Large-Scale Models of Radiation Chemistry and the Principle of Detailed Balancing

Large-scale kinetic models containing more than 50 homogeneous reaction steps have been developed to help understand the behavior of actinide solutions in various circumstances. One specific objective is to understand the behaviors in nitrate solutions as such solutions are used in actinide separations. A challenge arises in developing these large-scale models while ensuring compliance with the principle of detailed balancing because it can be very difficult to identify all embedded reaction loops. These loops can violate the principle of detailed balancing either by consisting of reversible steps that do not meet Wegscheider's condition or by having unopposed irreversible steps that cause illegality. Here we report the development of DETBAL, which is a software code that systematically identifies a basis of reversible loops and a basis of all loops within the model, and then automatically checks for illegal loops. We apply DETBAL to two recent large-scale models of the radiation of nitrate solutions, show that these models violate the principle of detailed balancing in many ways, provide potential solutions to these violations, and demonstrate the effect of some of these modifications.