Study on neutronics of VVER-1200 with accident tolerant fuel cladding

Abstract

Protective coatings deposited on traditional Zr-based fuel cladding materials potentially enhance accidental tolerance of Light Water Reactors due to reduced interaction between water and Zr alloys during accidental conditions. Enhancement of cladding performance and reduction of negative effects, such as heat generation, hydrogen production, oxidation, and embrittlement can be achieved by deposition of various coatings that are widely studied around the world. Even though thermal, mechanical, and chemical responses during accidental conditions are the main concern for these materials, the actual application of coated materials will be linked to standard operating conditions including economic consequences and transient response. Reference VVER-1200 fuel system with five coatings (Cr, CrN, ZrSi2, Cr2AlC, Fe(Cr)(Al)) is investigated from the neutron-physical point of view using the calculation package SCALE 6.2.2. In addition to the multiplication factor, specific fuel safety criteria are also examined for both the fresh fuel assemblies and fuel assemblies with burn-up up-to 70 MWd/tHM. All studied coatings entail certain negative effects in comparison with the reference case. The closest behavior to the reference VVER-1200 fuel assembly is found for ZrSi2 coating followed by Cr2AlC and Fe(Cr)(Al) coatings. Both Cr and CrN materials exhibit significant differences compared to the reference case.