Nuclear power has played a significant role in the supply of electricity over the past two decades. The two major nuclear accidents, namely Three Mile Island and Chernobyl, have considerably affected its further growth. Reconsideration of reactor design and safety aspects of nuclear power has been an active area of development. Elimination of some accident scenarios, simplification of systems and reliance on natural phenomena have been a major part of these activities, which led to the development of new design concepts.

Under the sub-programme on non-electrical applications of advanced reactors, the International Atomic Energy Agency has been providing a worldwide forum for exchange of information on integral reactor concepts. Two Technical Committee meetings were held in 1994 and 1995 on the subject where state-of-the-art developments were presented. Efforts are continuing for the development of advanced nuclear reactors of both evolutionary and innovative design, for electricity, co-generation and heat applications. While single purpose reactors for electricity generation may require small and medium sizes under certain conditions, reactors for heat applications and co-generation would be necessarily in the small and medium range and need to be located closer to the load centres.

The integral design approach to the development of advanced light water reactors has received special attention over the past few years. Several designs are in the detailed design stage, some are under construction, one prototype is in operation. A need has been felt for guidance on a number of issues, ranging from design objectives to the assessment methodology needed to show how integral designs can meet these objectives, and also to identify their advantages and problem areas.

The technical document addresses the current status of the design, safety and operational issues of integral reactors and recommends areas for future development.