Abstract: A solar oven that includes a multiple zone concentrator and a diffuse focal zone is disclosed. The solar oven may include at least one element of symmetry. In such a case, the diffuse focal zone substantially aligns with the oven symmetry element. The diffuse focal zone may include a central region and a peripheral region. The multiple zone concentrator has at least one reflective member for directing radiation to a plurality of portions of the diffuse reflective zone. The reflective member has a first reflective zone and a second reflective zone. The first reflective zone may include at least one of zonal element of symmetry offset from the oven symmetry element. Also, the first reflective zone has a profile that captures and directs radiation to at least a portion of the peripheral region of the diffuse focal zone.

Abstract: A solar oven that includes a multiple zone concentrator and a diffuse focal zone is disclosed. The solar oven may include at least one element of symmetry. In such a case, the diffuse focal zone substantially aligns with the oven symmetry element. The diffuse focal zone may include a central region and a peripheral region. The multiple zone concentrator has at least one reflective member for directing radiation to a plurality of portions of the diffuse reflective zone. The reflective member has a first reflective zone and a second reflective zone. The first reflective zone may include at least one of zonal element of symmetry offset from the oven symmetry element. Also, the first reflective zone has a profile that captures and directs radiation to at least a portion of the peripheral region of the diffuse focal zone.

Abstract: A method for immobilizing fission product radioactive iodine recovered from irradiated nuclear fuel comprises combining material comprising water, Portland cement and about 3-20 wt. % iodine as Ba(IO.sub.3).sub.2 to provide a fluid mixture and allowing the fluid mixture to harden, said Ba(IO.sub.3).sub.2 comprising said radioactive iodine. An article for solid waste disposal comprises concrete prepared by this method.BACKGROUND OF THE INVENTIONThis invention was made in the course of, or under a contract with the Energy Research and Development Administration. It relates in general to reactor waste solidification and more specifically to the immobilization of fission product radioactive iodine recovered from irradiated nuclear fuel for underground storage.