Advanced Reprocessing – The Potential for Continuous Chromatographic Separations

This concept paper, discusses the challenges and opportunities for an extractive chromatographic process for the separation of fission products and minor actinides from uranium and plutonium isotopes in irradiated nuclear fuel. The paper highlights the constraints of the PUREX process, a process that is universally accepted for reprocessing of spent nuclear fuel now and for GEN IV reactor systems. It also identifies the challenges that a new separation process would have to overcome to dislodge its acceptance by both the operators and regulators. Although the concept of using a chromatography technique for this separation is challenging, recent developments of continuous chromatography such as simulated moving bed (SMB) and/or continuous annular chromatography (CAC) provides a degree of encouragement. Equally the development of new stationary phases in particular inorganic exchangers, many of which have not been examined for this application enhances confidence that an alternative to the PUREX process is possible

The synthesis and properties of some chelating ion exchangers.

A series of oxine containing polymers, prepared by condensation techniques and by the coupling of oxine to diazotised poly(amino-styrenes), have been investigated in terms of their total capacities for Co(II), Ni(II), Cu(II),Zn(II), Al(III), and UO(Il) as a function of pH and their rates of equilibration with, solutions of metal ions. Other chelating polymers containing salicylic acid, alizarin or pyridyl azo resorcinol as the functional group have also been examined to determine their behaviour with the same six metals. An attempt to determine the magnitude of the stability constants for the metal-resin complexes, uranyl and copper-poly styrene chelates, has been made. It has been shown that the uranyl values lie somewhat lower than the stability constants of the corresponding metal-monomor complexes, whilst the copper values are of the same order as the corresponding metal-nonomer complex

The Acid and Radiation Stability of Some Commercial Ion Exchangers

This paper addresses the stability of commercial cation exchangers when in contact with nitric acid that are under consideration for UCLan’s alternative reprocessing process. The paper describes the acid tolerance of four commercial ion exchange resins when exposed to 7M nitric acid for one year. The acid degradation was measured by FT-IR and TGA before and post acid exposure. Zirconium uptake was measured pre and post acid exposure as a means of determining degradation of functional sites. The resins undergo a degree of acid degradation depending on their chemical composition i.e., polymeric backbone, in some instances loss of functionality but also the introduction of new functional sites. The likely radiation dose that ion exchange resins would receive from spent nuclear fuel dissolver liquor and from adsorbed radioactive cesium 137 were estimated. It was inferred that the radiation dose the exchangers would receive from adsorbed cesium isotopes would be comparatively low when compared with the radiation background of the spent fuel dissolver liquor

Separation of Cations from Nitric Acid Solutions Using Commercially Available Ion Exchange Resins

In a previous publication, the authors described a chromatographic process for the selective separation of fission products and minor actinides from uranium and plutonium in nitric acid solution. This paper has evaluated commercially available ion exchange materials for capacity, rate of uptake and selectivity for some fission products (inactive) and cerium (iii) and (iv) as surrogate for Pu and U. The fission products studied where Cs, Sr and Zr as these for various reasons present major challenges for the existing PUREX process and waste management. The commercial resins evaluated were various sulfonic acid, chelate ion exchangers and an undisclosed inorganic material all supplied by Purolite Ltd

Spent Nuclear Fuel—Waste or Resource? The Potential of Strategic Materials Recovery during Recycle for Sustainability and Advanced Waste Management

Nuclear fuel is both the densest form of energy in its virgin state and, once used, one of the most hazardous materials known to humankind. Though commonly viewed as a waste—with over 300,000 tons stored worldwide and an additional 7–11,000 tons accumulating annually—spent nuclear fuel (SNF) represents a significant potential source of scarce, valuable strategic materials. Beyond the major (U and Pu) and minor (Np, Am, and Cm) actinides, which can be used to generate further energy, resources including the rare earth elements (Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, and Tb), platinum group metals, (Ru, Rh, Pd, and Ag), noble gases (He, Kr, and Xe), and a range of isotopes useful for medical and energy generation purposes are also produced during fission. One reason for the accumulation of so much SNF is the low uptake of SNF recycle (or reprocessing), primarily due to the high capital and operational costs alongside concerns regarding proliferation and wastes generated. This study will highlight the predominantly overlooked potential for the recovery of strategic materials from SNF, which may offset costs and facilitate advanced waste management techniques for minimised waste volumes, thus increasing the sustainability of the nuclear fuel cycle on the path towards Net Zero. Potential challenges in the implementation of this concept will also be identified

Until Somebody Hears Me: Parental Voice and Advocacy in Special Education Decision-Making

