• Title/Summary/Keyword: Pyroprocessing

Search Result 149, Processing Time 0.032 seconds

Lab scale electrochemical codeposition experiments for comparison to computational predictions

  • Lafreniere, Philip;Zhang, Chao;Simpson, Michael;Blandford, Edward D.
    • Nuclear Engineering and Technology
    • /
    • v.52 no.9
    • /
    • pp.2025-2033
    • /
    • 2020
  • Signature-based safeguards (SBS) is being developed to assist tradition nuclear material accountancy methods in tracking material in pyroprocessing facilities. SBS involves identifying off-normal scenarios that would result in improper movement of material in a pyroprocessing facilities and determining associated sensor response signatures. SBS investigations are undertaken in the computational space utilizing an electrochemical transport code known as enhanced REFIN with anodic dissolution (ERAD) to calculate the affect of off-normal conditions in the electrorefiner (ER) on material movement. Work is undertaken to experimentally validate the predictions and assumptions made by ERAD for off-normal occurrences. These experiments were undertaken on a benchtop scale and involved operating an electrochemical cell at 10 separate current densities for constant current operations to deposit U and Gd at a W cathode. These experiments were then modeled using ERAD to compare calculated predictions versus analytical experimental results it was found. It was discovered both the experimental and calculated results reflect a trend of increased codeposition of U and Gd with increasing current density. ERAD was thus demonstrated to be useful for predicting trends from anomalous operation but will require further optimization to be utilized as a quantitative design tool.

Options Study for the Neutralization of Elemental Sodium During the Pyroprocessing of Used Nuclear Fuel

  • Westphal, Brian;Tolman, David;Tolman, Kevin;Frank, Steven;Herrmann, Steve;Warmann, Stephen;Marsden, Kenneth;Patterson, Michael
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
    • /
    • v.18 no.2
    • /
    • pp.113-118
    • /
    • 2020
  • An options study was performed for the treatment of residual elemental sodium in driver plenums following the chopping operation during the pyroprocessing of used nuclear fuel. Given the pending availability of a multi-function furnace for distillation and consolidation operations in the Fuel Conditioning Facility, the furnace was considered for the processing of driver plenums. Although two options (oxidation and distillation) could be performed in the multi-function furnace, neither option has been developed sufficiently to date to warrant the use of the furnace for treatment operations. Thus, it was decided to defer the treatment of elemental sodium from driver plenums in the multi-function furnace until more developed technologies and/or furnaces become available. In the interim, storage of the plenums and characterization efforts are recommended.

STATUS OF PYROPROCESSING TECHNOLOGY DEVELOPMENT IN KOREA

  • Song, Kee-Chan;Lee, Han-Soo;Hur, Jin-Mok;Kim, Jeong-Guk;Ahn, Do-Hee;Cho, Yung-Zun
    • Nuclear Engineering and Technology
    • /
    • v.42 no.2
    • /
    • pp.131-144
    • /
    • 2010
  • The Korea Atomic Energy Research Institute (KAERI) has been developing pyroprocessing technology for recycling useful resources from spent fuel since 1997. The process includes pretreatment, electroreduction, electrorefining, electrowinning, and a waste salt treatment system. This paper briefly addresses unit processes and related innovative technologies. As for the electroreduction step, a stainless steel mesh basket was applied for adaption of granules of uranium oxide. This basket was designed for ready handling and transfer of feed material. A graphite cathode was used for the continuous collection of uranium dendrite in the electrorefining system. This enhances the throughput of the electrorefiner. A particular mesh type stirrer was designed to inhibit uranium spill-over at the liquid Cd crucible. A residual actinide recovery system was also tested to recover TRU tracer. In order to reduce the waste volume, a crystallization method is employed for Cs and Sr removal. Experiments on the unit processes were tested successfully, and based on the results, engineering-scale equipment has been designed for the PRIDE (PyRoprocess Integrated inactive DEmonstration facility).

