WASTE SOLIDIFICATION BUILDING BENCH SCALE HIGH ACTIVITY WASTE SIMULANT VARIABILITY STUDY FY2008

Hansen, E ; Timothy Jones, T ; Tommy Edwards, T ; Alex Cozzi, A

关键词: AR FACILITIES;    ALUMINIUM;    AMERICIUM 241;    CEMENTS;    COPPER;    CURING;    FLOUR;    GALLIUM;    GROUTING;    HOT SPOTS;    MIXERS;    MIXTURES;    PHYSICAL PROPERTIES;    PORTLAND CEMENT;    SILVER;    SOLIDIFICATION;    STRESSES;    WASTE FORMS;    WASTES;    ZIRCON;   

DOI  :  10.2172/952437
RP-ID  :  SRNL-STI-2009-00101
PID  :  OSTI ID: 952437
Others  :  TRN: US0902506

学科分类：核能源与工程

美国|英语

来源: SciTech Connect

【 摘 要 】

The primary objective of this task was to perform a variability study of the high activity waste (HAW) acidic feed to determine the impact of feed variability on the quality of the final grout and on the mixability of the salt solution into the dry powders. The HAW acidic feeds were processed through the neutralization/pH process, targeting a final pH of 12. These fluids were then blended with the dry materials to make the final waste forms. A secondary objective was to determine if elemental substitution for cost prohibitive or toxic elements in the simulant affects the mixing response, thus providing a more economical simulant for use in full scale tests. Though not an objective, the HAW simulant used in the full scale tests was also tested and compared to the results from this task. A statistically designed test matrix was developed based on the maximum molarity inputs used to make the acidic solutions. The maximum molarity inputs were: 7.39 HNO{sub 3}, 0.11618 gallium, 0.5423 silver, and 1.1032 'other' metals based on their NO{sub 3}{sup -} contribution. Substitution of the elements aluminum for gallium and copper for silver was also considered in this test matrix, resulting in a total of 40 tests. During the NaOH addition, the neutralization/pH adjustment process was controlled to a maximum temperature of 60 C. The neutralized/pH adjusted simulants were blended with Portland cement and zircon flour at a water to cement mass ratio of 0.30. The mass ratio of zircon flour to Portland cement was 1/12. The grout was made using a Hobart N-50 mixer running at low speed for two minutes to incorporate and properly wet the dry solids with liquid and at medium speed for five minutes for mixing. The resulting fresh grout was measured for three consecutive yield stress measurements. The cured grout was measured for set, bleed, and density. Given the conditions of preparing the grout in this task, all of the grouts were visually well mixed prior to preparing the grouts for measurements. All of the cured grouts were measured for bleed and set. All of the cured grouts satisfied the bleed and set requirements, where no bleed water was observed on any of the grout samples after one day and all had set within 3 days of curing. This data indicates, for a well mixed product, bleed and set requirement are satisfied for the range of acidic feeds tested in this task. The yield stress measurements provide both an indication on the mixability of the salt solution with dry materials and an indication of how quickly the grout is starting to form structure. The inability to properly mix these two streams into a well mixed grout product will lead to a non-homogeneous mixture that will impact product quality. Product quality issues could be unmixed regions of dry material and hot spots having high concentrations of americium 241. Mixes that were more difficult to incorporate typically resulted in grouts with higher yield stresses. The mixability from these tests will provide Waste Solidification Building (WSB) an indication of which grouts will be more challenging to mix. The first yield stress measurements were statistically compared to a list of variables, specifically the batched chemicals used to make the acidic solutions. The first yield stress was also compared to the physical properties of the acidic solutions, physical and pH properties of the neutralized/pH adjusted solutions, and chemical and physical properties of the grout.