality assurance requirements for fire protection are documented in Procedure UNT-005-013, Fire Protection Program. Procedure UNT-005-013, Revision 12, Section 5.8.2.1.bA, states in part, Reviews include items such as design reviews to verify adequacy of wiring isolation and cable separation criteria in accordance with 10 CFR 50 Appendix R. 10 CFR Part 50, Appendix R, Section III.G specifies, Fire protection features shall be capable of limiting fire damage so that one train of systems necessary to achieve and maintain hot shutdown conditions from either the control room or emergency control station is free of fire damage. Contrary to the above, prior to February 17, 2012, the licensee failed to meet License Condition 2.C.9 by implementing and maintaining in effect all provisions of the approved fire protection program and Appendix R,Section III.G to ensure that one train of post-fire safe shutdown systems was free of fire damage. Specifically, the licensee failed to adequately evaluate the impact of fire damage on the dry cooling tower fans and ensure their availability at the alternate shutdown panel following a control room evacuation because of fire. This finding does not qualify for enforcement discretion as described in the Interim Enforcement Policy Regarding Enforcement Discretion for Certain Fire Protection Issues (10 CFR 50048) since this finding was not identified during their transition process. Because this finding is of very low safety significance and has been entered into the corrective action program (Condition Report 2012-00837), this violation is being treated as a non-cited violation, consistent with Section 2.3.2 of the NRC Enforcement Policy: NVC 05000382/2012007-01, Failure to Adequately Evaluate the Impact of Fire Damage on the Dry Cooling Tower Fans. |
Site: | Waterford |
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Report | IR 05000382/2012007 Section 1R05 |
Date counted | Mar 31, 2012 (2012Q1) |
Type: | NCV: Green |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.05 |
Inspectors (proximate) | G Miller M Young J Mateychick E Uribe |
INPO aspect | |
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Finding - Waterford - IR 05000382/2012007 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Waterford) @ 2012Q1
Self-Identified List (Waterford)
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