Patent Number: 047770082
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an isolating device for a water chamber in a steam generator for a nuclear reactor. 2. Description of the Prior Art In a pressurized water type nuclear reactor, as shown in FIG. 8, a nuclear reactor vessel (01), a water chamber (02a) in a steam generator (02) and a coolant pump (03) are mutually connected with one another by means of coolant pipes (04) to form a coolant circulating loop. And in an atomic power plant, for the purpose of inspection for confirming safety of the component instruments and the systems as well as replacement of the fuels, operation of the nuclear reactor is interrupted nearly once a year. Upon the inspection and fuel replacement, tasks relating to the nuclear reactor such as opening of a nuclear reactor vessel, extraction of fuels, inspection of a reactor core, charging of fuels, reassembly of a nuclear reactor, etc. are carried out in shielding water after the nuclear reactor vessel (01), a nuclear reactor cavity (05) and the like have been filled with shielding water. Then, inspection of thin tubes in the steam generator to be effected at that time is necessitated to be carried out under the condition that the water has been extracted, but the tasks relating to the nuclear reactor and the inspection of the thin tubes in the steam generator cannot be performed simultaneously, because the shielding water is filled during the work relating to the nuclear reactor. Accordingly, the time required for the inspection would become long, and this would limit improvement of the rate of operation of the atomic power plant. The present invention has been worked out in view of the above-mentioned background in the art. SUMMARY OF THE INVENTION It is therefore one object of the present invention to provide a novel isolating device for a water chamber in a steam generator for a nuclear reactor, which can reliably isolate the water chamber in the steam generator from nuclear reactor coolant pipes, a nuclear reactor vessel, a nuclear reactor cavity and the like and thereby makes it possible to carry out inspection of thin tubes in the steam generator simultaneously with the performance of other tasks relating to the nuclear reactor. According to one feature of the present invention, there is provided an isolating device for a water chamber in a steam generator for a nuclear reactor which steam generator includes, at its bottom, a water chamber communicating with a nuclear reactor vessel via coolant pipings and having a nozzle section formed between the water chamber and the coolant piping, which isolating device comprises a support arm having its outer end mounted to a manhole section of the water chamber and its inner end butted against an inner surface of the nozzle section, a plug pivotably attached to a tip end portion of the support arm and positioned within the nozzle section, and an angle adjusting screw interposed between the plug and the support arm, the plug being constructed in a foldable manner. The above-mentioned and other features and objects of the present invention will become more apparent by reference to the following description of preferred embodiments of the invention taken in conjunction with the accompanying drawings.