THERMOLUMINESCENCE DOSIMETRY AT HIGH-TEMPERATURE AND HIGH-DOSES

The increasingly wide spread use of electronuclear energy has led to t he need for an improved knowledge of the radiation doses received by v arious structural materials. Dose rates are particularly high in regio ns in the vicinity of the core of a reactor, steam generators and the pool in which spent fuel elements are stored; high dose rates will als o be encountered at high-level waste disposal sites. In most, involvin g gamma radiations resulting from the de-activation of fission product s, thermal conditions can be problematic: temperatures as high as 300- degrees-C can be reached inside the core or steam generators. Prelimin ary tests performed in high level waste disposal environments suggest that similar temperatures are likely to be reached. Thermoluminescence (TL) dosimetry can be employed if certain conditions are satisfied: t he TL products must possess at least one deep trap and must also be se nsitive over a sufficiently wide dynamic range. The following material s have been investigated for this purpose: dysprosium doped calcium su lphate powder, alumina and cerium doped ceramic glasses. The maximum d ose measurable depends on the material employed and ranges from a frac tion of a kilogray for alumina, to a few kilograys for calcium sulphat e and cerium doped glasses. A comparative study of the various availab le products has been performed in order to define the limits and to op timise their use.