(32b) Radioactive Demonstration of the Mineralization and Monolithing of a Melter Recycle Secondary Waste by Fluidized Bed Steam Reforming (FBSR)

Hanford is planning on vitrifying their salt supernate wastes also known as Low Activity Waste (LAW). The Hanford LAW vitrification facility has not yet been built but pilot scale melters have been operated with LAW simulants (non-radioactive Cs and I, and Re as a surrogate for Tc99) and the resulting treated off-gas condensate analyzed. The off-gas condensate is defined as the Waste Treatment Plant (WTP) secondary waste (SW) or (WTP-SW). It is the potential treatment of the WTP-SW stream via steam reforming that is addressed by this work. Recently, Savannah River National Laboratory (SRNL) has successfully operated a Bench scale Steam Reformer (BSR) in the SRNL Shielded Cell Facility (SCF) with radioactive Tank 48 material. The BSR is a unique SRNL design and this radioactive capability does not exist commercially nor at any other DOE site. SRNL also has expertise in monolithing waste and the analytical chemistry skills and equipment for measuring the durability of waste forms.

THOR® Treatment Technologies had performed a demonstration of the treatment of its proprietary THOR® process with a non-radioactive simulant at the Engineering Scale Technology Demonstration facilities located at Hazen Research, Inc. in Golden, CO. SRNL formulated the monolith chemistry to encapsulate the granular steam reformed product. SRNL also provided analytical chemistry support to measure properties of the small scale (2-in diameter by 4-in high) cylindrical monoliths generated from those granular products produced.

SRNL was then tasked to perform a radioactive demonstration of the THOR® Steam Reforming technology using Savannah River Site Defense Waste Processing Facility (DWPF) melter off-gas condensate which was chemically adjusted to the expected WTP-SW stream both chemically and radioactively.

The scope of work for this presentation consists of: 1) receipt, analysis, and chemical adjustment of recycle from the DWPF melter, 2) evaporation of the off-gas condensate by approximately 20X, 3) doping the concentrate with radioactive Tc99 and mixtures of Cs137 (radioactive) and Cs133 (non-radioactive) and I125 (radioactive) and I127 (non-radioactive) to make the DWPF melter recycle composition mimic the anticipated WTP-SW at Hanford, 4) mineralizing the doped concentrate with kaolin in the Bench scale Steam Reformer, 5) forming geopolymeric monoliths with the steam reformer product, and 6) all the analytical, durability, and leach testing steps involved.