DETERMINATION OF CL-36 IN THE GROUNDWATERS AND ORES AROUND A URANIUM DEPOSIT

We intend to use fission-induced Cl-36 as a tracer to study the transport of mobile radionuclides and the invasion of a uranium ore body by groundwater in Lianshanguan uranium deposit, which has been considered as a natural geochemical analogue for a nuclear waste repository. The ore and groundwater samples were selected around the uranium deposit. The measurement of Cl-36, was carried out using accelerator mass spectrometry at the China Institute of Atomic Energy. After correction for native Cl in the samples, the deduced Cl-36/Cl ratios range from 7000 x 10(-15) to 15000 x 10(-15) for ore samples and from 1200 x 10(-15) to 150 x 10(-15) for groundwater samples. The calculated Cl-36 contents range from 3.7 x 10(7) to 7.5 x 10(6) atoms/g in the ore samples and from 1.4 x 10(8) to 8.2 x 10(6) atoms/l in the groundwater samples. The calculated concentration of cosmogenic Cl-36 in the groundwater is 5 x 10(6) atoms. The result shows that the concentration of Cl-36 in groundwater is mainly due to in-situ production of Cl-36, leached from the ore body by the groundwater and the Cl-36 tracer can be used to investigate the invasion of the uranium ore body by groundwater and the geochemical isolation of groundwater in the uranium deposit area.