Design of a neutron interrogation cell based on an electron accelerator and performance assessment on 220 liter nuclear waste mock-up drums
Abstract
Radiological characterization of nuclear waste drums is an important task for the nuclear industry. The amount of actinides, such as 235U or 239Pu, contained in a package can be determined using non-destructive active methods based on the fission process. One of these techniques, known as neutron interrogation, uses a neutron beam to induce fission reactions on the actinides. Optimization of the neutron flux is an important step towards improving this technique. Electron accelerators enable to achieve higher neutron flux intensities than the ones delivered by deuterium-tritium generators traditionally used on neutron interrogation industrial facilities.
In this paper, we design a neutron interrogation cell based on an electron accelerator by MCNP-X simulation. We carry out photoneutron interrogation measurements on uranium samples placed at the center of 220 liter nuclear waste drums containing different types of matrices. We quantify impact of the matrix on the prompt neutron signal, on the ratio between the prompt and delayed neutron signals, and on the interrogative neutron half-life time. We also show that characteristics of the conversion target of the electron accelerator enable to improve significantly measurement performances.
Keywords
neutron interrogation cell design
Thickness measurement
Neutrons
Photonics
radiological characterization
235U
239Pu
nondestructive active methods
actinide fission reactions
Polyethylene
nuclear waste mock-up drum performance assessment
Radioactive pollution
Electron accelerators
neutron flux optimization
neutron interrogation
photoneutron
Nuclear measurements
radioactive waste storage