title: Multi-Scale Modeling of the Gamma Radiolysis of Nitrate Solutions.
abstract: A multiscale modeling approach has been developed for the extended time scale long-term radiolysis of aqueous systems. The approach uses a combination of stochastic track structure and track chemistry as well as deterministic homogeneous chemistry techniques and involves four key stages: radiation track structure simulation, the subsequent physicochemical processes, nonhomogeneous diffusion-reaction kinetic evolution, and homogeneous bulk chemistry modeling. The first three components model the physical and chemical evolution of an isolated radiation chemical track and provide radiolysis yields, within the extremely low dose isolated track paradigm, as the input parameters for a bulk deterministic chemistry model. This approach to radiation chemical modeling has been tested by comparison with the experimentally observed yield of nitrite from the gamma radiolysis of sodium nitrate solutions. This is a complex radiation chemical system which is strongly dependent on secondary reaction processes. The concentration of nitrite is not just dependent upon the evolution of radiation track chemistry and the scavenging of the hydrated electron and its precursors but also on the subsequent reactions of the products of these scavenging reactions with other water radiolysis products. Without the inclusion of intratrack chemistry, the deterministic component of the multiscale model is unable to correctly predict experimental data, highlighting the importance of intratrack radiation chemistry in the chemical evolution of the irradiated system.
authors: The University of Manchester , Dalton Cumbrian Facility, Westlakes Science and Technology Park, Moor Row, Cumbria, CA24 3HA, U.K.|The University of Manchester , School of Chemistry, Oxford Road, Manchester, M13 9PL, U.K.
authors: Gregory P
authors: GP
authors: Horne
authors: The University of Manchester , Dalton Cumbrian Facility, Westlakes Science and Technology Park, Moor Row, Cumbria, CA24 3HA, U.K.|The University of Manchester , School of Chemistry, Oxford Road, Manchester, M13 9PL, U.K.
authors: Thomas A
authors: TA
authors: Donoclift
authors: The University of Manchester , Dalton Cumbrian Facility, Westlakes Science and Technology Park, Moor Row, Cumbria, CA24 3HA, U.K.|National Nuclear Laboratory, Culham Science Centre , Abingdon, Oxfordshire, OX14 3DB, U.K.
authors: Howard E
authors: HE
authors: Sims
authors: National Nuclear Laboratory , Sellafield Central Laboratory, Sellafield, Seascale, Cumbria, CA20 1PG, U.K.
authors: Robin M
authors: RM
authors: Orr
authors: The University of Manchester , Dalton Cumbrian Facility, Westlakes Science and Technology Park, Moor Row, Cumbria, CA24 3HA, U.K.|The University of Manchester , School of Chemistry, Oxford Road, Manchester, M13 9PL, U.K.
authors: Simon M
authors: SM
authors: Pimblott