An attempt by the U.S. Nuclear Regulatory Commission to shorten and simplify the procedures for approving the construction of nuclear power plants was struck down yesterday by the U.S. Court of Appeals for the District of Columbia Circuit.

The court said that the NRC's "one-step" licensing rule, which would have enabled utilities to obtain construction and operating permits in the same proceeding, violates the Atomic Energy Act.

The rule was supported by the nuclear industry, which has not built any plants in more than a decade. The industry has feared that money spent to build a power plant under an NRC construction license would be wasted if a second, post-construction public hearing led to delays in obtaining an operating license. Such delays have cost nuclear operators billions of dollars in starting up power plants such as the one at Seabrook, N.H.

Anti-nuclear activists objected that the NRC's one-step licensing rule would have denied them a forum to question whether plants had been built in conformity with their construction licenses and could be operated safely. The court, in an opinion by Chief Judge Patricia McGowan Wald, agreed.

The law requires the NRC "to make specific findings after construction, including a finding that the plant will operate in conformity with the {Atomic Energy} Act," the court said. "When Congress requires 'findings,' it means findings -- not mere inferences. For the commission to 'find' that a plant conforms with the act simply because it conforms with a license issued years earlier is inadequate."

The NRC rule was never tested by an actual application. Industry spokesmen said when it was adopted they did not regard it as sufficient protection against public challenge. The industry wants the procedure adopted by Congress; in the last session, a one-step licensing bill failed by one vote in the House Energy and Commerce Committee.