Three riders to the supplemental appropriation for the Nuclear Regulatory Commission would change reactor licensing methods to speed them up, and also would freeze nuclear critics and the public out of the licensing process, the Union of Concerned Scientists charged yesterday.

The appropriations subcommittee on energy and water development, in a recent closed session, tacked on riders that "would impose an impossible burden on citizens," said Ellyn Weiss, UCS general counsel.

The subcommittee's report accompanying the bill defends the changes as "intended to better focus the scope of hearings to pertinent issues," arguing that "the hearing process has taken on an inordinate role with little substantive value" and should be streamlined.

One of the riders would require anyone raising safety or other issues to support them first with "a prima facie evidentiary showing of substantial and specific facts . . . supported by affidavits of persons having personal knowledge of the facts" before a hearing could be granted. That amounts to a legal case, Weiss said, and it would have to be prepared even before the NRC staff is required to release its safety conclusions.

Another appropriations rider would prohibit anyone except formal parties to the case from raising any issues before the NRC's licensing board. "This means that neither the public nor the NRC's outside experts not the licensing board itself can raise any safety issue that the utility and the NRC staff has ignored," Weiss said.

The third rider would keep the board from considering the financial status of the utility or any other issue considered in the earlier granting of a construction permit, ever though those conditions might have changed.

"Apparently some advocates of nuclear power still believe that the industry's problems can be wished away by silencing its critics," Weiss said. "That is the mind-set that brought on the Three Mile Island accident."

Rep. Tom Bevill (D-Ala.), chairman of the subcommittee, declined to comment on Weiss' view of the bill pending floor debate today. But Bevill has frequently lashed the NRC for licensing delays he said totaled nearly seven years for 13 backlogged plants and cost ratepayers $3 billion in extra charges.