Design and Safety Aspect of Lead and Lead-Bismuth Cooled Long-Life Small Safe Fast Reactors for Various Core Configurations

概要

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Design and safety aspects of long-life small safe fast reactors using liquid lead or leadbismuth coolant with metallic or nitride fuel are discussed. Neutronic analyses are performedto investigate the effect of core height to diameter ratio (H/D) on design performance of theproposed reactors. All reactors are subjected to the constraint of 12 years operation withoutrefueling and shuffling with constant 150MWt reactor power and also to the requirement of maximum excess reactivity during burnup to be less than 0.1%Δk. The results show that the pancake design with H/D of -2/3 gives the most negative coolant void coefficient under the requirements for excess reactivity. Modified designs with the central region axially fulfilled with fertile material are proposed to improve the coolant void coefficient. Ther al-hydraulicanalysis results show the possibility to operate the reactors up to the end of life without changing their orifice pattern, necessary pumping power for the proposed design smaller than the conventional large sodium cooled FBR, and the natural circulation contribution of 25-40% at the normal operating condition. The reactivity feedback coefficients are also estimated andappeared to be negative for all the components including the coolant density coefficient.
社団法人日本原子力学会の論文
1995-09-25