Period of Performance: 06/08/2015 - 03/07/2016


Phase 1 STTR

Recipient Firm

Information Systems Laboratories, Inc.
10070 Barnes Canyon Road Array
San Diego, CA 92121
Firm POC, Principal Investigator


The reactor vessel coolant level is currently measured primarily by differential pressure DP) and by heated junction thermocouple HTJC) probes. The DP gauge measures only collapsed water level and not two-phase level, while the HJTC probe indicates whether or not the water level has reached the elevation of a specific probe. The HJTC probes are typically located at discrete intervals so the measurement is not continuous. Gravimeter- based instruments have the potential for providing accurate, non-invasive and continuous reactor coolant inventory measurements. ISL will develop a new, innovative sensor designed to non-invasively measure coolant inventory distribution within the reactor vessel, based upon gravitational technology. The proposed study, if it establishes feasibility of the measurement technique, could lead to a major advancement for reactor coolant inventory monitoring, greatly enhancing the reactor performance in sustainability, safety and security aspects identified in Mission Supporting Transformative Research programs. Commercially available gravimeters with state-of-the-art sensitivity will be configured to measure coolant inventory in the Oregon State University MASLWR SMR prototype test facility, under a variety of conditions. Since the gravimeter-based system is non-invasive, our experiments not require modifications of the test facility and will be run concurrently with other testing. Accurate conversion of the gravitational output signals to coolant inventory information will be verified by comparison to data produced by the coolant level instrumentation in the MASLWR facility. The measured data will be compared to numerical models produced independently, for verification. After conclusion of the testing program, optimal gravimeter configuration and design features to enhance coolant inventory measurements will be determined, and implemented in the design of a commercialized system that will be directed to SMR applications. We will work with SMR vendors such as NuScale Power, LLC, to optimize the design according to their needs and expert feedback, in order to best commercialize the technology.