„A discussion on whether Poland has its own uranium deposits and could be self-sufficient when it comes to producing fuel for nuclear power plants is expected to return soon. The answer to the first question was until recently: it depends in which department this question will be asked,” writes prof. Andrzej Piotrowski, former Deputy Minister for Energy Responsible for the nuclear sector, for BiznesAlert.pl.
- For years, Russia’s behind-the-scenes efforts have sought to push affordable and emission-free nuclear power beyond the methods of power generation used in Western societies. At that time, the world market was rather hastily allowed to be dominated by uranium supplies from Russia. Dominance does not mean monopoly.
- The exploitation of uranium deposits in Poland took place mainly in the 1940s and 50s. The main areas where uranium was mined were the Kowar and Kletna regions in the Sowie Mountains and the Tatras.
- It is necessary to prevent radioactive leaks into the environment, which is why such waste needs to be managed safely. This creates not only current but also long-term costs. The radiation hazard is not limited to uranium mining waste.
- Uranium mining is a very intensive exploitation of the natural environment due to its low content in deposits. Natural uranium contains only about 0.7% of the isotope U-235. In the third generation power plants, uranium is used at a level of 3-5 percent enrichment. In advanced fourth-generation reactors still using low-enriched uranium, a uranium mixture called HALEU is approaching 20 percent enrichment.
Minister Marzena Czarnecka, in her speech at the Regional Chamber of Commerce in Katowice as part of the “Economic Opening of the Year”, suggested the amendment to the Act on departments, a new ministry will be handling resource policy, including nuclear policy. So we can expect a return of discussions about whether Poland has its own uranium resources and whether we can be self-sufficient when it comes to getting fuel for nuclear power plants in Poland. The answer to the first question was until recently: it depends in which department this question will be asked.
Prime Minister Donald Tusk has said publicly that nuclear power is necessary in Poland, so hopefully opinions that are not based on merit will soon dissipate. So, once and for all, we will establish that there are uranium ores in Poland and that this resource, despite the exploitation of some deposits during the „Cold War”, still exists in abundance in other places in excess of what Poland will need for the next hundred years to supply its nuclear power plants. However, the second question remains: should we focus on uranium mining and enrichment?
Russia’s game to disrupt uranium supply
For years, Russia’s behind-the-scenes efforts have sought to push affordable and emission-free nuclear power beyond the methods of power generation used in Western societies. At that time, the world market was rather hastily allowed to be dominated by uranium supplies from Russia. Dominance does not mean monopoly. Investments have already been initiated to restore the production of enriched uranium in Western countries. Russia made another move by provoking a revolt in Niger, which hit French manufacturing capacity and drove up the market price. However, not only are there multiple uranium deposits across the world, but also it is possible reestablish the ability to enrich uranium withing a few years.
History of uranium in Poland
The exploitation of uranium deposits in Poland took place mainly in the 1940s and 50s. The main areas where uranium was mined were the Kowar and Kletna regions in the Sowie Mountains and the Tatras. In Kowary, the activity was most intense in the years 1948-1954, when uranium deposits were exploited under Soviet supervision, as part of the „R1″enterprise. In the Tatras, exploitation was carried out on a smaller scale, mainly in the 1950s . After this period, interest in uranium in Poland gradually waned, mainly due to the low profitability of mining compared to more promising deposits discovered in other countries.
The threat of radon
Unfortunately, during the extraction of uranium ore, one of the main threats is radon, a naturally occurring noble gas, which is the decay product of uranium. Radon is radioactive. When it is inhaled, its breakdown products can settle in the lungs, increasing the risk of lung cancer. In addition to radon, uranium ore can contain other heavy metals and radioactive substances. Not all of these elements are released as raw materials, and combustible rocks, which are waste from the extraction process, so they must be stored somewhere. The risk of radioactive releases into the environment must therefore be prevented and such waste must be managed safely. This creates not only current but also long-term costs. The radiation hazard is not limited to uranium mining waste. Radioactive substances can also be found in other mining heaps, as well as in ash, as combustion processes concentrate the content of heavy elements in the waste.
