The five members of the Nuclear Regulatory Commission voted yesterday to allow the start-up of the Sequoyah nuclear power plant near Chattanooga, ending the 11-month halt on licensing that had been in effect since the accident at Three Mile Island.

A temporary license approved by the NRC yesterday afternoon will permit the Tennessee Valley Authority to load the Sequoyah reactor with uranium fuel, initiate its chain reaction and run the plant at low power levels not to exceed 5 percent of its full capacity of 1.14 million kilowatts.

The commission insisted that its action did not mean that it was beginning a process that would lead to licensing other nuclear power plants.

"What we've done here is the equivalent of giving an airplane crew permission to taxi on the runway," NRC Commissioner Peter Bradford said after the commissioners met to approve the Sequoyah testing license."It's a far cry from giving them permission to fly the plane."

Bradford said the halt to licensing would not end until the NRC granted a full operating permit to a nuclear plant. He said, "That won't happen until the commission establishes that the conditions have been met for a full operating license."

Commissioner Joseph M. Hendrie put it a little differently. He said the document the five commissioners were giving TVA was clearly a license, but added that he did not think the issuing of the license was an irreversible move if the NRC should decide not to grant TVA a permanent operating license.

Harold Denton, director of nuclear regulation for the NRC, told the commissioners the staff wanted to grant the fuel-loading license to TVA because the Sequoyah plant satisfied all public health and safety questions up to that point.

Denton said the Sequoyah plant would not suffer shutdowns like the one at Crystal River, Fla., because it had backup power supplies that would not black out its instrument control panel in case of a failure.

"We've assessed the generic implications of the Crystal River incident," Denton said, "and we do not feel they impact a plant like Sequoyah."

Denton said the NRC staff still had to assess a number of safety issues on the Sequoyah plant before suggesting a full operating license. Among the issues: periodic checking of flaws in water injection nozzles and a full inspection of the turbine, because a similar turbine had broken down at the Yankee-Rowe nuclear plant in Franklin, Mass.

Still weeks ahead of the NRC are three operating license requests.One is from Virginia Electric Power Co. for its North Anna 2 reactor, a second from Public Service Electric and Gas Co. for its Salem 2 reactor in southern New Jersey and the third from Pacific Gas & Electric Co. for its Diablo Canyon plant in California.