Abstract: Accurate evaluation of hydrogen (H₂) production yield in high α-radioactive solutions is crucial for ensuring the long-term storage safety of high-level radioactive liquid waste. The production of hydrogen from water radiolysis, induced by ionizing radiation, can lead to a dangerous buildup of gas pressure within storage tanks, presenting a significant risk of hydrogen explosion. In this study, a robust Monte Carlo simulation framework was developed to construct a comprehensive radiation absorbed dose model for aqueous solutions containing 89 representative radionuclides, and model the solutions in storage tanks of varying sizes and accurately calculate the contributions of α, β, and γ radiation as well as their three-dimensional spatial distributions. This model further integrates pure water radiolysis reaction kinetics to establish a hydrogen production model. The coupling of Monte Carlo simulations with radiolysis reaction kinetics provides a more accurate and detailed prediction of hydrogen production in the presence of radiation. The results from this combined model show that hydrogen concentration overall increases over time, exhibiting a small peak in the initial stage due to the interaction between hydroxyl radicals (·OH) and H₂ as well as their precursors. The concentration of hydrogen peroxide (H₂O₂) and oxygen (O₂) initially rises, followed by a decrease, and eventually stabilizes at equilibrium. Increasing the size of the storage tank leads to higher contribution ratios of β and γ radiation doses, influencing the non-monotonic variation of H₂ concentration, with a reduced peak value observed. This is largely associated with the increased G(·OH) values, which represent the yield of ·OH generated by β and γ radiation. The concentration of O₂ exhibits a monotonic increase, which is primarily driven by the enhanced reactions between ·OH and hydroperoxyl radicals (HO₂·), leading to O₂ production. Furthermore, the H₂O₂ concentration initially increases due to the elevated levels of ·OH radicals but decreases later due to the accelerated consumption of H₂O₂ through reactions with ·OH and solvated electrons (\mathrme_\mathrmaq^- ), both of which play critical roles in the aqueous radiolysis process. The findings of this study provide a deeper understanding of the complex interactions between radiation types, dose distributions, and the radiolytic kinetics governing hydrogen production in high-level radioactive waste storage tanks. By overcoming the limitations of traditional empirical models, this work establishes a more accurate theoretical framework for predicting the risks of hydrogen explosions in such storage systems, therefore, offers valuable insights into the safety management of high-level radioactive waste, laying the groundwork for more reliable predictions and effective mitigation strategies in the future.