The plant, 85 miles (137 kilometers) west of Chicago, where Exelon is based, ended an “unusual event,” the lowest of four federal emergency classification levels, at 8 p.m. local time yesterday, according to a filing to the Nuclear Regulatory Commission. Diesel generators being used to power the site were switched off, it showed.
Crews replaced a line insulator that failed in the switchyard of the 1,136-megawatt Byron 2 reactor, knocking out offsite power, at 10:18 a.m. on Jan. 30, Paul Dempsey, a company spokesman, said in a telephone interview yesterday.
The plant vented steam containing tritium to relieve pressure in the reactor until 3 a.m. local time yesterday, he said. There was no impact on the safety of employees or the public, he said.
Another unit at the plant, the 1,164-megawatt Byron 1, is operating at full capacity.
Krista Lopykinski, a spokeswoman at the plant, didn’t immediately reply to an e-mail today before regular business hours seeking comment.
Tritium is a naturally occurring radioactive form of hydrogen that is produced in the upper atmosphere and falls to the ground in rain water, according to the NRC. It is also a byproduct of nuclear plants, a weak type of radiation that doesn’t penetrate the skin, the federal agency said.
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