Using UVC Lights to Eliminate Biofouling in Pumped Cooling Systems

Biofouling is present at all depths of all oceans with character and magnitude dependent on local physical and biological factors such as temperature, food sources and light intensity. With advances in technology allowing the effective life of equipment to reach decades, biofouling is a key factor in determining the time this equipment can remain deployed maintenance free.Ultraviolet-C (UVC) lights have seen a lot of applications recently as a method to reduce biofouling on sensing devices by either integrating the lights directly or adding external assemblies. Contrastingly, very little has been published on integrating lights into larger systems. The work presented in this paper focuses on the design and integration of a UVC light assembly (utilizing technology enabling UVC LEDs) into the inlet of a pumped cooling system.Flow rates >3m/s are used within the piping system to control biofouling. At the piping inlets, however, the flow must be kept low to avoid drawing in foreign materials (such as fish, jellyfish or manmade debris). These zones of lower flow rate encourage bio-growth which will obstruct the inlets. The cooling system was deployed in a bio-rich coastal environment which necessitated the development of a UVC lighting assembly that could be used to ensure biofilm (a precursor to true biofouling) would not develop at the inlets during a 2-year maintenance-free deployment cycle.As part of system qualification, a prototype was deployed for 2 months at a depth of10 meters. Piping inlets with integrated UVC lights remained free of biofouling. A control unit with no UVC light assembly developed significant growth in the same period.