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Title: Electrolytic Reduction of Spent Light Water Reactor Fuel Bench-Scale Experiment Results

Abstract

A series of experiments were performed to demonstrate the electrolytic reduction of spent light water reactor fuel at bench-scale in a hot cell at the Idaho National Laboratory Materials and Fuels Complex. The process involves the conversion of oxide fuel to metal by electrolytic means, which would then enable subsequent separation and recovery of actinides via existing electrometallurgical technologies, i.e., electrorefining. Four electrolytic reduction runs were performed at bench scale using ~500 ml of molten LiCl – 1 wt% Li2O electrolyte at 650 ºC. In each run, ~50 g of crushed spent oxide fuel was loaded into a permeable stainless steel basket and immersed into the electrolyte as the cathode. A spiral wound platinum wire was immersed into the electrolyte as the anode. When a controlled electric current was conducted through the anode and cathode, the oxide fuel was reduced to metal in the basket and oxygen gas was evolved at the anode. Salt samples were extracted before and after each electrolytic reduction run and analyzed for fuel and fission product constituents. The fuel baskets following each run were sectioned and the fuel was sampled, revealing an extent of uranium oxide reduction in excess of 98%.

Authors:
Publication Date:
Research Org.:
Idaho National Laboratory (INL)
Sponsoring Org.:
DOE - NE
OSTI Identifier:
914582
Report Number(s):
INL/JOU-06-11324
Journal ID: ISSN 0022-3131; JNSTAX; TRN: US0803336
DOE Contract Number:
DE-AC07-99ID-13727
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Nuclear Science and Technology (Japan); Journal Volume: 44; Journal Issue: 3
Country of Publication:
United States
Language:
English
Subject:
11 - NUCLEAR FUEL CYCLE AND FUEL MATERIALS; BENCH-SCALE EXPERIMENTS; ELECTRIC CURRENTS; FISSION PRODUCTS; HOT CELLS; NUCLEAR FUELS; STAINLESS STEELS; URANIUM OXIDES; WATER; electrolytic reduction; electrometallurgical treatment; lithium chloride; lithium oxide; oxide reduction; spent light water reactor fuel