Yellow cake
The next stage of processing uranium ore is to increase the content of the isotope U-235. For this purpose, the ore is ground into powder to increase the surface on which chemical reagents can act. The ground ore is subject to disposal (etching). Ore powder is mixed with chemical solvents (usually sulfuric acid or sodium hydroxide) that dissolve uranium leaving other minerals as waste. Uranium in the form of a solution is then extracted from the mixture. Ion exchange, chemical deposition or solvent extraction processes are often used for this. Uranium from the solution is precipitated in solid form, e.g. as ammonium diuranoate (ADU) or magnesium diuranoate (MDU). The precipitate is dried and then roasted at a high temperature, resulting in a yellow cake – yellow cake, which contains about 80 percent uranium in the form of uranium oxide (U3O8). This substance has a characteristic yellow or brownish color, hence the name „yellow cake”.
Centrifuges and waste
Uranium from uranium oxide U3O8 is chemically converted to uranium hexafluoride (UF6) because UF6 is one of the few uranium compounds that is solid at room temperature and becomes a gas at around 56 degrees Celsius, which facilitates its use in the enrichment processes. The uranium enrichment process is a key step in the production of nuclear fuel because natural uranium contains about 99.3 percent of the uranium-238 isotope and only about 0.7 percent of the uranium-235 isotope, which is the fissile isotope used in most nuclear reactors.
In the centrifugal force enrichment method, UF6 gas is introduced into rapidly rotating cylinders (i.e. centrifuges). As a result of the centrifugal force, the heavier UF6 particles from U-238 move towards the outer walls of the cylinder, while the lighter ones from U-235 concentrate closer to the cylinder axis. The gas is then taken from different points of the cylinder, so that fractions of varying degrees of enrichment are obtained. After the enrichment process, the UF6 gas can be subjected to further purification processes. Centrifugation is currently the most effective and most commonly used method of uranium enrichment.
In the process of enrichment, in addition to UF6, other radioactive isotopes can be formed, as well as by-products such as plutonium. This implies the need for close supervision and control to prevent the proliferation of non-peaceful nuclear technologies and materials. In addition to radiation, UF6 is a very toxic and reactive substance, especially with water, which requires special precautions when storing and handling it. The wastes from the enrichment process, known as enrichment tails, contain depleted uranium and other radioactive substances. They require storage in safe conditions in specially prepared landfills.
And finally – uranium dioxide
UF6, once enriched, is converted to UO2 through a series of chemical reactions. This requires first reducing UF6 to metallic uranium and then oxidizing to UO2. At this stage, the main threat is still UF6, which must be stored and processed in conditions that prevent release into the atmosphere. In contrast, uranium dioxide, although less reactive than UF6, still requires procedures for radioactive material. Waste from this stage of the conversion process is mainly toxic chemical and radioactive materials. Their disposal requires specialized methods, which mainly involve reducing the volume and depositing the waste in safe, isolated places. The obtained UO2 is then pressed into small, hard granules. The UO2 granules are subjected to a sintering process, i.e. heat treatment, which increases their density and mechanical strength.
Fuel for nuclear reactors
In nuclear reactors of the third generation, fuel is prepared in the so-called. fuel rods. They are made of metal resistant to high temperature and corrosion (usually zirconium alloy), in which UO2 granules are placed. Tubes with UO2 granules are hermetically sealed, forming fuel rods.
In fourth-generation reactors, nuclear fuel is either prepared in the form of multi-layered TRISO balls for gas-cooled reactors, or the pellets are mixed with a liquid coolant such as liquid salts or metals. Thanks to this the risk of the rector’s core melting in the event of a cooling failure is eliminated. While the third generation reactors have structural protection against the impact of failure, the fourth generation reactors have a design that eliminates the threat.
For and against mining and enrichment
Uranium mining is a very intensive exploitation of the natural environment due to its low content in deposits. Natural uranium contains only about 0.7% of the isotope U-235. In the third generation power plants, uranium is used at a level of 3-5 percent enrichment. In advanced fourth-generation reactors still using low-enriched uranium, a uranium mixture called HALEU is approaching 20 percent enrichment.
Uranium enrichment is technologically complex and requires extensive surveillance. It is also a multi-step process in which significant amounts of waste are generated. The waste can be concentrated in terms of volume, but the residues must be stored “forever”. It is therefore no coincidence that uranium enrichment has been pushed to countries where environmental standards are more lenient and waste space is not as valuable as in Central Europe.
The decision to start uranium mining in Poland as well as the construction of an enrichment industry should therefore be considered not only in terms of energy independence, but also in terms of nuisance. And one more note: it is not identical to the production of nuclear fuel, which is made in the next phase and is distinguished by a significant profit margin in the value chain of the nuclear energy sector. The availability of enriched uranium does not mean access to fuel, which is also specific to each type of reactor.