05000387/FIN-2013005-01
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Finding | |
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| Title | Inadequate Procedural Guidance for Responding to an Internal Flooding Event in ECCS Rooms |
| Description | The inspectors identified a Green NCV of Technical Specifications (TS) 5.4.1, Procedures, because PPLs procedures EO-000-104, Secondary Containment Control and ON-169-002, Flooding in the Reactor Building were inadequate in that actions directed in the procedures could complicate an internal flooding event and may adversely affect aspects of PPLs flood design. Specifically, the procedures directed operators to enter a flooded room to assess the extent and source of the flooding; an action which could render multiple trains of emergency core cooling system (ECCS) inoperable due to communicating two watertight rooms. In addition to entering the issue into the CAP as Condition Reports (CRs)-2013-02099 and 2013-06417, PPL issued Operations Directive 13-07 which provided guidance to ensure that operators sent to investigate a room flooded alarm will do so in a manner that will not affect redundant trains. The performance deficiency is more than minor because it was associated with the procedure quality attribute of the Mitigating Systems cornerstone and affected the objective to ensure the capability of systems that respond to initiating events to prevent undesirable consequences (i.e., core damage). Specifically, the procedure to respond to a room flooded alarm was insufficient to ensure operator response would not potentially render multiple trains of ECCS inoperable. The finding was evaluated in accordance with IMC 0609.04, Initial Characterization of Findings, and Exhibits 2 and 4 of IMC 0609, Appendix A, The SDP for Findings At-Power. Since opening the watertight door with excessive flooding could bypass the flood protection feature and potentially degrade two or more trains of a multi-train system or function, a detailed risk assessment was performed. The condition was modeled using the Susquehanna standardized plant analysis risk (SPAR) model version 8.19 along with SAPHIRE version 8.09. As a bounding analysis, the condition was assumed to exist for greater than one year and the flooding was assumed to require a reactor shutdown which results in a plant transient with failure of high pressure coolant injection (HPCI) and core spray (CS) due to flood impacts. The flooding initiating event frequency was estimated to be about 1 in 10,000 years. The resulting change in core damage frequency was substantially less than 1E-7. The dominant sequences included a transient with a loss of all direct current (DC) power and a transient with failures to depressurize and reactor core isolation cooling (RCIC) failures. Since the change in core damage frequency was sufficiently low no further evaluation for large early release was required. The finding is related to the cross-cutting area of PI&R, Self and Independent Assessments, in that PPL did not conduct assessments to identify areas for improvement. In particular, the selfassessments were not of sufficient depth, comprehensive, appropriately objective, or selfcritical. Specifically, despite PPLs process requiring periodic verification that event driven procedures are technically and functionally correct, the periodic review completed in April 2013 failed to identify that actions specified in the procedure could invalidate the flood design. |
| Site: | Susquehanna  |
|---|---|
| Report | IR 05000387/2013005 Section 1R06 |
| Date counted | Dec 31, 2013 (2013Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.06 |
| Inspectors (proximate) | J Nicholson R Rolph S Barr T Daun T Hedigan A Turilin D Kern F Bower J D'Antonio J Grieves |
| Violation of: | Technical Specification - Procedures Technical Specification |
| CCA | P.6, Self-Assessment |
| INPO aspect | CL.2 |
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Finding - Susquehanna - IR 05000387/2013005 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Susquehanna) @ 2013Q4
Self-Identified List (Susquehanna)
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