"To take part in the largest international research project in nuclear fusion energy is a source of great pride," Guy Lacroix, the chief executive in charge of energy services at French energy company GDF Suez, said in a statement.
GDF Suez leads a consortium that includes Germany's M+W Group. The six-year contract is for the so-called Fusion for Energy program, an entity in charge of the European Union's activities at the International Thermonuclear Experimental Reactor in France.
The contract calls for design, construction and maintenance of air conditioning, electrical and mechanical installations for 13 buildings at the complex.
GDF Suez said in a statement work should begin at the complex in France starting in September. Construction should take about five years, with the bulk of the work planned for 2016.