Computer Simulation Studies Of Radiation Damage Stability (Fission-Track Annealing) and He Diffusion In Apatite Materials

点击翻译按钮获取中文摘要

The stability of radiation damage and the diffusion of gas in natural and synthetic calcium phosphate (apatite) is of major importance to environmental, geoscience and engineering problems, including nuclear waste storage. Deciphering the thermal histories of Earth's upper crustal rocks is an essential requirement for understanding geodynamic processes, long-term landscape evolution and in assessing hydrocarbon maturity in sedimentary basins. Key methods in thermal history reconstruction utilise apatite, measuring the accumulation and stability of nuclear radiation damage (fission-tracks FT) and of radiogenic helium - (U-Th)/He chronometry. Interpretation of sample data requires precise knowledge of the stability of the tracks and helium at elevated temperatures which at present is derived from empirical measurement of the fractional track shortening (annealing) or helium loss under different time - temperature conditions. Varying substitutions in the calcium phosphate (apatite) lattice produce differences in the FT stability and gas diffusion.This project will employ a parallel approach developing and employing a range of complementary computational methods to investigate radiation damage and gas diffusion in calcium phosphate materials, where the key issues are:The development of models for the interaction of impurity cations and anions, substituted in the calcium phosphate lattice;Modelling of He diffusion in the pure and defective lattice;Simulation of the processes of generation and annealing of nuclear fission tracks in different apatite structures.The outcome of the project wi4 be an improved and detailed understanding on the atomic scale of the influence of composition on the formation and stability of nuclear fission tracks and the diffusion of helium in apatite, an approach which can be applied subsequently to study damage and diffusion in increasingly complex materials.