Browse wiki
Jump to navigation
Jump to search
This telephone notification is provided in … This telephone notification is provided in accordance with 10 CFR 50.73(a)(1), to report an invalid actuation reportable under 10 CFR 50.73 (a)(2)(iv)(A).</br>On March 4, 2006, with Unit 1 in Mode 5 'Refuel,' Instrument Maintenance (IM) technicians were installing a Barton level indicator for reactor vessel level indicator 1B21-R452A as part of a system modification. At 0512 hours, momentary 'Reactor Vessel Water Low Level 2' alarms were received in the Main Control Room, and the Unit 1 High Pressure Core Spray (HPCS) Emergency Diesel Generator (1B EDG) auto-started. A Reactor Vessel Water Level Low 2 condition sends a start signal to HPCS and the 1B EDG; however, because the HPCS pump control switch was in pull-to-lock, the pump did not start and did not inject water into the reactor vessel.</br>The initiating signal was reset, and at 0524 hours the 1B EDG was shutdown with the Maintenance Switch placed in 'Maintenance.' </br>Investigation determined that the 1B EDG had auto-started approximately 15 minutes after the IM technicians had completed work and placed the 1B21-R452A indicator back in service. The computer point alarm typer data was reviewed, and it was observed that only a single set of alarm points were received. Typically, when an alarm is caused by improperly valving in an instrument, multiple alarm points are received due to 'ringing.' Based on the 15 minute time delay and the lack of ringing, the apparent cause was determined to be an air bubble that was introduced during the modification and then migrated to the level transmitter, resulting in an invalid low level signal and an auto-start of the 1B EDG. Corrective actions included reviewing the remaining Barton installation modification work packages for unusual piping configurations that could contribute to air entrapment, and-for adequate system isolation requirements; i.e., bypassing trip units or removing components from service in order to prevent inadvertent actuations.</br>This event is reportable under 10 CFR 50.73(a)(2)(iv)(A) as an invalid actuation of an EDG.</br>The licensee notified the NRC Resident Inspector.ensee notified the NRC Resident Inspector.
10:12:00, 4 March 2006 +
42,526 +
16:20:00, 25 April 2006 +
10:12:00, 4 March 2006 +
This telephone notification is provided in … This telephone notification is provided in accordance with 10 CFR 50.73(a)(1), to report an invalid actuation reportable under 10 CFR 50.73 (a)(2)(iv)(A).</br>On March 4, 2006, with Unit 1 in Mode 5 'Refuel,' Instrument Maintenance (IM) technicians were installing a Barton level indicator for reactor vessel level indicator 1B21-R452A as part of a system modification. At 0512 hours, momentary 'Reactor Vessel Water Low Level 2' alarms were received in the Main Control Room, and the Unit 1 High Pressure Core Spray (HPCS) Emergency Diesel Generator (1B EDG) auto-started. A Reactor Vessel Water Level Low 2 condition sends a start signal to HPCS and the 1B EDG; however, because the HPCS pump control switch was in pull-to-lock, the pump did not start and did not inject water into the reactor vessel.</br>The initiating signal was reset, and at 0524 hours the 1B EDG was shutdown with the Maintenance Switch placed in 'Maintenance.' </br>Investigation determined that the 1B EDG had auto-started approximately 15 minutes after the IM technicians had completed work and placed the 1B21-R452A indicator back in service. The computer point alarm typer data was reviewed, and it was observed that only a single set of alarm points were received. Typically, when an alarm is caused by improperly valving in an instrument, multiple alarm points are received due to 'ringing.' Based on the 15 minute time delay and the lack of ringing, the apparent cause was determined to be an air bubble that was introduced during the modification and then migrated to the level transmitter, resulting in an invalid low level signal and an auto-start of the 1B EDG. Corrective actions included reviewing the remaining Barton installation modification work packages for unusual piping configurations that could contribute to air entrapment, and-for adequate system isolation requirements; i.e., bypassing trip units or removing components from service in order to prevent inadvertent actuations.</br>This event is reportable under 10 CFR 50.73(a)(2)(iv)(A) as an invalid actuation of an EDG.</br>The licensee notified the NRC Resident Inspector.ensee notified the NRC Resident Inspector.
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>.
00:00:00, 25 April 2006 +
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>.
22:38:55, 24 September 2017 +
16:20:00, 25 April 2006 +
false +
false +
52.297 d (1,255.13 hours, 7.471 weeks, 1.719 months) +
10:12:00, 4 March 2006 +
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.