There is established a revolving fund, under the control of the Secretary, which shall be available without fiscal year limitation for all expenses necessary for the redemption (by the Secretary) of real property as provided in section
7425
(d) and section
2410 of title
28 of the United States Code. There are authorized to be appropriated from time to time such sums (not to exceed $10,000,000 in the aggregate) as may be necessary to carry out the purposes of this section.