INVESTIGATION AND ANALYSIS OF ENVIRONMENTAL RADIOACTIVITY LEVELS AT TYPICAL URANIUM MINES IN THE SOUTH OF CHINA.

The environmental radioactivity levels of two typical uranium mines in the south of China were investigated and analysed. According to the characteristics of uranium mines, the relevant parameters, including the surface gamma ray dose rate, concentration of radon in the air and concentration of radionuclides in the soil and surface water, of two uranium mines were evaluated and analysed. The results show that residents in the mining area were exposed to average maximum annual effective doses of 1.69 and 1.58 mSv due to the inhalation of radon and its daughters, while the employees received 2.59 and 1.87 mSv, respectively. Residents in the mining area were exposed to average maximum annual effective doses of 0.77 and 0.69 mSv due to gamma ray, while the employees received 1.64 and 1.33 mSv, respectively.

On-line detection of key radionuclides for fuel-rod failure in a pressurized water reactor.

For early on-line detection of fuel rod failure, the key radionuclides useful in monitoring must leak easily from failing rods. Yield, half-life, and mass share of fission products that enter the primary coolant also need to be considered in on-line analyses. From all the nuclides that enter the primary coolant during fuel-rod failure, (135)Xe and (88)Kr were ultimately chosen as crucial for on-line monitoring of fuel-rod failure. A monitoring system for fuel-rod failure detection for pressurized water reactor (PWR) based on the LaBr3(Ce) detector was assembled and tested. The samples of coolant from the PWR were measured using the system as well as a HPGe γ-ray spectrometer. A comparison showed the method was feasible. Finally, the γ-ray spectra of primary coolant were measured under normal operations and during fuel-rod failure. The two peaks of (135)Xe (249.8keV) and (88)Kr (2392.1keV) were visible, confirming that the method is capable of monitoring fuel-rod failure on-line.