Surface degradation of laminated metal226Ra foils used in school sealed sources in the UK.

In the few years leading up to this research, CLEAPSS noticed a small but steadily increasing number of calls from UK schools regarding a red-brown discolouration on the surface of the foil of their radium source. There were no reports of this type of discolouration on foils of other radionuclides. CLEAPSS and the University of Liverpool collaborated to investigate the nature and cause of this discolouration and the likelihood that the foils were becoming unsafe. The evidence indicates that the discolouration is principally caused by some combination of silicon, sulfur and possibly lead from within the foil diffusing into the face layer. There is no indication currently that the face layers are fragmenting on these foils, but the longer-term integrity of the discoloured foils now becomes questionable. Given the age of the foils and the radiotoxicity of radium, the recommendation from this research is that discoloured foils should be taken out of service and disposed.

Evidence for age-related performance degradation of (241)Am foil sources commonly used in UK schools.

The characteristics of alpha radiation have for decades been demonstrated in UK schools using small sealed (241)Am sources. There is a small but steady number of schools who report a considerable reduction in the alpha count rate detected by an end-window GM detector compared with when the source was new. This cannot be explained by incorrect apparatus or set-up, foil surface contamination, or degradation of the GM detector. The University of Liverpool and CLEAPSS collaborated to research the cause of this performance degradation. The aim was to find what was causing the performance degradation and the ramifications for both the useful and safe service life of the sources. The research shows that these foil sources have greater energy straggling with a corresponding reduction in spectral peak energy. A likely cause for this increase in straggling is a significant diffusion of the metals over time. There was no evidence to suggest the foils have become unsafe, but precautionary checks should be made on old sources.

The design and development of hypertext courseware for CAL in diagnostic radiography.

Educational software has been designed and developed for training within the field of diagnostic radiography and is particularly concerned with the science and technology of diagnostic X-rays. The material has been structured into hypertext networks and as such allows interactive exploration of the available information. The courseware development platform was Microsoft Windows and authoring was accomplished using the constructional tool kit ToolBook. The resulting CAL package is highly graphical in nature with a user interface designed to meet the 'friendliness' demands of the end user group. Mechanisms for navigation through, and orientation within, the hypertext have also been established which support two levels of user activities. By changing the level of user freedom, students using the system as a learning tool are restricted to more structured routes than experienced staff using the courseware as an information resource. An aim of this work has been to provide interactive educational activities to support the main courseware, and consequently a novel application has been developed using dynamic data exchange (DDE) and the spreadsheet software Excel. Through a ToolBook front end students can interactively alter an X-ray spectrum by changing the operating conditions of a simulated X-ray tube.