China
Africa
Explore chapters and articles related to this topic
Energy and Environment
Published in T.M. Aggarwal, Environmental Control in Thermal Power Plants, 2021
High-level radioactive waste management concerns management and disposal of highly radioactive materials created during production of nuclear power. The technical issues in accomplishing this are daunting, due to the extremely long periods radioactive wastes remain deadly to living organisms. Of particular concern are two long-lived fission products, Technetium-99 (half-life 220,000 years) and Iodine-129 (half-life 15.7 million years), which dominate spent nuclear fuel radioactivity after a few thousand years. The most troublesome transuranic elements in spent fuel are Neptunium-237 (half-life two million years) and Plutonium-239 (half-life 24,000 years). Consequently, high-level radioactive waste requires sophisticated treatment and management to successfully isolate it from the biosphere. This usually necessitates treatment, followed by a long-term management strategy involving permanent storage, disposal or transformation of the waste into a non-toxic form.
Nuclear Energy
Published in Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff, Radiation and Radioactivity on Earth and Beyond, 2020
Ivan G. Draganić, Zorica D. Draganić, Jean-Pierre Adloff
There exists a fundamental approach to the problem that may provide a technical solution. At present, only three components are separated from the spent fuel: uranium, plutonium and a remaining fraction which includes all fission products, transuranium elements and radionuclides from cladding and reactor material. The storage of high-level wastes could be greatly facilitated if efficient separation of the transuranium elements from the bulk waste is achieved. Neptunium, americium, curium, and plutonium are all long-lived a-emitters which constitute a major potential hazard on a time scale greater than 1000 years. Once separated, the transuranium elements could be consumed in nuclear reactors and, at the same time, contribute to energy production as part of the fissile material.
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
Interim storage: The spent fuel removed from the core must be cooled in water-filled storage pits for 6 months to a year, in order for the residual heat and radioactivity to decay. Following use in a reactor, the spent fuel elements are depleted in the useful nuclear fuel isotopes and contain fission products and transuranic elements. While they are no longer useful for production of electricity, special handling is required due to the residual radioactivity. The decay of fission products continues to provide an internal heat source for the fuel element, which requires cooling during an interim storage period. The heat source is a function of the duration of reactor operation, but following steady power operation the time dependence has the following variation: P(t)=0.066P0t-1/5-t+t0-1/5
Investigation of Radioisotopes Produced in the Core of a Navy Nuclear Reactor with Low- and High-Enriched Uranium Flues During One Cycle
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Javad Karimi, Mohsen Shayesteh, Alireza Valizade
In this research, for a small nuclear propulsion reactor, using the coupled MCNPX and CINDER codes, fuel burnup calculations for two types of fuel HEU (UO2-Zr) and LEU (U-10Mo) have been performed. The changes of the effective multiplication factor over time during the cycle were calculated for both fuels. The results show that different types of radioisotopes are produced, including transuranic elements and fission products. In this research, the characteristics of some of the most important radioisotopes were stated. The trend of changes in the results shows that the amount of transuranic elements produced in the reactor core for LEU fuel is significantly higher than HEU fuel, due to the large difference in the level of fuel enrichment. Investigating this issue is important because in the event of an accident in the Navy’s nuclear propulsion reactors, there is a possibility of radioactive material dispersion in the environment. The obtained results show that after several months of operation of the reactor, the activity of some of the radioactive materials produced, especially Pu-241, Pm-147, Cs-137 and Cs-134, is in the order of one hundred thousand curies (especially the fuel with low richness). Therefore, it is necessary to carefully investigate the distribution of these materials and their environmental effects. In future research, the dispersion of these radioisotopes in the water and air will be investigated using computational codes.
Fluorinated Carbonates as New Diluents for Extraction and Separation of f-Block Elements
Published in Solvent Extraction and Ion Exchange, 2020
Petr Distler, Miriam Mindová, Jan John, Vasilij A. Babain, Mikhail Yu. Alyapyshev, Lyudmila I. Tkachenko, Ekaterina V. Kenf, Laurence M. Harwood, Ashfaq Afsar
The irradiated nuclear fuel from nuclear power plants is highly radiotoxic, which is caused mainly by the transuranic elements it contains.[1] The major transuranic constituents, uranium and plutonium can be recovered in the PUREX process. Then, from the PUREX raffinate, the trivalent minor actinides and trivalent lanthanides may be co-extracted by the DIAMEX process. After these processes, European research programmes have developed the SANEX process, which selectively removes the trivalent minor actinides, Am and Cm, from the lanthanides for subsequent transmutation to non-radioactive elements or short-lived radionuclides in Generation IV reactors or dedicated ADT transmuters.[2] Various methods have been developed for reprocessing, with most processes being based on liquid-liquid extraction using different extracting compounds, mainly from the nitric acid solutions.[3]
Manhattan Project: The Story of the Century, by Bruce Cameron Reed. Springer Nature Switzerland AG, 2020,
Published in Technometrics, 2022
In 1934 Szilard assigned to the British Admiralty the patent where he described using neutrons for creating a fission chain reaction which can be implemented in constructing atomic bomb. At the same time E. Fermi and his Rome group in Italy started the neutron-bombarding experiments, showing that it is more effective than using positively charged alpha particles which are deflected by the positively charged nuclei, while there is no electric barrier for neutrons. For the source of neutrons, Fermi used radium decaying into radon gas, which emanated alpha particles for bombarding beryllium and yielding about 100,000-1,000,000 neutrons per second with energy up to 10 MeV, used in its turn for bombarding dozens of various target elements. Fermi found that the bombarding neutrons can be captured by the target material producing heavier isotopes, and due to beta-decay those become transuranic elements. Synthesizing new elements with atomic numbers beyond uranium, the heaviest-known element at that time, was announced by Fermi’s group, although that was criticized by German chemist Ida Noddack. Fermi found also that filtering materials with hydrogen, water, and paraffin moderators can slow the neutrons in colliding with protons there, and slow neutrons have more time in the vicinity of target nuclei to induce and increase a fission activation many times. Fermi was awarded the 1938 Nobel Prize, and after the ceremony in Stockholm he used the opportunity to leave from the fascist regime in Italy and to escape with his Jewish wife and children to England, then to the U.S. At the same time, A. Dempster in Chicago discovered several isotopes, particularly the new isotope U-235, which presents less than 1% within the uranium isotopes but plays the main role in the story of Manhattan Project.