Authors & Affiliations

Orlov M.A.
Innovation and Technology Center of the Proryv Project, Moscow, Russia

Orlov M.A. – Junior Researcher, Cand. Sci. (Phys.-Math.), Innovation and Technology Center of the Proryv Project. Contact: building 4, 2/8, Malaya Krasnoselskaya st., Moscow, Russia, 107140. Tel.: +7(919)770-53-08; e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it..


The article proposes simplified tools for maintaining the equilibrium reactivity mode (reactivity margin in a microcampaign below the effective delayed neutron fraction) throughout the entire service life of a fast reactor started with uranium nitride fuel and then operated in a closed nuclear fuel cycle. The neutronic analysis in view of partial refueling has shown that the basic "inherent safety" requirement can be met using just one or two modifications of the fuel load properties during a transition from a startup with a U fuel to a fuel with an equilibrium isotopic U-Pu composition. It is proposed to increase the burnup along the transition. The preferred option for adjusting the neutronic characteristics of the core is changing the gap between the fuel and the cladding in liquid metal sublayer fuel rods. A conservative option of modifying the fuel tablet density in gas gap fuel rods, and an advanced option where the low-absorption 15N isotope concentration in the fuel is changed are also considered. Optimization strategies for minor actinide utilization intended to decrease reactivity margin in the transition mode and to enable denaturation of Pu generated within the startup fuel load are suggested.
The research is relevant since fast reactors are expected to become more competitive (e.g., through power generation cost reduction) in the nearest future as they are started up with enriched uranium instead of U-Pu (this premise is being verified).

fast reactor, inherent safety, enriched uranium startup, reactivity excursion, transition mode to equilibrium composition fuel

Article Text (PDF, in Russian)


UDC 621.039

Problems of Atomic Science and Technology. Series: Nuclear and Reactor Constants, 2018, issue 1, 1:17