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The following is a summary of the informat … The following is a summary of the information provided via facsimile:</br>On March 27, 2014, at Exelon-Dresden Station, plant personnel identified that breaker UTC # 1185084 (3B CCSW Pump Breaker) was in the CLOSED condition, but did not indicate CHARGED. The breaker was last CLOSED successfully on March 19, 2014. The breaker charges the closing springs after a CLOSE operation. </br>The breaker was OPENED and removed from service on 3/28/14, Dresden notified (Nuclear Logistic, Inc.) NLI on 3/28/14 of the issue and the breaker was returned to NLI on RMA 351022093. </br>NLI performed a failure analysis on the breaker. The spring clamp cam 12mm nylon insert lock nut was not properly tightened on either side, resulting in insufficient clamping force of the cam on the jackshaft. In addition to the lock nuts not being sufficiently tightened, the closing springs were installed on the wrong side. There is a left and a right spring as identified by a red mark on the left spring. The left side spring is the shorter spring, and it was installed on the right side. Further evaluation by NLI determined that this may have been a contributing factor to the failure after the closing spring clamp started to move off the jackshaft.</br>The presence of the under torque nuts resulted in insufficient clamping force, allowing the clamp to move off the jackshaft. The springs being on the wrong sides began to exert excessive force to the cam as it rotated, and after many operations, it had slipped enough to become partially dislodged from the jackshaft. This bent the spring guide arms, preventing the rotation of the jackshaft to the CHARGED position and did not allow the motor cutoff switch to activate. The result was the breaker did not CHARGE and the motor continued to run until it burned up.</br>Several AHMG breakers (1200 and 2000A) for Dresden and Quad Cities were refurbished by Nuclear Logistics, Inc from 2008 to March 2014. At least one breaker was found with insufficient cam nut spring torque and had the two closing springs installed improperly. two closing springs installed improperly.
05:00:00, 27 March 2014 +
14:15:00, 11 July 2014 +
05:00:00, 27 March 2014 +
The following is a summary of the informat … The following is a summary of the information provided via facsimile:</br>On March 27, 2014, at Exelon-Dresden Station, plant personnel identified that breaker UTC # 1185084 (3B CCSW Pump Breaker) was in the CLOSED condition, but did not indicate CHARGED. The breaker was last CLOSED successfully on March 19, 2014. The breaker charges the closing springs after a CLOSE operation. </br>The breaker was OPENED and removed from service on 3/28/14, Dresden notified (Nuclear Logistic, Inc.) NLI on 3/28/14 of the issue and the breaker was returned to NLI on RMA 351022093. </br>NLI performed a failure analysis on the breaker. The spring clamp cam 12mm nylon insert lock nut was not properly tightened on either side, resulting in insufficient clamping force of the cam on the jackshaft. In addition to the lock nuts not being sufficiently tightened, the closing springs were installed on the wrong side. There is a left and a right spring as identified by a red mark on the left spring. The left side spring is the shorter spring, and it was installed on the right side. Further evaluation by NLI determined that this may have been a contributing factor to the failure after the closing spring clamp started to move off the jackshaft.</br>The presence of the under torque nuts resulted in insufficient clamping force, allowing the clamp to move off the jackshaft. The springs being on the wrong sides began to exert excessive force to the cam as it rotated, and after many operations, it had slipped enough to become partially dislodged from the jackshaft. This bent the spring guide arms, preventing the rotation of the jackshaft to the CHARGED position and did not allow the motor cutoff switch to activate. The result was the breaker did not CHARGE and the motor continued to run until it burned up.</br>Several AHMG breakers (1200 and 2000A) for Dresden and Quad Cities were refurbished by Nuclear Logistics, Inc from 2008 to March 2014. At least one breaker was found with insufficient cam nut spring torque and had the two closing springs installed improperly. two closing springs installed improperly.
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