A reactor at the St. Lucie Nuclear Power Plant had failed for over a day after being manually shut down

ST. LUCIE COUNTY – One of two reactors at the St. Lucie Nuclear Power Plant on Hutchinson Island was manually shut down on the morning of December 10th after operators noticed the water level in its steam generator had dropped.

According to an announcement by the Nuclear Regulatory Commission, the reactor in Unit 1 was shut down by a “manual reactor trigger” last Friday around 10:24 am – which means that it was a decision by the staff to shut down the unit.

The pressurized water reactor stayed offline until Sunday when it went back online, according to Florida Power & Light Co. spokesman Peter Robbins. Block 1 has been running at 100% capacity since Monday.

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What caused the closure?

An investigation is underway to find out why the water entering the generator – which is then converted to steam to create electricity – decreased, according to the NRC. It is classified as a “non-emergency” event by the Commission.

“We believe it was a valve that was accidentally closed,” Robbins told TCPalm. That led to the decision by the staff to shut down the reactor, he said. “Everything reacted exactly as it should and the device was switched off within a few minutes.”

It is “rare” for employees to shut down a reactor manually, Robbins said, although he was unable to immediately provide a list of manual shutdowns based on the history of the facility. The action is “something we do without hesitation if the situation calls for it,” he said in an email.

The shutdown doesn’t appear to have caused a problem that requires significant repairs, said Edwin Lyman, director of nuclear safety for the Union of Concerned Scientists.

“We know it wasn’t bad because the facility could be compensated, safely shut down, and stabilized. And then they returned to duty,” Lyman said.

“Any time a plant is unplanned or unexpectedly shut down, it could potentially trigger a more serious event. While they’re usually harmless, it doesn’t add any additional risks, ”Lyman said. “Every time you have one like this (shutdown), just one other thing has to go wrong and then you have a problem.”

Therefore, nuclear power plants must take steps to prevent these unplanned shutdowns, Lyman told TCPalm. The NRC calls reactor shutdowns “an important measure to protect the components of a nuclear power plant from failure or damage”.

St. Lucie Unit 2 – the reactor next to Unit 1 – was not affected by the shutdown and remained at full capacity, according to the NRC. There were no blackouts due to the shutdown, Robbins said.

Construction of Unit 1 began in 1970 and the reactor began operating in 1976. Construction of Unit 2 began in 1977 and went into operation in 1983. The facility cost $ 4.6 billion to build. The facility is located on 1,300 acres on Hutchinson Island and employs more than 700 people.

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Max Chesnes is a TCPalm environmental reporter who focuses on the problems of the Indian River Lagoon, St. Lucie River, and Lake Okeechobee. You can stay up to date with Max on Twitter @MaxChesnes, email him at [email protected] and call him at 772-978-2224.

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