Neutronic design and analysis of the accident-tolerant fuel (ATF) application to VVER-1000 nuclear reactor as well as evaluation of dynamic parameters

Abstract

In order to improve the safety of commercial nuclear reactors, this paper presents neutronic design and analysis of the accident-tolerant fuels (ATF) application to VVER-1000 nuclear reactor. The study commences by simulating a fuel assembly containing 2.4% enriched uranium. The simulation of a VVER-1000 reactor core loaded with standard uranium dioxide (UO2) fuel was then conducted using the MCNPX 2.6 code. This simulation yielded various neutronic and dynamic parameters, including the multiplication factor, excess reactivity, delayed neutron fraction, fuel and coolant temperature reactivity feedbacks, power peaking factor, and fuel burn-up. These values were subsequently compared with existing reference data. Finally, the reactor core was simulated using accident-tolerant fuel. The resulting data was analyzed to identify the optimal combination of fuel and cladding. Throughout the study, the MCNPX 2.6 software was employed for neutronic core analysis. Comparative analysis revealed that uranium carbide (UC) offers superior safety margins in both neutronic and dynamic aspects, outperforming uranium dioxide (UO2) and uranium mononitride (UN). Simulations exploring the use of silicon carbide (SiC) and FeCrAl as alternative cladding materials within the reactor core demonstrated potential advantages over traditional Zirconium (Zr). Results indicate that application of ATF can improve cycle length, temperature reactivity feedbacks and power peaking factor compare to the reference core (UO2 + Zr), significantly. © 2024 Elsevier B.V.