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18 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

HZ-PAN and AgZ-PAN Desorption Characterization

While previous research focused on adsorption of Kr and Xe on HZ-PAN and AgZ-PAN, recent focus has shifted to desorption. Preliminary testing was completed last year, providing valuable information to guild further research. Preliminary studies indicated that thermal swing operations, along with a sweep gas, are required for effective desorption from both AgZ-PAN and HZ-PAN. This series of tests focused on characterizing the bulk gases removed from each sorbent and relative separation of Kr and Xe from each other and from the bulk air. Single stage adsorption/ resulted in 99-100% separation of Xe from Kr, and 77-83% separation of Kr from air while concentrating Xe seven to tenfold and Kr three to fivefold when Xe is not present. Previous isothermal studies of both sorbents have shown that sorbent capacity is proportional to feed gas concentration. Therefore, it is anticipated that additional HZ-PAN stages will further concentrate and purify the final Kr stream with higher efficiency. It is expected that Xe will be released to atmosphere after desorption. However, it could also be purified further with more AgZ-PAN stages. Further testing should be done to determine maximum purity achievable for both Kr and Xe. Additionally, renewed focus on increasing Xe capacity on AgZ-PAN and Kr capacity on HZ-PAN is recommended.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2018

Cycle Testing of AgZ-PAN and HZ-PAN

Idaho National Laboratory (INL) has been conducting, as part of the off-Gas Sigma Team, producing and testing sorbents for the selective capture of xenon and krypton from surrogate nuclear fuel recycling off-gas streams. AgZ-PAN and HZ-PAN, both developed and produced at INL, have shown promising results for the selective capture and separation of xenon and krypton, respectively. Previous testing of both sorbents has focused on saturation and initial breakthrough capacities across a variety of operating conditions. However, the sorbents can only be truly viable for use in a process if they have sufficient longevity through multiple adsorption/desorption cycles. This research, therefore, focused on putting both sorbents through as many thermal swing adsorption/desorption cycles as possible over the course of one year. The primary focus of cycling tests was on AgZ-PAN, which previously demonstrated possible loss of capacity after multiple cycles. While capacity was shown to be recoverable over the short term, the goal is to ensure effective long-term viability so it was placed through 100 cycles, the estimated equivalent of one year of operation. HZ-PAN had not shown any deleterious effects from cycling during previous testing. Additionally, due to the colder temperatures required for Kr capture, each cycle required considerably more time to complete, so this sorbent was subjected to 50 cycles. Both sorbents maintained their capacities throughout the series, indicating promising potential for long-term reliability.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2017

Preliminary Desorption studies for HZ-PAN and AgZ-PAN

Adsorption of Kr and Xe on HZ-PAN and AgZ-PAN has been the studied extensively. Prior research focused on sorbent capacity and breakthrough of Kr and Xe, with desorption cycles completed in order to close material balances and prepare sorbents for further adsorption testing. This series of tests was designed to determine preliminary information about desorption to guide further research to optimize desorption cycles for each sorbent. A series of desorption tests were run using thermal and pressure swing operations. For AgZ-PAN, these tests indicated that both heat and carrier gas are likely necessary to removed adsorbed gases. However, vacuum pressure and heat may be sufficient to desorb gases from HZ-PAN, which should result in a cleaner Kr stream during desorption. Desorption optimization for both sorbents merits further study in order to make final waste form volume as small as possible.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2016

