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The following information was provided by … The following information was provided by the licensee via phone and email:</br>On 9/23/2025 at 2214 CDT, the South Texas Project Unit 1 (STP-1) train 'B' reactor containment fan cooler (RCFC) chilled water supply outside containment isolation valve, 1-CC-MOV-0137, was declared inoperable due to a material condition. This rendered train 'B' component cooling water inoperable which cascaded to train 'B' emergency core cooling system (ECCS) subsystem to render it inoperable. STP-1 entered technical specification (TS) 3.5.2 action 'A' for train 'B' ECCS, requiring restoration within 7 days or apply the requirements of the Configuration Risk Management Program (CRMP).</br>On 09/25/2025 at 1229 CDT, train 'A' essential chiller 12A was declared inoperable due to inability to maintain chiller water outlet temperature less than 52 degrees Fahrenheit. This cascaded down to the train 'A' ECCS subsystem to render it inoperable. STP-1 entered TS 3.5.2 action 'B' due to less than two of the required subsystems operable, to within 1 hour restore at least two subsystems to operable status or apply the requirements of the CRMP, or be in at least hot standby within the next 6 hours and in hot shutdown within the following 6 hours. </br>On 09/25/2025 at 1329 CDT, STP-1 entered the CRMP based on two ECCS subsystems remaining inoperable longer than 1 hour. These subsystems are used for accident mitigation. Unit 1 remains in mode 1.</br>* * * RETRACTION ON 10/20/2025 AT 1636 EDT FROM MARC HILL TO JOSUE RAMIREZ * * *</br>The following information was provided by the licensee via phone and email:</br>The purpose of this notification is to retract EN 57952, which was made on September 25, 2025, at 1736 EDT. (The) notification was initially made due to two of three trains of emergency core cooling system (ECCS) being declared inoperable. After the notification was made, South Texas Project determined using an engineering evaluation, that one of the two inoperable ECCS trains was operable because the elevated chilled water outlet temperature of the associated essential chiller (Train A) did not impact the technical specification specified function.</br>Therefore, this event was not a condition that could have prevented fulfillment of a safety function.</br>The NRC Resident Inspector has been notified.</br>Notified R4DO (Vossmar)has been notified.
Notified R4DO (Vossmar)
17:29:00, 25 September 2025 +
17:36:00, 25 September 2025 +
17:29:00, 25 September 2025 +
The following information was provided by … The following information was provided by the licensee via phone and email:</br>On 9/23/2025 at 2214 CDT, the South Texas Project Unit 1 (STP-1) train 'B' reactor containment fan cooler (RCFC) chilled water supply outside containment isolation valve, 1-CC-MOV-0137, was declared inoperable due to a material condition. This rendered train 'B' component cooling water inoperable which cascaded to train 'B' emergency core cooling system (ECCS) subsystem to render it inoperable. STP-1 entered technical specification (TS) 3.5.2 action 'A' for train 'B' ECCS, requiring restoration within 7 days or apply the requirements of the Configuration Risk Management Program (CRMP).</br>On 09/25/2025 at 1229 CDT, train 'A' essential chiller 12A was declared inoperable due to inability to maintain chiller water outlet temperature less than 52 degrees Fahrenheit. This cascaded down to the train 'A' ECCS subsystem to render it inoperable. STP-1 entered TS 3.5.2 action 'B' due to less than two of the required subsystems operable, to within 1 hour restore at least two subsystems to operable status or apply the requirements of the CRMP, or be in at least hot standby within the next 6 hours and in hot shutdown within the following 6 hours. </br>On 09/25/2025 at 1329 CDT, STP-1 entered the CRMP based on two ECCS subsystems remaining inoperable longer than 1 hour. These subsystems are used for accident mitigation. Unit 1 remains in mode 1.</br>* * * RETRACTION ON 10/20/2025 AT 1636 EDT FROM MARC HILL TO JOSUE RAMIREZ * * *</br>The following information was provided by the licensee via phone and email:</br>The purpose of this notification is to retract EN 57952, which was made on September 25, 2025, at 1736 EDT. (The) notification was initially made due to two of three trains of emergency core cooling system (ECCS) being declared inoperable. After the notification was made, South Texas Project determined using an engineering evaluation, that one of the two inoperable ECCS trains was operable because the elevated chilled water outlet temperature of the associated essential chiller (Train A) did not impact the technical specification specified function.</br>Therefore, this event was not a condition that could have prevented fulfillment of a safety function.</br>The NRC Resident Inspector has been notified.</br>Notified R4DO (Vossmar)has been notified.
Notified R4DO (Vossmar)
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100 +
00:00:00, 20 October 2025 +
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>.
11:20:02, 21 October 2025 +
17:36:00, 25 September 2025 +
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false +
0.005 d (0.12 hours, 7.142857e-4 weeks, 1.64376e-4 months) +
17:29:00, 25 September 2025 +
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.