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The inspectors identified an NCV of 10 CFR … The inspectors identified an NCV of 10 CFR Part 50.65 (a)(4), Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants, because Constellation did not assess and manage the increase in risk that resulted from maintenance activities that impacted the availability of the No. 21 charging pump. On February 4, 2009, operators isolated the Unit 2 core flush piping to prevent back-leakage of water from the charging system into one of the safety injection tanks. Isolating the core flush piping also prevented the ability of the No. 21 charging pump to automatically start on a safety injection actuation signal and deliver concentrated boric acid to the reactor coolant system (RCS). The inspectors noted that this function is modeled in the site specific probabilistic risk assessment (PRA) model. However, Constellation did not assess the risk associated with the unavailability of the No. 21 charging pump for an 8 day period. Immediate corrective actions included a re-evaluation of the risk and entering this issue into their CAP for resolution. The finding is more than minor because Constellations risk assessment did not consider risk significant structures, systems, and components (SSCs) (i.e. No. 21 charging pump) that were unavailable during the maintenance activity. The finding is associated with the configuration control attribute of the Mitigating Systems cornerstone and affects the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. The inspectors determined that the finding is of very low safety significance because the incremental core damage probability deficit was less than 1.0E-6. This finding has a cross-cutting aspect in the area of human performance, because Constellation did not appropriately plan and incorporate risk insights in work activities associated with maintenance activities that impacted the availability of the No. 21 charging pump (H.3.a)bility of the No. 21 charging pump (H.3.a)

Discovered date

23:59:59, 31 March 2009 +

Docket

05000317 + and 05000318 +

Event date

23:59:59, 31 March 2009 +

Finding integer

2 +

Finding type

Non-cited violation +

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WP.1 +

IR 05000317/2009002 +

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00:39:55, 29 October 2017 +

Person