Development of a Ceramic-Lined Crucible for the Separation of Salt from Uranium
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INTRODUCTION
ACTINIDE products are being recovered from Experimental Breeder Reactor-II (EBR-II) spent nuclear fuel by an electrometallurgical treatment process at the Idaho National Laboratory. The treatment process comprises a set of operations designed to recover actinides from radioactive fission products and place the fission products into acceptable waste forms.[1,2] Two distinct products are recovered during spent fuel treatment—a low-enriched uranium product and a U/TRU-group actinide product. The low enriched uranium products are currently being stored pending a disposition decision, while the actinide products are returned to the process to enable further testing.[3,4] Treatment of the EBR-II spent fuel was initiated in June 1996 and continues currently on the balance of the spent fuels. Batch operations performed on the spent fuel in the Fuel Conditioning Facility (FCF) include chopping, electrorefining, cathode processing, and casting. The FCF is an atmosphere-controlled, shielded hot cell facility where all operations are performed remotely by overhead cranes, electromechanical manipulators, or manual manipulators. Spent fuel is either dismantled into elements from assemblies or retrieved directly as BRIAN R. WESTPHAL, Metallurgical Engineer, K.C. MARSDEN, Mechanical Engineer, and J.C. PRICE, Process Engineer, are with the Idaho National Laboratory, Idaho Falls, ID 83415. Contact e-mail: [email protected] This article is based on a presentation given in the symposium ‘‘Materials for the Nuclear Renaissance,’’ which occurred during the TMS Annual Meeting, February 15–19, 2009, in San Francisco, CA, under the auspices of Corrosion and Environmental Effects and the Nuclear Materials Committees of ASM-TMS. Article published online September 1, 2009 METALLURGICAL AND MATERIALS TRANSACTIONS A
elements from storage containers. Initial fuel element handling operations are performed in the air cell of FCF prior to their transfer to the argon cell for element chopping. Elements are chopped into segments by either a solenoid-driven or pneumatic press depending on the fuel type driver or blanket, respectively. Table I contrasts the two EBR-II fuel types. Driver fuel was used in the core region of the reactor and contains a highly enriched uranium-zirconium alloy. Blanket fuel, consisting of depleted uranium, encircled the driver core. The segments are then loaded into an anode assembly, which contains up to nine perforated baskets depending on the fuel type. The anode assembly is installed into the electrorefiner commensurate with the fuel type Mk-IV for driver and Mk-V for blanket. Although the two electrorefiner vessels are identical in design, the electrode configurations, liquid contents, and process conditions are slightly different. During electrorefining[5] in both units, fuel is anodically dissolved in a LiCl-KCl eutectic salt such that the transport of uranium and deposition as a cathode is feasible. In addition to the LiCl-KCl, other chloride species are present in the electrorefiner salt due to the oxi
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