(a) Conclusiveness; delegation of powers

Determinations and decisions provided in this Act to be made by the Administrator or other agency head shall be final. Such determinations or decisions may be made with respect to individual purchases or contracts or, except for determinations or decisions under sections 253, 253a, and 253b of this title, with respect to classes of purchases or contracts. Except as provided in section 253(d)(2) of this title, and except as provided in section 486(d) of title 40 with respect to the Administrator, the agency head is authorized to delegate his powers provided by this Act, including the making of such determinations and decisions, in his discretion and subject to his direction, to any other officer or officers or officials of the agency.

(b) Basis of determinations; finding conclusive; preservation of findings; copy

Each determination or decision required by section 254 or by section 255(d) of this title shall be based upon written findings made by the official making such determination, which findings shall be final and shall be available within the agency for a period of at least six years following the date of the determination