NRC BEGINS SPECIAL INSPECTION AT LASALLE NUCLEAR PLANT FOLLOWING CONTROL
ROD PROBLEM DURING AUTOMATIC REACTOR SHUTDOWN
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The Nuclear Regulatory Commission will conduct a special inspection at the LaSalle Nuclear Power Station at Seneca, Illinois, following a problem with control rod instrumentation during an automatic shutdown of the Unit 1 reactor. The LaSalle plant near Seneca, Ill, is operated by Exelon Generation Co. and has two 1,197-megawatt reactors.

The utility declared a Site Area Emergency at the plant early Monday when reactor instrumentation showed that three control rods failed to insert fully into the reactor core during an automatic reactor shutdown. The plant was at 6 percent power when the automatic shutdown occurred.

Subsequently, the reactor instrumentation showed the plant was fully shut down. The plant staff verified that all control rods were fully inserted except for one for which the position indication remained indeterminate. The reactor has 185 control rods which control power and insert into the reactor core to shut down the reactor.

All plant safety systems functioned normally with the exception of the control rod position indications, and there was no release of radioactivity associated with the event. The reactor remained in a stable condition.

After verifying plant conditions, the utility terminated the Site Area Emergency Classification at 4:27 a.m. CST. A Site Area Emergency is the second highest of the four emergency categories in the NRC’s emergency response system. The emergency was declared because of the uncertainty caused by the instrumentation problems for the three control rods.

The NRC’s two resident inspectors responded to the plant and the agency staffed its emergency response facilities in its Region III office in Lisle, Ill., and its Headquarters in Rockville, Md., to monitor the situation at the LaSalle plant.

At the time of the incident, the plant was shutting down for a refueling outage. Preliminary information showed that the automatic reactor shutdown was caused by a malfunction of the plant’s turbine control system.

The NRC inspectors will review the circumstances surrounding the shutdown, including the control rod indication problems. A written report of the special inspection will be issued about 30 days following the completion of the inspection. It will be available on the NRC’s web site at:
http://www.nrc.gov/NRR/OVERSIGHT/ASSESS/listofrpts_body.html#lasa

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Thursday, February 22, 2007