To investigate the possibility to characterize radioactive wastes using available information and measurements in a coherent frame, a Bayesian formalism is built to couple gamma-ray spectrometry and tomographic scans. The gamma ray spectrometry is performed with four High Purity Germanium (HPGe) detectors placed around the waste and scanning 2 cm thick slices of a radioactive waste drum in a Gamma Scanning mode. The tomography provides the density of the drum matrix and identifies heterogeneities. The unknown chemical composition of the matrix and heterogeneities is handled with two parameters that represent the mass fractions of carbon and hydrogen of a fictive {C; Sn; H} material that would show a gamma ray attenuation behavior similar to that of the true material. The approach is tested by simulating the measurement of ²³⁹Pu gamma rays produced by a PuO₂ sphere placed in a drum slice in which two distinctive zones have been identified by tomography, in presence of ¹³⁷Cs background. With the studied simulated examples, depending on the sphere position, the use of the density prior information allows decreasing the plutonium mass uncertainty by up to a factor 3 compared to the case when the density prior is not used. In addition, the use of the density prior information provides a posterior plutonium mass distribution having a significant number of event related to the true plutonium mass, which is not the case when the density prior information is not used.

为了研究使用相干框架中的可用信息和测量来表征放射性废物的可能性，我们建立了贝叶斯形式主义，将伽马射线能谱和层析成像扫描相结合。伽马射线光谱分析是通过在废物周围放置四个高纯度锗（HPGe）检测器并以“伽马扫描”模式扫描2 cm厚的放射性废物鼓的切片来进行的。断层扫描提供鼓矩阵的密度并识别异质性。基质的未知化学组成和异质性可通过两个参数来处理，这些参数代表虚拟{C;碳和氢的质量分数。锡; H}材料将显示出与真实材料相似的伽马射线衰减行为。该方法通过模拟测量在¹³⁷ Cs背景下，由PuO ₂球产生的²³⁹ Puγ射线置于鼓片中，在该鼓片中已通过层析成像法确定了两个不同的区域。通过研究的模拟示例，取决于球体的位置，与不使用密度先验的情况相比，密度先验信息的使用可使mass质量不确定性降低多达3倍。另外，密度先验信息的使用提供了后p质量分布，该后to质量分布具有与真实p质量有关的大量事件，当不使用密度先验信息时情况并非如此。