How does the fuel change during the nuclear process?Isotope U-235 of uranium changes in the reactor into fission products. They are the reason for the strong radiation of spent fuel. Substances that are heavier than uranium are also formed in the fuel, such as plutonium. Otherwise the fuel assembly remains unchanged in size and in practice weighs as much as when loaded in the reactor. Fresh assemblies are shiny, but the oxide layer forming on the surface of the assemblies during the four-year fuel cycle makes them dark.Is the fuel radioactive? Fresh fuel is only weakly radioactive. Fresh fuel is delivered to the power plant by ordinary trucks. Where does the fuel used in Olkiluoto come from? The uranium is primarily mined in Canada, Kazakhstan and Australia and manufactured into fuel assemblies in Germany, Sweden and Spain. How much does one fuel assembly weigh (OL1/OL2/OL3)?The weight of the fuel assemblies used at the plant units in operation (OL1 and OL2) is 280–290 kg and the weight of the assemblies used at OL3 is ca. 780 kg. This weight includes the uranium pellets as well as all the structures of the assembly. The assemblies of the units in operation contain ca. 170–180 kg of uranium each and the assemblies of OL3 ca. 530 kg each. How many fuel pellets does one fuel rod contain?At Olkiluoto 1 and Olkiluoto 2, each fuel rod contains ca. 400 fuel pellets. The fuel rods of Olkiluoto 3 contain ca. 300 pellets.Where will TVO's spent fuel be placed for final disposal?Spent fuel from Olkiluoto will be emplaced for final disposal in the final disposal facility to be constructed in Olkiluoto by Posiva Oy for its owners TVO and Fortum. Final disposal is based on the use of multiple release barriers, which guarantee that nuclear waste cannot come into contact with organic nature or anywhere near people. These barriers include the state of the fuel, the final disposal canister, the bentonite buffer, the backfilling of the repository tunnels and the surrounding bedrock. Read more on Posiva's web site. How long does it take spent nuclear fuel to become safe?Even a rich natural uranium deposit is dangerous in terms of radiation. Spent fuel begins to resemble a rich uranium deposit after a few hundreds of thousands of years. The penetrating gamma radiation disappears from spent fuel in a few hundred years. The multiple barrier system used has been designed to guarantee that the spent fuel does not constitute a safety risk to future generations. The final disposal repository will be closed in a way that makes it possible for the normal life of society to go on above the repository. Read more on Posiva's web site. What are the consequences should there be an earthquake in the final disposal area? An earthquake would probably not affect final disposal at all. The final disposal facility is built inside an intact bedrock block and the stresses caused by the movement of the earth's crust will be relieved along existing block boundaries, while the actual block remains intact. Olkiluoto bedrock is stable and about 1800 million years old. For how long will uranium be available for exploitation and how will the price of fuel behave in the future? Uranium is quite a common element found everywhere in e.g. bedrock granite. The known uranium resources available for exploitation at reasonable mining costs are sufficient for the needs of the existing reactors for more than 80 years. Considerable amounts of uranium are obtained also as a by-product from e.g. copper and gold mining operations. Seawater constitutes an enormous potential uranium reserve, which so far has not been exploited at all. Phosphates also constitute an extremely large uranium reserve. The use of thorium as a fuel and the development of fast reactors are also realistic alternatives.The known uranium reserves are adequate to fulfil demand for several hundreds of years. During 1953 – 2003, the total amount of uranium used by all the reactors of the world was about 1.5 million tons. The known and estimated uranium reserves amount to ca. 15 million tons at present. Uranium only accounts for less than 10 percent of the production costs of nuclear fuel. Consequently, changes in uranium prices have only a small effect on the price of nuclear electricity. The sufficiency of uranium resources will not pose a problem to nuclear power production. Can nuclear fuel be recycled?The fuel can be recycled by separating components suited for reuse from the fuel. The amount of high-level waste can be reduced through reprocessing, but its radioactivity cannot be influenced with the methods available at present. Fuel is not being reprocessed in Finland. If spent fuel can be reprocessed, why doesn't TVO do it, but instead buys new fuel?By virtue of the Nuclear Energy Act, spent fuel may not be exported and there are no reprocessing facilities in Finland. The price level of reprocessing at present also makes it an uneconomical alternative for Finnish nuclear power plants. The amount of spent fuel generated in Finland is so small that reprocessing is not economically viable.Does TVO use MOX fuel, which contains plutonium?No. The fuel used in Olkiluoto is uranium oxide.