Multi-Column Xe/Kr Separation with AgZ-PAN and HZ-PAN

Previous multi-column xenon/krypton separation tests have demonstrated the capability of separating xenon from krypton in a mixed gas feed stream. The results of this initial testing with AgZ-PAN and HZ-PAN indicated that an excellent separation of xenon from krypton could be achieved. Building upon these initial results, a series of additional multi-column testing were performed in FY-16. The purpose of this testing was to scale up the sorbent beds, test a different composition of feed gas and attempt to improve the accuracy of the analysis of the individual capture columns’ compositions. Two Stirling coolers were installed in series to perform this testing. The use of the coolers instead of the cryostat provided two desired improvements, 1) removal of the large dilution due to the internal volume of the cryostat adsorption chamber, and 2) ability to increase the sorbent bed size for scale-up. The AgZ-PAN sorbent, due to its xenon selectivity, was loaded in the first column to capture the xenon while allowing the krypton to flow through and be routed to a second column containing the HZ-PAN for capture and analysis. The gases captured on both columns were sampled with evacuated sample bombs and subsequently analyzed via GC-MS for both krypton and xenon. The results of these tests can be used to develop the scope of future testing and analysis using this test bed for demonstrating the capture and separation of xenon and krypton using sorbents, for demonstrating desorption and regeneration of the sorbents, and for determining compositions of the desorbed gases. They indicate a need for future desorption studies in order to better quantify co-adsorbed species and final krypton purity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

ASC Poster - Concentration of Xe from Simulated Dissolver Off-gas Streams Utilizing a Solid Sorbent, AgZ-PAN

Idaho National Laboratory (INL) has developed and tested engineered sorbents to separate and capture volatile fission products such iodine (I), xenon (Xe), and krypton (Kr) from off-gas streams. As noble gases, Xe and Kr can be difficult to capture and separate. Historically, cryogenic distillation has been used to execute the separation, but this method can pose significant hazards. INL has successfully developed two sorbents for Xe and Kr capture, silver mordenite polyacrylonitrile (AgZ-PAN) and hydrogen mordenite polyacrylonitrile (HZ-PAN). Adsorption studies to date successfully separated and captured Xe from carrier gas streams, but those studies focused primarily on initial separation and capture. In addition, the ability to concentrate Xe through multiple adsorption and desorption cycles has not been studied and therefore is the focus on this presentation. Concentrating Xe during desorption is ideal to produce Xe that can be used for commercial and research applications.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Iodine Sorption on AgZ-PAN

The Department of Energy (DOE) Nuclear Fuel Cycle and Supply Chain Program Material Recovery and Waste Form Development (MRWFD) Campaign Off-gas Sigma Team has performed research and development on iodine control and iodine waste forms for the past several years. This research and development has included iodine adsorption tests using a laboratory-scale test system containing multiple-segmented fixed beds of iodine adsorbents. Iodine capture performance has been tested using (a) non-radioactive synthetic gas mixtures blended from air, nitrogen, NO, NO 2 , water, to simulate dissolver off-gas (DOG) and vessel off-gas (VOG) streams from used nuclear fuel aqueous reprocessing, (b) inorganic and organic iodine species, and (c) different sorbents. An initial test of silver-functionalized mordenite in polyacrylonitrile matrix (AgZ-PAN) was conducted to assess if this sorbent, initially designed for selective sorption of Xe that evolves into used fuel reprocessing off-gas streams, could also be a candidate for iodine sorption. This test was conducted using the same deep-bed test system and methodologies used in many prior iodine sorption tests using other sorbents. Diatomic iodine (I2) was used as the target iodide in a gas stream containing air, NO, NO 2 , and moisture designed to simulate an aqueous reprocessing dissolver off-gas (DOG) stream.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Alternative Materials Literature Review: A Review of Alternative Materials for Xenon Capture in Comparison to AgZ-PAN

A collaborative literature review between Idaho National Laboratory (INL) and Pacific National Laboratory (PNNL) was conducted to research alternative metals/materials for xenon adsorption in gaseous effluents generated from used nuclear fuel (UNF) reprocessing. The review was conducted to research sorbents that could outperform silver mordenite (AgZ) at ambient temperature. The use of silver requires complex and expensive waste disposal processes due to it being an RCRA metal, therefore alternative materials need to be researched and evaluated. The report details two different types of sorbent material: alternative zeolite materials and non-zeolite-based materials (i.e., MOFs, COFs, etc.). This report documents a brief history of the materials, what testing has been conducted on them, and what results suggest the possibility of outperforming the silver-based materials. Sorbent performance characteristics such as durability, capacity, and operating temperatures were evaluated. The simplicity of the sorbents was also evaluated, meaning how they are acquired (synthesized vs. naturally abundant). Recommendations were made for the most promising sorbents based on available research in the subject area and these recommended sorbents will be tested in the upcoming fiscal year. The recommended sorbents that are zeolite based are CHA zeolites, ZIF-69, and Na-ETS-10. The recommended sorbents that are non-zeolite based are SBMOF-1 and CC3.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Alternative Materials Literature Review: A Review of Alternative Materials for Xenon Capture in Comparison to AgZ-PAN

