Modelling high energy radiography of cast elbow pipes with a linear accelerator

Schumm, Andreas; EDF Recherche et Developpement; France

Jonchière, R.; EDF; France
Schumm, A.; EDF; France

ID: ECNDT-0250-2018
Session: X-ray & CT modeling 1
Room: G3
Date: 2018-06-14
Time: 09:00 - 09:20

Computer modelling of NDE techniques plays a vital role in performance demonstration, method development, data interpretation and physical understanding. The radiographic modelling code MODERATO developed at EDF is used extensively for gamma radiography.

For the inspection of cast elbow pipes with total wall thicknesses of up to 220mm, higher energies and activities are required to obtain results within reasonable exposure time, leading to the use of a portable linear accelerator. In order to adapt the modeling code MODERATO for this application, a number of developments were necessary.

The energy range of up to 6MeV required the implementation of high energy physics (pair production), which provides a non-negligible contribution to scattered radiation for this kind of source. A study was made to determine if Bremsstrahlung from secondary radiation had to be taken into account as well. The most significant effort, however, concerned the characterization and implementation of the linear accelerator’s source characteristics, including the effect of the collimation device, the actual spectrum and intensity, and the angular beam flux variation typical of X-Ray sources. We present the different actions taken to obtain a reliable characterization of the source, which involved both numerical modelling with reference codes and experimental measurements.