Title of paper

5. References

Geological Survey of Namibia. 2012. Strategic Environmental Management Plan (SEMP) for the Central Namib Uranium Rush. 2011 Annual Report. Windhoek. Ministry of Mines and Energy.
MME / Ministry of Mines and Energy. 2010. Strategic Environmental Assessment for the central Namib Uranium Rush. Final report. Windhoek. Ministry of Mines and Energy.

6. Further reading recommendations

Legal Assistance Centre / Stanford Law School. 2009. Striking a better balance: an investigation of mining practices in Namibia’s protected areas. Windhoek. LAC.
Hopwood, G. (ed.). 2013. Namibia’s New Frontiers: Transparency and Accountability in Extractive Industry Exploration. Windhoek. IPPR.
Koep, P. / H. Meyer van den Berg. 2013. Mining and Energy Law in Namibia. In O. Ruppel / K. Ruppel-Schlichting (eds.). 2013. Environmental Law and Policy in Namibia – Towards making Africa the tree of life. Windhoek. Hanns Seidel Foundation: 181-199.

Basics of Uranium and Radiation

By David Fig

1. Uranium

Uranium is a silvery-grey chemical element found in nature: in rock, in soil and in water. It is one of the heaviest of all the metals found on the planet. It has two properties that require caution when coming into contact with the metal. It is toxic or poisonous to humans and animals. And it is also radioactive. Shortly we will see that radioactive substances emit waves (radiation) that cause certain diseases. We need to protect ourselves against such harm.
Therefore uranium is not just any metal. Special precautions need to be taken to protect all of those working in a radioactive environment.
When it is mined, it is separated from the rest of the uranium-bearing rocks, ground into a fine powder, and then transported to the market. During these activities, the community of miners could be affected by contact with the uranium. They could breathe it in, swallow it, or it could enter the body through the skin. If precautions are not taken, the miners could carry uranium dust on their clothing, and their families could be affected too, especially if clothes have to be washed at home. Unless miners and their families are informed about the harmful properties of uranium, they will not realise the risks that they are taking.

2. Ionizing radiation

Radiation emitted from uranium is called ionizing radiation. Ionizing radiation contains enough energy to remove an electron (ionize) from an atom or molecule and to damage DNA in cells.

Sources of ionizing radiation include radioactive elements like uranium. But they can also include the handling and detonation of nuclear weapons, weapons made from depleted uranium, calibration and other measurement sources, as well as x-rays. Non-ionizing radiation is low-energy radiation that includes radiation from sources such as sunlight, microwaves, and radio frequencies.

Diseases caused by ionizing radiation include:

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  Cancers of all types
  
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  Leukaemia
  
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  Lymphomas
  
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  Multiple myeloma
  
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  Radiation sickness (acute radiation syndrome)
  
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  Genetic damage to offspring
  

Let us try to understand how radio-activity works. Certain elements (like uranium, radon gas, radium, strontium, caesium, polonium and plutonium) emit a form of energy called ionizing radiation. We say that these elements are radioactive.

But radioactive elements are not the only sources of ionizing radiation. There is also background radiation caused by the sun and cosmic rays coming in from outer space. There are also human made sources like x-ray machines. We all know that when we have an x-ray, the radiography workers leave the room to shield themselves from the radioactive rays which are passed through the patient to get a photograph of their inner organs and bones. The radiographers do not want to be exposed to the radioactivity of the x-rays each time they take an x-ray because they know it may have a cumulative negative effect on their health.
Most of the radioactive substances found in nature are the heavy elements. In the heavy elements, like uranium, the atomic bonds are looser than in the lighter elements. This means that the heavy elements are less stable and may lose one or more particle over time. This is the process of decay. In this process, the heavy elements release rays or waves of energy along with the atomic particles.
There are different kinds of radioactive rays. We are more familiar with x-rays, but there are also alpha (α) and beta (β) particles and gamma (γ) rays.

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  Alpha particles can be stopped by a sheet of paper.
  
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  Beta particles may be stopped by aluminium shielding.
  
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  Gamma rays can only be halted by much more substantial mass, such as a 4 cm thickness of lead or a 30 cm thickness of concrete.
  

Exposure to these different rays may lead to different kinds of diseases.

3. Electromagnetic spectrum

Gamma rays form part of the electromagnetic (EM) spectrum of radiation. All forms of radiation (including those that are not lethal) are measured somewhere along this spectrum.

The radiation travels and spreads out as it moves. Some of the types of radiation on the EM spectrum include visible light coming from a light bulb in your house or invisible radio waves sent out from a radio station. Other invisible forms of radiation include microwaves, infrared light, x-rays and gamma-rays.

Only a small part of the spectrum contains waves visible to the naked eye.

When the heavy metals decay, they shed one or more atomic particles. For example, uranium is most commonly found in the form of uranium-238. This means that each uranium atom is made up of 146 neutrons and 92 protons, totalling 238. When uranium decays, which takes a very long time, the uranium atom sheds 4 particles, resulting in a change in its chemical composition and becoming a different element, thorium-234.
In turn the thorium will decay within days to proactinum-234 and later in a few minutes to uranium-234. Ultimately if we follow the whole decay chain, we find that the original uranium-238 will decay into lead-206, which is stable and allows for no further decay. In each stage of decay, some energy is released.