Washing of the AW-101 entrained solids

BNFL Inc. (BNFL) is under contract with the US Department of Energy, River Protection Project (DOE-RPP) to design, construct, and operate facilities for treating wastes stored in the single-shell and double-shell tanks at the Hanford Site, Richland, Washington. The DOE-BNFL RPP contract identifies two feeds to the waste treatment plant: (1) primarily liquid low-activity waste (LAW) consisting of less than 2 wt% entrained solids and (2) high-level waste (HLW) consisting of 10 to 200 g/L solids slurry. This report describes the results of a test conducted by Battelle to assess the effects of inhibited water washing on the composition of the entrained solids in the diluted AW-101 low-activity waste (LAW) sample. The objective of this work was to gather data on the solubility of the AW-101 entrained solids in 0.01 M NaOH, so that BNFL can evaluate whether these solids require caustic leaching. The work was conducted according to test plan BNFL-TP-29953-9, Rev. 0, LAW Entrained Solids Water Wash and Caustic Leach Testing. The test went according to plan, with no deviations from the test plan. Based on the results of the 0.01 M NaOH washing, a decision was made by BNFL to not proceed with the caustic leaching test. The composition of the washed solids was such that caustic leaching would not result in significant reduction in the immobilized HLW volume

Status Report on Phase Identification in Hanford Tank Sludges

The US Department of Energy plans to vitrify Hanford's tank wastes. The vitrified wastes will be divided into low-activity and high-level fractions. There is an effort to reduce the quantity of high-activity wastes by removing nonradioactive components because of the high costs involved in treating high-level waste. Pretreatment options, such as caustic leaching, to selectively remove nonradioactive components are being investigated. The effectiveness of these proposed processes for removing nonradioactive components depends on the chemical phases in the tank sludges. This review summarizes the chemical phases identified to date in Hanford tank sludges

AN-107 entrained solids - Solubility versus temperature

This report describes the results of a test conducted by Battelle to assess the solubility of the solids entrained in the diluted AN-107 low-activity waste (LAW) sample. BNFL requested Battelle to dilute the AN-107 sample using sodium hydroxide and de-ionized water to mimic expected plant operating conditions. BNFL further requested Battelle to assess the solubility of the solids present in the diluted AN-107 sample versus temperature conditions of 30, 40, and 50 C. BNFL requested these tests to assess the composition of the LAW supernatant and solids versus expected plant-operating conditions

AW-101 entrained solids - Solubility versus temperature

This report describes the results of a test conducted by Battelle to assess the solubility of the solids entrained in the diluted AW-101 low-activity waste (LAW) sample. BNFL requested Battelle to dilute the AW-1-1 sample using de-ionized water to mimic expected plant operating conditions. BNFL further requested Battelle to assess the solubility of the solids present in the diluted AW-101 sample versus temperature conditions of 30, 40, and 50 C. BNFL requested these tests to assess the composition of the LAW supernatant and solids versus expected plant-operating conditions. The work was conducted according to test plan BNFL-TP-29953-7, Rev. 0, Determination of the Solubility of LAW Entrained Solids. The test went according to plan, with no deviations from the test plan

Washing and Caustic Leaching of Hanford Tank Sludge: Results of FY 1998 Studies

Sludge washing and parametric caustic leaching tests were performed on sludge samples tiom five Hanford tanks: B-101, BX-1 10, BX-112, C-102, and S-101. These studies examined the effects of both dilute hydroxide washing and caustic leaching on the composition of the residual sludge solids. ` Dilute hydroxide washing removed from <1 to 25% of the Al, -20 to 45% of the Cr, -25 to 97% of the P, and 63 to 99% of the Na from the Hdord tank sludge samples examined. The partial removal of these elements was likely due to the presence of water-soluble sodium salts of aluminate, chromate, hydroxide, nitrate, nitrite, and phosphate, either in the interstitial liquid or as dried salts

Removal of Sulfate Ion From AN-107 by Evaporation

Hanford low-activity waste solutions contain sulfate, which can cause accelerated corrosion of the vitrification melter and unacceptable operating conditions. A method is needed to selectively separate sulfate from the waste. An experiment was conducted to evaluate evaporation for removing sulfate ion from Tank AN-107 low-activity waste. Two evaporation steps were performed. In the first step, the volume was reduced by 55% while in the second step, the liquid volume was reduced another 22%. Analysis of the solids precipitated during these evaporations revealed that large amounts of sodium nitrate and nitrite co-precipitated with sodium sulfate. Many other waste components precipitated as well. It can be concluded that sulfate removal by precipitation is not selective, and thus, evaporation is not a viable option for removing sulfate from the AN-107 liquid