employment in the field of nuclear energy which requires specifically nuclear knowledge the acquisition of which calls for special training or at least five months' practical work and which relates to: (a) nuclear energy research in the fields listed in Annex I to the Treaty; (b) supervision, maintenance, repair or technical operation of installations and equipment for: - production, separation or any use of ores, source materials or special fissile materials or for the reprocessing of irradiated nuclear fuels; - isotope separation; - production of the special materials needed in the nuclear field, such as moderators and structural, cladding and shielding materials specially devised for nuclear purposes; - production of nuclear energy; - disposal of nuclear waste and radioactive impurities; - transport or storage of radioactive materials; - production, preparation or use of radioactive isotopes; (c) planning, designing or construction of installations or equipment or constituent parts of the installations or equipment used in the fields listed in subparagraphs (a) and (b); (d) protection against radiation