High Temperature Operable, Harsh Environment Tolerant Flow Sensors for Nuclear Reactor Applications

A commonly noted sensor need for nuclear power systems is flow sensing in the various heat transfer mediums and to monitor medium velocities and characterize mixing and/or cooling. This is particularly needed for small modular reactors designs where coolant flow is driven by natural convection, not by pumps. Such sensors must be able to tolerate high temperature, high pressure, and radiation (neutron and gamma) environments while being minimally disruptive of coolant flow. How this problem is being addressed. We propose to work with nuclear power original equipment manufacturers to develop such a small, high reliability, high temperature operable, liquid flow sensor. This development will be based on Sporian’s past experience with high temperature sensors and packaging, and facilitative ceramic electronics packaging technologies. What was done in Phase I. The Phase I effort included experimental evaluation of materials, design development, neutron irradiation testing, and proof of feasibility prototype demonstration. Key structural materials were experimentally evaluated for compatibility with boric acid, a chemical used to control reactions in pressurized water reactors. Simple sensor and packaging prototypes were tested in a research reactor to evaluate performance under neutron irradiation. Complete sensor and packaging prototypes in an original equipment manufacturer test facility to demonstrate performance in a relevant environment. What is to be done in Phase II. The Phase II effort will include: working with OEMs to guide technology develop and transition efforts; design and development of dedicated drive and signal conditioning electronics; development of the next generation of sensor and packaging designs; rigorous lab scale testing of prototype devices, including required regulatory compliance; highfluence neutron irradiation testing at a test reactor; and device demonstration in an application relevant test system. Commercial applications and other benefits. The ability to deploy a distribution of flow measurement sensors within the reactor vessel or reactor core would greatly improve the ability to continuously measure the amount of margin available, and operate at higher temperatures which would improve the thermal efficiency. This increase in efficiency will allow more electricity to be generated from the same nuclear fuel investment. The proposed sensor also has the potential to improve public safety and reduce negative environmental impacts by assuring reactor cooling system flow. A high temperature flow sensor could have various additional applications for flow sensing in fossil fuel, transportation, and industrial applications. For example, the sensor also has potential to provide compressor bleed air flow measurement for fossil fuel energy generation turbines. Key Words: Generation IV, nuclear power systems, SMR, flow sensor, neutron irradiation, high temperature, sensor, packaging, ceramics, efficiency.