The current stage of nuclear power development is often characterized by directly opposite trends: on the one hand, there is a growing understanding of the need to transition to a closed fuel cycle, and on the other hand, there is a very large uncertainty about the growth rates of nuclear power capacity. In such conditions, the main driver of the transition to SNF is not the need for capacity building and accelerated commissioning of fast reactors for extended fuel reproduction, but the need to reduce the amount of SNF accumulated in storage. In other words, at the transition stage of NPS development as a system, the main problem is to reduce the volume of SNF in VVER reactors by reprocessing. In conditions where it is not necessary to immediately put into operation a large number of fast reactors, the problem of involving dense fuel in the fuel cycle can be solved in a simpler way. Certain changes can be made to the FA of fast reactors, which can provide sufficient operating conditions for poorly justified fuels and provide the necessary energy processing, as well as the reactivity reserve.
As shown by the research carried out at NRC KI, this problem can be solved by using a fast reactor fuel assembly with intra-cassette heterogeneity, which contains two types of fuel elements: MOX fuel with a high plutonium share, and reproducing fuel rods made of dense fuel, for example, depleted uranium metal. The challenge of ensuring the reactivity and energy producing is assigned to the fuel elements made of MOX fuel, and the problem of compensation of reactivity and breeding is assigned to the metal fuel rods with depleted uranium. At the end of the campaign the fall of energy production of MOX-fueled rods is compensated by the growth of energy production of the breeding rods. Thus, the dense fuel located in the breeding rods reaches the limits of its operability only before unloading from the core.
To assess the capabilities of a fast reactor with heterogeneous fuel assembly in a two-component system of the Russian nuclear power industry in present paper material balances of fissile nuclides were calculated. For this purpose, three scenarios were considered: one with the traditional BN-1200 core layout, and two scenarios with heterogeneous fuel assembly of BN-1200. One of them provided for joint reprocessing of spent MOX-fueled rods and raw fuel rods, and the second – separate.
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|Country/Int. organization||Russian Federation|
|Affiliation/Organization||National Research Center “Kurchatov Institute”|