FBR type reactor plant

The present invention concerns an FBR type plant in which reactor core supports can easily be extracted. That is, the inside of a container boundary is replaced from an air atmosphere to an inert gas atmosphere by using an inert gas conditioner. Then, the reactor core is retracted and coolants are drained. Next, an operator enters a maintenance cask applied with radiation shieldings and goes down into the reactor container from an opening formed after the removal of a rotational plug by using a ceiling crane. The operator removes bolts, etc. by using a manipulator disposed in the maintenance cask, draws out reactor core supports, transfers them to a decaying pit and conducts repair and amendment. When the removal of the reactor supports from the reactor container is completed, the operator is hoisted together with the maintenance cask and comes out from the container boundary to the outside of the reactor building. (I.S.)