A self-revealing Green finding (
FIN) was identified for failure to adequately implement the modification procedural requirements of engineering directives manual (
EDM)-601, Engineering Change Manual, for a
temporary modification that installed a valve leak seal enclosure on
main steam drain valve
2SM-27. Specifically, EDM-601 required the weight and vibration response of the enclosure to be evaluated as part of the installation. The failure to consider this resulted in vibration induced piping failure upstream of the valve and an unexpected rapid plant down power. The failure to adequately implement a
temporary modification in accordance with EDM- 601 was a performance deficiency (
PD). The
PD was more than minor because it was associated with the design control attribute of the
initiating events cornerstone and adversely affected the cornerstone objective of limiting the likelihood of events that upset plant stability during power operations. Specifically, the performance deficiency resulted in a rapid down power to approximately 20 percent and subsequent actions to take the Unit 2 turbine generator offline to repair the leak. Using NRC
IMC 0609, Appendix A, The
Significance Determination Process for Findings At-Power, the finding was determined to be of very low safety significance because the it did not contribute to both the cause of a
reactor trip and affect mitigation equipment. The finding had a cross cutting aspect of consistent process, as described in the human performance crosscutting area because the licensee failed to use a consistent, systematic approach to make de.cisions during implementation of a
temporary modification.
