The main problems of transmutation of actinides and long-lived fission products from NPP spent fuel

Abstract

The paper formulates the main problems associated with research on transmutation, which should be paid attention to by today’s young researchers. The processes of production of hazardous nuclides during transmutation in reactor facilities are considered. The goals of transmutation and the choice of nuclides to be transmuted are discussed. The concept of radiotoxicity is explained as a measure of the radiological hazard of radioactive nuclides, based on the maximum permissible concentration of nuclides according to the IAEA standards. The problem of the formation of secondary radioactive nuclides in nuclear fuel during generation of neutrons for transmutation is discussed. The advantages and disadvantages of various methods of transmutation in nuclear installations are considered: inclusion of transmutable nuclides in nuclear fuel in fast reactors, transmutation in specialized thermal and fast transmutation reactor installations and ADS systems. The problem of accumulation of highly radioactive actinides in a transmutation facility during long-term transmutation and the problem of a potential hazard of the transmutation facility itself are discussed. The unacceptability of application of common-type power reactors for the transmutation of long-lived fission products is demonstrated.

Trends and Perspectives on Nuclear Waste Management: Recovering, Recycling and Reusing

“…A second point is that studies about the radiotoxicity of the highly active fission products have evidenced how the long-term threat due to such nuclides is lesser than that of the actinides [46]. As reported in [47], after 100 a from the discharge the radiotoxicity of the fission products derived from 1 ton of enriched U fuel would be of about 1.4 × 10 7 Sv.…”

“…After 100,000 a the radioactivity is produced rather exclusively by 237 Np (T½ = 2.144 × 10 6 a) an α-emitter which, through the short-lived 233 All these actinides, not present in the unirradiated nuclear fuel, strongly demand the use of transmutation approaches to transform highly radioactive nuclides in less hazardous ones [46]. A transmutation chain of actinides typically produced from a low-enriched Uranium fuel is schematically shown in Figure 4 .…”

“…The transmutation processes will be instead an integral part of the closed fuel cycles in specifically designed fast neutron reactors or in the accelerator-driven systems (ADS), where fluxes of high-energy neutrons are produced by spallation [46,47,[75][76][77].…”

“…Here the capture of neutrons by the isotopes contained in the waste provokes their fission and produces energy. It is notewhorty that, due the peculiar design of these installations, the ADSs could be used to generate nuclear power also from non-fissile nuclides, as 232 Th [46]. A further potentiality envisaged for ADSs is the feasibility to dispose of weapons-grade Plutonium more efficiently than to burn it as MOX fuel in conventional reactors [78].…”