Evaluation of Crud Behavior in Primary Circuit of Integral Reactor by Multi-region Model

Abstract

In order to evaluate behavior of deposited crud from structual materials surfaces, multi-region model dealing with radioactive corrosion products behavior has been developed to describe crud behavior in primary circuit of the integral reactor. The primary circuit of the integral reactor, which was adopted ammoniated water chemistry, was divided into nine control volumes. The transportation of the radioactive nuclei by the sedimentation, washing-out, and release of corrosion products were considered between ths control volumes and its associated surfaces in the model. Specific activities of separate radionuclides in the primary coolant as well as on the surfaces of structual materials that were washed by the coolant throughout fuel cycle were also simulated with operation mode. As a result, this multi-regional model was capable of evaluating the behavior of crud more exactly than the two or three nodes model simualtion codes. From this evaluation the integral reactor showed lower activities than the other commercial reactor because this was introduced the titanium alloy to the SG tube material and the avoidance of boric acid.