b'Real-time Axial NeutronNew sensor testing capabilities enable real-time neutron flux Flux Profile Measurementmonitoring at the Advanced Test Reactor Critical facility.at the Advanced TestR eal-time characterization of irradiation facilities improves the utilization of the core capabilities of test nuclear reactors. The ability to observe how Reactor Critical Facility the local neutron flux (level and spectrum) changes as control elements and experiments change will fundamentally transform our understanding of the underlying physical phenomena that govern the operation of present and advanced nuclear reactors, ultimately providing valuable information for the nuclear energy industry. The objective of this research was to demonstrate how advanced sensors could be used to significantly reduce the time and cost of experiments, improve our PROJECT NUMBER:understanding of experimental environments, and enable verification and validation 20A44-112 of simulation and modeling methods. This was accomplished by designing and fabricating a dedicated real-time instrument test train for the ATR Critical facility.TOTAL APPROVED AMOUNT: $824,000 over 3 years The first year of this project focused on the design and modeling of real-time axial neutron flux monitors, leveraging proven technologies pioneered at INL, to PRINCIPAL INVESTIGATOR:characterize the transient that occurs in the small B positions at ATR and the ATR Michael Reichenberger Critical facility. We found that the flux amplitude in those positions can fluctuate CO-INVESTIGATOR: as much as 380% depending on the outer shim control cylinder position. These Mary Rose Holtz, INL fluctuations create large uncertainties for experiment designs that lead to substantial deviations between simulation results and as-run measurements.The engineering design of the test fixture and flux monitor instrumentation was the objective of the second project year. Most experiments at ATR and ATR Critical facility require unique test fixture fabrication for the irradiation position within the reactor. This project was no different; however, a keen focus was given to the flexibility of this test fixture to facilitate multiple real-time instruments both present and future. New capabilities were established to electrodeposit enriched uranium for fission chamber development at INL, and trials were begun to characterize the process. Substantial work was also necessary to formalize the instrument design process as well. The test fixture and instrument designs were finalized, reviewed, and released so that the fabrication of the Quality Level 3 components could be initiated.The final year included the fabrication of the test fixture and instruments for ATR Critical facility. This unique capability that we delivered to ATR Critical facility will facilitate future instrument testing and scientific experiments. 22'