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DOE OSTI2015

Office of River Protection Advanced Low-Activity Waste Glass Research and Development Plan

The U.S. Department of Energy Office of River Protection (ORP) has initiated and leads an integrated Advanced Waste Glass (AWG) program to increase the loading of Hanford tank wastes in glass while meeting melter lifetime expectancies and process, regulatory, and product performance requirements. The integrated ORP program is focused on providing a technical, science-based foundation for making key decisions regarding the successful operation of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) facilities in the context of an optimized River Protection Project (RPP) flowsheet. The fundamental data stemming from this program will support development of advanced glass formulations, key product performance and process control models, and tactical processing strategies to ensure safe and successful operations for both the low-activity waste (LAW) and high-level waste vitrification facilities. These activities will be conducted with the objective of improving the overall RPP mission by enhancing flexibility and reducing cost and schedule. The purpose of this advanced LAW glass research and development plan is to identify the near-term, mid-term, and longer-term research and development activities required to develop and validate advanced LAW glasses, property-composition models and their uncertainties, and an advanced glass algorithm to support WTP facility operations, including both Direct Feed LAW and full pretreatment flowsheets. Data are needed to develop, validate, and implement 1) new glass property-composition models and 2) a new glass formulation algorithm. Hence, this plan integrates specific studies associated with increasing the Na2O and SO3/halide concentrations in glass, because these components will ultimately dictate waste loadings for LAW vitrification. Of equal importance is the development of an efficient and economic strategy for 99Tc management. Specific and detailed studies are being implemented to understand the fate of Tc throughout the WTP flowsheet and the underlying mechanisms that dictate its partitioning between streams within the LAW vitrification facility. These studies are aimed at increasing the single-pass Tc retention in glass and the potential use of high-temperature mineral phases to capture Tc. The Tc-bearing mineral phases would be thermally stable and resistant to Tc release during feed melting reactions or they could serve as alternative waste forms. The LAW glass research and development is focused on reducing the total volume of LAW glass produced and minimizing the impact of (or potentially eliminating) the need for recycle.

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DOE OSTI2015

Laboratory Optimization Tests of Technetium Decontamination of Hanford Waste Treatment Plant Direct Feed Low Activity Waste Melter Off-Gas Condensate Simulant

The Hanford Waste Treatment and Immobilization Plant (WTP) Low Activity Waste (LAW) vitrification facility will generate an aqueous condensate recycle stream (LAW Off-Gas Condensate) from the off-gas system. The baseline plan for disposition of this stream is to send it to the WTP Pretreatment Facility, where it will be blended with LAW, concentrated by evaporation and recycled to the LAW vitrification facility. Alternate disposition of this stream would eliminate recycling of problematic components, and would enable less integrated operation of the LAW melter and the Pretreatment Facilities. Eliminating this stream from recycling within WTP would also decrease the LAW vitrification mission duration and quantity of glass waste.

