No abstract

No abstract

As long as VVER-440 reactors exist, their fuel design is subject to ongoing improvement. Efforts to find the optimal fuel design continue and encompass increasingly extending ranges of both geometry and material parameters of fuel assemblies. This paper presents the results of optimized radial enrichment profiling for RK3+ fuel assemblies and discusses whether it is absolutely necessary to use burnable absorbers (Gd2O3 rods) in fuel assemblies suggested for prospective fuel cycles. Regarding RK3+ and RK2 fuel assemblies, this paper also presents thermohydraulic data yielded by computations performed using SC-1 certified software for a VVER-440 seven-assembly core fragment. These computations show that - compared to RK2 assemblies of the same capacity - RK3+ assemblies with optimized enrichment profile have more uniform radial temperature distributions and lower maximum outlet temperatures.

Throughout the existence of VVER-440 reactors, their fuel design was always subject to ongoing improvements. By the moment, extensive computations and RD&D have been performed to evaluate the feasibility of further improvement of VVER-440 fuel cycles and fuel design. This paper discusses computational assessments of basic neutronic parameters of prospective fuel cycles based on newly-designed fuel assemblies, namely RK3+, slim rod and RK3+SR. RK3+ stands for shroud less fuel assemblies with wide angle bars instead of shrouds and optimized pitches between fuel rods. Slim Rod means shrouded fuel assemblies with rods whose external diameter was reduced to 8.9 mm. RK3+SR is an abbreviation for shroud less fuel assemblies with wide angle bars instead of shrouds and rods whose external diameter was reduced to 8.9 mm. This paper demonstrates that, in the countries operating VVERs-440, a transition to new fuel design would improve both the energy output and the fuel cycle economy.

Since the introduction of VVERs-440, their fuel assemblies are subject to ongoing improvements. Until now, the basic structural parameters of fuel, such as rod diameter of 9.1 mm, have never changed. This paper focuses on computational estimates of basic neutronic parameters of the fuel cycle that involves assemblies consisting of fuel rods with diameter reduced to 8.9 mm.