Leaching Characteristics of the Metal Waste Form From the Electrometallurgical Treatment Process: Product Consistency Te
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S. G. Johnson, D. D. Keiser, S. M. Frank, T. DiSanto, A. R. Warren and M. Noy Argonne National Laboratory-West P.O. 2528 Idaho Falls, ID 83403 ABSTRACT
Argonne National Laboratory has developed an electrometallurgical treatment for spent fuel from the experimental breeder reactor II. A product of this treatment process is a metal waste form that incorporates the stainless steel cladding hulls, zirconium from the fuel and the fission products that are noble to the process, i.e., Tc, Ru, Nb, Pd, Rh, and Ag. The nominal composition of this waste form is stainless steel/15 wt% zirconium/ 1-4 wt% noble metal fission products /1-2 wt % U. Leaching results are presented from crushed sample immersion tests on simulated metal waste form samples. The test results will be presented and their relevance for waste form product consistency testing discussed. INTRODUCTION
The electrometallurgical (EM) treatment process of spent fuel at Argonne National Laboratory (ANL) yields three product streams: a uranium metal product, a contaminated salt waste stream and an irradiated cladding hull waste stream [1]. The stainless steel cladding hulls are consolidated into a metal waste form (MWF) ingot with a nominal composition of stainless steel components (80 wt%), zirconium (15 wt%), fission products noble to the process (1-5 wt%) and residual actinides (1-5 wt%). The last two categories include the elements: Tc, Ru, Ag, Rh, Pd, Nb, U and Pu [2]. The topic of waste form process qualification has been addressed for borosilicate glass [3] and the plutonium immobilization product [4]. The work discussed in this paper is part of an effort to qualify processing oa a MWF for disposal in a geologic repository. The main premise of this paper is that a method of performing assessing the consistency of the product produced from the metal waste fabrication for the electrometallurigal treatment process at Argonne is required. The fundamental objectives for a product consistency or product quality test are to: 1) detect an out-of-control process, 2) it must be operational in a remote (hot cell) environment and 3) it should be scalable to accommodate larger metal waste form ingots planned in the future. This paper examines using immersion testing with crushed material as a means of evaluating the consistency of the MWF. Other techniques are also being evaluated for this purpose and it is likely that a small number of tests will be used to monitor product consistency. These other methods may include the following: density measurements, hardness testing, microscopy, monolithic immersion tests, electrochemical corrosion measurements, elemental analysis and specific resistance measurements. Borosilicate glass high level waste relies on input process stream analysis, a short-term immersion test (ASTM C1285-97), and determination of crystalline content to establish the basis of a wellcontrolled process. The metal waste form resulting from the EM process can similarly rely on input stream analysis, although this information is not always timely and the issu
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