Determination of 36Cl in the groundwaters and ores around a uranium deposit

Abstract

We intend to use fission-induced 36Cl 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 36Cl was carried out using accelerator mass spectrometry at the China Institute of Atomic Energy. After correction for native Cl in the samples, the deduced 36Cl/Cl ratios range from 7000 × 10 −15 to 15000 × 10 −15 for ore samples and from 1200 × 10 −15 to 150 × 10 −15 for groundwater samples. The calculated 36Cl contents range from 3.7 × 10 7 to 7.5 × 10 6 atoms/g in the ore samples and from 1.4 × 10 8 to 8.2 × 10 6 atoms/1 in the groundwater samples. The calculated concentration of cosmogenic 36Cl in the groundwater is 5 × 10 6 atoms. The result shows that the concentration of 36Cl in groundwater is mainly due to in-situ production of 36Cl leached from the ore body by the groundwater and the 36Cl 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.