Abstract: A method includes: an arrangement step of arranging a phased array probe including a plurality of oscillators each of which is capable of emitting ultrasonic waves on an end surface of the rotor disc, in a parallel state in which the plurality of oscillators are arranged along a circumferential direction of the rotor disc; a first transmission step of emitting ultrasonic waves from the plurality of oscillators in the parallel state, while a timing of emitting the ultrasonic waves from each of the oscillators is controlled in a first emission pattern, and receiving reflection waves of the ultrasonic waves; and a second transmission step of emitting ultrasonic waves from the plurality of oscillators in the parallel state, while the timing of emitting the ultrasonic waves from each of the oscillators is controlled in a second emission pattern different from the first emission pattern, and receiving reflection waves of the ultrasonic waves.

Abstract: A method includes: an arrangement step of arranging a phased array probe including a plurality of oscillators each of which is capable of emitting ultrasonic waves on an end surface of the rotor disc, in a parallel state in which the plurality of oscillators are arranged along a circumferential direction of the rotor disc; a first transmission step of emitting ultrasonic waves from the plurality of oscillators in the parallel state, while a timing of emitting the ultrasonic waves from each of the oscillators is controlled in a first emission pattern, and receiving reflection waves of the ultrasonic waves; and a second transmission step of emitting ultrasonic waves from the plurality of oscillators in the parallel state, while the timing of emitting the ultrasonic waves from each of the oscillators is controlled in a second emission pattern different from the first emission pattern, and receiving reflection waves of the ultrasonic waves.

Abstract: A steam valve includes: a valve main body which has, on the inside thereof, a flow path through which steam flows, and has a valve seat formed in a portion of the flow path; a valve body which comes into contact with the valve seat, thereby shutting off the flow path, and is separated from the valve seat, thereby opening the flow path; a valve shaft which is connected to the valve body, extends in an upward direction from the valve body, and moves up and down, thereby bringing the valve body into contact with the valve seat and separating the valve body from the valve seat; a hydraulic drive unit which is disposed to be separated in a horizontal direction from the valve main body, at a position which does not overlap the valve main body in a case of being viewed from above, and has a drive rod which is driven forward and backward by oil pressure; a first link unit which connects the drive rod and the valve shaft and transmits the forward and backward drive of the drive rod to the valve shaft, thereby moving t

Abstract: A steam valve includes: a valve main body which has, on the inside thereof, a flow path through which steam flows, and has a valve seat formed in a portion of the flow path; a valve body which comes into contact with the valve seat, thereby shutting off the flow path, and is separated from the valve seat, thereby opening the flow path; a valve shaft which is connected to the valve body, extends in an upward direction from the valve body, and moves up and down, thereby bringing the valve body into contact with the valve seat and separating the valve body from the valve seat; a hydraulic drive unit which is disposed to be separated in a horizontal direction from the valve main body, at a position which does not overlap the valve main body in a case of being viewed from above, and has a drive rod which is driven forward and backward by oil pressure; a first link unit which connects the drive rod and the valve shaft and transmits the forward and backward drive of the drive rod to the valve shaft, thereby moving t