Slowing down calculations in light water and graphite reactors

The object of this study was to investigate the effect of different doses of gamma radiation on some specific groups of soil bacteria, namely Azotobacter and Clostridium. The reproliferation of these two groups following the exposure to gamma radiation was also investigated. Two soil samples were used in this study, the first was calcareous from the northern coast of Egypt and the second was alluvium from Bahtim. The investigated doses of gamma radiation were 0,100, 250 and 1000 Krad. The study revealed that both Azotobacter and Clostridium were affected with different magnitude by the gamma irradiation treatments. However, the survivity of Clostridium to gamma irradiation was greater than Azotobacter. The survivity of Azotobacter and Clostridium was more pronounced in the alluvial than in the calcareous soil sample. It was shown that increasing time of incubation after exposure to gamma radiation generally increased reproliferation of Azotobacter and Clostridium; being more marked with Clostridium than Azotobacter. (author)