Effects of Crud Diameter on Shutdown Dose Rate of Recirculation Pipes in Boiling Water Reactors

抄録

The effects of crud diameter on radioactive corrosion product buildup in the primary cooling pipes of boiling water reactors were evaluated and the following conclusions were obtained :
(1) The crud diameter affected the radioactivity buildup through two processes, i.e. deposition of crud on the fuel surfaces and adsorption of ionic cobalt on the fuel deposited crud. The contribution of the adsorption process to the radioactivity buildup for the plant where the average crud diameter was in the range of 110 μm was as large as that of the deposition process.
(2) As the result of numerical calculations by a radioactive corrosion product transport model, it was demonstrated that the shutdown dose rate was reduced by the suppres-sion of crud concentration in the primary coolant when the crud diameter remained constant, and it was reduced by the increase of the average crud diameter when the crud concentration remained constant.