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The team identified a finding of very low The team identified a finding of very low safety significance involving a noncited violation of 10 CFR 50.63, Loss of All Alternating Current (AC) Power, because Exelon\'s coping analysis did not determine whether the battery capability and capacity was sufficient to recover AC power at the end of the required coping period. Specifically, Exelon\'s battery sizing and station blackout (SSO) load profile calculation did not include those loads necessary to recover AC power, such as starting an emergency diesel generator (EDG) or closing 4 kV switchgear breakers. As a result, the calculation did not verify there was adequate direct current (DC). voltage available to critical equipment during the SSO coping period. Exelon entered the issue into their corrective action program and performed and operability assessment which determined the battery was operable. This issue was more than minor because it is associated with the design control. attribute of the Mitigating Systems cornerstone and affected the cornerstone objective of ensuring the availability, reliability and capability of systems that respond to initiating events. The team determined the finding was of very low safety significance because it was a design deficiency subsequently confirmed not to result in a loss of operability or functionality. The finding did not have a cross-cutting aspect because it was determined to be a legacy issue not considered to be indicative of current licensee performance.ndicative of current licensee performance.  +
23:59:59, 31 December 2009  +
05000352  +  and 05000353  +
23:59:59, 31 December 2009  +
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00:38:48, 21 February 2018  +
23:59:59, 31 December 2009  +
Failure to Verify Battery Capacity to Recover from Station Blackout  +