Nuclear power plant

Purpose: To reduce the operator exposure by cleaning the interior of a reactor pressure suppression chamber with a condensation cleaning system and decreasing the radioactivity density of the water in the suppression chamber. Constitution: There are provided a reactor pressure vessel, a main condenser, and impurity removing means arranged at a pipe communicating from the condenser with the reactor pressure vessel. A bypass of a valve provided in a pipe communicating from the condenser with the reactor pressure vessel at the pipe disposed with a value forming a pressure boundary at the outlet and inlet sides of the pressure suppressing chamber and the pressure suppressing chamber. Since a condensation cleaning system is used as a cleaning system, the water radioactive density in the pressure suppression chamber can be reduced to the condensed water. Simultaneously, it can prevent clads from accumulating in the pressure suppression chamber, and can reduce the exposure of the operator at a periodic inspection time. (Yoshihara, H.)