The Nuclear Regulatory Commission will likely fall behind schedule in issuing a key safety measure designed for U.S. power plants in the wake of Japan’s nuclear reactor meltdown last year, the agency’s chairman told a Senate committee Thursday.

The North Anna Nuclear power pant in Mineral, Va. (John McDonnell/THE WASHINGTON POST)

NRC Chairman Gregory Jaczko said U.S. nuclear power plants would likely miss the agency’s five-year goal for implementing orders aimed at avoiding the effects of earthquakes on the plants. An agency task force on the Japanese disaster said the measures should be put in place at the nation’s 104 nuclear power plants by 2016.

But Jaczko said the earliest completion date for key seismic upgrades at the plants would be in 2017, and 2019 for low-risk plants.

“This is an area in which we recognize that there is new information that tells us the plants may not be designed to the right seismic standards. For this one to be taking so long is a bit of a concern to me,” Jaczko said.

Commissioner George Apostolakis told Sen. Barbara Boxer (D-Calif.), chairman of the Senate panel, that plants in California would complete their seismic upgrades within five years.

Jaczko said that in the next few days, the NRC will begin taking comments from nuclear power plant officials on a proposed rule that would require the plants to maintain operations during blackouts indefinitely. Currently plants are required to maintain functions during four to eight hours of blackouts. In Japan, the plant lost power during the tsunami and earthquake, which speeded its meltdown.

On Monday, the NRC officially issued three orders to the nation’s power plants, Jaczko said: Plants must develop and implement measures to keep spent fuel rods cool after an extreme natural disaster; they are required to have sturdier venting systems to help prevent pressure-induced explosions; and they must have a reliable read of water levels in spent fuel containers.

The orders were considered the highest priority by the NRC task force on the Fukushima disaster, which issued its recommendations in July.

At the hearing, the commissioners worked to assure the Senate panel that a Fukushima-like event would not happen in the United States.

“Our infrastructure, our regulatory approach, our practices at plants, our equipment, our configuration, our designed basis, would prevent Fukushima from occurring under similar circumstances at a U.S. plant,” said commissioner William Magwood. “I just don’t think it would happen. But we can still improve, and we are going to improve.”

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