After ordering an investigation of a rare emergency Monday at Exelon s LaSalle County nuclear plant, federal regulators said they would inspect all Illinois nuclear power plants because of the company s recent disclosures about radioactive leaks. The Nuclear Regulatory Commission action came just hours after Exelon Nuclear declared the first "site-area emergency" in the nation since 1991 at LaSalle County Generating Station, about 75 miles southwest of Chicago.

State and federal regulators said no radioactivity was released during the emergency. And the reactor, one of two at the site, remained stable, they said. "All the indications are that it was an instrumentation problem" that did not threaten public health, said David Lochbaum, director of nuclear safety for the Union of Concerned Scientists, which advocates safety in the nuclear industry.

U.S. Rep. Jerry Weller (R-Ill.) requested NRC inspections last Wednesday, the day Exelon Nuclear announced radioactive tritium had leaked at Dresden Generating Station in Grundy County and Byron Nuclear Generating Station, about 25 miles southwest of Rockford. Earlier, Exelon had disclosed four tritium spills at Braidwood Generating Station in far southwest Will County between 1996 and 2003. As a result, tritium was found in groundwater outside the plant at levels that exceed U.S. Environmental Protection Agency standards.

Braidwood, Dresden and LaSalle all are in Weller s district."All being in the news at the same time ... all within a matter of weeks, certainly raises issues among my constituents," Weller said after a meeting with NRC, local and state officials. He was referring to both the tritium spills and the site-area emergency. Weller said he was particularly concerned that the public only learned about the tritium spills, a potential public health threat, late last year even though the first leak occurred a decade ago. By contrast, the site-area emergency was declared immediately, he noted.

"Exelon is responsible for what has occurred," Weller said, referring to tritium leaks. "We believe Exelon is responsible for fixing what has occurred. And we also believe Exelon should be held accountable for what has occurred." NRC spokesman Jan Strasma said the inspections would focus on systems that handle tritium, a byproduct of nuclear generation, at all of the state s nuclear facilities, seven of which are owned and operated by Exelon Nuclear.

Tritium can enter the body through ingestion, absorption or inhalation. Exposure can increase the risk of cancer, birth defects and genetic damage. The EPA considers it one of the least dangerous radioactive substances, in part because it leaves the body relatively quickly, but anti-nuclear activists have expressed concerns about the effects of chronic exposure.

Weller and state Rep. Careen Gordon (D-Coal City), who was among several state and local officials who attended the meeting with NRC officials at Weller s office, said they were reviewing disclosure requirements for the nuclear industry. "We believe a community has a right to know," Weller said.

At LaSalle, workers were shutting down a reactor for refueling at 12:28 a.m. Monday when the plant s turbine control system malfunctioned, triggering an automatic shutdown, according to a preliminary NRC analysis. Plant instruments indicated three of 185 control rods used to shut down the reactor were not fully inserted. If more than one control rod doesn t insert properly, a site-area emergency must be declared, said Craig Nesbit, an Exelon Nuclear spokesman. A site-area emergency, the second highest of four NRC emergency categories, indicates an actual or likely major failure, but one that is unlikely to cause a release of radioactivity beyond the plant s boundaries.

After the shutdown was triggered and the site-area emergency declared, workers reset their instruments, which then indicated only one control rod had not been inserted properly, Nesbit said. Meanwhile, the instruments indicated the reactor had completely shut down, he added. When the automatic shutdown started, the reactor was operating at 6 percent of its power. Exelon was shutting it down for a refueling that typically takes three to four weeks.

Nesbit and officials from the NRC and Illinois Emergency Management Agency all said later Monday it was not clear whether the one rod was inserted properly. It is possible the instrument readings wrongly indicated it had not, they said. A reactor can be completely shut down even if one control rod is not properly inserted, Strasma said.

If more than one control rod couldn t be properly inserted, nuclear fuel could have escaped into the cooling water, Lochbaum of the Union of Concerned Scientists said. That would have required a clean-up operation and brought radioactivity one barrier closer to the public, he said. "You reduce the margin of safety," said Strasma, who added that no radioactive substances were released during the emergency, which ended at 4:27 a.m.

"There actually wasn t a danger to the public during that time," said Patti Thompson, spokeswoman for Illinois Emergency Management Agency, which responded to the event along with the NRC. The last site-area emergency was declared in 1991 at Nine Mile Point 2 reactor in New York when power was lost to key instruments used to monitor the reactor, Strasma confirmed. NRC officials later said they would conduct a special investigation at LaSalle, and Nesbit said he expected Exelon to have a better idea Tuesday of what caused the malfunction.

Paul Gunter, director of the Reactor Watchdog Project at the Nuclear Information and Resource Service, said Monday s event at LaSalle "is an indication of aging of plant systems. It could very well be that it was a failure of sensor equipment." The event occurred at Unit 1, which entered service in 1982. Unit 2, which remained in operation Monday, entered service two years later.
(Chicago Tribune, 21/02/06)