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Posted on Sun, Mar. 17, 2002 story:PUB_DESC
Reactor realities
What does Davis-Besse damage mean?

Beacon Journal business writer

The Davis-Besse nuclear power plant survived a direct hit from a tornado.

Now it's trying to recover from a cavity.

That hole, discovered in a vital safety system, caused some 50 nuclear power experts to converge on the FirstEnergy Corp. plant in Oak Harbor, 25 miles east of Toledo. One group is charged with figuring out how boric acid ate a 6-inch-deep cavity in the plant's reactor vessel head. Another is devising a way to safely repair the 150-ton vessel head and get the plant operating.

The meter is running.

Every month the plant is down, the Akron-based company will spend $10 million to $15 million buying electricity to meet its customers' needs. Actual repairs are expected to cost another $5 million to $10 million.

How long such expenses will eat into FirstEnergy's $655 million in annual profit is unknown. Company officials hope to have the repair done by the end of May.

Some other utilities, though, have not been so fortunate when it comes to making repairs.

American Electric Power's Cook nuclear units in Michigan were shut down for more than 30 months starting in 1997 because of safety concerns, and were allowed to restart in 2000.

FirstEnergy officials don't expect such a lengthy shutdown. But the uncertainties surrounding Davis-Besse have made some Wall Street investors skittish, driving the company's stock down 7.8 percent since the problem was announced Monday.

What's more, nobody's sure how the plant closure might affect the electricity supply just yet. The last time Davis-Besse shut down unexpectedly was in 1998, when it was hit by a tornado. Davis-Besse's 883 megawatts of power is about 14 percent of FirstEnergy's generating capacity.

Although the plant was restarted within weeks, record temperatures and a sizzling economy had increased demand for electricity across the state to the point where FirstEnergy and other Ohio utilities had to ask their big industrial customers to cut back on their usage to prevent major blackouts.

Much has changed since then. The economy has cooled off. And new, specialized power plants have been built that run during times of high demand.

Restart initiative

But company officials are anxious to get Davis-Besse back online before the peak months of July and August.

So FirstEnergy is preparing to pour tens of millions of dollars into a hole 6 inches deep.

FirstEnergy, which announced the discovery of the cavity on Monday, hopes Davis-Besse will be making electricity again no later than the end of June, about when summer electricity usage begins to peak.

But that depends on a number of ifs:

If engineers and scientists don't find additional problems during their investigation. If they determine what caused the cavity and find a way to prevent new ones from starting. And if the Nuclear Regulatory Commission allows the repairs they devise.

``Based on what we know now, 60 to 90 days (past March 31) looks reasonable,'' Davis-Besse spokesman Richard Wilkins said. Still, he and others acknowledge the plant could be down longer.

``We consider ourselves to be in the preliminary stages of this,'' Wilkins said of the investigation.

`This place is full of engineers. And engineers love to fix,'' Wilkins said.

The problem ahead

What they have to fix is the hole the acid created when it ate through the carbon-steel portion of the 6 3/8-inch-thick reactor vessel head. The acid stopped when it ran into the 3/8-inch-thick stainless-steel lining.

The cavity was discovered after the plant was shut down in mid-February for refueling and a safety inspection.

The NRC mandated that 12 pressurized-water reactors, including Davis-Besse, undergo special inspections after cracks and leaking were discovered in 2000 and 2001 at some nuclear plants on parts called controlrod drive mechanism nozzles. The nozzles lead into the reactor vessel.

All inspections were supposed to have been done by Dec. 31, but FirstEnergy persuaded the NRC to delay the Davis-Besse inspection until February's scheduled refueling shutdown.

As a result, the Nuclear Regulatory Commission may take a harder line at granting extensions for plant safety inspections, said David Lochbaum, a nuclear engineer who now works for the Union of Concerned Scientists. ``The NRC was accommodating (to FirstEnergy) and got burnt,'' he said.

Ultrasonic tests found that five of Davis-Besse's 69 nozzles were cracked; one of those nozzles was severely corroded, and closer inspection revealed the underlying cavity, which is 4 by 5 inches wide. The cracks apparently allowed boronic water to leak through the nozzles and turn into boric acid.

The NRC has asked the nation's 102 other nuclear power plants to check for signs of similar cracks and cavities.

Dave Lockwood, Davis-Besse's regulatory affairs manager who is the go-between for FirstEnergy and government officials, is among the 50 people working to find what caused the cavity and then devise a solution.

``It's very methodical,'' Lockwood said of the ongoing efforts.

The ``root cause'' team is looking at data and records going back years, conducting interviews and doing research to determine how, and when, the cavity formed, Lockwood said.

One group starts at 6:30 each morning, talking with and reviewing actions taken by another group that worked overnight in the plant, he said.

That's followed by a 10 a.m. phone conference with engineers. Team leaders meet at noon to share information. At 2 p.m., the NRC gets an update. Then the night crew gets briefed when they come in, he said.

Until they determine what caused the cavity, they can't devise a way to permanently fix the problem, he said.

A tricky fix

There's also an outside chance that there are other cavities, or the start of cavities, elsewhere on the reactor head.

Whatever repairs are devised would have to withstand an environment of constant temperatures of 600 degrees Fahrenheit and pressures of 2,500 pounds per square inch.

Another option is to replace the entire damaged reactor vessel head -- FirstEnergy already has one on order but said it could take two years to make and then be installed.

Davis-Besse, which went online in 1977, has a license that expires in 2017, and it's likely FirstEnergy will seek to extend the license 20 years beyond that.

Brian Sheron, associate director at the NRC whose office is supervising the Davis-Besse investigation, said there was no danger. Even if the cavity had breached the reactor vessel, it would not have released radiation into the environment or led to the worst-case scenario, a meltdown of the plant's nuclear fuel, he said.

Any hole in the vessel would have allowed primary coolant to leak into the heavily reinforced dome where it would be contained, he said. Safety devices would have shut the reactor down immediately, he said.

That kind of accident would have shut the reactor down for a long, long time, he said. Any such breach would have been incredibly messy and costly for FirstEnergy to clean up, he said.

``It doesn't come close to Three Mile Island'' in terms of severity, Sheron said, referring to the 1979 partial core meltdown of a nuclear plant near Harrisburg, Pa.

Even so, Sheron said, ``Nobody likes to challenge safety systems. You want a reliable design rather than depend on a safety system.''

Learning opportunity

The nuclear energy industry is watching the Davis-Besse plant situation.

Depending on what is learned at Davis-Besse, there's the chance a number of the other 68 pressurized-water reactors around the country may have to undergo special inspections and be taken down temporarily to check for the same problem.

``It's too early to tell the impact on the industry,'' said Melanie Lyons, spokeswoman for the Nuclear Energy Institute, the Washington-based organization that represents nuclear power producers.

``Certainly the industry is taking it seriously. Corrosion is one of the issues we're looking at,'' said Chuck Welty, director of technology applications for EPRI, the Electric Power Research Institute in Palo Alto, Calif., that works with nuclear power providers. It sent a staff member to Davis-Besse to aid the investigation.

Lochbaum, of the Union of Concerned Scientists, described the damage to the Davis-Besse reactor head as ``pretty substantial.''

But he said the most important thing that should develop from the discovery of the cavity is how to better inspect nuclear reactors in the future.

``The information will be shared with all other (nuclear plant) owners. That way the other plants benefit from Davis-Besse,'' he said.


Jim Mackinnon can be reached at 330-996-3544 or jmackinnon@thebeaconjournal.com
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