Off-Gas Condensate and Cast Stone Analysis Results

Cantrell, Kirk J.; Leavy, Ian I.; Snyder, Michelle M.V.; Baum, Steven R.; Shen, Steve; Williams, Bruce A.; Saslow, Sarah A.; Krogstad, E. J.

doi:10.2172/1476714

Cited by 1 publication

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“…The initial waste received at the Radiochemical Processing Laboratory (RPL) was from tank 241-AP-105 (hereafter called AP-105). The AP-105 waste was filtered for the removal of solids (Geeting et al 2018a), it underwent ion exchange for the removal of cesium (Fiskum et al 2018), had GFCs added and was vitrified in a continuous laboratory-scale melter (CLSM) (Dixon et al 2018), and the condensate produced from vitrification was concentrated and converted to a non-glass waste form based on Cast Stone (Cantrell et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Vitrification of Hanford Tank Waste 241-AP-107 in a Continuous Laboratory-Scale Melter

Dixon

Stewart

Venarsky

et al. 2019

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Low-activity waste (LAW) stored in underground tanks on the Hanford Site in Washington State is planned to be filtered for solids removal and processed through ion exchange columns for cesium removal. These pretreatment steps will allow the waste to be transferred to the Hanford Tank Waste Treatment and Immobilization Plant's LAW Facility for immobilization into glass. The liquid waste will be combined with glass-forming chemicals (GFCs) to form a waste feed slurry that can be fed to electric melters for vitrification. The process of continuously converting the aqueous feed slurry into a melt is dynamic and includes multiple reactions, degassing, and dissolution processes that depend on heat from the melt below. In this conversion process, waste components are partitioned into one of two streams: glass and off-gas. Washington River Protection Solutions has requested processing information and chemical information associated with these waste products for actual waste from Hanford tank 241-AP-107 (referred to herein as AP-107). To acquire this type of information, a small-scale melter system was designed that would not require high volumes of input waste or the large resource commitment of a full-scale melter system, while also providing dynamic information that would be difficult to determine from batch reactions in a crucible system. A continuous laboratory-scale melter (CLSM) has been designed to operate with a continuous feeding process while periodically pouring glass product and collecting off-gas. The CLSM vessel has been sized to collect the relevant process and chemical information from obtainable volumes of AP-107 waste samples. A total 8.6 L of actual AP-107 tank waste were received after filtering for solids removal and ion exchange for cesium removal. This volume of AP-107 waste was mixed with GFCs to form an estimated 11.8 L of melter feed slurry. A mass of 7.01 kg of glass product were poured from the CLSM vessel during 10.07 hours of charging the AP-107 melter feed, indicating that about 15.0 kg of melter feed was vitrified into glass. These production values and other processing results from the AP-107 waste vitrification in the CLSM system are shown in Table ES.1. The CLSM system was also designed with the capability to fully divert the flow of off-gas produced in the CLSM vessel to a sampling line that could capture the volatile species of interest, such as technetium-99 (99 Tc). This novel sampling system avoided the difficulties of slipstream sampling and could be activated once the feeding reached a steady state within the CLSM vessel. Off-gas product samples captured via high-efficiency particulate air (HEPA) filters using this method, as well as selected glass product samples were sent to an analytical lab for chemical analysis. The calculated average retention of 99 Tc (mass of 99 Tc output in the glass per mass of 99 Tc input in the melter feed) during the off-gas sampling is shown in Table ES.1. The measured composition of the AP-107 glass product, compared to the target composition, is s...

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