Development and deployment of an autonomous sensor for the in-situ radioactivity measurement in the marine environment

An autonomous sensor for the in-situ radioactivity measurement is developed，based on NaI(Tl) crystal, to detect the activity concentrations of natural and anthropogenic radionuclides in seawater. Its electronics module, integral enclosure and spectrum analysis were presented. The energy, resolution and efficiency were calibrated. Monte Carlo simulation and the minimum detection estimations were realized. The sensor was tested in the water tank and then successfully deployed for the continuous monitoring in the marine environment in Qingdao offshore for the performance test, background measurement and environmental survey. Some results were deduced from the gamma ray spectra and discussed in comparison with those from the laboratory and literatures.