China
Africa
Explore chapters and articles related to this topic
The Environment Today
Published in Anco S. Blazev, Power Generation and the Environment, 2021
The period of time depends on the type of waste. Low-level waste that with low levels of radioactivity per mass or volume, such as some of the common medical or industrial radioactive wastes, may need to be stored only a few hours or days. High-level wastes, such as spent nuclear fuel or by–products of nuclear reprocessing, however, must be stored for years at a time.
The Other Energy Markets
Published in Anco S. Blazev, Global Energy Market Trends, 2021
Transportation of waste nuclear fuel is the responsibility of the U.S. Department of Energy, which will transport used nuclear fuel to the repository by rail and road, inside massive, sealed containers that have undergone safety and durability testing.
Vapor and Advanced Power Cycles
Published in Kavati Venkateswarlu, Engineering Thermodynamics, 2020
Nuclear fuel is a fuel used in a nuclear reactor to sustain a nuclear chain reaction. The general definition of the fuel that is a material used to produce heat is not applicable to nuclear fuel, since the heat in this case is generated by fission or disintegration of the fissile isotopes but not by the burning of fuel. Nuclear fuel is typically made up of one or more fissile isotopes such as 235U, 239Pu, and 233U, often in combination with a fertile isotope, 238U or 232Th. These fuels are in the solid form of metals, alloys, oxides, carbides, nitrides of uranium, plutonium, and thorium. The radioactive nature of nuclear fuels and their fission products are extremely hazardous to health. To avoid harmful effects of radiation, nuclear fuels are hermetically sealed inside a nonradioactive structural material known as cladding. Cladding is essentially an integral part of the nuclear fuel element, which serves different purposes. First it acts as a primary containment for radioactive fission products, and then it acts as a barrier avoiding direct contact of the fuel with coolant, and finally it transfers fission heat energy from fuel to coolant. Usually, nuclear fuel elements are manufactured in different shapes such as plates, pins, or rods and assembled in specific geometric configurations using spacers, end fittings, and other supporting hardware. The package of fuel elements is called a fuel assembly.
Spatiotemporal Analyses of News Media Coverage on “Nuclear Waste”: A Natural Language Processing Approach
Published in Nuclear Technology, 2023
Matthew D. Sweitzer, Thushara Gunda
Nuclear energy is one of the leading sources of low-carbon electricity across the world. It provided up to 10% of the global electricity supply in 2018.[1] Within the United States, the existing nuclear power fleet generates approximately 20% of the nation’s annual electricity.[2] Nuclear energy is also emerging as a key player for nations’ climate goals, with some estimating the need to double power generation by 2050.[3] In the United States, nearly all of the nation’s commercial spent nuclear fuel is currently stored at the reactor sites where it was generated, either submerged in pools of water (wet storage)[4] or in shielded casks (dry storage).[5] For the foreseeable future, the U.S. Nuclear Regulatory Commission has determined that the spent fuel can continue to be safely stored in licensed facilities.
Analysis of Nuclear Renewable Hybrid Energy Systems Modeling and Nuclear Fuel Cycle Simulators
Published in Nuclear Technology, 2018
Emma K. Redfoot, R. A. Borrelli
Reducing energy output below capacity for NPPs is suboptimal because of the impact of reactor fluctuations on materials and economic inefficiency.8 NPPs almost entirely comprise fixed and sunk costs. The majority of the costs for nuclear are capital and operations (not including fuel), costs that do not depend on how much electricity is sold. As of 2010, nuclear fuel accounts for about 10% of the levelized cost of electricity as compared to 70% to 80% for natural gas.9 Because of the relatively small role the fuel plays in the overall costs of running a NPP operation, lowering the power output does not greatly reduce the generating costs. Fluctuating older NPPs that were not designed for such maneuverability can accelerate the aging of the power plant, causing physical and economic damage.8 Assuming that economic conditions in the energy sector remain constant, NPPs must run at near full capacity to compete economically and avoid materials degradation.
Establishing an evaluation method for the aging phenomenon by physical force in fuel debris
Published in Journal of Nuclear Science and Technology, 2023
Seiya Suzuki, Yoichi Arai, Nobuo Okamura, Masayuki Watanabe
The physical properties of the fuel debris generated by the nuclear accident in Unit 4 of Chernobyl NPP were confirmed during cooling [12] and were considered to be affected by seasonal temperature changes. Repeated temperature changes of solid materials have been known to affect their brittleness. At the Chernobyl NPP, fuel debris known as fuel-containing materials (FCMs) continue to deteriorate, as presented in the report that the ‘Elephant’s Foot’ becomes smaller as time passes [13,14]. The matrices of the Chernobyl NPP FCMs are metastable and disintegrate due to mechanical stress, interaction with water, and self-irradiation, among others. The destruction rate appears to be related to the FCMs composition and location in the building [13,14]. The deterioration of Chernobyl NPP FCMs is presumed to continue because of the changes in environmental temperature including self-heating. The macromechanical strength of solids is generally affected by the condition of any internal cracks, and the growth of subcritical cracks is caused by heating – cooling cycles. Weathering can principally be divided into frost and hot weathering [15]. The fuel debris in 1F has been water cooled; thus, their deterioration is assumed to be mainly due to hot weathering. Moreover, the main components of nuclear fuel are oxides of uranium and plutonium. These nuclear fuel-oxide materials are considered to exhibit similar deterioration behavior as ceramics and minerals, which represent brittle materials. Brittle materials are known to form cracks called microcracks due to repeated thermal expansion and contraction. The micronized fuel debris generated by aging phenomenon is supposed to easily diffuse into the reactor due to the cooling water, especially plutonium, which is supposed to cause recriticality and spread of α nuclide contamination. Thus, from the safety-management perspective of fuel debris, clarifying the mechanism of fuel debris deterioration due to weathering is necessary. Temporal change can be evaluated by modeling the occurrence of cracks on the debris surface. Therefore, the number of repeated temperature changes and amount of change in cracks are measured to clarify the weathering behavior of fuel debris.