A Green self revealing finding for inadequate procedural guidance was identified. The inadequate procedural guidance resulted in a May 2,2011 Nine Mile Unit 1
scram due to a
turbine trip.
NMPNS determined that the turbine tripped when the
main turbine master trip solenoid (
MTS) actuated due to pressure fluctuations caused by a combination of leaking oil supply fittings to the
MTS; binding of the secondary speed relay linkages, and main shaft tuOe oil disCharge pressure fluctuations. These degraded conditions occurred because the governing work control documents and procedures that were implemented during the spiing 2O1i refuel outage contained inadequate detail and guidance.
NMPNS correltive actions included repairing the degraded components and initiating actions to revise the procedures. This 1nding is more than minor because it affected the procedure quality attribute of the
Initiating Events Cornerstone objective of limiting the likelihood of those events that upset plant stibility and challenge critical safety functions during shutdown as well as power operations. The finding was of very low safety significance because it did not contribute to both the likelihood of a
reactor trip and the likelihood that mitigation equipment or functions will not be available. This finding has a cross-cutting aspect in the area of human performance in that
NMPNS did not ensure that complete and accurate and upto-date design documentation and procedures were available to implement turbine maintenance during the spring 2Q11 refuel outage.
