Browse wiki
Jump to navigation
Jump to search
An automatic reactor scram on low reactor … An automatic reactor scram on low reactor water level occurred following a momentary loss of the UPS (Uninterruptible Power Supply) system. The power loss resulted in a lock-out of the RFP (Reactor Feed Pump) controls. The HPCI system started on low reactor level but did not inject, reactor level had risen above the initiation set-point. The RCIC did not receive an initiation signal. Overall plant response was as expected.</br>Prior to the transient the licensee was in the process of transferring UPS electrical loads to the alternate power supply. The momentary loss of UPS power locked-out the RFP controls during a downtrend in the reactor water level from the normal 201-203 inch operating band. Before Operators could establish manual control, reactor water level reached the 177 inch scram setpoint. Following the scram, reactor water level continued to decrease to the HPCI and RCIC initiation setpoint of 126 inches before recovering. HPCI received a start signal but RCIC did not for reasons under investigation. The unit will remain in mode 3 pending the results of the post-scram investigation and restart.</br>The licensee informed the NRC Resident Inspector and is planning on issuing a press release.</br>* * * UPDATE ON 09/14/05 @ 1918 BY TIM PAGE TO CHAUNCEY GOULD * * * </br>On September 14, 2005 at approximately 0213. an automatic reactor scram on low reactor water level occurred following a momentary loss of the UPS (Uninterruptible Power Supply) system. The power loss resulted in a lock-out of the RFP (Reactor Feed Pump) controls. A level transient occurred causing reactor water level to lower, resulting in an automatic reactor scram on low reactor water level. The HPCI system auto initiated on low reactor water level but did not inject as reactor water level had risen above the initiation setpoint. The RCIC system auto initiated (and sealed-in) and injected into the reactor vessel. Both systems operated as designed.</br>In addition, a Primary Containment Isolation System (PCIS) Group 2 isolation occurred, resulting in multiple system isolations. This included isolation signals to Reactor Water Cleanup, Reactor Building Ventilation, Containment Atmosphere Dilution. Torus Vent and Purge, Drywall Floor and Equipment Drain Sumps, Drywall Containment Atmospheric Monitors, Recirculation System Sample Lines, Traversing In-Core Probes, LPCI Inboard Injection Valves, Residual Heat Removal Drain to Radwaste, and auto initiation of Standby Gas Treatment. (Note that two Reactor Water Cleanup PCIS valves did not close due to their respective circuit breakers being in the open position for planned maintenance activities.)</br>The above event meets the reporting criteria of 10 CFR 50.72(b)(2)(iv)(B) for RPS actuation while the reactor was critical, as well as 10 CFR 50.72(b)(3)(iv)(A) for the valid actuation of systems listed in 10 CFR 50.72(b)(3)(iv)(B), including general containment isolation signals affecting containment isolation valves in more than one system, the HPCI system, and the RCIC system.</br>The NRC Resident Inspector has been briefed.e NRC Resident Inspector has been briefed.
06:13:00, 14 September 2005 +
04:48:00, 14 September 2005 +
06:13:00, 14 September 2005 +
An automatic reactor scram on low reactor … An automatic reactor scram on low reactor water level occurred following a momentary loss of the UPS (Uninterruptible Power Supply) system. The power loss resulted in a lock-out of the RFP (Reactor Feed Pump) controls. The HPCI system started on low reactor level but did not inject, reactor level had risen above the initiation set-point. The RCIC did not receive an initiation signal. Overall plant response was as expected.</br>Prior to the transient the licensee was in the process of transferring UPS electrical loads to the alternate power supply. The momentary loss of UPS power locked-out the RFP controls during a downtrend in the reactor water level from the normal 201-203 inch operating band. Before Operators could establish manual control, reactor water level reached the 177 inch scram setpoint. Following the scram, reactor water level continued to decrease to the HPCI and RCIC initiation setpoint of 126 inches before recovering. HPCI received a start signal but RCIC did not for reasons under investigation. The unit will remain in mode 3 pending the results of the post-scram investigation and restart.</br>The licensee informed the NRC Resident Inspector and is planning on issuing a press release.</br>* * * UPDATE ON 09/14/05 @ 1918 BY TIM PAGE TO CHAUNCEY GOULD * * * </br>On September 14, 2005 at approximately 0213. an automatic reactor scram on low reactor water level occurred following a momentary loss of the UPS (Uninterruptible Power Supply) system. The power loss resulted in a lock-out of the RFP (Reactor Feed Pump) controls. A level transient occurred causing reactor water level to lower, resulting in an automatic reactor scram on low reactor water level. The HPCI system auto initiated on low reactor water level but did not inject as reactor water level had risen above the initiation setpoint. The RCIC system auto initiated (and sealed-in) and injected into the reactor vessel. Both systems operated as designed.</br>In addition, a Primary Containment Isolation System (PCIS) Group 2 isolation occurred, resulting in multiple system isolations. This included isolation signals to Reactor Water Cleanup, Reactor Building Ventilation, Containment Atmosphere Dilution. Torus Vent and Purge, Drywall Floor and Equipment Drain Sumps, Drywall Containment Atmospheric Monitors, Recirculation System Sample Lines, Traversing In-Core Probes, LPCI Inboard Injection Valves, Residual Heat Removal Drain to Radwaste, and auto initiation of Standby Gas Treatment. (Note that two Reactor Water Cleanup PCIS valves did not close due to their respective circuit breakers being in the open position for planned maintenance activities.)</br>The above event meets the reporting criteria of 10 CFR 50.72(b)(2)(iv)(B) for RPS actuation while the reactor was critical, as well as 10 CFR 50.72(b)(3)(iv)(A) for the valid actuation of systems listed in 10 CFR 50.72(b)(3)(iv)(B), including general containment isolation signals affecting containment isolation valves in more than one system, the HPCI system, and the RCIC system.</br>The NRC Resident Inspector has been briefed.e NRC Resident Inspector has been briefed.
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, 14 September 2005 +
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>.
02:20:15, 2 March 2018 +
04:48:00, 14 September 2005 +
true +
-0.0592 d (-1.42 hours, -0.00845 weeks, -0.00195 months) +
06:13:00, 14 September 2005 +
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.