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FAQ - Frequent Questions and Answers1. What is energy ?
Energy is the power that moves all the bodies in the Universe. It is the capacity to produce work or heat.
2. How do we classify the sources of energy ?
– Non renewable - those are the energy resources available or existing on Earth in fixed quantities,
and which deplete as they are consumed. E.G.: Oil, coal, natural gas, nuclear energy by fission or
scission (uranium) and nuclear energy by fusion (deuterium).– Renewable - are the existing energy resources which do not deplete, as they result from natural phenomena periodically renewed. E.g.: solar energy, wind energy, biomass, hydraulic energy, geothermal energy. 3. What is the measuring unit for electric energy ?
The power of generators and electric engines is measured in watt (W) and the produced and consumed energy is
measured in watt/hour (Wh). As the use of these units lead to very high figures, the following multiples are normally used:
4. What is nuclear energy ?
It is the energy released when the fission of atoms occurs. In a nuclear reactor it occurs in a multiplying sequence
known as "chain reaction".
5. What is a "chain reaction" ?
It is the reaction that stimulates its own repetition. In a fission chain reaction, the nucleus of a fissile material absorbs a neutron and fissions, releasing additional neutrons. These, on their turn, may be absorbed by other fissile nucleus, releasing yet more neutrons.
6. . What is a nuclear reactor ?
It is a device where one can initiate, maintain and control a chain nuclear reaction. There is therein a nucleus formed by the nuclear fuel where the nuclear fission reaction phase is processed for the generation of electric energy.
7. What is the type of reactor used by the Brazilian nuclear plants ?
It is a Pressurized Water Reactor (PWR). A power nuclear reactor where the heat is transferred from the nucleus to a heat exchanger through water, which is maintained under high pressure to reach high temperatures without ebullition of the primary system. The steam is produced in the heat exchanger (steam generator) of the secondary circuit.
8. . What is nuclear fuel ?
Nuclear fuel is the name given to the material or substance that may generate energy through the scission of the respective nucleus and their atoms. In commercial nuclear reactors, the fuels used are the natural uranium or the enriched uranium. Thorium and plutonium are also nuclear fuels.
9. What is a nuclear element ?
Every chemical element which may be used to release energy in nuclear reactors or which may originate chemical elements that may be used for such purpose.
10. What is a nuclear mineral?
It is every mineral that contains in its composition one or more nuclear elements.
11. What is nuclear ore ?
It is every natural concentration of nuclear mineral where the nuclear element(s) occur in such a proportion or condition that allows its economic exploration.
12. What is natural uranium ?
It is the uranium as it is found in nature, containing 0,7% of 238-uranium and 99,3% of 238-uranium and traces of 234-uranium.
13. What is impoverished uranium ?
It is the uranium with a percentage of 235-uranium below 0,71% found in the natural uranium. It is found in irradiated fuel elements and in the residues of uranium isotopic separation processes.
14. What is enriched uranium ?
It is the physical process of removal of 238-uranium removal, consequently increasing the concentration of 235-uranium.
15. What are the processes to enrich the uranium ?
Several processes of uranium enriching have been developed. Among which: the Gas Diffusion and the Ultra-centrifugation (in an industrial scale), the Centrifuge Jet (in an industrial demonstration scale) and the Laser process (under research).
16. Can a nuclear plant cause or generate an atomic explosion?
No. A nuclear reactor to generate electric energy is built in way as to prevent the explosion as an atomic bomb. Such concern has no fundament whatsoever, as the concentration of 235-uranium is very low (circa 3%), not allowing the chain reaction to be processed fast enough to cause an explosion. A opposed to reactors which are designed to retain the radioactive substances, the bombs are designed to cause its dispersion effective.
17. What are Safeguards ?
Safeguards are a set of administrative, technical and political measures that allow the follow up and control of the use of nuclear materials, equipment and technologies as well as to ensure that these are not used for warlike purposes. Given the nature of these issue the performance and control of international safeguards is exercised by the International Atomic Energy Agency (IAEA), the United Nations agency responsible for the activities involving the nuclear energy.
18. What is radiation ?
It is the issuance or propagation of energy through mater or space, through electromagnetic disturbances presenting a double behavior: as a wave and as particles.
19. What is natural radiation ?
It is the radiation that exists in the environment, on the Earth crust, in our body or originated from the cosmic rays. It is also called background radiation.
20. Which are the natural sources of radiation ?
a) Cosmic rays - Radiations originated mainly from the sun, which reach the planet. The cosmic rays are partially armored by earth's atmosphere. Therefore, the higher the altitude the higher the exposure to the cosmic rays. For example, intercontinental aerial trips increase the exposure to cosmic rays. b) Ground - The radioactive elements of the natural series are part of the materials comprising the Earth crust. In some regions of the planet there is a higher concentration of these elements, for instance in Brazil, in the municipality of Poços de Caldas in Minas Gerais and in the coast of state Espírito Santo State. c) Water - Some elements of the natural radioactive series are contained in the subterranean waters. Some mineral water sources present higher concentrations of these elements. d) Air - The radon and thoran gases, contained in the natural radioactive series of the uranium and thorium, respectively, originate from the soil and rocks and are dispersed into the atmosphere. Closed environments, with little air renovation, such as subterranean mines or closed sites using air conditioner or heating, present higher concentration of these gases in the air. 21. What are the artificial sources of radiation ?
a) Medical, dental and industrial X-rays, used in diagnostics and in welding controls;b) Particles accelerators used in physics researches; c) Nuclear reactors used in researches and in the generation of electric energy; d) Medical and industrial irradiators used in therapies and in the conservation of food and several materials; e) Radioisotopes used in medical therapies. |