Protection device for thermonuclear system

This invention concerns a thermonuclear system having super conducting coils and ordinary conducting water-cooled coils together and it is an object thereof to prevent the freezing of cooling water when circulation of cooling water for ordinary conducting water-cooled coils is interrupted. That is, the interruption for the recycling of the cooling water is detected, water is introduced from another water source at the upstream to the cooling water pipeway and then discharged at the downstream. Further, in a case where the introduction of water from another source is no more possible, a pressurized gas is introduced to the upstream of the coil cooling water pipeway and cooling water is discharged together with the gas. With a such constitution, it is possible to prevent the freezing of the cooling water in the ordinary conducting coils while continuting cooling for the superconducting coils. Usually, about two weeks of time and much electric power have been required for cooling the superconducting coils from normal temperature to the vicinity of absolute zero degree. According to this invention, it is possible to economize such a great amount of energy. (K.M.)