Transportation and Disposal of Radioactive Waste

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THE TRANSPORT AND DISPOSAL OF RADIOACTIVE WASTE

Isotopes are nuclides of one element with the same chemical properties and a fixed number protons but a different number of neutrons in the nucleus. Many atomic nuclei are unstable and decay through a process referred to as "radioactive decay". During the process of radioactive decay, the nucleus emits one of the three types of nuclear radiation: alpha particles, beta particles or gamma rays. Each type of radiation is ionising, meaning collisions which occur as they penetrate substances damages the atom. Nuclear reactors use the isotope uranium-235 as fuel produced radioactive isotopes of barium (barium-141) and krypton (krypton-92) which produce radioactive waste referred to as spent fuel. Radioactive waste is categorized according to how hazardous it is. Radioactive waste is categorized to determine storage requirements, radioactive waste is categorized as Very Low Level Wastes (VLLW), Low Level Wastes (LLW), Intermediate Level Wastes (ILW) and High Level Wastes (HLW). Spent fuel is considered HLW and must therefore be carefully transported and stored as it hazardous to the environment and the public. The economic and environmental benefits and limitations of the transport and storage of spent fuel will be central to this essay.

Uranium is a metal with an mass number (A) of 184 and an atomic number (Z) of 92. Uranium has three main isotopes, uranium-238 (23892 U), uranium-235 (23592 U) and uranium-234 (23492 U). Nuclear reactors utilize uranium-235 as "fuel" and releases energy from the nucleus through a process referred to as "fission". The nucleus of a uranium-235 atom absorbs a free neutron causing the uranium-235 neutron to split into two smaller nuclei, barium-141 (14156 Ba) and krypton-92 (9236 Kr) as well as three neutrons and energy. This is used to generate electricity.

10 n+ 23592 U → 14156 Ba+ 9236 Kr+3 10 n+energy

Barium-141 and kryton-92 will emit ionizing radiation as the isotope decays. This will dilute the fuel, slowing down the reaction. Eventually the concentration of uranium-235 is too low to sustain fission reactions, this is then referred to as spent fuel. Spent fuel is extremely hot and highly radioactive, this is because the remaining uranium-235, krypton-92 and barium-141 are radioactive.

The combustion of fossil fuels for electricity and heat is responsible for 26% of global green house gas emission according to the Environmental Protection Agency ("Global Emissions") contributing greatly to global warming. Nuclear power is generates electricity and heat through fission of uranium-235 which does not produce green house gas emission, meaning it does not contribute to global warming however it does produce radioactive waste as a byproduct. Uranium is highly concentrated meaning it will yield significantly more energy as an equivalent amount of coal therefore nuclear energy will have significantly lower costs. According to the World Nuclear Association, "one kilogram of uranium will yield 20, 000 times as much energy as the same amount of coal" ("The Economics of Nuclear Power"). Despite nuclear energy being the most environment and ecological efficient source of energy the radioactive waste raised public concern therefore the International Atomic Energy Agency (IAEA) have published regulations for the transport of radioactive waste in 1961 which have been internationally recognized by organizations such as the International Civil Aviation Organizations (ICAO), International Maritime Organization (IMO) and regional transport organizations in over 60 countries ("Transport of Radioactive Materials"). The regulations aim to protect the public and the environment from ionization. At a molecular level, ionisation causes damage directly to biological molecules such as DNA and RNA. Through metabolic pathways, ionisation from surroundings interfere with chemical reactions. Molecular damage disrupts the...
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