PERFORMANCE ANALYSIS FOR ENHANCED CR-COATED FUEL CLADDING SYSTEM IN APR-1400 REACTOR

The conventional Zircaloy-uranium fuel-cladding system in pressurized water reactors faces challenges such as reduced mechanical strength, stability, and susceptibility to oxidation and embrittlement at high temperatures. The Accident Tolerant Fuel concept, aiming to address these issues, involves replacing or coating cladding with materials exhibiting enhanced corrosion resistance. This study explores the efficacy of ATF using a chromium coating and selecting an adhesive layer material (Niobium or Molybdenum) between cladding and coating. Neutronics analyses, employing the Serpent Monte Carlo 2.31 simulation tool on the APR-1400 reactor, assess the impact on different neutronics parameters. A sensitivity analysis involves varying coating thickness (10 µm, 15 µm, 20 µm) and adhesive layer thickness (2.20 µm, 3.20 µm, 4.20 µm) for Zircaloy cladding. Results show that adjusting ATF design parameters can match the original fuel-cladding cycle length. The 10 µm coating with 2.2 µm Nb adhesive layer exhibits minimal neutronics impact, suggesting it as an alternative cladding material. In 2D reactor core analysis, Nb outperforms Mo due to a lower reactivity difference and smaller absorption cross-section, enhancing thermomechanical properties with minimal neutronics impact. Implementing Cr-coating with Nb adhesive layers holds promise for enhancing safety and reliability in nuclear power plants, particularly in mitigating risks during high-temperature conditions and loss-of-coolant accidents.