Site characterization for decommissioning Kori Unit 1 is ongoing in South Korea after 40 years of successful operation. Kori Unit 1’s containment building is assumed to be mostly radioactively contaminated, and therefore radiation exposure management and detailed contamination investigation are required for decommissioning and dismantling it safely. In this study, site-specific Derived Concentration Guideline Levels (DCGLs) were derived using the residual radioactivity risk evaluation tool, RESRAD-BUILD code. A conceptual model of containment building for Kori Unit 1 was set up and limited occupational worker building inspection scenario was applied. Depending on the source location, the maximum contribution source and exposure pathway of each radionuclide were analyzed. The contribution of radionuclides to dose and exposure pathways, by source location, is expected to serve as basic data in the assessment criteria of survey areas and classification of impact areas during further decommissioning and decontamination of sites.

1. Introduction
2. Materials and Method
    2.1 Selection of radionuclides for Kori Unit 1containment building
    2.2 RESRAD-BUILD modeling
3. Results and Discussion
    3.1 DCGL derivation for interior surface ofcontainment building
    3.2 Analysis of radionuclide-specific exposurepathways
4. Conclusion
REFERENCES

• Jihyang Byon(Pusan National University)
• Sangjune Park(Pusan National University)
• Seokyoung Ahn(Pusan National University) Corresponding Author