Analysis of airborne radioactivity in containment and adjacent buildings under PWR accident conditions

Based on the main aerosol behavior, a multi-compartment post-accident airborne radioactivity calculation model is built in this paper, which can be used in post-accident radiation protection design and sensitivity analysis to establish foundation of design improvement. A post-accident airborne radioactivity calculation model for PWR with double-containment design is built, which contains 6 compartments: containment, annulus and 4 adjacent buildings. Airborne radioactivity in compartments are calculated and the removal effectiveness of containment spray system and retention and filtration effectiveness of annulus are analyzed. Based on the analysis, we can see that timely and effectively startup spray will greatly reduce the release of fission product out of containment during a nuclear accident. And the annulus space between the inner containment and outer containment will retain fission product released by containment and reduce the fission product by the filtration of annulus ventilation system. The analytical method is used to estimate the in-containment and adjacent facilities airborne radioactive of new-built nuclear power plants in China, which lay the foundation of equipment reliability and human accessibility analysis. (author)