In 1922, the UMHK built its first refinery for uranium ore, and by 1926 had a virtual monopoly of the world uranium market (holding most of the deposits known at the time), to be broken only by the German invasion of 1940. This uranium was mostly refined at Olen, Belgium. In 1939 , Frédéric Joliot-Curie, head of the French newly established "Centre National de la Recherche Scientifique" (CNRS), arranged for the UMHK to provide his organization with 5 tonnes of uranium oxide, technical assistance with the construction of a reactor and a million francs, in exchange for having all discoveries made by the CNRS patented by a syndicate, with profits shared between the CNRS and the UMHK. This uranium oxide was transferred to England before German troops entered Paris.