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Nuclear Fuels, Nuclear Structure, the Mass Defect, and Radioactive Decay
Published in Robert E. Masterson, Introduction to Nuclear Reactor Physics, 2017
Nuclear engineering is based in part on the observation that when the nucleus of a Uranium or Plutonium atom splits apart, the particles leaving the reaction have a lower mass than the particles entering the reaction. This mass difference can then be used to find the amount of energy ΔE released. According to Einstein’s equation, the amount of energy released is related to this mass difference Δm = min − mout byand the kinetic energy released in this process is usually quoted MeV. An electron volt is approximately equal to 1.6 × 10−19 J and 1 MeV—or 1 million Electron Volts is approximately equal to 1.6 × 10−13 J. Thus, if the mass difference between the particles entering the reaction and leaving the reaction is 1 AMU or 1.6605402 × 10−24 g, the amount of energy released from the conversion of 1 AMU of matter (1.6605402 × 10−24 g) into energy is 931.494 MeV × 1.6 × 10−13 J/MeV = 1.49 × 10−10 J.
A Nonintrusive Nuclear Data Uncertainty Propagation Study for the ARC Fusion Reactor Design
Published in Nuclear Science and Engineering, 2023
Alex Aimetta, Nicolò Abrate, Sandra Dulla, Antonio Froio
One of the most recent methodologies for the safety assessment and for the design verification of nuclear systems is the so-called best-estimate plus uncertainty (BEPU) approach,21,22 which qualifies the output computed by best-estimate computational codes providing an estimate of their uncertainty. Compared to other branches of nuclear engineering, e.g., thermal hydraulics and thermal mechanics, neutronics is characterized by two peculiarities. The first one is that, within a certain statistical tolerance, the Monte Carlo approach potentially allows for obtaining an exact solution to the neutron transport equation since no approximation is introduced in the reactor geometry and both the energy and the flying directions of neutrons are sampled continuously. Hence, being a discretization-free method, the Monte Carlo approach could be considered the reference best-estimate tool available for neutronic analyses. The second peculiarity of neutronics is that, independent of the approach used to solve the neutron transport equation, the model requires as input a set of complex experimental data regarding, essentially, the interaction between neutrons and matter. Thus, it should be clear that an additional source of uncertainty, beyond the statistical one induced by the Monte Carlo method, is due to the input nuclear data. In this respect, the BEPU approach applied to the neutronic design of a nuclear fission or fusion reactor means that the best-estimate values produced with Monte Carlo calculations should be provided with their uncertainties.
The Nuclear, Humanities, and Social Science Nexus: Challenges and Opportunities for Speaking Across the Disciplinary Divides
Published in Nuclear Technology, 2021
Nuclear engineering recognizes reactor design as a central skill and intellectual output of the discipline. To this end, nuclear engineers, as part of their education at both the undergraduate and graduate level, are trained in the scientific and engineering fundamentals of the field. Reactor physics, thermal hydraulics, structural mechanics, computation, and materials science are all mainstays of a nuclear engineering education. Much less attention, if any, has typically been paid in the discipline’s research and pedagogy to the social dimensions of design. How the designers’ imagination and expertise, the organizational site of the design work, and the institutional environment all shape the design process and its outcomes are seldom examined or theorized.9 Elsewhere, a large and growing body of work in the field of STS (Ref. 10) as well as design research11,12 (a subfield of mechanical engineering) has consistently emphasized the importance of understanding the design process in all its richness and complexity and making sense of the social factors that shape design outcomes. In their papers in this special issue, Tillement and Garcias13 and Schmid14 draw our attention to precisely these determinants of design outcomes.
Research activities on nuclear reactor physics and thermal-hydraulics in Japan after Fukushima-Daiichi accident
Published in Journal of Nuclear Science and Technology, 2018
Shuichiro Miwa, Yasunori Yamamoto, Go Chiba
In this chapter, research activities in nuclear thermal-hydraulics after the Fukushima -Daiichi accident are reviewed. Review of thermal-hydraulic researches in LWR's SAs published in Journal of Nuclear Science and Technology are well summarized by Prof. Kataoka [120], and summary of the SA researches in Japan before/after the Fukushima accident, based on the conference proceedings, is given in the article by Prof. Sugimoto [121]. AESJ's roadmap for thermal-hydraulics researches to improve LWR safety is reported by Nakamura et al. [4]. In the current review chapter, major nuclear thermal-hydraulic researches carried out in Japan after 2011 are classified into following groups: (1) severe accident researches, (2) Fukushima-Daiichi (1F) accident analysis, (3) development of new safety systems, (4) LWR safety research, and (5) development of next-generation reactors. For reviewing the notable thermal-hydraulics researches, works published in major nuclear engineering related journals and conference proceedings are mainly selected.