Quantitative evaluation of thin uranium foils using X-ray radiography

The quality of research reactor fuel plates fabricated for irradiation testing purposes is dependent on the distribution of uranium bearing fuel phase within the fuel meat. This distribution is routinely monitored in plate type fuel to avoid excessive variability in local power that can lead to 'hot spots' that increase the probability for fuel failure. X-ray imaging has been routinely used to successfully eliminate this failure mode. However, characterization of this variability at a much higher resolution is also critical to support fuel performance assessment and traditional analysis techniques are not sufficient to meet research needs. An accurate and reproducible method for using X-ray imaging to non-destructively locate the distributed fuel phase and to evaluate the local uranium density in a fuel plate has been developed and is discussed in this paper. Four mini research reactor fuel plats were radiographed along with a well characterized U-8Mo step wedge using identical radiography exposure conditions. The intensity distribution inside the foil were then correlated with the intensity values of the U-8Mo step wedge. Considering the attenuation and density, the spatial distribution of effective fuel thickness was estimated and eventually the distribution of average fuel loading for each fuel plate was estimated. Results demonstrate that the X-ray imaging can be utilized to estimate fuel loading variation in the fuel plate samples and can serve as a representative method for the assessment of nuclear fuels plates for research purposes.