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The future of nuclear energy
Published in Tina Soliman Hunter, Ignacio Herrera Anchustegui, Penelope Crossley, Gloria M. Alvarez, Routledge Handbook of Energy Law, 2020
An analysis of the regulatory approach adopted by each State is beyond the scope of this chapter, but it is important to highlight certain key aspects that are common to the legal framework of several – if not all – jurisdictions engaged in nuclear activities. The first is that nuclear law is a highly complex and intertwined legal architecture comprised of international and national rules enriched by the unique political and legislative choices of individual states as well as the often-significant role of international organizations in providing ongoing international support and regulatory guidance. The second aspect is the assumption that, at both the international and domestic level, peaceful uses of nuclear energy must contend with the risks posed by ionizing radiations as well as the security of nuclear material. Thirdly, that nuclear energy is generated in power plants from nuclear material, which includes plutonium, uranium-233 or enriched uranium (fissionable material).51 Fourth, that nuclear reactors for power generation are generally assumed to be fixed installations or, at the very least, that the process of generating power for commercial uses takes place in a stationary facility. Existing and developing nuclear technology may question such assumptions and warrant profound revisions of national and international rules. The following section will illustrate how advancements in nuclear technology may challenge such assumptions.
Measuring stiffness of soils in situ
Published in Fusao Oka, Akira Murakami, Ryosuke Uzuoka, Sayuri Kimoto, Computer Methods and Recent Advances in Geomechanics, 2014
Fusao Oka, Akira Murakami, Ryosuke Uzuoka, Sayuri Kimoto
The geological disposal facility of nuclear material needs to be stable and safe for an extremely long period of time. Therefore it is necessary to predict thelong-term behavior of disposal facilities. Bentonite is considered to be buffer material in Trans-Uranium (TRU) disposal facilities due to its remarkable expansion characteristics. Bentonite buffer materials are expected, as a self-sealing barrier to water channels, to prevent leaks of radiation-contaminated groundwater and to mitigate stress caused by rock creep. TRU disposal facilities will be constructed under several hundred meters. It is believed that such buffer materials in the facilities, which exist in compacted and unsaturated state atearly stages, will gradually become saturated through long-term exposure to groundwater. However, there are few mathematical models which can express the mechanical behaviors of bentonite materials while shifting from unsaturated state to saturated state (e.g. Alonso et al. (1990); Alonso et al. (1999)). Therefore, it is not clear of the mechanical behavior of bentonite materials in the TRU disposal facility during saturation. This paper describes the saturation process using a soil-water-air coupled finite element code DACSAR-MP proposed by Kanazawa et al. (2012) in which elasto-plastic model proposed by Takayama et al. (2013) is implemented. This paper is a comprehensive summary of the saturation process of bentonite and its mathematical modelling. The details will be discussed in the article by Takayama et al. (2004).
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
Nuclear material safeguards: Nuclear materials, in particular those materials which are key to the development of a nuclear weapon, such as separated plutonium, must be protected from diversion into the hands of terrorists. Special safeguard procedures have been developed to control special nuclear material (SNM). Special nuclear material includes plutonium and highly enriched uranium. However, uranium fuel used in common commercial reactors has enrichment far below that required for weapon uses.
Development of a water Cherenkov neutron detector for the active rotation method and demonstration of nuclear material detection
Published in Journal of Nuclear Science and Technology, 2023
Kosuke Tanabe, Masao Komeda, Yosuke Toh, Yasunori Kitamura, Tsuyoshi Misawa, Ken’ichi Tsuchiya, Norimitsu Akiba, Hidetoshi Kakuda, Kazunari Shibasaki, Hiroshi Sagara
Because the detectability and the measurement time depend on the type and amount of nuclear material, we plan to demonstrate the detection of nuclear materials other than natural uranium, such as enriched uranium and plutonium, including smaller quantities on the order of several grams. In particular, it is important to demonstrate the detection of enriched uranium concealed in a container, which is difficult to achieve by passive methods. In future studies, we plan to examine a versatile detector design and moderator shape for practical situations involving suspicious objects of different sizes and the presence or absence of shielding materials. Besides, the effect of extremely eccentric distribution of nuclear material on its detectability would be also a future study though the active rotation method has the robustness to the asymmetry of the measurement objects.
Analysis of Major Benchmark Uncertainties for Fast Metal Assemblies in the ICSBEP Handbook
Published in Nuclear Science and Engineering, 2023
Theresa Cutler, Kelsey Amundson, Jesson Hutchinson, Nick Thompson
Table V and Table VI summarize the mean, median, and max for each component type, for HMF and PMF, respectively. The min is not shown, as it is always zero. Units are uncertainty (pcm), except for the last column, which is the quantity of the applicable benchmark parameters. Figure 8 shows pie diagrams for component-type contribution to the total uncertainty. Fuel, reflector, and structural are the most important components for uncertainty in both HMF and PMF benchmarks, accounting for >75% of the total uncertainty. Both mean and median uncertainties are always larger for PMF series than HMF series, except for structural uncertainty median. For all categories except cladding and absorbers in the PMF series, means are larger than median values. It can be seen that structural has the greatest median contribution to uncertainty for HMF but least for PMF. Fuel has the largest mean for both series, which points to the importance of using well-characterized special nuclear material (i.e., HEU or plutonium).
Advancements in Yttrium Hydride Moderator Development
Published in Nuclear Technology, 2023
Holly Trellue, Chase Taylor, Erik Luther, Theresa Cutler, Aditya Shivprasad, J. Keith Jewell, Dasari V. Rao, Michael Davenport
The special nuclear material used was HEU metal discs known as C-discs. The discs were unclad. There were six total, with an average mass of 3920 g and an average enrichment of 93.1 wt% 235U. The axial reflectors included Be and depleted uranium discs. Electric aluminum oxide heaters with NiCrome heating elements were used to heat a central region (which included HEU and YHx) significantly more than the rest of the assembly, thus minimizing competing effects. These heaters were manufactured to be slim and used materials that did not have the potential to complicate the results. The heaters were a coil with alumina shells on the top and bottom. A picture of each is shown in Fig. 8. Graphite plates were also used throughout the assembly and had slots for resistance temperature detectors included in them so that the temperature could be monitored at multiple points continuously.