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DOE OSTI2016

COMSOL Multiphysics Model for HLW Canister Filling

The U.S. Department of Energy (DOE) is building a Tank Waste Treatment and Immobilization Plant (WTP) at the Hanford Site in Washington to remediate 55 million gallons of radioactive waste that is being temporarily stored in 177 underground tanks. Efforts are being made to increase the loading of Hanford tank wastes in glass while meeting melter lifetime expectancies and process, regulatory, and product quality requirements. Wastes containing high concentrations of Al 2 O 3 and Na 2 O can contribute to nepheline (generally NaAlSiO 4 ) crystallization, which can sharply reduce the chemical durability of high level waste (HLW) glass. Nepheline crystallization can occur during slow cooling of the glass within the stainless steel canister. The purpose of this work was to develop a model that can be used to predict temperatures of the glass in a WTP HLW canister during filling and cooling. The intent of the model is to support scoping work in the laboratory. It is not intended to provide precise predictions of temperature profiles, but rather to provide a simplified representation of glass cooling profiles within a full scale, WTP HLW canister under various glass pouring rates. These data will be used to support laboratory studies for an improved understanding of the mechanisms of nepheline crystallization. The model was created using COMSOL Multiphysics, a commercially available software. The model results were compared to available experimental data, TRR-PLT-080, and were found to yield sufficient results for the scoping nature of the study. The simulated temperatures were within 60 ºC for the centerline, 0.0762m (3 inch) from centerline, and 0.2286m (9 inch) from centerline thermocouples once the thermocouples were covered with glass. The temperature difference between the experimental and simulated values reduced to 40 ºC, 4 hours after the thermocouple was covered, and down to 20 ºC, 6 hours after the thermocouple was covered. This level of precision is considered acceptable for the scoping nature of the model and the subsequent laboratory glass studies Using the model, two additional glass pouring cycles were conducted. Representative thermocouple data were plotted to show the variations between the two cycles. This provides preliminary data that will be used in laboratory experiments to determine the potential for controlling nepheline crystallization in glass by varying the glass pouring conditions.

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DOE OSTI2015

Laboratory Optimization Tests of Decontamination of Cs, Sr, and Actinides from Hanford Waste Treatment Plant Low Activity Waste Off-Gas Condensate Simulant

The Hanford Waste Treatment and Immobilization Plant (WTP) Low Activity Waste (LAW) vitrification facility will generate an aqueous condensate recycle stream (LAW Off-Gas Condensate) from the off-gas system. The baseline plan for disposition of this stream is to send it to the WTP Pretreatment Facility, where it will be blended with LAW, concentrated by evaporation and recycled to the LAW vitrification facility. Alternate disposition of this stream would eliminate recycling of problematic components, and would enable less integrated operation of the LAW melter and the Pretreatment Facilities. Eliminating this stream from recycling within WTP would also substantially decrease the LAW vitrification mission duration and quantity of glass waste.

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DOE OSTI2017

Investigation of variable compositions on the removal of technetium from Hanford Waste Treatment Plant low activity waste melter off-gas condensate simulant

The Low Activity Waste (LAW) vitrification facility at the Hanford Waste Treatment and Immobilization Plant (WTP) will generate an aqueous condensate recycle stream (LAW Off-Gas Condensate) from the offgas system. The plan for disposition of this stream during baseline operations is to send it to the WTP Pretreatment Facility, where it will be blended with LAW, concentrated by evaporation and recycled to the LAW vitrification facility again. The primary reason to recycle this stream is so that the semi-volatile 99 Tc isotope eventually becomes incorporated into the glass. This stream also contains non-radioactive salt components that are problematic in the melter, so diversion of this stream to another process would eliminate recycling of these salts and would enable simplified operation of the LAW melter and the Pretreatment Facilities. This diversion from recycling this stream within WTP would have the effect of decreasing the LAW vitrification mission duration and quantity of glass waste. The concept being tested here involves removing the 99 Tc so that the decontaminated aqueous stream, with the problematic salts, can be disposed elsewhere.

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DOE OSTI2017

Bench scale experiments for the remediation of Hanford Waste Treatment Plant low activity waste melter off-gas condensate

The Low Activity Waste (LAW) vitrification facility at the Hanford Waste Treatment and Immobilization Plant (WTP) will generate an aqueous condensate recycle stream (LAW Off-Gas Condensate) from the off-gas system. The plan for disposition of this stream during baseline operations is to send it to the WTP Pretreatment Facility, where it will be blended with LAW, concentrated by evaporation and recycled to the LAW vitrification facility again. The primary reason to recycle this stream is so that the semi-volatile 99Tc isotope eventually becomes incorporated into the glass. This stream also contains non-radioactive salt components that are problematic in the melter, so diversion of this stream to another process would eliminate recycling of these salts and would enable simplified operation of the LAW melter and the Pretreatment Facilities. This diversion from recycling this stream within WTP would have the effect of decreasing the LAW vitrification mission duration and quantity of glass waste. The concept being tested here involves removing the 99 Tc so that the decontaminated aqueous stream, with the problematic salts, can be disposed elsewhere.

