Low Draft Temperature Sensor Gen-IV Simulation Test Planning and Hardware Development

No method exists for testing fiber optic sensors to Gen-IV reactor relevant environments, especially the very high temperature reactors (VHTR). Luna is currently funded to develop drift-free fiber optic sensors for measurement of temperature in Gen-IV reactors, especially the next generation nuclear plants (NGNP). These reactors are planned to operate at temperatures above 1000°C and neutron fluence up to 022-2cm. Accurate temperature measurement is needed to identify hot spots, control thermal cycles, to perform temperature compensation of other sensors, and is therefore critical to the safe operation of these reactors. A Gen-IV simulation methodology is needed to accurately determine the durability of the fiber optic sensor and address any challenges discovered. Luna proposes to develop a methodology and hardware to test prototype optical fiber sensors to near Gen-IV fluence (5x1020 cm-2 ) and temperatures (up to 1200°C) simultaneously in the Massachusetts¿ Institute Technology Nuclear Reactor (MITR). The proposed project will also identify durability challenges of fiber optic sensors for focused test method development. Testing of the sensors will be completed by another project. Luna investigated several research reactors and concluded that the MITR facility is the most viable facility for generating prototypical Gen-IV irradiation for testing sensors. Luna demonstrated durability of fiber optic temperature sensors to be greater than 500 hours at 1000°C and also made measurements on previously irradiated sensors confirming no significant damage in the sensor fiber leads after 5.15 E18 n/cm2 at elevated temperatures (up to 700 °C). MIT and Luna will model, design and construct a facility for leaded testing of fiber optic sensors to prototypical VHTR irradiation. Luna will construct and calibrate a series of test sensors and assemble a data acquisition system for monitoring the sensors real-time. Commercial Applications and other Benefits as described by the awardee: Low-drift temperature measurement will enable commercialization of Gen-IV reactor designs as well as increase safety in PWR (pressurized water reactors) and other Gen-III designs already in operation. Since the sensors will be radiation tolerant and high-temperature capable, they will also find application in space probes, rocket engine monitoring, rocket engine development and in gas turbine health monitoring. In particular, the proposed testing methodology will enable advancement of the technology readiness level (TRL) of fiber optic sensors for use in future Gen-IV designs.