Safety of One Firm’s Nuclear Reactors to Be Probed by NRC

The Nuclear Regulatory Commission will reassess the long-term safety of nuclear reactors designed by the Babcock & Wilcox Co., according to Victor Stello, the agency’s acting executive director for operations.

But Stello said in a statement issued here Monday that the NRC staff believes the reactors, including the Rancho Seco nuclear plant near Sacramento, can operate safely in the interim.

“The NRC has recognized since the Three Mile Island accident in 1979 that Babcock and Wilcox plants are more sensitive in their response to operational events than other pressurized water reactors,” the statement said.

“A number of recent events has reinforced the concerns about these plants and led the staff to conclude that the re-evaluation is necessary,” Stello said.

One such “event” occurred at Rancho Seco in December, when a power failure led to what authorities called a minor leak of radioactive steam into the atmosphere. An NRC official later said that a crucial design difference between the Rancho Seco control system and the one used to train its operators--and the operators of other Babcock & Wilcox plants--may have contributed to the leak.

The NRC said its staff intends to determine if the current requirements for Babcock & Wilcox reactors are “appropriate for the long term and lead to a level of safety at these reactors that is comparable to other pressurized water reactors.”

The statement added, “The assessment will include thermal-hydraulic design, instrumentation, controls and power supplies along with a review of operating experience and operator training and responses.”

The NRC said utilities have been making modifications at Babcock & Wilcox plants but “the number and complexity of events has not decreased as expected. The staff also recognizes that there are significant differences among plants that need to be considered.”