Since the Fukushima nuclear accident in 2011, there has been a growing need to strengthen severe accident management guidelines (SAMGs) and find appropriate methods for validating SAMGs. The validation of SAMGs is currently performed in terms of their usability, using a full-scope simulator, a tabletop drill, and a severe accident analysis code. However, given that the use of these rely on human expertise, and the workflow of SAMGs is very complex, a new validation method is needed. In this study, a model of a SAMG workflow has been developed using Colored Petri Nets (CPN) as a new validation method. In addition, time delay, which is required for SAMG actions, has been factored in. In order to verify usable SAMGs instead of existing validations by SAMG documents, the SAMGs were validated using computing technology. The modified CPN models, which are representative of the limited plant states during implementation of SAMGs, were simulated for computer-assisted validation. It has been verified that the novel validation method can complement existing validation methods. (C) 2018 Elsevier Ltd. All rights reserved.