Orbisphere K1100/K1200 Sensors are maintenance-free, optical Luminescent Dissolved Oxygen Sensors designed for monitoring oxygen in power plants. The K1100 series also includes a sensor version for nuclear power applications. One zero point calibration per year is all that is needed with the K1100 sensor series. Traditional electrochemical (EC) sensors display significant drift after only a few months, demanding regular re-calibration and substantial operator time. Due to its luminescent technology, the K1100 sensor series is designed for minimal drift, resulting in it being the most stable sensor with the longest calibration interval in the nuclear industry. With no membranes to replace and no electrolyte solution to replenish, the K1100 series is virtually maintenance-free requiring only two minutes of maintenance per year. Sensor accuracy is unaffected by process changes or low flow events with no polarisation time, eliminating unnecessary operator interventions in radioactive zones. In addition, corrosive or hazardous chemicals are not required, making the annual task faster, easier and safer without reducing measurement precision. The complete system consists of a 510 Controller, cable, and the K1100 Luminescent Dissolved Oxygen Sensor series. The sensor is compatible with Orbisphere 28 mm flow chambers previously used with EC sensors, eliminating the need for engineering changes to weld, add, and test new connections: an ideal retrofit. The installation is fast and easy and does not require special preparation. The plug-and-play sensor is ready immediately ready for measurement.