Any reservation of radioactive mineral substances, fissionable materials, or source material, together with the right to enter upon the land and prospect for, mine, and remove the same, inserted pursuant to Executive Order 9613 of September 13, 1945, Executive Order 9701 of March 4, 1946, the Atomic Energy Act of 1946 [42
et seq.], or Executive Order 9908 of December 5, 1947, in any patent, conveyance, lease, permit, or other authorization or instrument disposing of any interest in public or acquired lands of the United States, is released, remised, and quitclaimed to the person or persons entitled upon August 19, 1958 under the grant from the United States or successive grants to the ownership, occupancy, or use of the land under the applicable Federal or State laws: Provided, however, That in cases where any such reservation on acquired lands of the United States has been heretofore released, remised, or quitclaimed subsequent to August 12, 1954, in reliance upon authority deemed to have been contained in the Atomic Energy Act of 1946, as amended, or the Atomic Energy Act of 1954 [42
et seq.], as heretofore amended, the same shall be valid and effective in all respects to the same extent as if public lands and not acquired lands had been involved. The foregoing release shall be subject to any rights which may have been granted by the United States pursuant to any such reservation, but the releases shall be subrogated to the rights of the United States.