Hendrik de Bruijn was secretary of the Dutch National Commission for the Euratom research programme from 1958. This commission organised research for the high temperature gas-cooled reactor project at the research centre in Petten and concentrated the work mainly on irradiation matters. In addition to this research work the 'Foundation of Fundamental Research on Matter' at Utrecht undertook in association with Euratom studies.
From 1959 onwards de Bruijn was Head of the Chemistry and Chemical Engineering Division for the Dutch contract partner, the 'Reactor Centrum Nederland' in the Organisation for Economic Cooperation and Development (OECD)/Euratom Joint venture Dragon High Temperature Reactor Project.
The OECD High Temperature Reactor 'Dragon' Project was established on 23/03/1959 as an international joint undertaking by Austria, Denmark, Euratom (representing Belgium, France, Germany, Italy, Luxembourg and the Netherlands), Norway, Sweden, Switzerland and the United Kingdom with the aim of designing a high temperature gas cooled reactor. It based its work on the studies that the United Kingdom Atomic Energy Authority (UKAEA) had undertaken since 1956 at its Atomic Energy Research Establishment (AERE) in Harwell. All participating nations had a strong political motivation in this European enterprise. The Netherlands especially saw in the Dragon Project a political instrument for involving the United Kingdom in continental Europe and regarded it mainly as a long-term research and development activity. The Netherlands, in contrast to Germany and France for example, did not seek actively to promote the political, commercial or industrial aspects of the project.