FLOW DAMPER, PRESSURE ACCUMULATION AND WATER INJECTION DEVICE, AND NUCLEAR POWER EQUIPMENT

To include a cylindrical vortex chamber 35, a small flow-rate pipe 37 connected to a peripheral plate 35C of the vortex chamber 35 along a tangential direction thereof, a large flow-rate pipe 36 connected to the peripheral plate 35C with a predetermined angle with respect to the small flow-rate pipe 37, an outlet pipe connected to an outlet 39 formed in a central part of the vortex chamber 35, and a straightening plate 50 that is arranged in a part between the outlet 39 and the peripheral plate 35C of the vortex chamber 35, and when jets flow into the vortex chamber 35 from the small flow-rate pipe 37 and the large flow-rate pipe 36, straightens impinging jets from the small flow-rate pipe 37 and from the large flow-rate pipe 36 having flowed into the vortex chamber 35 toward the outlet 39.