A collaborative literature review between Idaho National Laboratory (INL) and Pacific National Laboratory (PNNL) was conducted to research alternative metals/materials for xenon adsorption in gaseous effluents generated from used nuclear fuel (UNF) reprocessing. The review was conducted to research sorbents that could outperform silver mordenite (AgZ) at ambient temperature. The use of silver requires complex and expensive waste disposal processes due to it being an RCRA metal, therefore alternative materials need to be researched and evaluated. The report details two different types of sorbent material: alternative zeolite materials and non-zeolite-based materials (i.e., MOFs, COFs, etc.). This report documents a brief history of the materials, what testing has been conducted on them, and what results suggest the possibility of outperforming the silver-based materials. Sorbent performance characteristics such as durability, capacity, and operating temperatures were evaluated. The simplicity of the sorbents was also evaluated, meaning how they are acquired (synthesized vs. naturally abundant). Recommendations were made for the most promising sorbents based on available research in the subject area and these recommended sorbents will be tested in the upcoming fiscal year. The recommended sorbents that are zeolite based are CHA zeolites, ZIF-69, and Na-ETS-10. The recommended sorbents that are non-zeolite based are SBMOF-1 and CC3.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Xe Concentration Activity

INL conducted extensive studies to understand how the Xe capacity of AgZ-PAN changes under various conditions including flowrate, temperature, concentration, carrier gas, and irradiation of the sorbent. Therefore, it is well understood that AgZ-PAN can capture Xe under a wide range of conditions. While these studies were performed to prove that Xe can be completely desorbed from the column, the ability to concentrate Xe during desorption was not studied. Concentrating Xe during desorption would be ideal so as to produce Xe that can be used for commercial and research applications. This report investigates the Xe concentrating potential of AgZ-PAN by running multiple Xe adsorption-desorption cycles, collecting the desorbed effluent from a saturated AgZ-PAN column, and then loading it onto a fresh column.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Adsorbents and adsorption models for capture of Kr and Xe gas mixtures in fixed-bed columns

Off-gases produced during the reprocessing of used nuclear fuel (UNF) include 129-I 2 , 3-HHO, 14-CO 2 , 85-Kr, and 135-Xe, which are volatilized out into the off-gas. In order to meet regulatory requirements for reprocessing plant emissions, these gases must be captured and removed from the o?-gas stream prior to o?-gas emission. Of particular interest are the noble gases, Kr and Xe, which can be fairly difficult to remove from the off-gas due to their low chemical reactivity. Thus, this work is focused on utilizing engineered adsorbents, AgZ-PAN and HZ-PAN, to capture Kr and Xe from a mixed-gas stream at relatively low temperatures (191–295 K) and various flow rates (50–2000 mL/min). Isothermal data for Kr and Xe on each adsorbent are analyzed to produce the Langmuir parameters needed to model the mixture adsorption capacities at relevant temperatures using the Extended Langmuir model. Those parameters are then incorporated into a fixed-bed adsorption model developed in this work using the Mulitphysics Object-Oriented Simulation Environment (MOOSE). That model is used to simulate breakthrough times for Kr and Xe in packed columns of AgZ-PAN and HZ-PAN, ranging in length from 6 to 20 in., at relevant temperatures and flow rates. Breakthrough times varied from nearly instantaneous for Kr in AgZ-PAN to 30 h for Xe in HZ-PAN. After the developed model was validated by comparisons with experimental break-through data, the model framework was used to simulate the performance of multiple fixed-bed columns connected in series.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Performance Criteria for Capture and/or Immobilization Technologies (Revision 1)

