Dual-mode heat removal system that allows first direction natural circulation flow through a heat exchanger during nuclear reactor emergency cooling and allows opposite direction forced flow through the heat exchanger during decay heat removal

Abstract

Piping loops can carry either forced or natural circulation coolant flow from and back to a nuclear reactor depending on reactor and coolant state, and can transition between the two. The loop flows into a heat exchanger that cools the coolant and may even condense the coolant. The heat exchanger can drive natural circulation coolant flow, and a pump on the loop can drive forced circulation. Coolant direction may be reversed through the heat exchanger in different modes. Loops may be installed directly on existing isolation condenser systems or come off of a primary loop generating electricity commercially. Actuation valves may isolate and actuate the system merely by disallowing or allowing coolant flow. Different flow modes and coolant direction may be similarly achieved by pump actuation and/or valve opening/closing. Beyond the pump and simple valve actuation, loops may be entirely passive.