The evolving plan for most of the KE and KW Basin sludges is disposition to WIPP as remote handled (RH) TRU. Because the hydrogen gas concentration in the sealed transportation cask destined for WIPP is limited by flammability safety, the number of containers and shipments to WIPP likely will be driven by the rate of hydrogen generated by the contained uranium metal’s reaction with water. Therefore, gas generation testing with uranium metal particles of known surface area and immobilized in candidate (grout) solidification matrices was used to identify the effectiveness of various candidate solidification matrices to inhibit the rate of the uranium metal-water reaction.