[en] A preliminary design study of tritium safety systems for the fusion experimental reactor building has been carried out as part of the tritium plant design for the ITER(CDA)/FER. FER building was used as the reference reactor building in the present study, because its general layout has rather been clarified. The major items described in this report are as follows; (i) Review of the Japanese regulations related to tritium safety for the protection of worker's and public radiation, (ii) Review of the facility zoning in the Japanese commercial plants for spent fuel reprocessing, PWR, etc., (iii) Review of air-leak tightness of the Japanese nuclear facilities, (iv) Zoning of fusion reactor building (controlled and uncontrolled areas), (v) Design of room air detritiation systems for normal operation, invessel component maintenance, and accidental large tritium spills, (vi) Amount of tritiated waste water, solid waste and environmental tritium exhaust from room air detritiation systems, (vii) Required ventilation flow rate and operation time period at a large tritium spill, (viii) Requirements for the reactor building design. (author)