Obtaining artificial ruthenium from transmutation products of99Tc

Abstract

99TC is one of the most long-lived fission products (T1/2 = 2.14.105 yr) and has a considerable yield in the fission of nuclear fuel by neutrons ( -6 mass %). Its content is -I kg/ton in spent thermal-reactor fuel and may be 2-3 times greater in fast-reactor fuel. On the basis of the total electrical-energy production in reactors around the world, which was 252 GW-hr in 1994 [1], the accumulation of 99Tc may be -7.5 ton/yr. Despite many years of searching for applications of technetium, the total world demand for this nuclide currently is no more than a few hundred grams per year, principally for scientific research. Therefore, some non-Russian programs and Russian concepts for the treatment of radioactive wastes provide for the isolation of this radionuclide in a separate fraction and its storage until methods for rendering it harmless have been developed [2][3][4][5].A radical approach to the 99Tc problem calls for its transmutation; in non-Russian waste-treatment programs, combustion of this nuclide and some other fission products with actinides is envisaged. The rational for this is that the 99Tc nucleus has a high capture cross section for thermal and intermediate neutrons and the transmutation products formed are of low radioactivity. It has now been proven that, in principle, the combustion of 99Tc may be conducted in various reactors: in light-and heavy-water power reactors, in fast reactors, and in special transmutational reactors currently under development and also in neutron-generating linear accelerators [6][7][8][9][10][11]. However, there has been virtually no consideration of the practical application of the transmutation products of 99Tc --principally ruthenium, which belongs to the platinoid subgroup.Ruthenium, which costs $t0/g [12], is mainly used in the electrical-engineering and electronics industries. The world demand for this element is 7.4 ton/yr, with reserves of around 3100 ton [13] and could be completely satisfied by the transmutation of the 99Tc stored at power reactors. The extensive research on the development of methods of isolating platinoid metals from spent reactor fuel in various countries has led to limited success [13], and consequently the transmutation of 99Tc is not currently regarded as an industrially significant method of obtaining platinoid metals.In the present work, we consider the irradiation and processing of a technetium target to obtain ruthenium that is suitable for practical use.

Technetium transmutation and production of artificial stable ruthenium

“…The content of more heavy isotopes 102 Ru and 104 Ru was less than 0.01%. Our experimental data on isotope composition of obtained artificial ruthenium are in agreement with calculated data [7,8]. One can conclude that prepared artificial ruthenium has a quite another isotope composition than natural ruthenium has.…”

“…The kinetics of isotopes [100][101][102][103][104][105] Ru accumulation and that of the radionuclides of rhodium and palladium in Tc target have been calculated at the Institute of Physical Chemistry of the Russian Academy of Sciences (IPC-RAS) for the thermal neutron fluxes with different radiation hardness [7][8][9]. A necessary set of parameters has been calculated for the industrial production of artificial stable Ru, pure enough for applications in non-nuclear industry.…”

Decontamination of alkaline solution from technetium and other fission products and from some actinides by reductive coprecipitation and sorption on metals

“…Alternatively, technetium may be transmuted into the stable precious metal ruthenium by irradiation in a strong neutron flux (Kozar and Peretrukhin 1996). Part of the expense for technetium isolation could therefore be recouped by its subsequent transmutation into stable ruthenium and by the sale of this precious metal.…”

“…Part of the expense for technetium isolation could therefore be recouped by its subsequent transmutation into stable ruthenium and by the sale of this precious metal. Ruthenium, isolated from ore, currently costs $5 to $10 per gram, depending on purity (Kozar and Peretrukhin 1996).…”