Insurers have always been reluctant to proffer insurance solution to the nuclear sector, especially since the occurrence of very serious accidents such as Chernobyl and Three Miles Island. However, this sector is particularly monitored and most of the incidents happening on nuclear sites could be covered by conventional insurers. That is why, underwriters of AXA Corporate Solutions have considered that exploiting this market with adequate limits, by granting third party liability coverage to contractors operating on nuclear power plants, could be profitable and so have decided to hire a trainee to help developing the project. My job, in collaboration with a team of engineers and underwriters of AXA, was first to verify that the market was interesting enough to justify the creation on a new nuclear contract. Then, we had to verify the adequacy of the limits of the contract figured out by AXA engineers to fit with the importance of losses expected. The next stage was to study the most serious incidents in a generic way, in order to verify that none of them would jeopardize the project, and also to facilitate the evaluation of each contracting company: in fact, the activities of each company can be associated with basic components of nuclear power plants, for which we have figured out scenarios of incidents. With the help of these scenarios of incidents, an excel tool has been designed which allows the user to evaluate any contracting company working in the nuclear sector. The evaluation could help judging whether or not offering coverage to a company would be profitable. This tool will also be useful to provide a first idea of the premium to ask to every single company: the determined amounts of premium could next be adapted with additional information from a risk management engineer who would monitor the activities of the studied contracting company. This contract would be first proposed to the contractors of the French nuclear market, and then, if it is a success, it would also be proposed at a global scale. The study focuses especially on PWR (pressurized water reactors), because it is the technology of almost all French reactors. However, as all the nuclear reactor technologies are made on the same principles, this study would have only to be slightly modified, in particular the scenarios, to be suitable also for other technologies.