Power reactors can be used for partial short-term transmutation of radwaste. This transmutation is beneficial in terms of subsequent storage conditions for spent fuel in long-term storage facilities. CANDU-type reactors can transmute the main minor actinides from two or three reactors of the VVER-1000 type. A VVER-1000-type reactor can operate in a self-service mode with transmutation of its own actinides.

We report development of generators for periodic, satellite-free fluxes of mono-disperse drops with diameters down to 10 µm from cryogenic liquids like H2, N2, Ar and Xe (and, as reference fluid, water). While the breakup of water jets can well be described by Rayleigh's linear theory, we find jet regimes for H2 and N2 which reveal deviations from this behavior. Thus, Rayleigh's theory is inappropriate for thin jets that exchange energy and/or mass with the surrounding medium. Moreover, at high evaporation rates, axial symmetry of the dynamics is lost. When the drops pass into vacuum, frozen pellets form due to surface evaporation. The narrow width of the pellet flux paves the way towards various industrial and scientific applications.

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.

The utilization (transmutation using the released energy) of Np, Am, and Cm in a specialized VVER-type reactor operating power 1000 MW(e) is studied by computational means. Five successive reactor runs, where the fuel elements contain Np, Am, Cm, and enriched uranium, are studied. It is shown that Np, Am, and Cm produced by several VVER-1000 reactors can be utilized in one run (900 days) of a specialized reactor without any technological and structural changes. Up to 4% of the reactor power comes from the fission of these radionuclides.The problems of handling radwastes from nuclear power plants must be solved in order for nuclear power to be developed on a large scale. Np, Am, and Cm occupy a special place in this problem. On the one hand, these radionuclides are sources of long-lived α radiation, which is most hazardous to human health; on the other hand, they are initial materials for obtaining explosives, i.e., they are fraught with the danger of nuclear weapons proliferation. At the present time, transmutation is actually the only, realistically, realizable method for destroying substantial quantities of the dangerous radionuclides that are produced in nuclear power reactors. When transuranium isotopes are irradiated by neutrons in power or specialized reactors and additionally undergo their intrinsic radioactive decay, other isotopes with large fission cross sections are produced [1]. Consequently, Np, Am, and Cm can be annihilated in practice by means of fission, i.e., they can be transformed into fission products without making large economic expenditures. It is obvious that the annihilation of transuranium isotopes by means of fission must be accompanied by the production of energy, which can easily be used in a power reactor.We shall present the basic chains of transformation of Np, Am, and Cm in the spectrum of a VVER reactor up to the first fissile isotope, though in reality it proceeds even further: 237 Np(n, γ) 238 Np(β) 238 Pu(n, γ) 239 Pu, 241 Am(n, γ) 242 Am(β) 242 Cm(α) 238 Pu(n, γ) 239 Pu, 243 Am(n, γ) 244 Am(β) 244 Cm(n, γ) 245 Cm, 244 Cm(n, γ) 245 Cm. It is evident that 237 Np and 241 Am transform into 238 Pu, substantial quantities of which will accumulate in the fuel. Active conversion of 238 Pu into fissile 239 Pu requires a time comparable to the VVER fuel-run time. For this reason, the most suitable scenarios for efficient burning of 237 Np and 241 Am in the VVER spectrum are those with multiple fuel reprocessing and multiple re-irradiation. The average time required for fission of a single nucleus in the VVER spectrum can be evaluated on the basis of the chains presented above.The results of the calculations of the transmutation of comparatively small quantities of Np, Am, and Cm which were placed in the form of individual targets into the core of various reactors are presented in [2]. It is shown that a CANDU heavy-

Radiotoxicity and decay heat power of the spent nuclear fuel of VVER-1000 type reactors are calculated during storage time up to 300,000 y. Decay heat power of radioactive waste (radwaste) determines parameters of the heat removal system for the safe storage of spent nuclear fuel. Radiotoxicity determines the radiological hazard of radwaste after its leakage and penetration into the environment.