Research on water radiolysis models and their behavior in high flux research reactors

A water radiolysis model is developed for high flux research reactors, with application to the Tsinghua High Flux Reactor (THFR). Refined G-value calculations (gamma and neutron) and supplemented reactions for alkaline conditions are validated against literature experiments, showing good agreement. Parametric studies reveal that molecular product concentrations scale with the square root of the dose rate due to the bimolecular nature of elementary reactions, and decrease with temperature, with a progressively slowing rate of decrease, reflecting different temperature dependencies of the competing production and consumption kinetics. THFR simulations show steady state reached within ∼1 s in most regions. Notably, despite the dose rate being two orders of magnitude lower than that in the core, upper and lower plena exhibit significant importance on the coolant radiolysis due to the square root scaling and long residence times.