Officials investigating US nuke reactor shutdown

Exelon Nuclear officials believe a failed piece of equipment at a switchyard caused the shutdown.

Chicago: US officials said they may have
traced a power failure at a nuclear reactor in Illinois to a
failed piece of equipment at a switchyard that delivers power
to and from the plant.

After the shutdown yesterday morning at Exelon Nuclear`s
Byron Generating Station, operators began releasing steam to
cool the reactor from the part of the plant where turbines
produce 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 US Nuclear Regulatory Commission spokeswoman declared
the incident an "unusual event," the lowest of four levels of
emergency. Commission officials also said the release of
tritium was expected.

Spokeswoman Viktoria Mitlyng said officials can`t yet
calculate how much tritium was released. They know the amounts
were small because monitors around the plant didn`t show
increased levels of radiation, she said.

Tritium is relatively short-lived and penetrates the body
weakly through the air compared to other radioactive

Exelon Nuclear officials believe a failed piece of
equipment at a switchyard caused the shutdown, but they were
still investigating an exact cause.

The switchyard is similar to a large substation that
delivers power to the plant from the electrical grid and from
the plant to the electrical grid.

Candace Humphrey, Ogle County`s emergency management
coordinator, said county officials were notified of the
incident as soon as it happened and that public safety was
never in danger.

"It was standard procedure that they would notify county
officials," she said. "There is always concern. But it never
crossed my mind that there was any danger to the people of
Ogle County."

Another reactor at the plant was operating normally.

In March 2008, federal officials said they were
investigating a problem with electrical transformers at the
plant after outside power to a unit was interrupted.