This is the author's accepted manuscript. The original publication is available at http://dx.doi.org/ 10.1111/j.1467-8578.2006.00430.x.When a family finds out their child has a disability, they enter the world of special education which has its own terminology, rules, settings and personnel. In addition to grappling with the meaning of their child's special needs, families are also thrown into the role of principle advocate for their child. The research study reported here presents the findings from focus groups conducted in the United States of America with 27 diverse families on their efforts to obtain the best educational outcomes for their children. In this article, Robyn Hess, Amy Molina and Elizabeth Kozleski bring their collective past experiences, as a school psychologist, bilingual counsellor and special education teacher respectively, to bear on this topic and frame the issue from a systemic perspective. They argue that engaging in conversation with families around their needs, as well as assisting them in their efforts to advocate for their child, is the first step in creating more equal partnerships between parents of children with special needs and educational professionals

Removal of Cesium from Simulated Spent Fuel Dissolver Liquor

With a resurgence of the nuclear industry’s fortunes, waste management will be an even greater consideration; reducing wastes, better segregation and treatment that lower the impact on waste storage facilities and repositories, in particular geological repositories will help the sustainability of the industry. We at the University of Central Lancashire (UCLan) proposed in a previous publication a sequential chromatographic separation process, Alternative Reprocessing Technology (ART) for Fission Products (FPs) and Minor Actinides (MAs) separation from spent fuel dissolver liquor, as an improvement to/replacement for PUREX (Plutonium Uranium Redox Extraction). This publication addresses the removal of one particular fission product, cesium, and its impact on waste management, and down-stream PUREX operations. Although our proposed process is still in its infancy, its impact on the PUREX process could be significant, with major gains in the separation circuit, waste management of High Level Waste (HLW) and subsequently waste disposal to and design of a geological repository. This paper briefly describes; our concept, some preliminary experimental data and why re-classification of the bulk of HLW (High Level Waste) to Intermediate Level Waste (ILW) would be possible

The Effect of Gamma Irradiation on the Ion Exchange Properties of Caesium-Selective Ammonium Phosphomolybdate-Polyacrylonitrile (AMP-PAN) Composites under Spent Fuel Recycling Conditions

The caesium radioisotopes 134Cs, 135Cs, and 137Cs are highly problematic medium-lived species produced during nuclear fission, due to their high radioactivity and environmental mobility. While many ion exchange materials can readily isolate Cs+ ions from neutral or basic aqueous solutions, only ammonium phosphomolybdate (AMP) functions effectively in acidic conditions, removing caesium even down to trace levels. Composites of AMP in a porous polymeric support such as polyacrylonitrile (PAN) can be used to selectively remove Cs+ ions from acidic aqueous decontamination liquors as well as other liquid wastes, and are promising for the isolation of Cs+ isotopes in spent fuel reprocessing. While both AMP and PAN have demonstrable acid stability, and PAN has known resistance to gamma radiation, AMP-PAN composites have received only a limited analysis of their physiochemical and ion exchange performance following irradiation. In this publication, we explore the effect of high levels of gamma irradiation on the ion exchange properties of AMP and AMP-PAN as a Cs+-selective adsorbent under spent fuel dissolver liquor concentrations and acidity. We demonstrate no significant reduction in performance with respect to uptake kinetics or capacity upon irradiation, abiding by the same absorption mechanism observed in the established literature

A comparative study of microwave and barrier discharge plasma for the regeneration of spent zeolite catalysts

Due to their acid characteristics and pore structure, which can induce high product selectivity; zeolite catalysts are used extensively in industry to catalyse reactions involving hydrocarbons. However, these catalysts can suffer from deactivation due to cracking reactions that result in the deposition of carbon leading to poisoning of the acid sites and blocking of the pores [1]. Depending upon the reaction and the particular catalyst involved this deactivation may take place over several months or even years but in some cases occurs in minutes. Therefore, zeolite catalysts are frequently reactivated / regenerated. This generally involves a thermal treatment involving air which results in oxidation of the carbon [2]. However, the oxidation of carbon is highly exothermic, and if not carefully controlled, results in the generation of exceedingly high localized temperatures which can destroy the zeolite structure and result in subsequent loss of catalyst activity. More conservative thermal treatments can result in incomplete regeneration and again a catalyst displaying inferior activity. This paper explores the use of non-thermal plasma which had been either generated using microwaves or via a barrier discharge to regenerate spent zeolite catalysts. The catalyst, H-mordenite, was tested for the disproportionation of toluene (Figure 1) using conventional heating. The spent catalyst was then regenerated using a plasma or conventional thermal treatment before having its activity re-evaluated for the toluene disproportionation reaction as previous. Fig. 1. Reaction Scheme for Toluene Disproportionation. Interestingly, not only is plasma regeneration highly effective but also catalysts can be regenerated in greatly reduced times. There is an additional advantage in that plasma regeneration can impart physical properties that result in a zeolite that is resistant to further deactivation. However, the results are highly dependent upon the experimental conditions involved for plasma regeneration. References Wu J, Leu L., Appl. Catal., 1983; 7:283-294. M. Guisnet and P. Magnoux, Deactivation of Zeolites by Coking. Prevention of Deactivation and Regeneration. In: Zeolite Microporous Solids: Synthesis, Structure, and Reactivity. E.G. Derouane, F Lemos, C. Naccache, F. Ramôa Ribeiro, Eds. Pages 437-456. Springer 1992