The M8 Power Calibration Experiment (M8CAL)

The M8 calibration experiment was a series of 23 irradiations in TREAT performed to determine the relationship between the fission power generated in the TREAT core and the fission power generated in experiment fuel located in an in-core experiment vehicle and irradiated by core neutrons. The experiment was planned to provide the essential calibration information specifically needed for planning and analysis of the M8 test (and subsequent tests similar in geometry to M8) to be performed in the post-upgrade TREAT core. Irradiations were performed in TREAT cores loaded with a full-slotted (to optimize hodoscope performance) and with a half-slotted (to maximize energy deposition). Tests included a few selected low-power irradiations of fresh IFR-type U-Zr and U-Pu-Zr fuel pins supplemented by multiple irradiations of uranium-zirconium monitor wires ranging from low steady-state power to high-power maximal transients. This report describes the M8CAL test hardware, measurements, analysis assumptions, and methods used to deduce power coupling between the reactor and experiment fuel--including both absolute magnitudes and axial distributions. Power coupling results are reported for fresh IF fuel pins under high-power transient test conditions appropriate to the planned M8 transient test. In line with previous calibration data, measured dependence of power coupling on the specificsmore » of each irradiation is also shown to correlate well with the in-core axial locations of the TREAT control rods. Estimates are made for maximal test fuel energy deposition capabilty in controlled transients.« less