05000382/FIN-2011007-08
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Finding | |
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| Title | Failure to Adequately Manage the Risk Involved with a Maintenance Window for the Turbine Driven Essential Feedwater Pump |
| Description | The team identified a Green noncited violation of 10 CFR 50.65(a)(4), which states, in part, that the licensee shall assess and manage the increase in risk that may result from the proposed maintenance activities. Specifically, on October 28, 2010 the turbine driven essential feedwater pump was out of service for maintenance for approximately 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. During this time the licensee unknowingly entered the Orange risk window (crossed a risk threshold) due to a faulty assumption in the probabilistic risk assessment model. This finding was entered into the licensees corrective action program as Condition Report CR-WF3-2011-06653. The team determined that the failure to perform adequate risk assessments is a performance deficiency. This finding was more than minor because it was associated with the human performance attribute of the Mitigating Systems Cornerstone, adversely affecting the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. In accordance with NRC Inspection Manual Chapter 0609, Attachment 4, Phase 1 Initial Screening and Characterization of Findings, the issue was identified as requiring a Phase 2 evaluation. A Region IV Senior Reactor Analyst performed a Phase 2 significance determination using NRC Inspection Manual Chapter 0609, Appendix K, Maintenance Risk Assessment and Risk Management Significance Determination Process. In accordance with Appendix K: Delta-CDF = [CCDPActual CCDPflawed] * duration /8760 The licensee bounded the duration of the turbine driven essential feedwater pump maintenance at 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> in a year. The flawed ICDP was 3.1E-5, the actual ICDP was 3.1E-5 + 1.9E-5 = 5.0E-5. The difference was 1.9E-5. Delta-CDF = 1.9E-5 * 12/8760 = 2.6E-8 Therefore, the issue was determined to have very low safety significance (Green). This finding was determined to have a cross-cutting aspect in the area of problem identification and resolution associated with the self and independent assessments component because the licensee performed a probabilistic risk assessment model update in April 2009, which failed to identify the faulty assumption |
| Site: | Waterford  |
|---|---|
| Report | IR 05000382/2011007 Section 1R21 |
| Date counted | Dec 31, 2011 (2011Q4) |
| Type: | NCV: Green |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.21 |
| Inspectors (proximate) | C Smith T Farnholtz W Sifre J Leivo E Uribe N Hernandez |
| CCA | P.6, Self-Assessment |
| INPO aspect | CL.2 |
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Finding - Waterford - IR 05000382/2011007 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Waterford) @ 2011Q4
Self-Identified List (Waterford)
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