Pilgrim had another unplanned shutdown yesterday morning, September 6th – the second shutdown in nearly three weeks due to a valve malfunction.

The first shutdown was on August 18 and lasted several days. It was caused by a failed valve that is designed to prevent radioactive contamination from leaking into the environment during an accident.

Yesterday, at approximately 8:30am, Pilgrim was manually shut down again when water levels in the reactor pressure vessel fluctuated due to a mechanical malfunction in another valve. The valve is designed to pump water into the reactor vessel, which is boiled and created into steam. The steam is what is used to turn a turbine and create electricity. The water also serves other important purposes – for instance, it makes up water that keeps the nuclear fuel cool.

The shutdown occurred at the same time Pilgrim was operating at reduced power due to the cooling water coming in from Cape Cod Bay being too warm. Pilgrim license requires the incoming water to not exceed 75 degrees F. This has become a problem for Pilgrim over the last few years due to rising air and water temperatures.

On top of this most recent valve problem, Pilgrim also had a electrical arcing in a power line going to the plant on Monday night – another problem that has occurred in the past.

Pilgrim has had a long history of mechanical problems and unplanned shutdowns. The NRC created a webpage early this year dedicated to Pilgrim. It was started due to Pilgrim’s poor performance and the high level of public interest in what’s happening at the aging plant.

The U.S. Nuclear Regulatory Commission is currently investigating the valve problems.

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