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.

Abstract: Provided are embodiments for a system including a zero-cross circuit. The system includes a first channel and a second channel Each channel includes a generator, a generator relay, and a bus tie relay. In addition, the system includes a zero-cross circuit, wherein the zero-cross circuit synchronizes the operation of the first and second channel, and at least one controller configured to control the operation of the first channel and the second channel based on an input from the zero-cross circuit. Also provided is a method for operating the zero-cross circuit with low phase delay. The method includes receiving an inverting input, receiving a non-inverting input, and comparing the inverting input and the non-inverting input. The method also includes receiving feedback from an output of the comparator; and outputting a waveform based on the comparison of the inverting input and the non-inverting input and the feedback.