M8 power calibration (M8CAL) hodoscope report
TREAT test M8 will be performed to determine, for IFR fuel, the transient fuel-failure threshold and pre- and postfailure fuel movement that could lead to shutdown. The fast-neutron hodoscope, an ex-reactor instrument, measures test fuel motion in a 10-wide by 36-high array of channels. Hodoscope data—both transient and steady state—obtained in M8 power calibration tests are analyzed. Since the transient data are for an unfueled test vehicle, corrections to them are formulated to attain a constant, power-normalized reactor-background response for all channels in a transient. Corrections for axial flux tilt, detector deadtime, detector nonlinearities, and detector efficiencies are described. Scan data are reported for both fueled and unfueled scans. The hodoscope signal-to-noise ratio is determined from scan data. Finally, both transient and scan data are used to derive a hodoscope performance estimation for test M8. One conclusion is that the smallest mass change that can be detected by the hodoscope on a 4-ms time scale is of the order of 0.55 g of fissile material per pixel, which is some 8% of the portion of the fissile mass of a fuel pin that is subtended by a hodoscope row. Systematic errors that may raise this minimum sensitivity are also evaluated. The M8CAL data show that there is appreciable axial flux tilting as a function of control-rod position, with the variation from top to bottom of the hodoscope array approaching 20%. Rod-position changes perturb ion-chamber readings as well. Refinements of the hodoscope data-handling algorithms to compensate for those effects are described; some anomalies remain unexplained.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Nuclear Energy
- DOE Contract Number:
- AC02-06CH11357
- OSTI ID:
- 10200318
- Report Number(s):
- ANL-IFR-240; 154299
- Resource Relation:
- Other Information: PBD: Oct 1994
- Country of Publication:
- United States
- Language:
- English
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