Vacuum arc with a distributed cathode spot as a plasma source for plasma separation of spent nuclear fuel and radioactiv
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MA TECHNOLOGIES
Vacuum Arc with a Distributed Cathode Spot as a Plasma Source for Plasma Separation of Spent Nuclear Fuel and Radioactive Waste R. Kh. Amirov, N. A. Vorona, A. V. Gavrikov, G. D. Lizyakin, V. P. Polishchuk, I. S. Samoilov, V. P. Smirnov, R. A. Usmanov, and I. M. Yartsev Joint Institute for High Temperatures, Russian Academy of Sciences, Izhorskaya ul. 13-2, Moscow, 127412 Russia e-mail: [email protected] Received February 27, 2015
Abstract―Results from experimental studies of a vacuum arc with a distributed cathode spot on the heated cathode are presented. Such an arc can be used as a plasma source for plasma separation of spent nuclear fuel and radioactive waste. The experiments were performed with a gadolinium cathode, the properties of which are similar to those of an uranium arc cathode. The heat flux from the plasma to the cathode (and its volt equivalent) at discharge voltages of 4−15 V and discharge currents of 44−81 A, the radial distribution of the emission intensity of gadolinium atoms and singly charged ions in the arc channel at a voltage of 4.3 V, and the plasma electron temperature behind the anode were measured. The average charge of plasma ions at arc voltages of 3.5−8 V and a discharge current of 52 A and the average rate of gadolinium evaporation in the discharge were also determined. DOI: 10.1134/S1063780X15100013
1. INTRODUCTION One of the promising ways of solving a number of problems concerning the creation of a closed nuclear fuel cycle (CNFC) and more efficient use of nuclear resources [1, 2] is the development of technologies for plasma reprocessing of spent nuclear fuel (SNF) and radioactive waste (RW) [3]. Uranium and plutonium isotopes extracted from SNF and RW can be used as a fuel for fast-neutron reactors, as well as components of the mixed-oxide (MOX) uranium−plutonium fuel for light-water thermal-neutron reactors or the mixednitride uranium−plutonium fuel for the BREST-type reactors, now under development. Traditional radiochemical methods allow one to reprocess SNF; however, they include technological processes involving liquid reactants, which results in a considerable (by several orders of magnitude) increase in the amount of RWs requiring additional storage costs. Moreover, the total industrial capacities of the existing radiochemical plants are insufficient to reprocess the accumulated SNF [2]. A special problem is transportation of SNF from the nuclear reactor to the reprocessing plant, which requires additional financial costs and enhances environmental risks. In recent years, a novel method of SNF and RW reprocessing involving plasma technologies—the socalled plasma separation—is being widely discussed in
the literature [3–5]. The method is based on the spatial separation of ions in electric and magnetic fields of a special configuration [6, 7]. The separation is carried out in plasma, which enables neutralization of the space charge, thereby removing limitations on the current and increasing the efficiency of the process. To develop the technology for plas
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