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DOE OSTI2017

Standard High Solids Vessel Design De-inventory Simulant Qualification

The Hanford Tank Waste Treatment and Immobilization Plant (WTP) is working to develop a Standard High Solids Vessel Design (SHSVD) process vessel. To support testing of this new design, WTP engineering staff requested that a Newtonian simulant be developed that would represent the de-inventory (residual high-density tank solids cleanout) process. Its basis and target characteristics are defined in 24590-WTP-ES-ENG-16-021 and implemented through PNNL Test Plan TP-WTPSP-132 Rev. 1.0. This document describes the de-inventory Newtonian carrier fluid (DNCF) simulant composition that will satisfy the basis requirement to mimic the density (1.18 g/mL ± 0.1 g/mL) and viscosity (2.8 cP ± 0.5 cP) of 5 M NaOH at 25 °C.1 The simulant viscosity changes significantly with temperature. Therefore, various solution compositions may be required, dependent on the test stand process temperature range, to meet these requirements. Table ES.1 provides DNCF compositions at selected temperatures that will meet the density and viscosity specifications as well as the temperature range at which the solution will meet the acceptable viscosity tolerance.

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DOE OSTI2017

Simulant Basis for the Standard High Solids Vessel Design

The Waste Treatment and Immobilization Plant (WTP) is working to develop a Standard High Solids Vessel Design (SHSVD) process vessel. To support testing of this new design, WTP engineering staff requested that a Newtonian simulant and a non-Newtonian simulant be developed that would represent the Most Adverse Design Conditions (in development) with respect to mixing performance as specified by WTP. The majority of the simulant requirements are specified in 24590-PTF-RPT-PE-16-001, Rev. 0. The first step in this process is to develop the basis for these simulants. This document describes the basis for the properties of these two simulant types. The simulant recipes that meet this basis will be provided in a subsequent document.

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DOE OSTI2017

Enhanced LAW Glass Correlation - Phase 2 (Final Report, Rev. 0)

The Office of River Protection is examining options to optimize the LAW facility and LAW glass waste form. VSL and Atkins have evaluated several potential incremental improvements for ORP in support of its evaluation of WTP LAW facility optimization. The objective of the present work was to continue the development of an Enhanced LAW Glass Correlation that can be used to determine the appropriate waste loading, glass composition, and amounts and types of glass former additives for LAW processing at the WTP for any given LAW composition that is delivered to the LAW vitrification facility. The intent is that this correlation, along with the enhanced LAW glass property-composition models, can be used for LAW processing at the WTP with the higher waste loading LAW glass formulations that have been developed for ORP at the VSL.

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DOE OSTI2019

Effluent Management Facility Stack Monitor Qualification: Assessment with Surrogate Stacks

Sampling and monitoring at the Waste Treatment and Immobilization Plant (WTP) Effluent Management Facility (EMF) exhaust is required to meet the regulatory criteria that governs stacks that may exceed the 0.1-millirem per year threshold limit given in Title 40 of the Code of Federal Regulations, Part 61, National Emissions Standards for Hazardous Air Pollutants, Subpart H, National Emission Standard for Emissions of Radionuclides other than Radon from Department of Energy Facilities. As a result, the flow conditions and probe location must be within certain bounds as prescribed by the American National Standards Institute/Health Physics Society (ANSI/HPS) standard N13.1-1999. Compliance with the standard may be demonstrated by tests on the stack itself, or with a surrogate stack (i.e., a scale model or other geometrically similar stack). Pacific Northwest National Laboratory (PNNL) has performed scale model stack tests for 11 of the 20 emission points that are planned for the WTP. Additionally, PNNL has full scale stack results from Idaho National Laboratory and PNNL facility stacks to use as references. One or more WTP scale model stack results were expected to be appropriate as a surrogate stack to the EMF. This report describes the EMF stack monitoring location as well as an assessment of existing surrogate stacks used to qualify the EMF stack sampling location.

