A study on DCGL determination and the classification of contaminated areas for preliminary decommission planning of KEPCO-NF nuclear fuel fabrication facility

Abstract

As a part of the preliminary decommissioning plan of KEPCO-NF fuel fabrication facility, DCGLs of three target radionuclides, U-234, U-235, and U-238, were derived using RESRAD-BUILD code and contaminated areas of the facility were classified based on contamination levels from the derived DCGLs.

From code simulations, one-room modeling results showed that the grinding room in building #2 was the most restrictive (DCGL(gross) 10493.01 Bq/m(2)). The DCGL(gross) results in contaminated areas from one-room modeling were slightly more conservative than three-room modeling. Prior to the code simulation, field survey and measurements conducted by each survey unit. For a conservative approach, the most restrictive DCGL(gross) in each survey unit was taken as a reference to classify the contaminated areas of the facility. Accordingly, seven rooms and 37 rooms in the nuclear-fuel buildings were classified as Class 1 and Class 2, respectively. As expected, fuel material handling and processing rooms such as the grinding room, sintering room, compressing room, and powder collecting room were included in the Class 1 area. (C) 2019 Korean Nuclear Society, Published by Elsevier Korea LLC.