Before the Commission enters into any arrangement or amendment thereto under the authority of this section, the basis for the proposed arrangement or amendment thereto which the Commission proposes to execute (with necessary background and explanatory data) shall be submitted to the Energy Committees (as defined by section
2014 of this title), 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 on which either House is not in session because of adjournment of more than three days: Provided, however, That the Energy Committees, after having received the basis for the proposed arrangement or amendment thereto, may by resolution in writing waive the conditions of, or all or any portion of, such forty-five-day period.