This is a 60-day optional telephonic notification of an invalid actuation of the Unit 1 Turbine Driven
Auxiliary Feed Water Pump (TDAFWP). This report is being made under
10CFR50.73(a)(2)(iv)(A).
On 28 February 2013, at 1534 CST, during restoration of the Unit 1 TDAFWP from steam admission valve maintenance, steam was inadvertently admitted to the TDAFWP turbine, resulting in the TDAFWP delivering auxiliary feed water flow to the steam generators.
On 28 February 2013, the Unit 1 TDAFWP was removed from service for replacement of the hand switch and air-supply solenoid to the TDAFWP steam admission valve. The tagout utilized for this maintenance closed the TDAFWP trip-throttle valve to ensure that steam remained isolated from the TDAFWP. During the replacement of the hand switch and air-supply solenoid, the normally closed steam admission valve failed to the open position. This went unnoticed by Operations personnel. When the TDAFWP trip throttle valve was reopened during post-maintenance restoration, the failed-open steam admission valve provided a steam path to the TDAFWP. The TDAFWP started and supplied approximately 60-70 gpm feed water flow to each steam generator for approximately one minute prior to being secured by the operators. No main turbine load reduction was required to maintain reactor power within limits.
This was an invalid actuation of the TDAFWP due to no automatic actuation signals being present and no operator actions being taken with the intent of starting the TDAFWP.
During a normal TDAFWP start, the steam admission valve is opened in concert with steam supply valves aligned in series with the steam admission valve. During this event, the steam supply valves remained closed (steam flow bypassed these valves through normally open warm-up valves). Therefore, this event was a partial actuation of the TDAFWP.
The TDAFW Pump is a third, independent train of AFW. No other portions of the auxiliary Feed Water System actuated or received actuation signals during this event.
The primary cause of this event was determined to be not complying with the tagging checklist when sequencing the tagout restoration steps. Corrective actions are scheduled to complete on 30 May 2013.
The licensee will notify the NRC Resident Inspector.
