The Nuclear Regulatory Commission has decided it will not grant any operating or construction licenses for nuclear power plants until it adopts a new set of safety, siting and emergency standards.

The decision will be disclosed by the NRC tomorrow to the House Commerce subcommittee on energy and power, chaired by Rep. John Dingell (D-Mich.).

The move will prolong well into 1980 what has been a de facto moratorium on nuclear licenses since the accident at Three Mile Island last March 28. Just how long it will last depends on how quickly the NRC can draw up new licensing regulations.

At least four and as many as seven of the 92 nuclear plants under construction are sure to be stalled indefinitely by the NRC decision, including the North Anna 2 plant in Virginia.

Those seven plants, being built at a total cost of $8 billion, are so far along in construction that they would be ready to receive operating licenses before spring.

Four of them, including the North Anna plant, could have begun operating by the end of this year. The other three are Salem 2 in New Jersey, Diablo Canyon 1 in California and Sequoyah I in Tennessee. The three plants expected to be ready early next year are Zimmer in Ohio, McGuire in North Carolina and La Salle 1 in Illinois.

The NRC has decided it needs "a pause" to implement Three Mile Island lessons in currently operating plants, and then to sift through the 44 safety recommendations of the President's Commission on Three Mile Island, Harold Denton, director of nuclear reactor regulation, said in an interview. "Operating plans have got to be our first priority . . . but if it all goes well, I would think we could (resume licensing) by the springtime of 1980," he said.

If the NRC delays a startup of the North Anna unit, about 70 miles southwest of Washington, customers of Virginia Electric & Power Co. might see the impact in their utility bills. The Richmond-based firm has said it needs to begin operating the nuclear unit as soon as possible to reduce its dependence on generating plants that use more costly fossil fuels.

Even as the NRC told The Washington Post it was calling a halt to new licensing, two leading members of Congress involved in nuclear lawmaking said in separate interviews that they believe a three-year halt to new nuclear construction would be in the best interests of the United States.

"The moratorium I envision would say no more construction permits for three years or until the NRC certifies to Congress the lessons we learned from Three Mile Island," Rep. Morris K. Udall (D-Ariz.), chairman of the House Interior Committee and of its subcommittee on energy and the environment, said in an interview.

"I lean toward letting the plants finish that are under construction, but if we pass a moratorium that is conditional on safety and emergency plans then I think we're saying to the industry there are real serious safety questions," Udall said.

Sen. Gary Hart (D-Colo.), chairman of the Senate Environment subcommittee on nuclear regulation, says, "I think that new construction permits and licenses should be help up pending the adoption of new siting and safety policies. I would agree with Mo (Udall) that a three-year halt to new construction might sound right."

Neither Hart or Udall would say whether the Senate or House would follow their lead on a construction moratorium, but both feel that sentiment has shifted toward a moratorium since Three Mile Island.

"There's been a perceptible shift in the House," Udall said. "And I think the House has generally been a little more positive on nuclear than the Senate. I think everybody's moved over about 15 to 20 degrees."

Sources said that when the NRC tells Congress tomorrow about its plans to hold up nuclear licensing, it will also reveal that it is considering a drastic change in siting policy against plants located close to large population centers.

One source said that proposals being considered by the NRC include one to shut down plants sited 10 miles or less from large cities. Two being looked at most closely are the Indian Point plants of Consolidated Edison Co., north of New York City and the Zion plant of Commonwealth Edison Co., just outside Chicago.

"We've got a range of options facing us now about these two plants that range all the way from additional plant features to shutting the plants down," the NRC source said. "It's going to require a more detailed look, but it's clear that with these two plants and maybe some others we've got some severe problems."

The presidential commission that investigated Three Mile Island found that one of the most serious lessons to be learned had to do with the location of nuclear plants. Had the Pennsylvania accident been any worse, the commission concluded, as many as 1 million persons would have required evacuation from their homes.

The NRC is reviewing its emergency evacuation procedures and is understood to have come to a tentative finding that it cannot safely evacuate the regions around plants like Indian Point, should that ever be necessary. Said a highly placed NRC source: "There are just too many people involved. We've going to find out that we can't move that many people."

In the House and Senate, Udall and Hart are now writing amendments to the Atomic Energy Act of 1954 that would take the Three Mile Island accident into account. Udall and Hart agree that the amendments most likely to pass Congress are those that impose stiffer penalties on electric companies for safety violations.

Udall and Hart said they will ask to raise the civil penalty limits for NRC rules violations from $5,000 to $100,000 drop the monthly limit of $25,000, and seek to impose a maximum fine for each violation of as much as $700,000.

Hart and Udall also said they will seek a bill that suspends or revokes a nuclear plant's license for violations as serious as those at Three Mile Island.

While the NRC has fined Met Ed $155,000 in civil penalties, it is not finished with its investigation of how Met Ed should be punished for its role in the accident.

The NRC's Office of Inspection and Enforcement is still investigating why Met Ed didn't inform it of: radiation escapes the first day of the accident that ranged from 10 to 40 rems an hour, a suspected hydrogen explosion inside the containment, and superheated (2,500 degrees) temperatures inside the uranium fuel package that suggested that at least part of the reactor core was no longer covered by cooling water.

"We've argued about whether there's anything criminal here," an NRC source said. "But to be criminal, it would have to be willful and so far we haven't seen anything that's willful. In spite of that we should have been told these things, and there's a lot of turmoil here about this phase of the investigation."

One amendment Udall said he will attempt to make to the Atomic Energy Act would call for escalated civil penalties for repeat violations and for criminal penalties for flagrant violations of NRC rules.

"I think flagrant violations have to be considered criminal," Udall said. "I think we've got to assess it and look at it in that context."

Hart, Udall and NRC Chairman Joseph M. Hendrie all agree that the report last week by the President's Commission on Three Mile Island stiffened their resolve to get tougher on nuclear safety. The irony is that none of them agrees with the stiffest recommendation in that report, which is to abolish the five-member, independent NRC and create a new agency in the executive branch run by a single administrator.