TESTING OF A COMPUTER PROGRAMME FOR CALCULATING THE Sr-85 YIELD AS WELL AS FALLOUT Sr-89 AND Sr-90 IN A SINGLE LSC MEASUREMENT WITH DETECTION LIMITS CONFORMING TO ISO 11929

摘要

Sr-89 (t_(1/2) = 50.5 days) and Sr-90 (t_(1/2) = 28.81 years) are produced by nuclear fission with relatively large fission yields. The value of the ratio (activity Sr-89/activity Sr-90) in nuclear fuel varies with the degree of burn-up. For nuclide inventories of reactors in the middle and at the end of an operating period, respectively, the German Risk Study on Nuclear Power Stations gives mean values for this ratio of 19.8 and 23.6. The mean value for fuel rods with maximum burn-up (i.e. just prior to removal from the reactor) is initially 12.3, which decreases to almost 1 after cooling for half a year.