Three reactors had problems that led to shutdowns over the weekend, according to the Nuclear Regulatory Commission’s Event Notification Report page:
1. Saturday morning, Unit 2 at the Dresden nuclear plant in Illinois automatically shut down on a sudden pressure relay actuation. Following the scram, one of the unit’s reactor circulation pumps failed to run back to minimum speed automatically, forcing operators to take compensatory measures. Cause of the pressure relay actuation is under investigation. The reactor was at 100 per cent power when the trip took place.
2. Saturday evening, operators scrammed the Unit 1 reactor at Georgia’s Vogtle nuclear power plant after a Main Steam Isolation Valve failed shut. The incident was the second shutdown in a week at the Vogtle facility, following a problem with the steam generators serving Unit 2 last Tuesday.
3. And Sunday evening, the Unit 1 reactor at the Salem nuclear power plant in Georgia shut down automatically after a generator protection relay tripped. There was an auxiliary feedwater system activation as a result of the shutdown. This was the second shutdown in a week for Unit 1, which had to be scrammed last Tuesday following the failure of a steam generator feed pump.