A nuclear reactor in Byron, Illinois was forced to shut down after what the US Nuclear Regulatory Commission (NRC) described as an ‘unusual event’, when the plant lost power.
Steam was being vented to reduce pressure, according to officials from Exelon Nuclear and federal regulators.
The nuclear power generating plant is located 95 miles northwest of Chicago, and diesel generators began supplying power to the plant, while operators began releasing steam to cool the reactor from the part of the plant where turbines are producing electricity, not from within the nuclear reactor itself, officials said.
The steam contains low levels of tritium, a radioactive form of hydrogen, but federal and plant officials insisted the levels were safe for workers and the public.
The NRC declared the incident an "unusual event," the lowest of four levels of emergency. Commission officials also said the release of tritium was expected.
Exelon Nuclear officials believe a failed piece of equipment at a switchyard caused the shutdown. The switchyard is similar to a large substation that delivers power to the plant from the electrical grid and that takes power from the plant to the electrical grid. Officials were still investigating the equipment failure.
NRC spokeswoman Viktoria Mitlyng said officials cannot yet calculate how much tritium is being released. "They know the amounts of tritium are small because monitors around the plant aren't showing increased levels of radiation", she said.
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