Fission Product Release Measurements in the Dragon Reactor Cores 8 and 9 Charge III

During the irradiation of Cores 8 and 9 of the third fuel charge in the Dragon Reactor, purge gas from 32 fuel elements was analysed and the specific activity of a number of radioactive isotopes determined by γ-spectrometry. The results of these analyses, together with purge flow and power rating data has enabled the fraction of generated fission products which escape into the purge gas to be calculated. The results of these calculations are tabulated in this report. In the majority of cases the release to birth ratios determined were in the region 10^-4-10^-3, with the exception of the HT Matrix elements which in general gave release to birth ratios in the region 10^-4-10^-3. The use of capillary bore sample lines was investigated during this period and it was shown to be possible to determine fission products with half-lives in the region of 8-10 s. The level of activity of Xe-133, Kr-85m, Kr-88 and Xe-135, in the primary coolant was determined regularly throughout both cores, at various levels of purge and by-pass purification. Measurement of the total activity in the primary coolant continued to be made by means of the installed ion chambers. (author)