Browse wiki
Jump to navigation
Jump to search
86 +
On April 16, 2010 at 1917 hrs., Unit 1 rec … On April 16, 2010 at 1917 hrs., Unit 1 received an ECCS (emergency core cooling system) loss of cooling accident (LOCA) signal on high drywell pressure. Based on plant data, drywell pressure reached a maximum pressure of approximately 1.25 psig, which is below the LOCA and RPS (reactor protection system) signal actuation pressure of 1.85 psig. At this time, the cause of the drywell pressure increase is under investigation. RPS logic did not initiate due to drywell pressure not reaching the actuation setpoint of 1.85 psig. Although the ECCS logic prematurely actuated, the signal is being treated as 'valid' for the ECCS actuation until further investigation is completed. All expected ECCS actions occurred as a result of the signal. The LOCA logic has been reset and all affected systems have been returned to normal or standby configuration.</br>As a result of the LOCA system actuations, several cooling tower fans tripped and condenser vacuum began to decrease. Reactor power was reduced to approximately 86 percent as a result of decreasing condenser vacuum. Power is being maintained at approximately 86 - 88 percent at this time. There are no other plant issues or concerns at this time.</br>The licensee notified the NRC Resident Inspector.</br>According to the licensee, normal drywell operating pressure is .5 to 1.2 psig. Prior to the event, drywell pressure had been steady at approximately 1.0 psig. Current drywell pressure is .6 psig. According to the licensee, ECCS systems that started (but did not inject) included: Core Spray pumps, Residual Heat Removal pumps, High Pressure Coolant Injection pump, and the Diesel Generators. An event review team is assessing this event to determine the root cause.</br>* * * RETRACTION FROM GRIFFIS TO KLCO ON 4/17/2010 AT 1719 EDT* * * </br>On April 16, 2010, Hatch Unit 1 received a LOCA ECCS initiation from a high drywell pressure signal. Based on the information available at that time, a notification was made to the NRC assuming the signal to be valid until further investigation could be completed.</br>After further review, the determination has been made that the initiation signal originated from a faulted ATTS (Analog Transmitter Trip System) card and not from a valid high drywell pressure condition. Based on this information, this condition did not require an NRC notification in accordance with 10CFR50.72 and, as such, is being retracted through this updated response.</br>The licensee notified the NRC Resident Inspector.</br>Notified the R2DO (Hopper)dent Inspector.
Notified the R2DO (Hopper)
23:17:00, 16 April 2010 +
45,850 +
01:29:00, 17 April 2010 +
23:17:00, 16 April 2010 +
On April 16, 2010 at 1917 hrs., Unit 1 rec … On April 16, 2010 at 1917 hrs., Unit 1 received an ECCS (emergency core cooling system) loss of cooling accident (LOCA) signal on high drywell pressure. Based on plant data, drywell pressure reached a maximum pressure of approximately 1.25 psig, which is below the LOCA and RPS (reactor protection system) signal actuation pressure of 1.85 psig. At this time, the cause of the drywell pressure increase is under investigation. RPS logic did not initiate due to drywell pressure not reaching the actuation setpoint of 1.85 psig. Although the ECCS logic prematurely actuated, the signal is being treated as 'valid' for the ECCS actuation until further investigation is completed. All expected ECCS actions occurred as a result of the signal. The LOCA logic has been reset and all affected systems have been returned to normal or standby configuration.</br>As a result of the LOCA system actuations, several cooling tower fans tripped and condenser vacuum began to decrease. Reactor power was reduced to approximately 86 percent as a result of decreasing condenser vacuum. Power is being maintained at approximately 86 - 88 percent at this time. There are no other plant issues or concerns at this time.</br>The licensee notified the NRC Resident Inspector.</br>According to the licensee, normal drywell operating pressure is .5 to 1.2 psig. Prior to the event, drywell pressure had been steady at approximately 1.0 psig. Current drywell pressure is .6 psig. According to the licensee, ECCS systems that started (but did not inject) included: Core Spray pumps, Residual Heat Removal pumps, High Pressure Coolant Injection pump, and the Diesel Generators. An event review team is assessing this event to determine the root cause.</br>* * * RETRACTION FROM GRIFFIS TO KLCO ON 4/17/2010 AT 1719 EDT* * * </br>On April 16, 2010, Hatch Unit 1 received a LOCA ECCS initiation from a high drywell pressure signal. Based on the information available at that time, a notification was made to the NRC assuming the signal to be valid until further investigation could be completed.</br>After further review, the determination has been made that the initiation signal originated from a faulted ATTS (Analog Transmitter Trip System) card and not from a valid high drywell pressure condition. Based on this information, this condition did not require an NRC notification in accordance with 10CFR50.72 and, as such, is being retracted through this updated response.</br>The licensee notified the NRC Resident Inspector.</br>Notified the R2DO (Hopper)dent Inspector.
Notified the R2DO (Hopper)
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, 17 April 2010 +
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>.
02:09:53, 2 March 2018 +
01:29:00, 17 April 2010 +
true +
false +
0.0917 d (2.2 hours, 0.0131 weeks, 0.00301 months) +
23:17:00, 16 April 2010 +
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.