US Chicago Nuclear Power Plant Shutdown accident
- From: "Uno" <Uno@xxxxxxx>
- Date: Tue, 21 Feb 2006 05:17:29 GMT
Emergency Declared At Nuclear Site During Shutdown
Officials Say No Radiation Released
POSTED: 6:24 pm CST February 20, 2006
UPDATED: 7:48 pm CST February 20, 2006
SENECA, Ill. -- An emergency was declared at a nuclear power plant early
Monday when operators could not confirm the position of three control rods
after the reactor shut down, officials said.
There were no injuries, no radiological releases and no equipment damage at
the LaSalle Generating Station in rural Brookfield Township in LaSalle
County, according to Exelon Nuclear officials.
The plant, which is owned by Chicago-based Exelon Corp., was scheduled to
shut down early Monday for a refueling outage.
According to the Illinois Emergency Management Agency, the reactor did not
shut down properly.
"The unit went to zero power," said Craig Nesbit, an Exelon spokesman.
"Simultaneously, we got an indication in the control room that three of the
control rods had not inserted themselves in the right way."
Company officials said instruments showed three of the 185 control rods
failed to insert fully into the reactor core and operators declared a "site
area emergency" at 12:28 a.m. That is the second-highest of the four
emergency categories in the U.S. Nuclear Regulatory Commission's emergency
response system.
The emergency was over about four hours later, Exelon Nuclear officials
said.
Operators reset the control rod position indication system and then found
only one rod was out of position, company officials said.
Exelon Nuclear officials are trying to determine why the control rod
indicators originally showed the rods weren't inserted properly. The NRC
said it also will investigate the shutdown and the IEMA is monitoring the
station.
"The main purpose of control rods is to absorb neutrons," said Dr. Hussein
Khalil of Argonne National Laboratory. "To serve essentially as a poison in
the core, to suck up excess neutrons and prevent the chain reaction from
proceeding. If we have too much production of neutrons, compared to
absorption, we can have a chain reaction that begins to build up and can
potentially take off and cause an accident."
Preliminary information showed a malfunction of the plant's turbine control
system caused the automatic reactor shutdown, according to the NRC.
The nature of the incident -- a control rod not going into the reactor --
triggered the site area emergency, but "it never really progressed into
being a danger," said IEMA spokeswoman Patti Thompson.
The plant, which is near Seneca, is about 55 miles southwest of Chicago.
.
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