Mar 1, 2009

DOE awards Iron Phosphate-Based Glasses for Immobilizing high Molybdenum Containing Waste

Glass is considered a preferred matrix for immobilization of nuclear waste through a fusion and melt vitrification process, and currently the only glass that is approved for this purpose is based on borosilicate composition. Unfortunately, many nuclear waste streams contain components that are either poorly soluble or chemically incompatible in borosilicate glasses.

A poor solubility restricts the waste loading and increases the waste form volume, causing an increase in both cost and storage space. One such waste stream that is generated from recycling of commercial spent nuclear fuel (SNF) undertaken by Advanced Fuel Cycle Initiative (AFCI) Program of DoE contains a high concentration of molybdenum along with combined cesium/strontium (Cs/Sr) + lanthanide (LnFP) + transition metal (TMFP) fission product, see Table 1 and the Statement of Work (SOW) in Attachment 1 for the complete range of components in the waste stream.

Many of these elements, particularly molybdenum, are marginally soluble[1] in borosilicate glasses so an alternative glass (or glasses) possessing a higher solubility limit for these elements would result in a higher waste loading. This task of developing an acceptable glass waste form for immobilizing high molybdenum AFCI waste stream has been undertaken jointly by Pacific Northwest National Laboratory (PNNL) and Savannah River National Laboratory (SRNL). MO‐SCI Corporation is submitting this proposal in response to the attached SOW prepared by PNNL.