A couple of things from today’s NRC Event Reports:
1. Yesterday morning, the Monticello nuclear plant in Minnesota reported that an employee had tested positive for alcohol during a random Fitness for Duty screening. The employee’s access to the plant has been terminated.
2. Comanche Peak in Texas reported a problem with a valve in an airlock in containment. During a walkthrough prior to restart of the Unit 1 reactor following a refueling outage, operators discovered that the airlock valve was constructed with aluminum. Aluminum is not considered sufficient to maintain pressure boundary integrity during a loss-of-coolant accident (LOCA).
According to the report:
“Aluminum is a restricted/limited material in containment because it is not compatible with accident conditions and has failures with multiple adverse effects. Due to this condition, the valve would potentially lose pressure integrity during a LOCA with containment spray actuation.
“Compensatory measures have been taken to prevent containment spray from affecting this valve and at this time, the airlock is operable.
“Luminant Power determined this issue to be reportable at 1545 [CDT] on 10/18 per 50.72(b)(3)(ii)(B) Comanche peak Unit 1 being in an unanalyzed condition that significantly degrades plant safety.”
Luminant’s excuse– It’s always been that way:
“This material was installed during original construction and discovered during a licensee self-assessment.”
Construction of the Unit 1 reactor began in 1974, and it came online in 1990.