[NukeNet] Monticello accident prompts alert to other nuclear plants

[Mike Ewall]

Entergy Nuclear owns three reactors affected by the steam valve weld 
failure in MN.

*Monticello accident prompts alert to other nuclear plants*
Tom Meersman <mailto:meersman at startribune.com>, Star Tribune

Federal officials have alerted the owners of four nuclear power 
plants about a potential safety problem that caused an automatic 
shutdown last week at Xcel Energy's Monticello nuclear plant in Minnesota.

"Typically when there's a problem at one plant, we look to see if any 
aspects have the potential of applying to other plants," said Jan 
Strasma, spokesman for the Nuclear Regulatory Commission. "It's a 
precautionary or prudent notification."

At the time of the Jan. 10 incident, Monticello had been operating 
for a record 637 consecutive days, 161 days longer than ever before, 
according to Xcel officials. Typically nuclear plants shut down for 
refueling every 18 to 20 months, and are out of service for four to 
five weeks, during which utilities also schedule major maintenance 
and inspections.

The Monticello plant remained closed Wednesday, one week after a 
35,000-pound control box broke loose from its support beams and fell 
about a foot onto a large pipe carrying radioactive steam. The pipe 
did not rupture or leak.

Strasma said his agency has notified managers of four Northeast 
plants similar to Monticello in age, design, and layout about the 
incident in Minnesota. The plants are Vermont Yankee, Oyster Creek in 
New Jersey, Nine Mile Point in New York and Pilgrim in Massachusetts, he said.

The Monticello plant, about 45 miles northwest of the Twin Cities, 
began operating in 1970.

Two months ago Xcel received federal permission to extend the plant's 
license for 20 years after its current license expires in 2010. State 
regulators have! also gi ven the utility permission to expand 
radioactive-waste storage in casks outside the plant, but the 
Minnesota Legislature has the option to review that decision.

Suspicion has focused on the control box's welds, which may have been 
weakened by vibrations.

Charles Bomberger, Xcel's general manager for nuclear asset 
management, said the steam pipe struck by the falling box didn't 
rupture. He said steam pipes are designed, anchored and tensioned to 
withstand much more severe shocks and stresses, including earthquakes.

Even if the pipe had leaked, only a small amount of steam would have 
been released and isolated within the plant, Bomberger said.

"I don't want to sugarcoat it; this was a significant problem," 
Bomberger said. "It's got the full attention of Xcel." The utility 
will fully evaluate the cause of the problem, repair it, check for 
other possible damage and report everything to federal authorities, he said.

"We anticipate a relatively short-term outage that will be measured 
in days, not weeks," he said. "I think we have our arms around what caused it."

George Crocker, a nuclear safety advocate in Lake Elmo, said the 
incident should be a warning for several reasons.

"Market forces that push nuclear plants to the limit, coupled with 
aging issues, coupled with the lack of understanding about how these 
components and materials perform over time as they're subjected 
thermally and radiologically -- all of these factors are increasing 
the likelihood that a really unforgiving event will occur," said 
Crocker, executive dirrector of the North American Water Office.

The group is a nonprofit organization that has raised concerns about 
nuclear problems for more than two decades and also works on 
renewable-energy policy.

Bomberger rejected the notion that Monticello has been pushed to the 
limit, or that it's risky. Nuclear plants have multiple backup 
systems to provide layers of safety, he said. Maintenance occurs on 
many parts and sy! stems ev en while the plant is at full power 
production, he said enabling Monticello to run for longer periods 
between shutdowns.

Bomberger said that setting records for consecutive days of operation 
shows that Monticello is being operated more efficiently, and that 
equipment failure and other problems are more likely when a plant is 
stopped and started than when it's running at a constant rate.

"I firmly do not believe that just because we have a long continuous 
run that we are running the equipment harder and that's it's going to 
wear out faster," he said.

Tom Meersman • 612 673-7388 • meersman at startribune.com 
<mailto:meersman at startribune.com>