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DOE OSTI2019

Dead-End Filtration and Crystalline Silicotitanate Cesium Ion Exchange with Hanford Tank Waste AW-102

The Direct Feed Low-Activity Waste (DFLAW) flowsheet provides for the initial production of immobilized low-activity waste (ILAW) by feeding low-activity waste (LAW) directly from tank farms to the Hanford Tank Waste Treatment and Immobilization Plant (WTP) LAW facility for immobilization. Prior to the transfer of feed to the WTP LAW facility, tank supernatant waste will be pretreated by the Tank Side Cesium Removal (TSCR) system to meet the WTP LAW waste acceptance criteria (<3.18E-5 Ci 137Cs/mole of Na). This pretreatment facility will filter the waste to remove suspended solids and remove cesium from the waste stream through ion exchange. Bench-scale filtration testing of 7.4 liters of diluted of AW-102 supernate was conducted using dead-end filtration in the hot cells of the Radiochemical Processing Laboratory at Pacific Northwest National Laboratory. A Mott 70-mm disc filter (media grade 5) was used to capture solids. The filter area was adjusted to 2.2 in2 to match the planned TSCR supernate process volume to surface area ratio. There was no indication of filter fouling and no recoverable solids were observed on the filter. Ion exchange testing with the filtered, diluted AW-102 supernatant was conducted using crystalline silicotitanate (CST) ion exchange media. The IONSIV R9140-B CST was provided by Honeywell UOP, LLC in 2018 (Lot number 8056202-999). The column testing operations were prototypic to the intended Low-Activity Waste Pretreatment System operations in a lead-lag column format, although on a small-scale basis with 10-mL CST beds. The feed was processed downflow through the lead column and then through the lag column at ~1.8 bed volumes per hour (BV/h). After 88.6 BVs of feed processing, the volume in the feed bottle dropped below the inlet tube and the lead column fluid headspace was displaced with air. Feed processing was suspended while a new column was prepared and installed into the lead position. A total of 450 BVs of diluted AW-102 feed were processed through the new lead column; only 4.3% Cs breakthrough was achieved. This volume of feed was insufficient to generate useful Cs loading information without extrapolation. A straight-line extrapolation was used to determine the 50% breakthrough of the lead column and contract limit breakthrough from the lag. The values were found to be 1200 BVs and 930 BVs, respectively.

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DOE OSTI2019

Cesium Removal from Tank Waste Simulants Using Crystalline Silicotitanate at 12% and 100% TSCR Bed Heights

The Direct Feed Low-Activity Waste flowsheet provides for the early production of immobilized low-activity waste (LAW) by feeding waste directly from Hanford tank farms to the Hanford Tank Waste Treatment and Immobilization Plant (WTP) for vitrification. Prior to the transfer of feed to the WTP LAW Vitrification Facility, tank waste supernatant will be pretreated by the Tank Side Cesium Removal (TSCR) system to meet the WTP LAW waste acceptance criteria (<3.18E-5 Ci 137 Cs/mole of Na). This pretreatment will remove cesium from the waste stream using ion exchange (IX). The selected media for IX is crystalline silicotitanate (CST), product number UOP-IONSIV-R9140-B, manufactured by Honeywell UOP LLC (Des Plaines, IL). Testing was requested by Washington River Protection Solutions to better define IX processing using Low-Activity Waste Pretreatment System (LAWPS) prototypic IX unit operation process steps at full height and medium height. The information is intended to significantly contribute towards establishing accurate process flowsheets for the individual feed campaigns planned for the LAWPS. Column testing at both the medium (12% of the full bed height) and full height scales was conducted to evaluate process variables and scale up performance of Cs exchange onto the CST, Lot 8056202-999. Nominal process conditions used 5.6 M Na simulant processed at 1.8 bed volumes per hour (BV/h) at 20 °C. Process variables included 1) increased process temperature to 35 °C, 2) increased Na concentration to 6.0 M, 3) added organics to the 5.6 M Na simulant, and 4) flowrate changes. The medium scale tests used single columns containing 44 mL of <25 mesh CST in a 1.44 cm diameter column, 27 cm tall CST bed. The full height columns used lead/lag columns containing 1.15 L unsieved (as-received) CST in 2.54-cm-diameter columns, 226 cm tall CST beds. Two process flowrates were tested at the full height: 1.30 and 1.82 BV/h. IX testing with simulant solutions was conducted using TSCR prototypic IX unit operations: feed processing, feed displacement with 0.1 M NaOH, water rinse, and solution expulsion with compressed air.

