REACTIVITY CONTROL MECHANISM FOR REACTOR AND REACTOR FUEL ASSEMBLY INCORPORATING ITS REACTIVITY CONTROL MECHANISM

摘要

PURPOSE:To simplify a reactor core and automatically charge negative reactivity at the time of abnormality by housing liquid containing neutron absorbers in the inside of a liquid housing tube, making an air tight structure of the upper part of the liquid surface, pressing and lowering the liquid surface by gas pressure produced due to absorption of neutrons, and compensating reactivity lowering in a reactor. CONSTITUTION:For instance, seven reaction control mechanisms are disposed in the inside of a hexagon wrapper tube 2, liquid sodium which is a coolant is introduced in the wrapper tube 2 from an entrance nozzle 15, and each control mechanism 7 is cooled. Liquid metal 10 such as lead is airtightly sealed in neutron absorption substance housing tubes 8, and neutron absorption substance 11 such as boron is floated. When a reactor reaches a critical point and the substance 11 absorbs neutrons, helium gas is produced, and the liquid surface of the liquid metal 10 floating the substance 11 is gradually pressed and lowered as it is balanced with the helium gas previously injected in the lower part of the mechanism 7. Thereby same effect as pulling-out of control rods is brought, control rod operation is reduced, and negative reactivity can be automatically charged at the time of abnormality.