(A) study on the radiation shielding analysis for LILW vitrification facility

Abstract

In recent years, NETEC of KHNP is planning the vitrification plant for LILW(Low- and Intermediate- Level Waste). It has mainly two advantages. One is that it can reduce the volume of LILW and the other is that it can produce vitrified crystals which show little leaching. Through these advantages, it is predicted that the vitrification plant will treat the LILW discharged from the Uljin unit 5 and 6 in future. But until now, there has been no experience in construction and operation of a vitrification plant in Korea. Therefore, by carrying out radiation shielding analysis which is an essential part of the safety analysis of vitrification plants, this research was conducted to acquire information that can assist in the detail design and operation plan of vitrification plants hereafter. In this study, the sensitivity analysis for the equivalent dose rate in field according to the distance and shielding material, was performed. As a result, it was founded that the effect of the thickness of the 1st shielding material more diminished as farther from the radiation source. Therefore, it could be expected that it would be more effective to simultaneously use a 2nd shielding material and a 1st shielding material of moderate thickness than to meaninglessly increase the thickness of the 1st shielding material. And a radiation area was designated based on this result. Also the substance for the 1st shielding material should be lead, which has a high shielding efficiency. And for the 2nd shielding material, which does not have a important role in short distance shielding, concrete was considered, because it can be easily used during construction and can also divide radiation areas. The results of this study make it possible for the worker’s maintenance areas and free accessible area to be divided effectively. Also the equivalent dose rate in field in the entire area was effectively decreased. The results of this study will be useful for detail design of vitrification plants...