2018 | AFC ACCOMPLISHMENTS 108 Improved on-line instrumentation for fuel system parameters such as temperature, axial extension of the fuel, and gas release offer the potential to speed development through improved understanding of in-reactor phenomena.Typically this information either cannot be obtained at all (e.g., fuel temperatures) or can only be acquired through destructive post-irradiation examinations. In the latter case, destructive examinations require a substantial amount of additional resources and time to complete and the limited number of examinations that can be performed provide only a partial picture of in-reactor behavior.The objective of the Sensor QualificationTest was to demonstrate the ability to reliably obtain data from the loop in the center flux trap of the AdvancedTest Reactor (ATR), with the ultimate goal being the instrumentation of fuel pins for the AccidentTolerant Fuel-2 (ATF-2) test. Project Description: The Sensor QualificationTest was a non-fueled experiment intended to demonstrate the capability to instrument the loop in the center flux trap of the ATR.The experiments were intended to mimic the instrumentation planned for theATF-2 test, with thermocouples for temperature measurements as well as linear variable displacement transducers (LVDTs) for measurements of axial fuel growth and gas release. In the case of gas release, the LVDT measured the deflection of a small bellows, which in turn was a function of the gas pressure within the pin. Given that the tests were non-fueled, a gas panel was designed so that a pressure history within the rod could be prescribed and in turn enable comparisons between the applied pressure and the pressure measured from the displacement of the bellows. In addition, the rodlets were fabricated with tungsten pellets which served as a source of gamma heating to elevate temperatures within the pin. Figure 1 shows a schematic of the experiment and of the instrumentation used in the test. Accomplishments: The Sensor QualificationTest was substantially more complex than a typical non-fuel experiment in the ATR.Test execution required the design and fabrication of instrumentation that was housed within dummy fuel rods, running gas lines and electrical leads out of the test train, through the reactor head, and into the gas panel and the data collection systems.An experiment in theATR critical facility was required to ascertain the impact of the equipment onATR reactor physics The Sensor Qualification Test Principal Investigator: Gary Povirk Collaborators: Bryon Curnutt, Brian Durtschi, Stephen Evans, Gary Hoggard, Nate Oldham, Connor Woolum Figure 1. A schematic of the instrumented top tier of the Sensor Qualification Test and the bottom tier with uninstrumented pins.