Feb 25 - Knight Ridder/Tribune Business News - Robert Manor Chicago Tribune

Another problem struck an Exelon Corp. nuclear plant when electrical equipment Friday unexpectedly began giving off smoke at the Byron Generating Station, located about 90 miles west of Chicago.

Although relatively minor, the incident was at least the fourth problem to hit an Exelon nuclear plant since Monday.

"It's not been a good week," said Craig Nesbit, spokesman for Chicago-based Exelon's nuclear operation.

Operators at Byron declared "an unusual event," the lowest of four federal emergency classifications, at 8:54 a.m. after smoke was found in a room connecting two buildings at the Byron Unit 1 reactor.

Nesbit said the smoke came from a pump, electrical breaker and small heater that function to keep water in an outdoor tank from freezing in cold weather. Among other purposes, he said, the tank is a backup source of water to cool the reactor in an emergency.

Exelon said that there were no injuries and no release of radiation, and that the plant continued to operate normally. The smoke stopped after power was cut to the equipment.

The most serious of the week's problems came on Monday, when Exelon declared an emergency at its LaSalle County Generating Station. Because of an equipment malfunction, plant operators could not confirm that the Unit 1 reactor had properly shut down. Later investigation showed it had.

On Wednesday, undetermined electrical problems forced the shutdown of the 34-year-old Quad Cities 1 reactor, the latest of several setbacks at the nuclear plant. The plant is in Cordova, Ill., across the Mississippi River from Davenport, Iowa.

Nesbit said electrical problems outside the plant caused the reactor to shut down automatically as a protective measure. Exelon is investigating the nature of the problem, he said.

Such unplanned reactor shutdowns are not rare.

"Some plants may have none in a year, some might have one, some might have more," he said.

But the two Quad Cities reactors have been running at 85 percent of capacity since the start of the year, Nesbit said. Quad Cities 2 reactor was shut down for two days in late December and Quad Cities 1 for two days in January so technicians could fix equipment needed to release steam from the reactor in case of an emergency.

Nesbit said the equipment apparently had been damaged by vibration that began after the reactor's generating capacity was increased in 2002. The Nuclear Regulatory Commission allowed Exelon to increase each reactor's output to 912 megawatts from 819.

In mid-2005, the two reactors were shut down for a total of 13 days as Exelon retrofitted other equipment apparently damaged by vibration.

On Thursday, Exelon was forced to shut down the Limerick Unit 2 reactor in southeastern Pennsylvania, about 40 miles northwest of Philadelphia. Equipment needed to release steam from the reactor during emergencies was found to have malfunctioned. The problem was different from the one at Quad Cities.

The problems this week come against the backdrop of the investigation into radiation leaks at three Exelon nuclear plants.

Water containing tritium has leaked at the Dresden Generating Station in Grundy County and at the Byron plant.

Earlier, Exelon had disclosed four tritium spills at its 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.

Exelon and the Nuclear Regulatory Commission are investigating the leaks.

 

 

rmanor@tribune.com