The capture and subsequent immobilization of regulated volatile radionuclides from the off-gas streams of a used nuclear fuel (UNF) reprocessing facility has been a topic of substantial research interest for the US Department of Energy and its international counterparts. Removal of specific radionuclides from the plant effluent streams before discharge to the environment is required to meet regulations set forth by the US Environmental Protection Agency. Upon removal, the radionuclides, as well as associated sorbents that cannot be regenerated in a cost-effective manner, are destined for conversion to a waste form. Research in separation and capture methodologies has included a wide range of technology types, and studies of waste forms are correspondingly diverse. In considering the future development and implementation of both sorbents and waste forms, it is necessary to identify benchmark measures of performance to objectively evaluate each sorbent system or waste form. Sets of performance criteria and associated metrics have been developed for sorbent and waste form evaluation. These criteria address physical, radiological, and chemical characteristics, technical practicality, technical maturity, cost, and, for sorbents, system performance. The criteria and metrics appear to be robust and should be applicable despite the eventual waste classification (as either high- or low-level waste). They are flexible enough to address both aqueous reprocessing and electrochemical reprocessing of UNF. These criteria sets can serve as tools to evaluate performance at multiple stages within the development process, and in this revision (Revision 1) they have been used to assess technologies relating to krypton/xenon separations and iodine capture from off-gas streams arising from UNF reprocessing. Assessment of krypton/xenon separations using engineered forms of two zeolite minerals (silver mordenite and hydrogen mordenite in a polyacrylonitrile-based binder [AgZ-PAN/HZ-PAN]) found that the zeolite-based separation is relatively advanced in its development, but several key issues require resolution. First, desorption processes for both krypton and xenon require refinement to provide an understanding of the product purity that can be achieved. Second, adsorption rate data is needed in order to calculate the bed depth required for effective separation. Finally, it is strongly recommended that a technical review of krypton/xenon separation by AgZ-PAN/HZ-PAN be performed to synergize available data and assess the cost savings and operational benefits that may be realized from implementation of this technology. Assessment of metal organic frameworks (MOFs) for their use in the separation of krypton/xenon found that the ideal separation would be performed using a single-column system with a MOF selective for krypton over xenon. A robust research effort should work to identify a krypton-selective MOF designed to operate at temperatures of approximately 0°C or higher, which could be preferred over cryogenic krypton/xenon capture for used fuel reprocessing off-gas streams. In the case of the CaSDB-MOF (the most well-understood xenon sorbent to date), two issues are judged of high importance. First, xenon breakthrough capacity for the CaSDB-MOF in prototypical conditions should be determined. Preliminary research indicates that breakthrough may be near immediate, presenting a substantial obstacle in separative system design. Second, development of desorption methodology should be performed to determine regeneration time, energy requirements, and the product stream composition. Silver-based sorbents (AgZ and AgAero) for use in iodine capture from the dissolver off-gas were evaluated against the established criteria. These sorbents are significantly better understood for this application as a result of research efforts over the past decade. The potential implementation of AgAero at a large scale is hindered by its physical degradation by components of the dissolver off-gas stream. Less is known about the adsorption of iodine by these sorbents from other off-gas streams in the plant. Initial experimental efforts have been closely coordinated in an effort to understand organic iodine (such as would be found in the vessel off-gas) adsorption by AgZ and AgAero. Future work should expand this experimental program, and analysis of other reprocessing facility off-gas streams such as the vitrification off-gas stream should be conducted to better understand other potential applications for iodine sorbents. A review of iodine waste form development shows that this area is diverse and that multiple promising waste forms have been identified for the immobilization of radioactive iodine. Efforts related to the direct conversion of iodine sorbents (including AgZ and AgAero) should be continued because of the advantages of direct conversion in a waste management strategy and other sorbents should continue to be advanced as merited.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Multi-Column Kr/Xe Separation Testing at Representative Superficial Velocities with DGOSPREY Model Validation

