A little about uranium

What is uranium?

Uranium is a metallic element that is slightly radioactive - about the same level as one of our most common rocks, granite. Uranium is the most abundant radioactive element in the Earth's crust. There are three isotopes of natural uranium, all with half-lives of millions of years. Of the three isotopes, uranium-235 has the special property that when it is split, by free neutrons, large amounts of energy are released. This is the process used to produce energy in a nuclear power plant.

How is uranium mined?

There are three main methods used in uranium mining. The most common is mining, followed by open-pit mining and underground leaching. A small amount of uranium is obtained as a by-product of the production of other minerals, mainly from mines.

The largest producers of uranium in the world today are Canada, Australia and Russia.

The fuel chain

Natural uranium is too low in the fissile isotope uranium-235 to be used directly as fuel in a nuclear reactor. Therefore, the minable uranium ore must be processed in a number of steps.

• The ore is crushed and treated with dilute sulphuric acid to dissolve the uranium from the ore. The uranium is then precipitated from the acid solution in the form of uranium oxide (chemically known as U3O8). In this form, the uranium is sold from the mine.
• In the next step, the uranium oxide is converted into uranium hexafluoride, UF6, in which the natural uranium is enriched to increase the uranium-235 content from 0.71% to between three and five percent.
• Finally, the gas is converted into uranium dioxide, UO2, which can be pressed and sintered into a ceramic material. In a fuel fabrication plant, the uranium dioxide is pressed into finger-thick cuttings with a density of about 10 g/cm³. The cuttings are inserted into cladding tubes, usually consisting of an alloy that is 90% zirconium.

Where does OKG's uranium come from?

OKG has contracts with several different suppliers of uranium. Most of it comes from Canada, but we also get uranium from Russia and other countries.

All uranium ore that OKG uses for its fuel production is required to be origin-labeled.

All uranium ore that OKG uses for its fuel production is origin-labeled, which means that we always know which country the uranium comes from. However, the uranium that comes from the peace project, which involves reusing uranium from nuclear weapons, has special codes that give us the country of origin but not the exact mine.

How does OKG control its fuel chain?

The environmental requirements OKG imposes on our uranium suppliers are very comprehensive and the company conducts its own audits at each stage of the fuel chain. OKG has a program that requires us to evaluate and review our suppliers based on environmental, health and quality aspects.

We do this, for example, by visiting the mines and factories, talking to residents and politicians, interviewing local trade unions and examining how the companies interact with and support the local population. We also look at certifications, such as ISO 9000 and ISO 14000, and at continuous improvement. All this means that we have enough information to make a proper evaluation of the suppliers.

The working environment in the mines

Mining operations in a uranium mine are marginally different from those in other mines. However, uranium ore has a slightly higher level of radiation than other ores, so special measures are required in the mine to manage radon in the air, radium in the water and, in some cases, direct radiation. The planning and monitoring of radiation protection measures is facilitated by the fact that radioactivity can be measured even at low harmless levels with simple measuring equipment. High radon levels

In the 1940s, large quantities of uranium were mined for the high-priority nuclear weapons program. Ventilation and other environmental issues were the last priority, which led to high radon levels and several miners developing lung cancer. Nowadays, ventilation in all commercial uranium mines is such that the maximum permitted intake of radon for miners is at the same level as now applies to Swedish homes. As a result, there is no longer any evidence of increased lung cancer rates related to radon inhalation among miners. Radiation in mines

The direct radiation, gamma radiation, is read on a small personal dosimeter worn by all employees. At all commercial mines, there are precise values for the maximum permissible dose, just as at all Swedish nuclear power plants. If the uranium content of the ore is high, the direct radiation from the radioactive decay products of uranium can give such high radiation doses that special radiation shields must be installed to protect the miners. With lower uranium levels, mining can be carried out in the same way as in any other type of mine. Radiation doses to mine workers are regularly well below the maximum levels set by the authorities, a situation similar to that of workers at Swedish nuclear power plants.

A few curiosities

The industry today takes far more responsibility than it did in the 1950s and 1960s, when the Cold War between the US and the Soviet Union resulted in the US mining uranium in Canada for use in nuclear weapons.