Fission product deposition in the HTGR type reactor primary coolant circuit

The mechanism of fission fragment transport and deposition in the primary coolant circuit of the high temperature gas cooled reactor (HTGR) is studied analytically using the model of heat-mass analogy. On the base of the particle balance equation for the surface of pipelines walls the expression for evaluating the deposition constant #betta# which is determined as the ratio of the velocity of irreversible particle deposition on the wall to a number of particles in a gas coolant and takes into account the resulting effect of adsorption, desorption, chemical interaction and diffusion into the wall is obtained. The results of #betta# calculation for 131I and 134Cs isotopes in the case of their deposition on the steel pipe surface as well as that for 137Cs deposition on the surface of a titanium pipe at hellium temperature of 300-700 deg C are taken as an example. #betta# is turned to be equal to 2 0-1 1x10-5 x10-3 c-1 respectively. On the basis of the re-- sults of the obtained data comparison with the experimental data it is concluded that the proposedmethod for the deposition constant determination assures satisfactory accuracy for integral estimating the ffassion products activity in the HTGR coolant circuits