Searching for optimal accident tolerant fuel for the VVER-1200 reactor from the neutronic point of view

ABSTRACT

In an attempt to find an optimum fuel, which can withstand the harsh operation condition in the VVER-1200 reactor, different fuel types were investigated in this work. Uranium carbide and uranium nitride are proposed as alternative fuels to UO₂. MCNPX 2.7 with cross-section library ENDF/B-VII was used to design 3D model of VVER-1200 to investigate the neutronic properties of the suggested fuel types. The output results of the burnup of the proposed fuels have been analyzed to determine which of them achieves the longest fuel cycle. It was found that UO₂ and U¹²C achieved criticality till 35 GWD/MTHM, while U¹⁴N and U¹⁵N achieved criticality at 30 GWD/MTHM and 24 GWD/MTHM, respectively. The traditional method of reactivity management has been tested on the proposed fuel to determine to what extent it is valid for them. To ensure the operation safety of the proposed fuel, some safety factors such as moderator temperature coefficient (MTC‎), fuel temperature coefficient (FTC‎), and effective delayed neutron fraction (β_eff) have been calculated. The distribution of the thermal neutron flux and normalized power has been displayed to give us a good insight view of the VVER-1200 assembly to determine which of the proposed fuels is optimum compared to UO₂.

KEYWORDS:

• Accident tolerant fuel (ATF)
• power distribution
• safety parameters
• uranium carbide
• uranium nitride

Acknowledgements

I would like to express my deep thanks and gratitude to Rosatom Company for providing a training course in this type of reactor, Ahmed Abdelghafar Galahom.

Disclosure statement

No potential conflict of interest was reported by the authors.