According to the “Nuclear Power Plant Design Safety Regulations” (HAF102-2016), the integrity and availability of equipment, shell, gates, electrical penetrations and other equipment inside the containment need to be analyzed. Therefore, for each nuclear power plant model, the radiation environmental condition is supposed to be calculated. This article uses third generation PWR as the research object, firstly introduces the radiation environmental condition calculation methods applied in previous engineering applications, and then analyzes the potential influencing factors of the environmental condition, afterwards the article conducts a refined analysis of radiation environmental conditions. The refined analysis uses the containment source term calculation software independently developed by China Nuclear Power Engineering Co., Ltd. Finally, this article compares and summarizes the results of refined analysis and conservative analysis. This article explores the influencing factors of the radiation environmental condition, realizes the optimization of radiation environment and improves the refined radiation protection design capability, also, it provides a research direction of the future optimization and application.