AGENCY FINDS ERRORS IN NUCLEAR REFUELING.

Byline: Matthew L. Wald The New York Times

The Nuclear Regulatory Commission has concluded that troubling refueling errors that occurred at a Connecticut nuclear plant were common at 14 other reactors around the country. But it said the utilities had moved to correct the problem.

The errors involve the way many nuclear fuel assemblies are removed from a reactor when a plant is refueled, a process that involves replacing one-third of the assemblies.

Reactor operators at Northeast Utilities' Millstone 1 plant in Waterford, Conn., had been removing all the assemblies and temporarily storing them in the plant's spent fuel pool.

Theoretically, an abundance of assemblies in the pool, especially ones recently removed from a reactor, could generate so much heat that cooling water would boil away, raising the possibility that the fuel would melt down outside the reactor and release radioactivity into the atmosphere.

After employees at Millstone brought the storage problem to the commission's attention, top managers at the commission ordered a survey of all 110 commercial reactors in the United States. The survey found that the practice was common, possibly because it reduces radiation exposure for plant workers.

In a report made public last week, the commission staff said the practice violated the license conditions of some plants because their pools had never been analyzed to see if they could hold all the fuel.

The reactors are Cooper, in Brownville, Neb., owned by the Nebraska Public Power District; McGuire 1 and 2, in Cowans Ford Dam, S.C., and Oconee 1, 2 and 3, in Lake Keowee, S.C., all owned by Duke Power Co.; North Anna 1 and 2, in Mineral, Va., owned mainly by the Virginia Electric & Power Co.; South Texas 1 and 2, in Matagorda County, of which Houston Lighting & Power Co. is the biggest owner; Summer, in Jenkinsville, S.C., of which South Carolina Electric & Gas Co. is the biggest owner; Turkey Point 3 and 4, near Miami, owned by Florida Power & Light Co.; and Alvin W. Vobtle, in Waynesboro, Ga., of which Georgia Power Co. is the biggest owner.

The NRC staff said all representatives of all the plants promised to study their fuel pools to determine if they are threatened with overheating and, if they are, to change storage practices before the next refueling. Another option was to increase the cooling capacity of the pools.

A spokesman for Duke Power Co., Richard Zuercher, said that when the three-reactor Oconee plant first opened in 1973, engineers had intended to remove only one-third of the fuel during refueling, but decided by 1982 that it was safer and easier to remove all of it.

``We analyzed it long before we did it,'' he said, and found the cooling capacity adequate to handle the whole core.

Paul Blanch, a former engineer at Northeast Utilities, said the utilities should have corrected the problems long ago. The NRC sent a notice to utilities late last year warning them to check for problems in the ways they handled spent fuel, Blanch said.