A finding of very low safety significance was self-revealed on June 21, 2009, for the failure to adequately implement the requirements of Nuclear Operating Procedure (
NOP)-WM-4300, Order Execute Process. Specifically, a supervisor authorized work order steps to be performed out of sequence on level switches for the
moisture separator reheaters (
MSR). The failure to perform steps in order led to some steps being missed and ultimately to a main
turbine trip and associated reactor
scram. The licensee entered this item into their corrective action program as CR 09-60855. The licensees immediate actions included response to the reactor
scram and formation of a troubleshooting team to conduct a root cause investigation of the failure of the
MSR level indicators. The finding was determined to be more than minor because the finding was associated with the
Initiating Events cornerstone attribute of procedure quality and affected the cornerstone objective of limiting the likelihood of those events that upset plant stability. Specifically, inadequate adjustment and calibration of the level switches following replacement resulted in a main
turbine trip and reactor
scram from full power. The inspectors determined the finding could be evaluated using the
SDP in accordance with
IMC 0609,
Significance Determination Process, Attachment 0609.04, Phase 1 - Initial Screening and Characterization of Findings, Table 4a, for the
Initiating Events cornerstone. While the finding resulted in a
reactor trip, it did not contribute to the likelihood that mitigation equipment would not be available, therefore, the inspectors determined the finding to be of very low safety significance. This finding has a cross-cutting aspect in the area human performance, resources per
IMC 0305 H.2(c), because the licensee did not ensure that procedures were adequate to assure nuclear safety. Specifically, the generic instrumentation and control instruction and the work order for conducting maintenance on the
moisture separator reheater level switches did not contain critical vendor information or guidance to reflect the significance of taking as-found data to support calibration of the replacement switches
