Bonds issued by the Corporation under this section shall be negotiable instruments unless otherwise specified therein, shall be in such forms and denominations, shall be sold at such times and in such amounts, shall mature at such time or times not more than fifty years from their respective dates, shall be sold at such prices, shall bear such rates of interest, may be redeemable before maturity at the option of the Corporation in such manner and at such times and redemption premiums, may be entitled to such relative priorities of claim on the Corporation’s net power proceeds with respect to principal and interest payments, and shall be subject to such other terms and conditions, as the Corporation may determine: Provided, That at least fifteen days before selling each issue of bonds hereunder (exclusive of any commitment shorter than one year) the Corporation shall advise the Secretary of the Treasury as to the amount, proposed date of sale, maturities, terms and conditions and expected rates of interest of the proposed issue in the fullest detail possible and, if the Secretary shall so request, shall consult with him or his designee thereon, but the sale and issuance of such bonds shall not be subject to approval by the Secretary of the Treasury except as to the time of issuance and the maximum rates of interest to be borne by the bonds: Provided further, That if the Secretary of the Treasury does not approve a proposed issue of bonds hereunder within seven working days following the date on which he is advised of the proposed sale, the Corporation may issue to the Secretary interim obligations in the amount of the proposed issue, which the Secretary is directed to purchase. In case the Corporation determines that a proposed issue of bonds hereunder cannot be sold on reasonable terms, it may issue to the Secretary interim obligations which the Secretary is authorized to purchase. Notwithstanding the foregoing provisions of this subsection, obligations issued by the Corporation to the Secretary shall not exceed $150,000,000 outstanding at any one time, shall mature on or before one year from date of issue, and shall bear interest equal to the average rate (rounded to the nearest one-eighth of a percent) on outstanding marketable obligations of the United States with maturities from dates of issue of one year or less as of the close of the month preceding the issuance of the obligations of the Corporation. If agreement is not reached within eight months concerning the issuance of any bonds which the Secretary has failed to approve, the Corporation may nevertheless proceed to sell such bonds on any date thereafter without approval by the Secretary in amount sufficient to retire the interim obligations issued to the Treasury and such interim obligations shall be retired from the proceeds of such bonds. For the purpose of any purchase of the Corporation’s obligations the Secretary of the Treasury is authorized to use as a public debt transaction the proceeds from the sale of any securities issued under chapter
31 of title
31, and the purposes for which securities may be issued under chapter
31 of title
31 are extended to include any purchases of the Corporation’s obligations hereunder. The Corporation may sell its bonds by negotiation or on the basis of competitive bids, subject to the right, if reserved, to reject all bids; may designate trustees, registrars, and paying agents in connection with said bonds and the issuance thereof; may arrange for audits of its accounts and for reports concerning its financial condition and operations by certified public accounting firms (which audits and reports shall be in addition to those required by sections
9105 and
9106 of title
31, may, subject to any covenants contained in any bond contract, invest the proceeds of any bonds and other funds under its control which derive from or pertain to its power program in any securities approved for investment of national bank funds and deposit said proceeds and other funds, subject to withdrawal by check or otherwise, in any Federal Reserve Bank or bank having membership in the Federal Reserve System; and may perform such other acts not prohibited by law as it deems necessary or desirable to accomplish the purposes of this section. Bonds issued by the Corporation hereunder shall contain a recital that they are issued pursuant to this section, and such recital shall be conclusive evidence of the regularity of the issuance and sale of such bonds and of their validity. The annual report of the Board filed pursuant to section
831h of this title shall contain a detailed statement of the operation of the provisions of this section during the year.