1. Concept evolution

Around 1956, as the first carbon dioxide reactors were being built, the development stages for HTRs were initiated. The work carried out at the Harwell Nuclear Research Centre in the UK was exploited by Project Dragon, under the patronage of the Nuclear Energy Agency of the Organisation for Economic Co-operation and Development (NEA of the OECD). The project was formalized by an agreement signed in Paris in 1959 between Great Britain, Austria, Denmark, Norway, Sweden, Switzerland and EURATOM (Germany, Belgium, Netherlands, Italy, Luxembourg and France). The history of HTRs in Europe thus began in a highly international context.

The characteristics of the main HTR reactors already built or planned are shown in the table 1 .

The Dragon project had two complementary missions:...