ROCKVILLE, Md. — A top official with the Nuclear Regulatory Commission said Monday that the nuclear crisis in Japan did not warrant any immediate changes at U.S. nuclear plants.
The commission's inspectors at each site have been told to double-check that emergency equipment and precautions mandated years ago were still in place, including temporary hoses and fittings and other last-ditch backup equipment, said the official, William Borchardt, the executive director for operations.
The inspectors were also asked to verify that plant operators knew where the equipment and materials were, Borchardt said, "to make sure they haven't fallen into disuse because they haven't been used.
"Every single day, we assess whether or not there is some additional regulatory action that needs to be taken immediately in order to address the information we have to date," he said in a briefing to the commission.
The NRC is to vote soon on a plan to conduct a 90-day study of the significance of the Japanese events for U.S. reactors, the commission's chairman, Gregory Jaczko, said, with updates after 30 and 60 days. But Borchardt and other staff members have said repeatedly that they did not yet have a full picture of events in Fukushima.
The information emerging is sometimes contradictory. While the primary containment for two of the reactors was previously reported to have been damaged by explosions, Borchardt said that at this point they "appear to be functional." He was referring to the steel shells, shaped like inverted light bulbs, that surround the reactor vessels and a doughnut-shaped pool of water around them used for pressure suppression.
The secondary containment structures, the weaker, boxy buildings that also enclose the spent-fuel pools, have been heavily damaged by hydrogen explosions. That hydrogen was presumably created by fuel damage in the reactor vessels, and then vented to the secondary containment.
One question for U.S. regulators is whether steps they have ordered in the past 20 years, to "harden" the vent pipes, had also been taken in Japan, or whether at Fukushima those vents were only ductwork that was overpressurized when workers opened valves to release excess pressure from the primary containment.
That is one of many questions that must be answered to determine the extent to which U.S. plants are subject to the same hazards.
NRC officials said they were confident about preparations already in place but open to improvements. During the 90-minute briefing, two commissioners used the phrase "systematic and methodical" to describe the approach they wanted to use in applying lessons from Japan to America's nuclear plants.
As if to underscore the point, a different department of the commission announced Monday that the NRC had issued a 20-year license extension to the Vermont Yankee reactor, which is a near twin of Fukushima Daiichi No. 1. Commission officials said that if the accident in Japan showed a need for changes in Vermont or elsewhere, they would order them promptly, even before the 20-year extension began.
One commissioner, Kristine L. Svinicki, said, "Some may characterize that our faith in this technology is shaken." But she added: "Nuclear safety is not and cannot be a matter of faith. It must be a matter of fact."
The commission has sent 11 staff members to Tokyo, where they are helping U.S. Embassy officials to understand what is happening and, as commissioners put it, "interacting" with their counterparts at the Japanese nuclear safety agency and executives at Tokyo Electric Power Co.
Jaczko said Sunday that there were no plans to send the NRC staff members to Fukushima itself. Commission officials said that two more NRC groups would travel to Japan this week.