As part of an initiative to preserve knowledge in the area of fast reactors, the purpose of this publication is to develop a taxonomy of the Fast Reactor Knowledge Preservation System (FRKPS) that will preserve the world’s knowledge base in this area. The publication identifies basic requirements of this taxonomy on the basis of experience gained. The need for such taxonomy arises from the fact that during the past 15 years there has been stagnation in the development of fast reactors in many countries that were formerly involved in intensive development. Many specialists who were involved in the studies and development work have already retired or are coming close to retirement. In other countries that are still actively pursuing the evolution of fast reactor technology, the lack of young scientists and engineers moving into this branch of nuclear power is a critical issue.