A CONCEPTUAL STUDY OF PYROPROCESSING FOR RECOVERING ACTINIDES FROM SPENT OXIDE FUELS

  • Yoo, Jae-Hyung;Seo, Chung-Seok;Kim, Eung-Ho;Lee, Han-Soo
    • Nuclear Engineering and Technology
    • /
    • v.40 no.7
    • /
    • pp.581-592
    • /
    • 2008
  • In this study, a conceptual pyroprocess flowsheet has been devised by combining several dry-type unit processes; its applicability as an alternative fuel cycle technology was analyzed. A key point in the evaluation of its applicability to the fuel cycle was the recovery yield of fissile materials from spent fuels as well as the proliferation resistance of the process. The recovery yields of uranium and transuranic elements (TRU) were obtained from a material balance for every unit process composing the whole pyroprocess. The material balances for several elemental groups of interest such as uranium, TRU, rare earth, gaseous fission products, and heat generating elements were calculated on the basis of the knowledge base that is available from domestic and foreign experimental results or technical information presented in open literature. The calculated result of the material balance revealed that uranium and TRU could be recovered at 98.0% and 97.0%, respectively, from a typical PWR spent fuel. Furthermore, the anticipated TRU product was found to emit a non-negligible level of $\gamma$-ray and a significantly higher level of neutrons compared to that of a typical plutonium product obtained from the PUREX process. The results indicate that the product from this conceptual pyroprocessing should be handled in a shielded cell and that this will contribute favorably to retaining proliferation resistance.

Transfer characteristics of a lithium chloride-potassium chloride molten salt

  • Mullen, Eve;Harris, Ross;Graham, Dave;Rhodes, Chris;Hodgson, Zara
    • Nuclear Engineering and Technology
    • /
    • v.49 no.8
    • /
    • pp.1727-1732
    • /
    • 2017
  • Pyroprocessing is an alternative method of reprocessing spent fuel, usually involving the dissolving spent fuel in a molten salt media. The National Nuclear Laboratory designed, built, and commissioned a molten salt dynamics rig to investigate the transfer characteristics of molten lithium chloride-potassium chloride eutectic salt. The efficacy and flow characteristics of a high-temperature centrifugal pump and argon gas lift were obtained for pumping the molten salt at temperatures up to $500^{\circ}C$. The rig design proved suitable on an industrial scale and transfer methods appropriate for use in future molten salt systems. Corrosion within the rig was managed, and melting techniques were optimized to reduce stresses on the rig. The results obtained improve the understanding of molten salt transport dynamics, materials, and engineering design issues and support the industrialization of molten salts pyroprocessing.

Conceptual design of neutron measurement system for input accountancy in pyroprocessing

  • Lee, Chaehun;Seo, Hee;Menlove, Spencer H.;Menlove, Howard O.
    • Nuclear Engineering and Technology
    • /
    • v.52 no.5
    • /
    • pp.1022-1028
    • /
    • 2020
  • One of the possible options for spent-fuel management in Korea is pyroprocessing, which is a process for electrochemical recycling of spent nuclear fuel. Nuclear material accountancy is considered to be a safeguards measure of fundamental importance, for the purposes of which, the amount of nuclear material in the input and output materials should be measured as accurately as possible by means of chemical analysis and/or non-destructive assay. In the present study, a neutron measurement system based on the fast-neutron energy multiplication (FNEM) and passive neutron albedo reactivity (PNAR) techniques was designed for nuclear material accountancy of a spent-fuel assembly (i.e., the input accountancy of a pyroprocessing facility). Various parameters including inter-detector distance, source-to-detector distance, neutron-reflector material, the structure of a cadmium sleeve around the close detectors, and an air cavity in the moderator were investigated by MCNP6 Monte Carlo simulations in order to maximize its performance. Then, the detector responses with the optimized geometry were estimated for the fresh-fuel assemblies with different 235U enrichments and a spent-fuel assembly. It was found that the measurement technique investigated here has the potential to measure changes in neutron multiplication and, in turn, amount of fissile material.

