Impact of High-LET Radiolysis on Gas Production and Transient Kinetics in Aqueous Homogeneous Reactors

Aqueous Homogeneous Reactors (AHRs) exhibit a strong coupling between radiation chemistry and reactor kinetics, wherein radiolysis-induced gas production critically governs transient behaviors via void reactivity feedback. Historically, the predictive accuracy of reactor dynamic models has been severely constrained by the lack of reliable radiolytic yields (G-values) under extreme high-linear-energy-transfer (LET) conditions. To bridge this gap, this study establishes a physically consistent multiscale framework by integrating recently published high-LET G-values—derived from heavy-ion radiolysis experiments—into a macroscopic reactor dynamics model. Utilizing these experimentally validated microscopic source terms, which accurately capture pronounced track-structure effects, a stiff radiation-chemical kinetic model was developed. This model incorporates water radiolysis, nitrate effects, and secondary redox reactions to enable the precise prediction of steady-state gas generation. The calculated hydrogen production rates demonstrate excellent agreement with experimental benchmark data, yielding a relative deviation within ±13%. Furthermore, the chemically derived gas source terms were dynamically coupled into a comprehensive multiphysics framework encompassing point kinetics, conjugate heat transfer, and bubble transport. Validation against the TRACY and SILENE benchmark experiments confirms that the proposed model successfully reproduces transient power excursions, oscillatory behaviors, and quenching phenomena driven by void feedback. This work establishes a robust theoretical and computational basis for the safety analysis of solution-type nuclear reactors.