In global atomic power, a large amount of depleted uranium as a waste of the enrichnent plants are stored. With exhaustion of natural uranium stocks, the depleted uranium can be involved in a fuel cycle with simultaneous utilization of weapon-grade plutonium. Plutonium has very high multiplicating properties, and its utilization should be most effective with use of excessive neutrons for new nuclear fuel production. In the report, the main properties of weapon-grade plutonium modes with addition of depleted uranium in power WER-type reactors are determined. All the constructional and thermal characteristics including the fuel element design are supposed to be as for the WER reactor. The nuclear fuel loading into the fuel elements is varied only. The use of existing designs of power reactors seemes to be the most expedient from the viewpoint of quick realization of plutonium modes, if it will be possible to provide the nessesary safety level. Concentration of uranium and plutonium isotopes and multiplication factor with respect to nuclear fuel burnup are calculated. It is determined that at considered weapon-grade plutonium loadings, the loading of uranium is about twice less than in regular mode of WER-1000 with uranium fuel. It is shown that in plutonium mode, the multiplication factor decreases faster with respect to nuclear fuel burnup than in regular mode of WER-1000. It results in shorter fuel lifetime than in WER-1000. Temperature coefficient of reactivity is evaluated. For considered plutonium mode it appeares to be positive. It is stipulated by influence of a resonance at 0.3 eV in fission cross-section of Pu-239. The future development of modern atomic power engineering is connected to the necessity of expansion of a raw base. It can be realized by involvement of the depleted uranium in nuclear fuel cycle (NFC). During the years of existence of atomic power engineering, the large resources of depleted uranium are accumulated as a waste of the enrichnent plants. For utilization of depleted uranium, it is necessary to add to him a fissile material with high multiplicating properties. For this purpose, the weapon-grade plutonium can be used. The plutonium is a very valuable material. It is not found in nature. Weapon-grade plutonium was specially produced for military purposes. Now it is subject to defense conversion. Utilization of the weapon-grade plutonium for involvement of depleted uranium in NFC will allow to conduct its conversion with high efficiency. The aim of the present paper is to find out basic mode properties for the weapon-grade plutonium use with depleted uranium in used now nuclear power reactors. The core structure of WER-1000 has been taken for the basis of power reactor core structure with construction and heating engineering parameters saved wherever possible. It has been assumed that only nuclear fuel load varies in the fuel elements while the structure of the elements remains the same. Such an approach, i.e. the use of already existing power reactor structures, seems the most sutable from the viewpoint of the quickest realization of plutonium modes. The fuel elements are considered in which the mixture of weapon-grade plutonium with U-238 is placed instead of the slightly enriched uranium. The weapon-grade plutonium was supposed to consist of the Pu-239 with about 5% Pu-240.
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