Browse wiki

Jump to navigation Jump to search
ENS 57832
Show incoming properties 
Category
ENS Notification  and Power Reactor
CFR
10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation +, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident +, 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material +, 10 CFR 50.72#b2ivB +  and 10 CFR 50.72#b3v +
Current power
0  +
Description
The following information was provided by … The following information was provided by the licensee via phone and email:</br>At 2058 CDT on 7/28/2025, a spurious trip of the reactor building exhaust ventilation (system) caused a subsequent trip of the reactor building supply ventilation (system). This ventilation system failure resulted in the degradation of reactor building differential pressure and at 2200 CDT the differential pressure exceeded the technical specification limit, resulting in the inoperability of Secondary Containment. This condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72 (b)(3)(v). </br>Failure of the ventilation system also resulted in elevated temperatures in the steam chase area of the plant. Operators reduced power to slow the temperature rise, however, at 2324 CDT on 7/28/2025 with Unit 1 in mode 1 at 41 percent power, the reactor was manually scrammed due to steam chase temperatures reaching the procedural limit. The scram was not complex, with all systems responding normally post-scram. Reactor water level is being maintained via the feedwater system. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves. This condition is being reported as a four-hour, non-emergency notification per 10 CFR 50.72 (b)(2)(iv)(B). There has been no impact to the health and safety of the public or plant personnel. </br>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>Steam chase temperature has begun to lower, and the licensee intends to cooldown to mode 4 for maintenance.nds to cooldown to mode 4 for maintenance.  +
Discovered date
01:58:00, 29 July 2025  +
Emergency class
Non Emergency +
Entered date
03:45:00, 29 July 2025  +
Event date
01:58:00, 29 July 2025  +
Event description
The following information was provided by … The following information was provided by the licensee via phone and email:</br>At 2058 CDT on 7/28/2025, a spurious trip of the reactor building exhaust ventilation (system) caused a subsequent trip of the reactor building supply ventilation (system). This ventilation system failure resulted in the degradation of reactor building differential pressure and at 2200 CDT the differential pressure exceeded the technical specification limit, resulting in the inoperability of Secondary Containment. This condition is being reported as an eight-hour, non-emergency notification per 10 CFR 50.72 (b)(3)(v). </br>Failure of the ventilation system also resulted in elevated temperatures in the steam chase area of the plant. Operators reduced power to slow the temperature rise, however, at 2324 CDT on 7/28/2025 with Unit 1 in mode 1 at 41 percent power, the reactor was manually scrammed due to steam chase temperatures reaching the procedural limit. The scram was not complex, with all systems responding normally post-scram. Reactor water level is being maintained via the feedwater system. Decay heat is being removed by discharging steam to the main condenser using the turbine bypass valves. This condition is being reported as a four-hour, non-emergency notification per 10 CFR 50.72 (b)(2)(iv)(B). There has been no impact to the health and safety of the public or plant personnel. </br>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>Steam chase temperature has begun to lower, and the licensee intends to cooldown to mode 4 for maintenance.nds to cooldown to mode 4 for maintenance.  +
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>.
ENS 57832 +, ENS 57832 +, ENS 57832 +, ENS 57832 +, ENS 57832 +, ENS 57832 +, ENS 57832 +, ENS 57832 +, ENS 57832 +, ENS 57832 +, ENS 57832 +, ENS 57832 +, ENS 57832 +, ENS 57832 +, ENS 57832 +  and ENS 57832 +
Initial power
100  +
Last update date
00:00:00, 29 July 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>.
11:20:05, 31 July 2025  +
NRC officer
Jordan Wingate +
Notification date
03:45:00, 29 July 2025  +
Originated by
Lt Zlotnik +
Reactor critical
true  +
Reactor scram
false  +
Reactor type
GE-3 +
Region
NRC Region 3 +
Reporting criterion
10 CFR 50.72(b)(2)(iv)(B), RPS System Actuation +, 10 CFR 50.72(b)(3)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident +  and 10 CFR 50.72(b)(3)(v)(C), Loss of Safety Function - Release of Radioactive Material +
Reporting time
0.0742 d (1.78 hours, 0.0106 weeks, 0.00244 months)  +
Site
Monticello +
Start date
01:58:00, 29 July 2025  +
State
Minnesota +
System
Feedwater +, Secondary containment +  and Main Condenser +
Title
Manual Reactor Scram  +
Turbine component
Turbine bypass valve +
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.
https://www.nrc.gov/reading-rm/doc-collections/event-status/event/2025/20250731en.html#en57832  +
Unit
1  +
 
Retrieved from "https://kanterella.com/Special:Browse/:ENS-5F57832"