[en] The aim of this report has been to detect and describe differences between rules regarding fire safety and the interpretation of the rules and make suggestions on how all parties involved are able to develop a harmonized approach to the fire conditions and how fire requirements aspects can be optimized and modernized. International and national laws and requirements for fire protection are compared and analyzed with the content and structure of the USNRCs RG.1189, which is considered the document that has the most complete accounts of the fire requirements both in terms of structure and content. The national laws, rules and guidelines that have been studied are general fire protection rules as well as nuclear specific rules. The studied national rules also includes Safety Analysis Reports (SAR) and Technical Specifications (TS). This study shows that the Swedish SAR and TS are markedly different from each other in how the fire requirements are presented as well as the methodology and level of detail of how they are fulfilled. These differences make it difficult to compare the quality of the fire protection between different sites and it also makes it different to learn from each other. The main reason to the differences are the lack of national guidance of how to fulfil the general requirements. The main conclusion of the screening of national requirements, is that many of the references used in the SAR are not suited for operation at a nuclear plant. The differences are often the purpose, examples of purposes that are not necessarily met by complying with national laws, rules, advices are: - Prevent fire to influence redundant safety equipment in different fire cells. - Prevent fire to influence redundant safety equipment in the same fire cell. - Prevent extensive consequences of fire in cable rooms. - Prevent extensive consequences of fires in oil that are not included in the Swedish regulation for handling highly flammable liquids. The international regulations regarding fire safety at nuclear power plants that have been studied are regulation from USA, Finland, Great Britain, Canada, Germany and the international organisations IAEA and WENRA. The conclusion of this study is that the differences between the regulations mostly are differences in detailed fire safety design. Some differences can not easily be explained by national. Differences and the resulting effect on the overall fire safety is very difficult to evaluate. Regarding how to improve the Swedish regulations regarding fire safety at nuclear power plants there are different possibilities. One is to complement the regulations with acceptable solutions on how to design the fire protection. If this shall be done IAEAs Safety Guides seem to be the easiest of the more detailed fire requirements to adopt to Swedish conditions. Another way of improving the regulation is to give more guidance on how to proof that the rules are fulfilled. In this case the Canadian guidelines may be a good source of ideas and information