Previous testing of AgZ-PAN and HZ-PAN for the separation and removal of xenon and krypton from air have been promising. This report details the results of multi-column testing at superficial velocities chosen to emulate probably velocities in a full-scale used nuclear fuel reprocessing facility. Additionally, results were used to validate the DG-OSPREY model under development at Georgia Institute of Technology.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Purification of Gas and Liquid Streams Using Composite Sorbents Embedded in a Polyacrylonitrile Matrix

As new sorbents are developed for purifying gases or liquids via physisorption and/or chemisorption processes, the objective is typically to increase the specific surface area (SSA) to maximize the available binding sites for capturing various species of interest. One downfall to making a sorbent more porous is that it often leads to a product that is fragile or friable and can be damaged (resulting in unwanted powders), thus imposing process limitations. Techniques can be used to enhance the mechanical integrity of a sorbent, including heat treatments or pelletization with extrusion or granulation processes, but these can result in collapsed, unavailable pore structures within the sorbent, which decreases the diffusivity and eventually reduces the capacities of target species. An alternative approach for improving the mechanical integrity of the sorbent is to bind it (or encapsulate it) within a porous matrix that passively holds the sorbent in place. Typically, this approach leads to a decrease in sorption efficiency on the basis of starting sorbent mass, because the active sorbent is diluted by the binding matrix material and the active surfaces of the sorbent are somewhat obscured by the binding matrix; however, it comes with the advantage that the active sorbent is held in place and better protected from disintegrating during operation. One approach to securing the active sorbent is to embed it in a macroporous, passive polyacrylonitrile (PAN) matrix to create a composite sorbent. When optimized, the PAN matrix is highly porous and allows for gaseous or aqueous media transport through the product, providing adequate binding site access between the active sorbent and the species of interest. Including a polymer in the composite sorbent limits the maximum operating temperature, above which the composite sorbent incurs loss of structural integrity (e.g., decomposes) and/or reduction in SSA. Composite sorbents have been demonstrated with sulfide aerogels (SnS-PAN) for capturing I2(g), hydrogen mordenite (HZ-PAN) and silver-exchanged mordenite (AgZ-PAN) for capturing Kr and Xe, nanoparticle metal oxides (Nano-Composite Arsenic Sorbent, or N-CAS) for removing arsenic from water, ammonium molybdophosphate (AMP-PAN) for removing cesium-137 (137Cs) from aqueous nuclear waste streams, and The Phosphate Sponge (TPS) composite, which is being used to remove inorganic/ortho-phosphates in water treatment processes to mitigate introduction to the environment, which impedes toxic algae bloom formations. This chapter provides details on production of these materials along with options to optimize the synthesis process. It also includes experimental techniques to characterize products and assess their performance.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2019

Purification of Gas and Liquid Streams Using Composite Sorbents Embedded in a Polyacrylonitrile Matrix

As new sorbents are developed for purifying gases or fluids via physisorption and/or chemisorption processes, the push is typically to increase the available specific surface area (SSA) to maximize the available binding sites for capturing various species of interest. One downfall to making a sorbent more porous is that it often leads to a product that is fragile or friable and can be damaged (resulting in unwanted powders), thus imposing process limitations. Techniques can be used to enhance the mechanical integrity of a sorbent including heat treatments or pelletization with extrusion or granulation processes but these can result in collapsed, unavailable pore structures within the sorbent, which leads to decreased diffusivity and eventual reduction of desired capacities of target species. An alternative approach for improving the mechanical integrity of the sorbent is to bind it (or encapsulate it) within a porous matrix that passively holds the sorbent in place. Typically, this approach leads to a decrease in sorption efficiency on the basis of starting sorbent mass, because the active sorbent is diluted by the binding matrix material and the active surfaces of the sorbent are somewhat obscured by the binding matrix, but it comes with the advantage that the active sorbent is held in place and better protected from powderization during operation. One approach to accomplish this is to embed the active sorbent in a macroporous passive polyacrylonitrile (PAN) matrix to create a composite sorbent. When optimized, the PAN matrix is highly porous and allows for gaseous or aqueous media transport through the product providing adequate binding site access between the active sorbent and the species of interest. Including a polymer in the composite sorbent limits the maximum operating temperature above which the composite sorbent incurs loss of structural integrity (e.g., decomposes) and/or reduction in SSA. Composite sorbents have been demonstrated with sulfide aerogels (SnS-PAN) for capturing I2(g), hydrogen mordenite (HZ-PAN) and silver-exchanged mordenite (AgZ-PAN) for capturing Kr and Xe, nano-particle metal oxides (N-CAS) for removing arsenic from water, ammonium molybdophosphate (AMP-PAN) for removing 137Cs from aqueous nuclear waste streams, and the phosphate sponge (TPS) composite, which is being used to remove inorganic and orthophosphates from water treatment processes to mitigate introduction to the environment impeding toxic algae bloom formations. This chapter provides details on production of these materials along with options to optimize of the synthesis process. It also includes experimental techniques to characterize products and assess their performances.

