Ionizing radiation induced chemical reactions have been intensively studied in recent years to design radiation sensitive materials for application in the combination of radiotherapy and chemotherapy. In dilute aqueous solutions ([solute] < 0.1 M), e.g. biological systems, most of the energy deposited by ionizing radiation is absorbed by water molecules, and any subsequent chemical reactions are initiated by the products of water radiolysis. The reactive species from water radiolysis include aqueous electrons, hydroxyl radicals and hydrogen peroxide, which can be used to react with especially designed radiation sensitive prodrugs and nanocarriers. For example, Fu et al. reported an antibody drug conjugate (ADC) where a fibroblast activation protein (FAP) targeted antibody and cytotoxin monomethyl auristatin E (MMAE) are linked by an N-alkyl-4-picolinium group. The picolinium can react efficiently with aqueous electrons, leading to cleavage of the carbamate group and release of MMAE. Tumour-bearing mice that received the ADC and radiotherapy showed efficient drug release at the irradiated site, indicating high precision local control of drug release. Although radiation induced drug release shows high potential for combination therapy, reported useful reactions are rare. One reason could be that the radiation-induced radical species are all highly reactive and short-lived, making it difficult to predict possible products and study reaction mechanisms. Kinetic models have been extensively used in predicting short-lived species (e.g. singlet oxygen , superoxide radical and hydroxyl radical ) mediated advanced oxidation processes. These species react rapidly and unselectively with organic compounds to form reactive intermediates, which is difficult to measure. Elementary reaction-based mathematical models that integrate the kinetics of each chemical reaction with reaction pathways, and the numerical solutions of their related ordinary differential equations (ODEs), can predict the time-dependent distribution of starting materials and reactive intermediates. However, to precisely predict the yield of each species at a given time, the reaction rate of each elementary reaction should be known before calculating the numerical solution.