부식생성물 평가코드를 이용한 제염해체 폐기물 발생량 분석연구

Abstract

The radionuclide accumulated on the inside and outside of the different systems of nuclear power plant is caused by the corrosion product activation of reactor structural materials and by the fission product. Since form, volume and distribution of radionuclide vary according to the reactor type, size and structural materials, it is not easy to calculate the inventory of surface contamination. However, there are two methods to evaluate the surface contamination accumulated on the inside of the system. The one is to evaluate through the direct measurement and the other one is to evaluate the inventory of surface contamination by using the computerized program with numerical model to analyze behavior of corrosion product within the coolant. Of these, when using the calculation method based on the numerical model that is applied for the radioactivity assessment, it is expected to directly impact on choosing a decommissioning method as the evaluation technique for radioactivity inventory. Consequently, this study compares and analyzes the five codes of corrosion product evaluation. Also on this study, the codes are evaluated in order to verify whether they can be used to analyze the waste generation amount of decontamination and decommissioning. For the last, the ways to improve the accuracy are proposed. In this study, the different codes were compared and analyzed for the research on decontamination and decommissioning waste generation by using the codes of corrosion product evaluation. The water chemistry factor and the calculation method according to the mechanism for each code were analyzed, as well as, improvement points and advantages and disadvantages were compared for each code. When the national application plan for Korea and overall circumstances are concerned, CRUDMIT code is expected to be the most suitable among the other codes. Beside CRUDMIT code, the operation history of nuclear power plant should be compiled as a database since the code calculation value from the previous models is still useful even after it is disassembled. Also, in order to use hereafter the code, which is suitable for decontamination and decommissioning, the improvement and supplementation measures are required to apply the numerical formulas to the influence factors on the amount of corrosion product generation and for the relations between accidents and radioactivity. Lastly, additional analysis is required by applying the events such as control rod malfunction, coolant pump stop and station blackout.