Browse wiki
Jump to navigation
Jump to search
During a routine inspection on December 6, … During a routine inspection on December 6, 2016, Tennessee Valley Authority (TVA) found the Unit 2 Reactor Building Containment Vertical Tendon V281 rock anchor/tendon anchor coupling had failed. The anchor coupling appears to have sheared in the threaded portion allowing the anchor head for the vertical tendon and the anchor head for the rock anchor tendon to separate. TVA had inspected the failed tendon coupling on October 19, 2016, and identified no signs of component specific damage or improper installation creating the potential for an unknown common mode failure.</br>Cause of Deficiency: At this time, the cause for the failure of the V281 rock anchor/tendon anchor coupling is unknown.</br>Safety Significance: As noted previously, the cause for the failure of the V281 rock anchor/tendon anchor coupling is unknown. As a result, the extent of condition can not be determined at this time. If multiple containment tendons are found to be losing the capability to carry tendon design force, and this condition was left uncorrected, it could reduce the capability of the containment structure to perform its design function. TVA had previously completed an analysis of containment structure integrity considering a single tendon coupler failure as a result of a similar failure of a Unit 1 Reactor Building Containment Vertical Tendon V9 in 2009 and determined that the containment structure is maintaining its design capability.</br>Interim Action: Upon discovery on December 6, 2016, the following actions were taken by BLN (Bellefonte) personnel:</br>Access to the Unit 2 tendon gallery was restricted. The area of the V281 tendon failure was subsequently cleaned. Grease samples were obtained and sent to TVA Central Labs for analysis. The couplings from both the rock anchor and tendon anchor locations were removed and sent to TVA Central Labs for metallurgical analysis. Grease samples were also collected from adjacent tendons (V272 through V290) to evaluate if conditions are similar to tendon V281 samples. The failure was entered into the BLN Corrective Action Program (Condition Report 1239343).</br>Update Schedule: TVA plans to provide an update to this report by May 25, 2017 following the completion of the metallurgical and grease analysis.</br>The Licensee has notified the NRC Construction Inspector (Baptist). the NRC Construction Inspector (Baptist).
06:00:00, 6 December 2016 +
52,476 +
12:20:00, 6 January 2017 +
06:00:00, 6 December 2016 +
During a routine inspection on December 6, … During a routine inspection on December 6, 2016, Tennessee Valley Authority (TVA) found the Unit 2 Reactor Building Containment Vertical Tendon V281 rock anchor/tendon anchor coupling had failed. The anchor coupling appears to have sheared in the threaded portion allowing the anchor head for the vertical tendon and the anchor head for the rock anchor tendon to separate. TVA had inspected the failed tendon coupling on October 19, 2016, and identified no signs of component specific damage or improper installation creating the potential for an unknown common mode failure.</br>Cause of Deficiency: At this time, the cause for the failure of the V281 rock anchor/tendon anchor coupling is unknown.</br>Safety Significance: As noted previously, the cause for the failure of the V281 rock anchor/tendon anchor coupling is unknown. As a result, the extent of condition can not be determined at this time. If multiple containment tendons are found to be losing the capability to carry tendon design force, and this condition was left uncorrected, it could reduce the capability of the containment structure to perform its design function. TVA had previously completed an analysis of containment structure integrity considering a single tendon coupler failure as a result of a similar failure of a Unit 1 Reactor Building Containment Vertical Tendon V9 in 2009 and determined that the containment structure is maintaining its design capability.</br>Interim Action: Upon discovery on December 6, 2016, the following actions were taken by BLN (Bellefonte) personnel:</br>Access to the Unit 2 tendon gallery was restricted. The area of the V281 tendon failure was subsequently cleaned. Grease samples were obtained and sent to TVA Central Labs for analysis. The couplings from both the rock anchor and tendon anchor locations were removed and sent to TVA Central Labs for metallurgical analysis. Grease samples were also collected from adjacent tendons (V272 through V290) to evaluate if conditions are similar to tendon V281 samples. The failure was entered into the BLN Corrective Action Program (Condition Report 1239343).</br>Update Schedule: TVA plans to provide an update to this report by May 25, 2017 following the completion of the metallurgical and grease analysis.</br>The Licensee has notified the NRC Construction Inspector (Baptist). the NRC Construction Inspector (Baptist).
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, 6 January 2017 +
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>.
12:32:08, 1 January 2018 +
12:20:00, 6 January 2017 +
false +
false +
31.264 d (750.33 hours, 4.466 weeks, 1.028 months) +
06:00:00, 6 December 2016 +
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.