X-ray inspection setups for the disposal canister lid weld

The X-ray inspection setup for the sealing weld in the final deposition canister needs to deliver as much information about possible weld defect as possible. An alternate approach using three linear detectors instead of one is therefore proposed. The detectors intended to be used are direct conversion Gallium-Arsenide detectors (GaAs). Two detectors (or three in the case considered in this work) provide a possibility of doing stereographic radiography for identification of distinct nearby indications and for evaluation of their location and extension in the depth direction. A simple geometric model was developed to demonstrate the capability of stereoscopic radiography in this application. The stereoscopic radiography seems to be quite promising. From the initial results of using the CIVA-X-ray modelling module in this development work it was concluded that the results should be compared to the results of some more established modelling software because the CIVA-X-ray module is quite new and lack some properties that may be essential in high energy X-ray modelling, for example modelling of pair production. For modelling the output spectrum of the accelerator is needed. Numerical data for the output spectra of a 6 MV and a 10 MV linear accelerator were found in the literature and these are reproduced in this work. The spectra are given as photons per MeV per incident electron so knowledge about the amount of incident electrons is still needed for both types of accelerators.

The problem of synchronizing the accelerator pulsing, the readout of the detector(s) and the canister rotation is also briefly addressed in this work as well as the needed accelerator type and the pulse transducer for rotation monitoring. Based on present knowledge the accelerator needs to be a 9 MV Varian Linatron Mi or a similar accelerator by for example EuroMeV.