Used nuclear fuel dry storage unit: aspects related to nuclear licensing and scientific dissemination

Several regulatory models license Pressurized Water Reactors to operate for 40 years considering possible equipment obsolescence, phenomena that lead to aging of its main components of systems involving the nuclear part and the reduction of safety margins. In pressurized light water (PWR) reactors design there are spent fuel pools for the storage of used fuel elements with capacity to receive the recharges throughout the lifetime of the plant. At each recharge one third of the fuel elements are exchanged. These used fuel elements, after sometime, would then be stored in definitive facilities. However, to date, there is no definitive solution, considered acceptable, for the storage of these used nuclear fuels. Due to the development of the state of the art and safety analyzes carried out, it was demonstrated that the original projects of the Nuclear Plants were conservative. In this way, with modifications of design and improvements and modernization and reassessments of safety margins, it is possible to increase the lifetime of these plants from 40 to 60 years. With this additional operating time, the nuclear power plants face the challenge of stocking the used Fuel elements from these additional 20 years. An alternative that has proven to be interesting and safe is the dry storage system. The present work intends to present the characteristics of this technology, aspects of operation of this storage and discuss regulatory aspects to assist in the licensing of this type of installation. (author)