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DOE OSTI2019

SRNL Report on Vendor Solicitation and Selective Ion-Electrode Testing

Effective operation of the Hanford Tank Waste Treatment and Immobilization Plant (WTP) will require information collected from sampling and/or monitoring to maintain environmental compliance, product quality, and operating efficiency. The U.S. Department of Energy (DOE) – Office of River Protection (ORP) recognizes the potential long-term benefit of developing real-time, in-line monitoring (RTIM) at the WTP to improve the current strategy of collecting tens of thousands of samples and analyzing them. In-line monitoring can decrease processing time associated with waiting for sample analysis, reduce workers’ exposure to radiation and chemical hazards, decrease secondary waste volumes, potentially improve product quality, and provide production support and enhance overall operational control. The Assistant Manager, WTP chartered an Integrated Technical Team (ITT), which includes personnel from the Savannah River National Laboratory (SRNL), Bechtel National, Inc., and DOE-ORP, to evaluate the capability and potential benefits of replacing routine sample collection requirements with real-time, in-line monitoring. The initial focus of the ITT is the Direct Feed Low Activity Waste (DFLAW) Program. This work scope is being performed in multiple phases. Phase 1 is Requirements and Opportunities Analysis, Phase 2 is Applications and Benefits Determination, and Phase 3 is Qualification and Demonstration. Phase 1 included 6 tasks and was completed by SRNL in 2017. The tasks in Phase 1 were: (1) determining the functional requirements for determining analytes and properties of streams, (2) determining the technical basis for process control, (3) determining the sampling points within the Low Activity Waste (LAW) facility and Effluent Management Facility (EMF), (4) data quality and management, (5) process control challenges, and (6) preparing a Preliminary Analysis Plan. DOE-ORP was briefed on the findings from the Phase 1 tasks and requested that Phase 2 work focus on establishing a basis for a materials balance approach that minimized process sampling. The Phase 2 work scope contains tasks to evaluate a materials balance only approach as well as continuing scoping evaluations for instruments that could be used for RTIM. The Phase 2 work scope was completed by both SRNL and Pacific Northwest National Laboratory (PNNL). The tasks performed in Phase 2 were: 1. Overall program administration and technical oversight 2. Evaluation of a Material Balance Approach, a. Evaluation of uncertainty of this approach compared to uncertainty of current methods b. Evaluation of automating the material balance within the framework of existing control software, c. Development of the methodology to obtain and evaluate data during cold commissioning to support a material balance approach, and d. Development of a framework to utilize during presentation of the revised approach to stakeholders and regulators. 3. Screening Evaluations of Instruments to Supplement the Material Balance Approach, a. AP-105 melter condensate evaluations, and b. Screening testing with simulants. 4. Evaluation of the current DFLAW feed qualification program to identify analytes that could be eliminated, a. Inorganic analytes, b. Radionuclides, and c. Organic analytes. This report describes the results of Task 3b, Screening testing with simulants. The Savannah River National Laboratory requested demonstrations of commercially available analytical instruments by the vendors or laboratory demonstration. The techniques tested included: Raman spectroscopy, Infrared spectroscopy (IR), laser induced breakdown spectroscopy (LIBS), X-Ray Fluorescence Spectroscopy (XRF), and ion-selective electrochemical probes. Additionally, the instrumentation would need to be durable enough to withstand the environment of the plant, preferably with little to no maintenance. The insertion point of the instrument would be dependent upon the instrumentation.

