10 CFR part 50.65(a)(4), requires, in part, that before performing maintenance activities, the licensee shall assess and manage the increase in risk that may result from the proposed maintenance activity. Contrary to the above, on February 4, 2008, the licensee tagged out and drained the emergency switchgear room ventilation coolers 1-VS-AC-6 and 2-VS-AC-6, rendering them
inoperable, without properly assessing the risk. The components were erroneously thought to be included in the recently added chilled water piping replacement risk term. The licensee recognized the error on February 4, 2008, prior to releasing work. The omitted components were selected in the Safety Monitor program and risk for both units increased to a slightly elevated (Yellow) risk condition. In accordance with Manual Chapter (MC) 0612, Appendix E, example 7.e, the issue is more than minor. The finding was evaluated per
MC 0609, Appendix K, and found to be of very low safety significance (Green) because the change in risk had existed for only a short period of time prior to being corrected and the necessary compensatory actions were in-place. This finding was entered into the licensees corrective action program as CR 090374
