Occupational exposure during BWR refueling and annual maintenance periods is determined by radioactive corrosion products, such as 6°C o and 58 Co deposited on major components and piping of the primary cooling system.The authors have investigated behavior of radioactive corrosion products, e.g. generation, activation and deposition processes, in the primary cooling system, and then expressed the findings as mathematical equations. These provide corrosion product simulation models to predict the amounts of radioactive corrosion products depositing on components and piping.The effects of corrosion product reduction procedures on shutdown dose rate were evaluated using the model The procedures were incorporated into the Japanese Improvement and Standardization Program. Improvements of operational procedures to control water chemistry, such as NifFe ratio, as well as application of hardware improvements resulted in an extremely low occupational exposure of less than 90 man·remfyr for currently constructed BWR plants.
The analysis of X‐ray diffraction line profile broadening reveals the relationship between lattice microstrain and crystallite size for some microcrystalline quartz in natural quartzose rocks which crystallized slowly and statically. The mean microstrain of quartz microcrystallites increases proportionally with the reciprocal of the crystallite size and its magnitude reaches 0.18% (1.8×10−3) for crystallites ∼43 nm in diameter. This large lattice microstrain is ascribed to the internal pressure derived from the surface energy of the quartz microcrystallite.
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