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DOE OSTI2019

Iodine Distribution During Evaporation of Hanford Waste Treatment Plant Direct Feed Low Activity Waste Effluent Management Facility Simulant

The Hanford Waste Treatment and Immobilization Plant (WTP) Low Activity Waste (LAW) vitrification facility will generate an aqueous condensate recycle stream from the off-gas system. The baseline plan for disposition of this stream during full WTP operations is to send it to the WTP Pretreatment Facility, where it will be blended with LAW, concentrated by evaporation, and recycled to the LAW vitrification facility. However, during the Direct Feed LAW (DFLAW) scenario, planned disposition of this stream involves concentrating the condensate in a new evaporator at the Effluent Management Facility (EMF) and returning it to the LAW melter. The LAW melter condensate stream will contain components, e.g. halides and sulfates, that are volatile at melter temperatures, have limited solubility in glass waste forms, and present a material corrosion concern. Further, some minor constituents in the melter condensate, such as volatile organic compounds and iodine, have been found to be at least partially volatile in the EMF. The condensate from the EMF will be sent to the Hanford Effluent Treatment Facility (ETF). The presence of some recalcitrant organics and iodine, as 129I, are expected to be problematic in the ETF. In order to better predict and prepare for the distribution of organics and 129I in the flowsheet, it is key to understand their chemistry and experimentally determine their behavior during evaporation. To do this, modeling and testing were performed to examine the speciation of iodine under relevant conditions, as well as determine partitioning of iodine and the organics in the EMF evaporator. This overall program examines the potential treatment and immobilization of the LAW melter condensate stream to enable alternative disposal. The objective of this task was to (1) perform modeling to determine the speciation and fate of iodine species, (2) prepare a simulant of the LAW Melter Off-gas Condensate expected during DFLAW operations, (3) spike in the key volatile organics and non-radioactive iodine, and (4) demonstrate evaporation in order to predict the final composition of the effluents from the EMF evaporator to aid in planning for their disposition. The results of the modeling of iodine speciation indicate that the iodine is expected to remain in the evaporator pot as iodide and possibly iodate ion if the pH is raised to 11.5-12, which is the planned condition for the EMF. Experimental testing confirmed that the iodide remained in the evaporator concentrate and was below detection limits in all condensate and knock-out pot samples, indicating it was not volatile. The organic nitrile compounds that were added to the simulant were absent from the evaporator feed solution, either lost through evaporation, or more likely, decomposition. The acetone and methylene chloride were below the target values in the feed and condensate samples, and were presumably lost to evaporation or decomposition.

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DOE OSTI2019

Review of Submerged Bed Scrubber Assumptions in the Hanford Waste Treatment and Immobilization Plant Bases and Requirements Document

A review was performed of the assumptions in the Hanford Waste Treatment and Immobilization Plant Bases and Requirements Document (BARD) for the Low Activity Waste (LAW) Submerged Bed Scrubber (SBS). This review was performed to evaluate how the assumptions impact the TOPSim process models that utilize the assumptions for system modeling. The RPP Integrated Flowsheet uses TOPSim to model the entire waste retrieval and treatment process for the Hanford tank waste. This model relies on a number of inputs, including the BARD. The BARD represents the basis for the WTP process models; as such, it contains some assumptions that are valid for the models that will not accurately reflect actual operation. For example, the amount of LAW condensate generated is overstated in the BARD to allow for conservatism in the design of the condensate handling unit operations. The assumptions in the BARD for the LAW SBS were reviewed to evaluate how actual operation could differ from the design basis assumptions. It should be noted that this review did not evaluate nor is it intended to address issues related to design of the WTP facility such that the information in this report is should not be viewed as issues with the design of the WTP facility nor should the information be used without additional evaluation to generate design concerns.

