Abstract:
Radioactive levels of
137Cs,
60Co,
65Zn and
90Sr in decommissioning site of Jinan MNSR were surveyed finally by detecting β and γ spectra.
65Zn in all samples was not detected. In reactor pool, the highest level of 49.3 Bq/kg of
60Co exists at pool bottom just below the reactor core, and is produced by neutron activation. In other survey units, the highest levels of 5.7, 6.8 and 8.1 Bq/kg of
137Cs,
60Co and
90Sr exist in transport passage, reactor hall and soil, respectively, and probably come from contamination of decommissioning practice. The survey results indicate that radioactive levels in all samples are lower than the clearance levels and the acceptable levels derived from the effective dose of 10 μSv/a, and that in most of samples are close to the background levels. The detection lower limits of
137Cs,
60Co and
65Zn are 1.1, 1.0 and 1.3 Bq/kg, respectively. The uncertainty of survey results is less than 33.0%. The relative deviation between the measured value and the certified value of standard material GBW08304a is less than 3%.