Several advocacy groups have petitioned the Nuclear Regulatory Commission to suspend reactor licensing until a full review of the Fukushima disaster in Japan is complete.

Public Citizen, Southern Alliance for Clean Energy and San Luis Obispo Mothers for Peace are among the organizations urging the NRC to delay licensing while the agency and a presidential commission conduct a full study of the Fukushima disaster's implications.

The Fukushima Daiichi nuclear power station, operated by Tokyo Electric Power Co., was hit by a tsunami in the wake of the Tohoku Earthquake on March 11. The tsunami knocked out the generators that ran the cooling systems. That resulted in a partial meltdown in at least one of the six reactors on the site, as well as hydrogen explosions that destroyed two reactor buildings. Spent fuel in a reactor that was already shut down for maintenance was damaged when the water that cools them partially boiled away.

At a press conference, the groups said they were concerned that the NRC was bowing to pressure from the nuclear industry and moving forward with new plant licenses. The major concern, they said, was that operators may not have studied what happens when grid power to cooling systems is lost.

Another issue is whether many plants that are already under construction may require expensive retrofits, the cost of which could ultimately fall on ratepayers.

Sara Barczak, high risk energy director at the Southern Alliance for Clean Energy, said the problem is that the nuclear industry has downplayed the seriousness of the Fukushima crisis and has pushed for building reactors whose safety is questionable.

Barczak pointed to the Bellefonte Nuclear Generating Station in Alabama as an example. The reactor is a 1960s-era design, as construction was originally started in the late 1970s before being suspended in 1988. She said only two other reactors of this type have been built and neither is still operating.

Dr. Arjun Makhijani, president, Institute for Energy and Environmental Research, said the biggest issue is that the Fukushima crisis is the first time a nuclear accident has involved spent fuel rods, and it is important to study what an accident that involves a loss of coolant would mean in American reactors.

Makhijani said the petition isn't a bid to stop constructing nuclear plants entirely or shut them all down, though some of the groups backing it might have that goal. I know we have 104 operating reactors, and we can't shut them down overnight, he said. We have a serious interest in keeping them safe while they are operating.

He added that opposition to nuclear power by environmentalists wasn't necessarily what stopped construction before. It was Wall Street, he said, noting that many companies were not seeing a sufficient return on investment.