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DOE OSTI2019

Evaluation of a Material Balance Only and Material Balance with Real-Time In-line Monitoring Approaches for DFLAW Processing

The Assistant Manager, WTP chartered an Integrated Technical Team (ITT), which includes personnel from the Savannah River National Laboratory (SRNL), Pacific Northwest National Laboratory (PNNL), from the Savannah River National Laboratory (SRNL), Pacific Northwest National Laboratory (PNNL), Bechtel National, Inc., and DOE-ORP, to evaluate the capability and potential benefits of replacing sample collection/analyses requirements with real-time, in-line monitoring. The initial focus of the ITT is the Direct Feed Low Activity Waste (DFLAW) Program. This work scope is being performed in multiple phases. The Phase 2 work scope contains tasks to evaluate a materials balance only approach as well as continuing scoping evaluations for instruments that could be used for Real-Time In-Line Monitoring (RTIM). The Phase 2 work scope for evaluation of a materials balance approach was completed by both SRNL and PNNL and is documented in this report. The material balance evaluation included a review of the WTP Low Activity Waste (LAW) vitrification process as well as the WTP Effluent Management Facility (EMF) process. Sampling requirements and unit operations were reviewed to determine which sample requirements could be met with a material balance without significantly increasing processing or reporting uncertainties.

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DOE OSTI2019

Cold Crucible Vitrification of CST and Simulated Hanford Tank Waste

The Direct Feed Low-Activity Waste (DFLAW) flowsheet provides for the initial production of immobilized low-activity waste (ILAW) by feeding low-activity waste (LAW) from tank farms to the Hanford Waste Treatment and Immobilization Plant (WTP) LAW Facility for immobilization. Prior to the transfer of feed to the WTP LAW Vitrification Facility, tank supernatant waste will be pretreated by the Tank-Side Cesium Removal (TSCR) system to meet the WTP LAW waste acceptance criteria (<3.18× 10 -5 Ci 137 Cs/mole of Na). This pretreatment will remove cesium from the waste stream through ion exchange (IX). The selected media for IX is crystalline silicotitanate (CST).

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DOE OSTI2019

Impact of Crystalline Silicotitanate Particle Size on Cesium Removal Efficiency

Washington River Protection Solutions is working on a Tank-Side Cesium Removal (TSCR) system to remove Cs from Hanford tank waste supernate. Removal of 137 Cs from tank waste supernate by TSCR results in a low-activity waste (LAW) form that can be fed directly to the Hanford Waste Treatment and Immobilization Plant (WTP) LAW vitrification facility, where the supernate can be vitrified into a glass form. Crystalline silicotitanate (CST) ion exchange media, manufactured by Honeywell UOP, LLC (product IONSIV TM R9140-B), was selected for use as the ion exchange media to remove Cs at TSCR. The particle size used in testing is expected to impact the kinetic performance of the ion exchange media. Therefore, two single-column systems were tested with CST Lot 2002009604. One column contained <25 mesh sieve cut fraction and the other column contained <35 mesh sieve cut fraction. Flowrate through both test systems was adjusted to match the CST contact time expected for the full-scale operation, i.e., matched bed volumes per hour (BV/h) at 1.83 BV/h. The feed was processed downflow through the columns until ~1000 BVs of feed were processed. The waste acceptance criteria (WAC) limit for the WTP LAW vitrification facility is <3.18E-5 Ci 137 Cs per mole Na. For a tank waste containing 156 µCi/mL 137 Cs and 5.6 M Na, up to 0.114% of the influent 137 Cs concentration may be delivered to the WTP (based on 137 Cs content in AP-107 tank waste); this required a Cs decontamination factor of 876. The WAC limit was used as one of the relevant process parameters, along with the 50% breakthrough point, Cs loading per gram of CST, and the mass transfer zone.

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