The Auxiliary Cooling Water System (ACWS) is the used to remove heat from plant equipment during operation. For the OPEN100, the system is a closed loop and utilizes water as a medium to transfer heat from large components like the turbine generator, large pumps and smaller loads such as heat exchangers, and sample coolers. The use of a closed loop without an open air or additional water based, heat sink minimizes the impact of the plant on the surrounding environment.