A permanent Silver Spring headquarters for the Nuclear Regulatory Commision and its 2,600 employes was approved yesterday by the House Public Works Committee, thus ending more than three years of dispute over where the scattered NRC offices would be consolidated. The committee also endorsed a temporary consolidation of all NRC employes in Bethesda -- where most already work in leased office space -- until the permanent Silver Spring headquarters can be built. The permanent headquarters building, to be located at an undetermined site near Silver Spring's Metro subway station, will cost $113 million, according to estimates, and take five to six years to build.

The proposed interim consolidation in Bethesda, expected to cost $3 million and take 18 months, now is being reviewed by the General Accounting Office.

Top NRC officials and the General services Administration have argued that both permanent and temporary consolidations should be in downtown Washington -- where NRC commissioners and their staff now have offices. The House Public Works Committee in 1978 endorsed a downtown site.

But intensive efforts by Maryland congressmen and the vast majority of NRC employes turned the tide. More than 80 percent of the NRC's staff lives in Montgomery County and works in half a dozen leased buildings in Bethesda, Silver Spring and Rockville.