The Commission is authorized to purchase any interest in facilities for the production of special nuclear materials, or in real property on which such facilities are located, without regard to the provisions of upon certification by the Commission that such action is necessary in the interest of the common defense and security, or upon a showing by the Commission that advertising is not reasonably practicable. Partial and advance payments may be made under contracts for such purposes. The Commission is further authorized to requisition, condemn, or otherwise acquire any interest in such production facilities, or to condemn or otherwise acquire such real property, and just compensation shall be made therefor.section 6101 of title 41