polyacrylonitrile, aerogel, gaseous capture, aqueo↗
DOE OSTI2019

Separation of Xenon from Krypton in UNF Reprocessing Off-Gas

Reprocessing of used nuclear fuel (UNF) results emits several volatile radionuclides that must be removed from the bulk off gas prior to release in order to meet U.S. regulatory emission requirements. After other volatile radionuclides have been removed, krypton (Kr) remains, along with associated with xenon (Xe) in the gas stream. The half-life of Xe is short enough that by the time UNF is sufficiently cooled to be reprocessed Xe is no longer a radiological concern and it may be release to atmosphere or collected for other purposes. Kr, however, must be placed in long term storage. In order to ensure the smallest practical volume for long term storage, the Xe, which is nearly ten times the volume of Kr, must be separated from the Kr. Although cryogenic distillation has been used successfully for this purpose, high capital and operational cost, along with safety considerations, made development of gas adsorption processes for separation of Xe and Kr attractive. INL developed an engineered form sorbent consisting of silver mordenite in a polyacrylonitrile matrix (AgZ-PAN) capable of complete separation of Xe from Kr in a single pass, allowing Kr to be captured downstream with no detectable Xe present.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2026

INL Intern Poster Session

Characterization of off-gas constituents from nuclear fuel reprocessing can be measured using a residual gas analyzer. Characterization of this off-gas is important in a closed fuel cycle, where gasses such as Nox, Kr, I, and C-14 need to be removed from reprocessing plants to meet regulatory requirements. Both Kr and Xe have low chemical reactivity, making capture and separation difficult. Solid sorbents can be used to capture these gases as an alternative to cryogenic distillation, which is energy intensive and hazardous. AgZ-PAN and HZ-PAN are two solid sorbents that have demonstrated selective capture of Xe and Kr. A residual gas analyzer can be used to obtain breakthrough curves that demonstrate how well this adsorption and separation occur. The breakthrough curve is dependent on packing density, column size, and flow rate. Data obtained from the RGA was verified with a gas chromatographer.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Solid Sorbent Cost Sensitivity Analysis: A Framework for UNF Reprocessing Sorbent Cost Comparison

Solid sorbents have been the subject of research and development across the U.S. Department of Energy national laboratory complex for many years. They are generally accepted as a safer alternative to cryogenic distillation for noble gas capture, and they present an easier pathway in development of long-term waste forms after iodine capture. As more types of sorbents have been proposed for capture of volatile radionuclides, it has become necessary to compare them based on performance and cost criteria. This report details cost and performance information for three promising sorbents and provides a cost sensitivity analysis. The goal of this analysis is to establish a framework which can be utilized to directly compare future sorbents, with differing properties, to the sorbents discussed in this report. Direct comparison is instrumental to making informed decisions to efficiently guide research and minimize laborious detours. In all cases, sorbent capacity is a major cost driver as it influences the mass of sorbent, operational footprint, and disposal cost requirements., However, sorbent price can greatly increase the cost of a capture technology. For sorbents used in krypton capture, the purity of krypton released to storage is the highest cost driver.

11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