Numerical neutron emission spectrometry and radiation of VVER-1200 reactor fuel

Abstract. The VVER-1200 (V-491) reactor is a water-cooled power reactor, the design of which provides for higher fuel and coolant operating parameters compared to the VVER-1000 (V-320) reactor. For long-term and trouble-free operation of the reactor, the fuel is modified by adding various homogeneous compounds and heterogeneous inclusions. Uranium-gadolinium fuel in a homogeneous design with axial profiling of fuel elements has received practical application. The possibility of heterogeneous use of Gd 2 O 3 , ZrB 2 , Am 2 O 3 and other burnable and alloying additives is being investigated. Such additives make it possible to maintain the thermal conductivity of the fuel at the level of conventional oxide fuel. The studied modifications show satisfactory behavior under irradiation at extremely high temperatures and burnup. However, the issues of radiation safety when handling both fresh and spent fuel remain less studied. In this work, a computational assessment of the neutron component of the radiation characteristics of a UO 2 composition with a heterogeneous variant of the localization of nat Gd 2 O 3 and Am 2 O 3 microcapsules was carried out. This design option does not impair the thermal conductivity of the fuel and has a positive effect on the nuclear physical and thermophysical properties of the fuel. Americium has been studied not only as a possible alternative to Gd, but also from the perspective of its possible utilization in thermal reactors. The influence of Am on the photon component of the radiation characteristics of fresh fuel is considered. It is concluded that the radiation safety of fresh and irradiated products containing Am should be achieved primarily by solving problems of protection from photon radiation. The research is carried out to develop procedures and regulations for handling new fuel during its manufacture and after irradiation in the reactor. The studies were carried out using verified calculation codes of the MCNP 6.2 and Nedis 2m programs.