Gaborone, Botswana – What do elephant dung and gold mine tailings have in common? Both provide excellent samples to establish the level of naturally occurring radioactivity in Botswana’s efforts to define baseline levels for background radiation as the country gets ready to license its first ever uranium mine.
“We need to be able to monitor any possible radiation release to the environment as a result of uranium mining – but to be able to do that we first need to establish how much naturally occurring radiation there is,” said Richard Shamukuni, Chief Radiation Protection Officer at the country’s Radiation Protection Inspectorate. People are exposed to natural radiation from the sun, cosmic rays and also naturally occurring radioactive materials found in the earth’s crust. It is important to regulate industries that work with materials that emit naturally occurring radiation, in order to protect the public against its effects, he said.
Enter elephant dung. Elephants devour hundreds of different plant species – and radiation present in any of these plants will appear in the manure. “Using the dung sample saves us having to analyze the various plant species one by one,” Shamukuni explained. Gold mine tailings are analyzed because small quantities of uranium are often naturally present in gold ore.
Until 2014, Botswana did not have the equipment or know-how to carry out environmental radioactivity measurements. With the help of the IAEA, the Radiation Protection Inspectorate has since set up an environmental laboratory, fitted with gamma and alpha spectrometry systems as well as other equipment and materials required for radioactivity monitoring. Most radioactive sources produce gamma rays and alpha particles, which are of various energies and intensities. The respective spectrometry systems can be used to detect and measure these emissions.
The IAEA, through its Technical Cooperation Programme, recently funded the fellowship of a nuclear chemist and a radioecologist from Botswana. They learned how to operate the equipment and manage the experiments by working alongside experienced scientists in Portugal and South Africa.
The lab currently analyses around five samples per week. Most of these have shown radioactivity levels that were in line with normal background levels that cause no harm to people or the environment. A few samples from the country’s Central District, near where uranium mining is planned, have shown slightly higher background levels. For the time being, the cause for these readings is not known. “More studies are needed before uranium mining can start,” Shamukuni said.
The government has recently approved the environmental impact assessment of the uranium mine planned near Serule village, some 350 kilometers north of the capital Gaborone. Putting in place regular monitoring of soil, groundwater and air samples is part of the plan.
“Botswana is building a centre of excellence in the region for measurement of environmental radioactivity,” said Martina Rozmaric, a radiochemist at the IAEA involved with the Botswana project. “This is extremely important for a country that plans to start uranium mining in a couple of years.”