Prospective 18-month fuel cycles for VVER-440:advantages of new uranium-erbium fuel assemblies
28th Symposium of AER on VVER Reactor Physics and Reactor Safety (2018, Olomouc, Czechia)
Fuel management issues
Eighteen-month fuel cycles may be an option for further development of VVER-440 fuel cycles. 18-month cycles are understood as those with a core operating for about 520–530 effective days at uprated power. Furthermore, an average burnup of 60–65 MWd/kg is advisable for fuel assemblies to be unloaded from the core.
This paper presents the results of development of VVER-440 18-month fuel cycles based on newly-designed fuel assemblies, namely:
- RK3+ – shroudless fuel assemblies with wide angle bars instead of shrouds and optimized pitches between fuel rods;
- Slim Rod – shrouded fuel assemblies with rods whose external diameter was reduced to 8.9 mm;
- RK3+SR – shroudless fuel assemblies with wide angle bars instead of shrouds and rods whose external diameter was reduced to 8.9 mm.
This paper also discusses issues related to using erbium as burnable poison in VVERs-440 and compares neutronic parameters of steady-state cores with uranium-gadolinium and new uranium-erbium fuel. The conclusion is that erbium is a promising burnable poison to be used in VVERs-440.