Characterisation of the low-energy photon attenuation in gamma-ray spectroscopy of bituminized radioactive waste drums using a peak-to-Compton ratio

In gamma-ray spectroscopy of radioactive waste, the uncertainty on the activity can be very high for low energy photons – particularly below 100 keV – if the chemical composition of the matrix is not known with a good precision. Particularly, high atomic number (high-Z) elements increase photoelectric absorption. We present here the development of a new method characterizing photon attenuation in a homogeneous waste matrix, using a peak-to-Compton ratio extracted from the gamma spectrum.