|"ANALYSIS INDICATES CONTAINMENT COOLERS MAY NOT HAVE AUTOMATICALLY STARTED IN SLOW SPEED FOLLOWING POSTULATED MAIN STEAM LINE BREAK" |
"Information provided by another plant identified a condition where Containment Fan Coolers may trip if running in fast speed and not start automatically in slow speed, following a Loss of Coolant (LOCA) or Main Steam Line Break (MSLB). Wolf Creek commenced evaluation to determine if our Containment Coolers were susceptible to this condition.
"Investigation and analysis as of this date indicate that in the case of a Main Steam Line Break, the coolers could trip while running in fast speed and not be able to be automatically started by the sequencer in slow speed due to present electrical design configuration. The peak containment pressure in this case would exceed the analysis of record by approximately 5 psig.
"For the spectrum of the smaller break LOCA's, where actuation is delayed until pressurizer low pressure Safety Injection or the Containment Hi 1 pressure signal, analysis shows that the Containment Pressures would not be exceeded if the Containment Fan Coolers did not automatically start in slow speed. For a Large Break LOCA, analysis shows that the Containment Cooler Fans would be shed prior to tripping, and would be automatically started in slow speed by the sequencer.
"Wolf Creek is currently in a defueled condition, for Refueling Outage 16. Continued evaluation and analysis of this issue is ongoing. This issue will be resolved prior to the plant entering Mode 4, where Technical Specification 3.6.6 requires Containment Fan Coolers be operable."
The information was originally received from Callaway.
The licensee notified the NRC Resident Inspector.