Contrary to
10 CFR 50, Appendix B, Criterion XVI, Corrective Action, as of March 2002, the licensee failed to promptly identify and correct a
condition adverse to quality involving pressurizer ambient heat losses that exceeded the capacity of those pressurizer heaters powered from the Standby Shutdown Facility (SSF). Evidence of this condition, which may have existed from the time the SSF was put into service in 1986 until the condition was discovered in March 2002, included pressurizer insulation problems (since pre-operational testing) and numerous Problem Investigation Process reports since 1996 identifying pressurizer heater capacity concerns. As a result of the failure to promptly identify and correct this condition, an insufficient number of pressurizer heaters powered from the SSF has been available to assure natural circulation during certain postulated SSF events. This issue has a low to moderate safety significance because of the importance of the SSF powered pressurizer heaters to maintain a pressurizer steam bubble during events where the SSF is used to achieve
safe shutdown. Specifically, without a steam bubble to maintain primary system pressure,
reactor coolant system (
RCS) subcooling would be jeopardized, and single phase
RCS natural circulation would be interrupted due to voiding in the hot leg. Decay heat would then challenge the pressurizer
safety relief valves, and a failure of one of these valves to reseat would
lead to core damage since the SSF standby makeup pump is of insufficient capacity to recover the resultant loss in
RCS inventory.
