The Commission may determine from time to time that other material is special nuclear material in addition to that specified in the definition as special nuclear material. Before making any such determination, the Commission must find that such material is capable of releasing substantial quantities of atomic energy and must find that the determination that such material is special nuclear material is in the interest of the common defense and security, and the President must have expressly assented in writing to the determination. The Commission’s determination, together with the assent of the President, shall be submitted to the Energy Committees and a period of thirty days shall elapse while Congress is in session (in computing such thirty days, there shall be excluded the days on which either House is not in session because of an adjournment for more than three days) before the determination of the Commission may become effective: Provided, however, That the Energy Committees, after having received such determination, may by resolution in writing, waive the conditions of or all or any portion of such thirty-day period.

The Commission is authorized, to the extent it deems necessary to effectuate the provisions of this chapter, to purchase without regard to the limitations in section 2074 of this title or any guaranteed purchase prices established pursuant to section 2076 of this title, and to take, requisition, condemn, or otherwise acquire any special nuclear material or any interest therein. Any contract of purchase made under this section may be made without regard to the provisions of section 6101 of title 41, 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. Just compensation shall be made for any right, property, or interest in property taken, requisitioned, or condemned under this section: Providing, That the authority in this section to commit United States funds for any activities pursuant to any subsequent arrangement under section 2160(a)(2)(E) of this title shall be subject to the requirements of section 2160 of this title.

The Commission shall establish guaranteed purchase prices for plutonium produced in a nuclear reactor by a person licensed under section 2134 of this title and delivered to the Commission before January 1, 1971. The Commission shall also establish for such periods of time as it may deem necessary, but not to exceed ten years as to any such period, guaranteed purchase prices for uranium enriched in the isotope 233 produced in a nuclear reactor by a person licensed under section 2133 or section 2134 and delivered to the Commission within the period of the guarantee. Guaranteed purchase prices established under the authority of this section shall not exceed the Commission’s determination of the estimated value of plutonium or uranium enriched in the isotope 233 as fuel in nuclear reactors, and such prices shall be established on a nondiscriminatory basis: Provided, That the Commission is authorized to establish such guaranteed purchase prices only for such plutonium or uranium enriched in the isotope 233 as the Commission shall determine is produced through the use of special nuclear material which was leased or sold by the Commission pursuant to section 2073 of this title.

Before the Commission establishes any guaranteed purchase price or guaranteed purchase price period in accordance with the provisions of section 2076 of this title, or establishes any criteria for the waiver of any charge for the use of special nuclear material licensed and distributed under section 2073 of this title, the proposed guaranteed purchase price, guaranteed purchase price period, or criteria for the waiver of such charge shall be submitted to the Energy Committees and a period of forty-five days shall elapse while Congress is in session (in computing such forty-five days there shall be excluded the days in which either House is not in session because of adjournment for more than three days): Provided, however, That the Energy Committees, after having received the proposed guaranteed purchase price, guaranteed purchase price period, or criteria for the waiver of such charge, may by resolution in writing waive the conditions of, or all or any portion of, such forty-five-day period.