05000293/FIN-2015008-02
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Finding | |
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| Title | Licensee-Identified Violation |
| Description | LER 05000293/2015-010-00 described an unanalyzed condition in which Entergy identified that selected MOVs were subject to fire-induced failures. As a result, Entergy determined that the postulated fire damage might adversely affect their ability to achieve or maintain post-fire safe shutdown. Failure to ensure that one train of equipment, necessary to achieve and maintain safe shutdown, would remain free of fire damage was a licensee-identified performance deficiency. This performance deficiency was more than minor because it was associated with the Protection Against External Factors (e.g., fire) attribute of the Mitigating Systems cornerstone and adversely affected the cornerstone objective to ensure the availability and reliability of systems that respond to initiating events to prevent undesirable consequences (i.e., core damage). This performance deficiency was a violation of Pilgrim Operating License Condition 3.F which, in part, required Entergy to implement and maintain in effect all fire protection features described in licensee submittals and as approved by the NRC. The Pilgrim FPP required Entergy to maintain one train of equipment necessary to achieve and maintain safe shutdown free of fire damage. Contrary to Pilgrim's License Condition, from 1992 (i.e., when susceptibility for potential MOV damage was identified in IN 92-18) until present, Entergy did not maintain one train of equipment necessary to achieve and maintain safe shutdown free of fire damage. Specifically, Entergy determined that some MOVs, which were required to support safe shutdown, could have been disabled as a result of fire damage to unprotected MOV control circuits. Entergy entered this issue into their corrective action program as CRs CR-PNP-2015-07993 and CR-PNP-2015-08286. Corrective actions taken or planned included additional analysis of safe shutdown methods and design modifications to eliminate the identified susceptibility to the postulated fire damage for selected MOVs. Compensatory measures included fire watches in the affected fire areas. Entergy evaluated this issue using the guidance in IMC 0609, Appendix F, "Fire Protection SDP," and determined that this issue was of very low safety significance. A Region 1 Senior Reactor Analyst (SRA) reviewed Entergy's evaluation and concluded that their significance determination was reasonable and appropriately bounded by conservative assumptions. Based upon detailed cable routing analysis and plant walkdowns, Entergy identified four plant areas where postulated fire damage could potentially compromise the credited safe shutdown trains. The four FAs were 1.9 (RB east side, Elev. 23-foot and 51-foot), 1.10 (RB west side, Elev. 23-foot and 51-foot), 3.1 (MCR), and 3.2 (CSR). Entergy documented their risk evaluations in Engineering Calculation Nos. EC-61592 and EC-61735. The inspection team walked down the four affected fire areas and sampled selected cables for independent verification, including consideration of: ignition sources and estimated fire frequencies, fire propagation and duration, probability of non-suppression and fire damage severity factors. The SRA verified that Entergy properly adhered to the guidance in IMC 0609, Appendix F, to assess the risk significance of postulated fire damage to targeted MOV cables outside of the MCR (i.e., in FAs 1.9, 1.10, and 3.2). The SRA used the Pilgrim Standardized Plant Analysis Risk (SPAR) model to independently estimate the conditional core damage probabilities for the postulated fire scenarios and calculated comparable results. Based upon the Appendix F screening criteria and consideration for both zone of influence and hot gas layer fire damage state scenarios (FDS1 and FDS2, respectively), Entergy estimated the increase in risk to core damage associated with the targeted MOV cables outside of the MCR to be 2.3E-7/year. Using similar methodology for FA 3.1 (MCR), Entergy estimated the increase in risk to core damage associated with the targeted cables in selected control room panels to be 3.8E-7/year. Collectively, the overall increase in core damage frequency for this performance deficiency was in the mid E-7 range, or very low risk significance (Green). |
| Site: | Pilgrim |
|---|---|
| Report | IR 05000293/2015008 Section 4OA7 |
| Date counted | Dec 31, 2015 (2015Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | Licensee-identified |
| Inspection Procedure: | |
| Inspectors (proximate) | D Orr E Dipaolo J Patel J Richmond J Rogge L Dumont W Cook |
| Violation of: | License Condition - Fire Protection License Condition |
| INPO aspect | |
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Finding - Pilgrim - IR 05000293/2015008 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Pilgrim) @ 2015Q4
Self-Identified List (Pilgrim)
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