The top U.S. nuclear regulator said today there's no meaningful difference in safety between submerging spent nuclear fuel in water and encasing it in concrete casks.

"We don't have technical information that says it is safer to be in one or the other," Nuclear Regulatory Commission Chairman Gregory Jaczko told a House Appropriations subcommittee.

"The likelihood of anything happening is so small, it's hard to say that one is safer than the other. It's like [the odds of] winning the Powerball versus winning another lottery."

Nuclear activists and some congressional Democrats have warned that the Japan nuclear disaster shows the NRC has allowed a dangerous situation to exist for years with the storage of spent nuclear fuel.

Sen. Dianne Feinstein (D-Calif.) said Tuesday that the NRC should look at requiring nuclear plants to encase spent fuel in "dry" concrete containers instead of allowing it to remain in pools for years (Greenwire, March 30).

She complained that some nuclear fuel being stored in water was placed there in 1984.

Jaczko told Feinstein the NRC will be renewing its inquiry into the safety of spent fuel pools. But he stressed that his agency's regulations are strong and assured senators on the panel that the pools can safely store the spent fuel for up to 100 years.

The NRC requires spent fuel to be kept in pools for some time after it is removed from a reactor core. But it imposes no limit on how long the fuel can stay in the ponds before being moved to more hardened containers.

In the United States, most spent fuel remains on site at nuclear plants because the country has not developed a facility to store it. Congress and other federal entities have been debating for years whether to build a long-term storage facility at Yucca Mountain, Nev.

The United States has 71,862 tons of the waste, according to a recent analysis by the Associated Press.

Three-quarters of that waste is stored in water-filled cooling pools like those at the Japanese plant, stored outside the thick concrete containment barriers that block the release of radioactive material in an accident. The rest is encased in "dry casks" constructed of steel and thick concrete.

Jaczko also told the Energy and Water Subcommittee that his agency has enough money to conduct safety reviews in the wake of the Japan nuclear crisis and continue licensing nuclear reactors.

"We have the resources to continue with the licensing procedures," Jaczko said. "Right now, we're continuing to move forward with the licensing issues that we have."

Rep. Denny Rehberg (R-Mont.) told Jaczko he worries about a shift similar to what he called "the overreaction in the Gulf," referring to a permitting slowdown in the Gulf of Mexico after the BP PLC spill last year.

"I don't want to see this come to a halt as a result of something that happened somewhere else," Rehberg said.

Jaczko didn't address the situation in the Gulf, which is at the center of a finger-pointing match between congressional Republicans and the Obama administration. Republicans say Obama is hampering domestic production, and the administration has accused industry of sitting on leases and permits.

Some congressional Democrats have called for a moratorium on license renewal and new license reviews for U.S. reactors until the problems in Japan are better understood. But the Obama administration is opposed to halting the license reviews.

About half of the U.S. reactors have already received license renewals for an additional 20 years of operation. NRC is currently conducting a two-pronged safety review as a result of the crisis at Japan's Fukushima Daiichi reactor, Jaczko said.

There is a 90-day review that he termed a "quick look" to see if there are any immediate changes suggested for the United States as a result of the overheating reactor. A six-month review, he explained, will seek to determine "what really are the causes of the challenges in Japan."

He said the NRC is "cataloging" the costs of its responses to the Japan crisis, but doesn't expect to have to ask for more money in a supplemental appropriations request.

"I don't foresee that now," Jaczko said, "but it's very much evolving situation."

Rep. Nita Lowey (D-N.Y.) pressed Jaczko on the safety of the Indian Point nuclear reactor near New York City, where some residents and elected officials are pushing for closure of the plant. Jaczko rejected the criticism.

"We believe Indian Point is safe," Jaczko said. "In the very unlikely event something would happen, the right steps would be taken to protect the nearby population."