Browse wiki
Jump to navigation
Jump to search
On December 23, 2002, at approximately 020 … On December 23, 2002, at approximately 0200 with the plant at 100% power, a reactor trip occurred following a Generator fault. The appropriate alarms were received just prior to the trip. In addition, the trip signal opened a series of breakers and the Turbine and Reactor tripped sequentially. The Turbine Stop Valves closed within one second. The Steam Generator level shrinkage caused a low level in the Steam Generators starting the Auxiliary Feedwater System within 6 seconds, which was an expected occurrence. During and after the plant trip all main and auxiliary equipment functioned as designed and plant operators stabilized the plant in MODE 3.</br></br>The generator stator fault on phase A was found to be due to an arc to ground associated with the T-4 high voltage bushing. Specifically, stator cooling water was leaking through a pin-hole at the joint area (braze material) of the tubular lead conductor and the cooling water inlet fitting. The leaking cooling water traveled along the bushing body underneath the insulation package where the leaking coolant picked up contaminants (making it more conductive). The leaking contaminated water ultimately traversed the entire bushing to the point of contacting the housing enclosure (ground).</br></br>Per vendor evaluation, the leak was due to a void/porosity issue with the braze material itself. This was most likely a fabrication deficiency that deteriorated over time.</br></br>The leak was repaired through re-brazing on the T-4 tubular lead connector and system integrity was confirmed through pressure testing. Other appropriate corrective actions are being addressed in accordance with the Millstone Corrective Action Program.h the Millstone Corrective Action Program. +
On December 23, 2002, at approximately 020 … On December 23, 2002, at approximately 0200 with the plant at 100% power, a reactor trip occurred following a Generator fault. The appropriate alarms were received just prior to the trip. In addition, the trip signal opened a series of breakers and the Turbine and Reactor tripped sequentially. The Turbine Stop Valves closed within one second. The Steam Generator level shrinkage caused a low level in the Steam Generators starting the Auxiliary Feedwater System within 6 seconds, which was an expected occurrence. During and after the plant trip all main and auxiliary equipment functioned as designed and plant operators stabilized the plant in MODE 3.</br></br>The generator stator fault on phase A was found to be due to an arc to ground associated with the T-4 high voltage bushing. Specifically, stator cooling water was leaking through a pin-hole at the joint area (braze material) of the tubular lead conductor and the cooling water inlet fitting. The leaking cooling water traveled along the bushing body underneath the insulation package where the leaking coolant picked up contaminants (making it more conductive). The leaking contaminated water ultimately traversed the entire bushing to the point of contacting the housing enclosure (ground).</br></br>Per vendor evaluation, the leak was due to a void/porosity issue with the braze material itself. This was most likely a fabrication deficiency that deteriorated over time.</br></br>The leak was repaired through re-brazing on the T-4 tubular lead connector and system integrity was confirmed through pressure testing. Other appropriate corrective actions are being addressed in accordance with the Millstone Corrective Action Program.h the Millstone Corrective Action Program. +
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>.
1 +
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>.
04:42:52, 1 December 2017 +
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.