Citation Formats

Steven D. Herrmann. Electrolytic Reduction of Spent Light Water Reactor Fuel Bench-Scale Experiment Results. United States: N. p., 2007. Web. doi:10.3327/jnst.44.361.
Steven D. Herrmann. Electrolytic Reduction of Spent Light Water Reactor Fuel Bench-Scale Experiment Results. United States. doi:10.3327/jnst.44.361.
Steven D. Herrmann. Sun . "Electrolytic Reduction of Spent Light Water Reactor Fuel Bench-Scale Experiment Results". United States. doi:10.3327/jnst.44.361.
@article{osti_914582,
title = {Electrolytic Reduction of Spent Light Water Reactor Fuel Bench-Scale Experiment Results},
author = {Steven D. Herrmann},
abstractNote = {A series of experiments were performed to demonstrate the electrolytic reduction of spent light water reactor fuel at bench-scale in a hot cell at the Idaho National Laboratory Materials and Fuels Complex. The process involves the conversion of oxide fuel to metal by electrolytic means, which would then enable subsequent separation and recovery of actinides via existing electrometallurgical technologies, i.e., electrorefining. Four electrolytic reduction runs were performed at bench scale using ~500 ml of molten LiCl – 1 wt% Li2O electrolyte at 650 ºC. In each run, ~50 g of crushed spent oxide fuel was loaded into a permeable stainless steel basket and immersed into the electrolyte as the cathode. A spiral wound platinum wire was immersed into the electrolyte as the anode. When a controlled electric current was conducted through the anode and cathode, the oxide fuel was reduced to metal in the basket and oxygen gas was evolved at the anode. Salt samples were extracted before and after each electrolytic reduction run and analyzed for fuel and fission product constituents. The fuel baskets following each run were sectioned and the fuel was sampled, revealing an extent of uranium oxide reduction in excess of 98%.},
doi = {10.3327/jnst.44.361},
journal = {Journal of Nuclear Science and Technology (Japan)},
number = 3,
volume = 44,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2007},
month = {Sun Apr 01 00:00:00 EDT 2007}
}
  • A series of bench-scale experiments was performed in a hot cell at Idaho National Laboratory to demonstrate the separation and recovery of uranium metal from spent light water reactor (LWR) oxide fuel. The experiments involved crushing spent LWR fuel to particulate and separating it from its cladding. Oxide fuel particulate was then converted to metal in a series of six electrolytic reduction runs that were performed in succession with a single salt loading of molten LiCl – 1 wt% Li2O at 650 °C. Analysis of salt samples following the series of electrolytic reduction runs identified the diffusion of select fissionmore » products from the spent fuel to the molten salt electrolyte. The extents of metal oxide conversion in the post-test fuel were also quantified, including a nominal 99.7% conversion of uranium oxide to metal. Uranium metal was then separated from the reduced LWR fuel in a series of six electrorefining runs that were performed in succession with a single salt loading of molten LiCl-KCl-UCl3 at 500 °C. Analysis of salt samples following the series of electrorefining runs identified additional partitioning of fission products into the molten salt electrolyte. Analyses of the separated uranium metal were performed, and its decontamination factors were determined.« less
  • A series of tests were performed to demonstrate the electrolytic reduction of spent light water reactor fuel at bench-scale in a hot cell at the Idaho National Laboratory Materials and Fuels Complex (formerly Argonne National Laboratory - West). The process involves the conversion of oxide fuel to metal by electrolytic means, which would then enable subsequent separation and recovery of actinides via existing electrometallurgical technologies, i.e., electrorefining. Four electrolytic reduction runs were performed at bench scale using ~500 ml of molten LiCl -- 1 wt% Li2O electrolyte at 650 ºC. In each run, ~50 g of crushed spent oxide fuelmore » was loaded into a permeable stainless steel basket and immersed into the electrolyte as the cathode. A spiral wound platinum wire was immersed into the electrolyte as the anode. When a controlled electric current was conducted through the anode and cathode, the oxide fuel was reduced to metal in the basket and oxygen gas was evolved at the anode. Salt samples were extracted before and after each electrolytic reduction run and analyzed for fuel and fission product constituents. The fuel baskets following each run were sectioned and sampled, revealing an extent of uranium oxide reduction in excess of 98%.« less
  • A collaborative effort between the Idaho National Laboratory (INL) and Korea Atomic Energy Research Institute (KAERI) is underway per an International Nuclear Energy Research Initiative to advance the development of a pyrochemical process for the treatment of spent nuclear oxide fuel. To assess the effects of specific process parameters that differ between oxide reduction operations at INL and KAERI, a series of 4 electrolytic reduction runs will be performed with a single salt loading of LiCl-Li2O at 650 °C using a test apparatus located inside of a hot cell at INL. The spent oxide fuel for the tests will bemore » irradiated UO2 that has been subjected to a voloxidation process to form U3O8. The primary variables in the 4 electrolytic reduction runs will be fuel basket containment material and Li2O concentration in the LiCl salt. All 4 runs will be performed with comparable fuel loadings (approximately 50 g) and fuel compositions and will utilize a platinum anode and a Ni/NiO reference electrode. The first 2 runs will elucidate the effect of fuel form on the electrolytic reduction process by comparison of the above test results with U3O8 versus results from previous tests with UO2. The first 3 runs will investigate the impact that the cathode containment material has on the electrolytic reduction of spent oxide fuel. The 3rd and 4th runs will investigate the effect of Li2O concentration on the reduction process with a porous MgO cathode containment.« less
  • Preparations are underway to demonstrate the electrolytic reduction of spent oxide nuclear fuel in the Hot Fuel Examination Facility (HFEF) and Argonne National Laboratory--West (ANL-W). The electrolytic reduction process, developed by the Laboratory's Chemical Technology Division, operates in an electrochemical cell that uses a molten solution of lithium chloride and dissolved lithium oxide as the electrolyte. The spent oxide fuel is loaded into a permeable steel basket as the cathode in the electrochemical cell and a platinum electrode functions as the anode. When an electrical potential is applied, the uranium oxide and other metal oxides are reduced to metal andmore » remain in the cathode basket. Oxygen gas is formed at the platinum anode and dissipates into the system's argon atmosphere. Once reduced to metal, the spent fuel is capable of further electrometallurgical treatment in an electrorefiner to recover uranium and to ultimately effect the disposition of fission products into ceramic and metal waste forms. Thus, the electrolytic reduction process expands the electrometallurgical treatment capability to include spent oxide fuel. This report describes the bench-scale test preparations that are underway to demonstrate the electrolytic reduction of spent oxide fuel.« less
  • A conventional PWR of type VVER-440 operating in a sustainable advanced fuel cycle mode with complete recycling of TRU elements in an Inert Matrix Combined Fuel Assembly (IMC-FA) in the same reactor was investigated. A preliminary assessment with the differences between various nuclear fuel cycles in terms of the risk analysis and its indicators has been conducted. The results indicate that the sustainable advanced fuel cycle option can, for the same amount of energy generation, significantly reduces both the amounts and radiotoxicity of the spent nuclear fuel in comparison with the conventional once-through UO2 or MOX fuel cycles.