Single-Pass Flow Through (SPFT) Testing of Fluidized-Bed Steam Reforming (FBSR) Waste Forms

Abstract

EXECUTIVE SUMMARYTwo samples of fluidized-bed steam reforming (FBSR) mineral waste form product were subjected to single-pass flow-through (SPFT) testing. Sample LAW 1123 resulted from pilot-scale FBSR processing with a Hanford Envelope A low-activity waste (LAW) simulant. Sample SBW 1173 resulted from pilot-scale FBSR processing with an Idaho National Laboratory (INL) simulant commonly referred to as sodium-bearing waste (SBW). The pilot-scale waste forms were made at the Science and Technology Applications Research (STAR) facility in Idaho Falls, Idaho. The durability of the two FBSR waste forms was assessed via the SPFT test in this study. Both samples were multiphase mineral waste forms, so the SPFT test results provide an overall release rate from the multiple mineral species in each sample and are dependent on the amount of each phase present and the mineralogy of the phases present. SPFT testing was performed at temperatures of 25°, 40°, 70°, and 90°C on LAW 1123, while SBW 1173 was only tested at 70° and 90°C. The 70° and 90°C data were compared to each other and the LAW-1123 results were compared to previous testing performed by the Pacific Northwest National Laboratory (PNNL) on a LAW Envelope C (high organic content) waste simulant.The objectives of this study were to obtain forward dissolution rate data for both STAR FBSR bed products (using SPFT tests). Also, a qualitative comparison of the FBSR bed products to a glass waste form (specifically the low-activity reference material (LRM) glass) was performed. For these comparisons, the relative surface areas of the FBSR and glass products had to be measured. Due to the more porous and irregular surface of FBSR bed products, the surface area of the bed products was determined using the Brunauer, Emmett, and Teller (BET) measurement method. The surface area of a glass is much smoother and the calculated geometric surface area is typically used for determining dissolution behavior.Presently there are no specifications or standard release rates that the FBSR tested materials have to meet, e.g. the data from the FBSR testing is normally used during subsequent Performance Assessment (PA) calculations. Since a PA calculation is not part of this study, the LAW and SBW steam reforming samples were compared to each other, to previous LAW FBSR SPFT results, and to the results from the LRM reference glass. The experimental durability data generated from this study suggests that an FBSR mineral waste form product would be an adequate alternative form to borosilicate glass. The tested FBSR mineral waste forms showed normalized release rates for matrix elements such as Si to be more than 200X slower than the LRM glass. However, further durability testing and mineral phase information is recommended to further substantiate these findings.

Fluidized Bed Steam Reformer (Fbsr) Product: Monolith Formation and Characterization

“…PCT Leachate standards and blanks (ppm) 28 Table 12. PCT Leachate Standards (g/L) 28 4,5,6 Hanford Envelope A and Envelope C simulants both performed well during PCT and SPFT testing and during subsequent performance assessment modeling. 5,7 This is partially due to the high aluminosilicate content of the mineral product which provides a natural aluminosilicate buffering mechanism 2,3,4 that inhibits leaching and is known to occur in naturally occurring aluminosilicate mineral analogs.…”

Radionuclide and Contaminant Immobilization in the Fluidized Bed Steam Reforming Waste Product

“…The measured BET surface areas were measured in this study on a carbon-free basis (coal removed by roasting), and the value measured by McGrail et al (2003a) (coal removed manually) was obtained for comparison. The geometric surface area is from Lorier et al (2005). …”

Secondary Waste Form Down-Selection Data Package—Fluidized Bed Steam Reforming Waste Form

“…Figure 6.3. A Picture of Disassembled PCT Vessel (Russell et al 2006) This protocol has been used at SRNL and is covered in several articles and reports published by Jantzen and her collaborators (Jantzen 2004(Jantzen , , 2006a(Jantzen , b, 2007(Jantzen , 2008Jantzen et al 2004;2005a, b;Lorier et al 2005;Pareizs et al 2005;Crawford and Jantzen 2007). The PCT has been conducted on both the granular FBSR product and on the FBSR product encapsulated in various binders.…”

“…They determined that this occurred at a flow rate of 140 mL/d or a q/S of 1.4  10 -9 m/s. Lorier et al (2005) used four temperatures, 25 °C, 40 °C, 70 °C and 90 °C and five buffer solutions for 14-16 days. They used 1 gram 1 of specimen in their tests.…”