Washington (Platts)--24Mar2011/113 pm EDT/1713 GMT

Exelon's nuclear fleet continues to operate safely and no immediate changes are needed to address issues raised by the ongoing crisis at Japan's Fukushima I plant, Exelon Chairman and CEO John Rowe said Thursday.

"I believe that there is little opening for new nuclear plants in the near future, but that view has come from economics, not safety," Rowe said on a webcast for Exelon investors and analysts. "I believe that plants in the US are safe, especially those at Exelon, and we continue to give safety number-one priority."

Exelon owns and operates 17 nuclear power units, the nation's largest commercial fleet.

Some enhancements will surely be made as a result of reviews being conducted of the Fukushima accident, but "we're not seeing any cost disaster for our nuclear fleet here," Rowe said.

Operators are conducting walkdowns and reviewing safety systems at Exelon's nuclear units, Rowe said, and the US Nuclear Regulatory Commission and nuclear industry are conducting their own reviews.

Rowe said the cost of upgrades that might be required cannot be estimated, even to within an order of magnitude, "because we simply don't know what kind of changes are being talked about for what plants, and indeed no one knows at the moment."

Exelon should have a better sense of what actions might be required "in about six months," when some of these reviews have been completed, Chris Crane, president and chief operating officer at Exelon, said on the webcast.

Exelon said in 2009 that it did not plan to build new nuclear units and would focus instead on capacity uprates at its existing nuclear plants. It said at the time the uprates were expected to add from 1,300 MW to 1,500 MW of capacity over the next several years, the equivalent of one large new nuclear unit.

The company does not expect at this point to change its power uprate plans, though it will review lessons learned from the accident at Fukushima and incorporate changes if and as needed, Rowe said.

Lessons learned from reviews of the Fukushima events will be available before Exelon must apply to US NRC for approval of the more significant capacity increases, so-called "extended power uprates," Rowe said.

Seven of Exelon's reactors are GE-design boiling water reactors, with so-called Mark I containments, similar to the Japanese reactors that were crippled March 11 following an earthquake and tsunami. Those Exelon units are Dresden-2 and -3 and Quad Cities-1 and -2 in Illinois, Oyster Creek in New Jersey, and Peach Bottom-2 and -3 in Pennsylvania.

Mark I BWRs in the US implemented "extensive modifications" in the early 1990s at the request of the NRC, "including design changes to control hydrogen and pressure through venting the containment," Crane said. Hydrogen buildup is believed to have caused explosions last week that destroyed three secondary reactor containment buildings at Fukushima.

Tokyo Electric Power Co. operators lost the ability to cool the Fukushima reactors and spent fuel pools after the earthquake cut offsite power to the plants and, about an hour later, the tsunami washed away fuel tanks for emergency diesel generators, leaving the plant without AC power. By contrast, fuel tanks for generators at Exelon's Mark I BWRs are buried underground or enclosed in vaults, Crane said. The Exelon units also have two different sources of offsite power, he said.

"None of Exelon's plants are in major earthquake zones," and the plants are "designed to withstand [the] highest level of seismic activity for that location, with additional margin," Exelon said in slides accompanying the webcast. None of Exelon's nuclear units are in areas in danger of tsunamis, but the plants are designed to withstand severe flooding, Crane said.

Exelon has various means to replenish water in spent fuel pools at its reactors, even if their cooling systems were to be compromised, Chip Pardee, chief operating officer at Exelon Generation, said on the webcast.

--Steven Dolley, steven_dolley@platts.com

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