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The following information was provided by … The following information was provided by the licensee via fax:</br>On 4/28/2022, at 2338 EDT, Sequoyah received an unexpected alarm for seismological recording initiated. At 2341 EDT, unexpected alarm 1/2 Safe Shutdown Earthquake response spectra exceeded was received. The National Earthquake Information Center was contacted to confirm there was no seismic activity, and this was also confirmed on the U.S. Geological Survey website. The alarms were determined to be invalid, and they occurred due to a failure in the seismic monitoring system. This failure results in loss of ability to assess the Emergency Action Level for Initiating Condition HU2 `Seismic event greater than Operating Basis Earthquake (OBE) levels' per procedure EPIP-1, `Emergency Plan Classification Matrix.'</br>If an actual seismic event had occurred, HU2 could not be assessed. However, compensatory measures have been implemented and include assessing OBE criteria based on alternative criteria contained in procedure AOP-N.05, `Earthquake,' which provides conservative guidance when seismic instruments are unavailable. </br>This is an eight-hour, non-emergency notification for an event resulting in a major loss of Emergency Assessment Capability. This event is reportable in accordance with 10 CFR 50.72(b)(3)(xiii). There is no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified." </br>The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:</br>The faulty detector was removed from service, so the remaining detector provides conservative detection as the only source to make-up the logic for a seismological alarm.ke-up the logic for a seismological alarm. +
03:38:00, 29 April 2022 +
55,867 +
07:04:00, 29 April 2022 +
03:38:00, 29 April 2022 +
The following information was provided by … The following information was provided by the licensee via fax:</br>On 4/28/2022, at 2338 EDT, Sequoyah received an unexpected alarm for seismological recording initiated. At 2341 EDT, unexpected alarm 1/2 Safe Shutdown Earthquake response spectra exceeded was received. The National Earthquake Information Center was contacted to confirm there was no seismic activity, and this was also confirmed on the U.S. Geological Survey website. The alarms were determined to be invalid, and they occurred due to a failure in the seismic monitoring system. This failure results in loss of ability to assess the Emergency Action Level for Initiating Condition HU2 `Seismic event greater than Operating Basis Earthquake (OBE) levels' per procedure EPIP-1, `Emergency Plan Classification Matrix.'</br>If an actual seismic event had occurred, HU2 could not be assessed. However, compensatory measures have been implemented and include assessing OBE criteria based on alternative criteria contained in procedure AOP-N.05, `Earthquake,' which provides conservative guidance when seismic instruments are unavailable. </br>This is an eight-hour, non-emergency notification for an event resulting in a major loss of Emergency Assessment Capability. This event is reportable in accordance with 10 CFR 50.72(b)(3)(xiii). There is no impact on the health and safety of the public or plant personnel. The NRC Resident Inspector has been notified." </br>The following additional information was obtained from the licensee in accordance with Headquarters Operations Officers Report Guidance:</br>The faulty detector was removed from service, so the remaining detector provides conservative detection as the only source to make-up the logic for a seismological alarm.ke-up the logic for a seismological alarm. +
Has query"Has query" is a predefined property that represents meta information (in form of a <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Subobject">subobject</a>) about individual queries and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.
100 +
00:00:00, 29 April 2022 +
Modification date"Modification date" is a predefined property that corresponds to the date of the last modification of a subject and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.
11:30:14, 2 May 2022 +
07:04:00, 29 April 2022 +
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0.143 d (3.43 hours, 0.0204 weeks, 0.0047 months) +
03:38:00, 29 April 2022 +
URL"URL" is a <a href="/Special:Types/URL" title="Special:Types/URL">type</a> and predefined property provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a> to represent URI/URL values.