Investigation of neural network-based cathode potential monitoring to support nuclear safeguards of electrorefining in pyroprocessing

  • Jung, Young-Eun;Ahn, Seong-Kyu;Yim, Man-Sung
    • Nuclear Engineering and Technology
    • /
    • v.54 no.2
    • /
    • pp.644-652
    • /
    • 2022
  • During the pyroprocessing operation, various signals can be collected by process monitoring (PM). These signals are utilized to diagnose process states. In this study, feasibility of using PM for nuclear safeguards of electrorefining operation was examined based on the use of machine learning for detecting off-normal operations. The off-normal operation, in this study, is defined as co-deposition of key elements through reduction on cathode. The monitored process signal selected for PM was cathode potential. The necessary data were produced through electrodeposition experiments in a laboratory molten salt system. Model-based cathodic surface area data were also generated and used to support model development. Computer models for classification were developed using a series of recurrent neural network architectures. The concept of transfer learning was also employed by combining pre-training and fine-tuning to minimize data requirement for training. The resulting models were found to classify the normal and the off-normal operation states with a 95% accuracy. With the availability of more process data, the approach is expected to have higher reliability.

A Study on the Fabrication of Uranium-Cadmium Alloy and its Distillation Behavior (우라늄-카드뮴 합금의 제조 및 증류거동에 대한 연구)

  • Kim, Ji-Yong;Ahn, Do-Hee;Kim, Kwang-Rag;Paek, Seung-Woo;Kim, Si-Hyung
    • Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
    • /
    • v.8 no.4
    • /
    • pp.261-267
    • /
    • 2010
  • The pyrometallurgical nuclear fuel recycle process, called pyroprocessing, has been known as a promising nuclear fuel recycling technology. Pyroprocessing technology is crucial to advanced nuclear systems due to increased nuclear proliferation resistance and economic efficiency. The basic concept of pyroprocessing is group actinide recovery, which enhances the nuclear proliferation resistance significantly. One of the key steps in pyroprocessing is "electrowinning" which recovers group actinides with lanthanide from the spent nuclear fuels. In this study, a vertical cadmium distiller was manufactured. The evaporation rate of pure cadmium in vertical cadmium distiller varied from 12.3 to $40.8g/cm^2/h$ within a temperature range of 773 923 K and pressure below 0.01 torr. Uranium - cadmium alloy was fabricated by electrolysis using liquid cadmium cathode in a high purity argon atmosphere glove box. The distillation behavior of pure cadmium and cadmium in uranium - cadmium alloy was investigated. The distillation behavior of cadmium from this study could be used to develop an actinide recovery process from a liquid cadmium cathode in a cadmium distiller.

Study on Oxidation or Reduction Behavior of Cs-Te-O System with Gas Conditions of Voloxidation Process (휘발산화 공정 조건에 따른 Cs-Te-O 시스템의 산화 환원 거동 연구)

  • Park, Byung Heung
    • Korean Chemical Engineering Research
    • /
    • v.51 no.6
    • /
    • pp.700-708
    • /
    • 2013
  • Pyroprocessing has been developed for the purpose of resolving the current spent nuclear fuel management issue and enhancing the recycle of valuable resources. Pyroprocessing has been developed with the dry technologies which are performed under high temperature conditions excluding any aqueous processes. Pyro-processes which are based on the electrochemical principles require pretreatment processes and a voloxidation process is considered as a pretreatment step for an electrolytic reduction process. Various kinds of gas conditions are applicable to the voloxidation process and the understanding of Cs behavior during the process is of importance for the analyses of waste characteristics and heat load on the overall pyroprocessing. In this study, the changes of chemical compounds with the gas conditions were calculated by analyzing gas-solid reaction behavior based on the chemical equilibria on a Cs-Te-O system. $Cs_2TeO_3$ and $Cs_2TeO_4$ were selected after a Tpp diagram analysis and it was confirmed that they are relatively stable under oxidizing atmospheres while it was shown that Cs and Te would be removed by volatilization under reducing atmosphere at a high temperature. This work provided basic data for predicting Cs behavior during the voloxidation process at which compounds are chemically distributed as the first stage in the pyroprocessing and it is expected that the results would be used for setting up material balances and related purposes.