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Reactor Physics
The division's objectives are to promote the advancement of knowledge and understanding of the fundamental physical phenomena characterizing nuclear reactors and other nuclear systems. The division encourages research and disseminates information through meetings and publications. Areas of technical interest include nuclear data, particle interactions and transport, reactor and nuclear systems analysis, methods, design, validation and operating experience and standards. The Wigner Award heads the awards program.
Meeting Spotlight
International Conference on Mathematics and Computational Methods Applied to Nuclear Science and Engineering (M&C 2025)
April 27–30, 2025
Denver, CO|The Westin Denver Downtown
Standards Program
The Standards Committee is responsible for the development and maintenance of voluntary consensus standards that address the design, analysis, and operation of components, systems, and facilities related to the application of nuclear science and technology. Find out What’s New, check out the Standards Store, or Get Involved today!
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Sam Altman steps down as Oklo board chair
Advanced nuclear company Oklo Inc. has new leadership for its board of directors as billionaire Sam Altman is stepping down from the position he has held since 2015. The move is meant to open new partnership opportunities with OpenAI, where Altman is CEO, and other artificial intelligence companies.
A. Chaieb, R. Largenton, A. Ambard, B. Baurens, M. Ton That
Nuclear Technology | Volume 210 | Number 2 | February 2024 | Pages 232-244
Research Article | doi.org/10.1080/00295450.2023.2232664
Articles are hosted by Taylor and Francis Online.
CYRANO3 is the thermal-mechanical industrial code developed and used by Electricité de France (EDF) to simulate nuclear fuel rod performance under normal and transient conditions (power ramp tests) in pressurized water reactors and during transport and storage periods, as well. This code has already been successfully used by EDF for the last 30 years to justify normal operations and category 2 transients, covering various types of fuels: UO2, UO2 + gadolinium, mixed oxide, and various claddings, as well those proposed by nuclear fuel suppliers: Zircaloy-4, Zirlo,™ and Optimized Zirlo.™
The CYRANO3 code was recently improved to allow for modeling fuel melting. In this paper, a global overview of CYRANO3’s ability to simulate past power-to-melt (P2M) ramps is presented with a focus on recent developments carried out to assess fuel rod behavior under these conditions. CYRANO3 is demonstrated to be a powerful tool to provide reliable values of melted radii.
As part of validation of these development works, CYRANO3 calculations have been used to assess two P2M ramp experiments carried out in the BR2 experimental core in Belgium (HBC-4 P2M ramp), and in the R2 experimental core in Sweden (xM3 P2M ramp). The main objectives of the work are to expand knowledge of the thermal-mechanical behavior of high-burnup fuel under P2M ramps by making interpretations of test simulations and to validate newly developed computational models for fuel melting that have been implemented in an extended version of the CYRANO3 fuel code.
For both rods, the steady-state irradiation power history was captured and modeling was performed. The key results of the steady-state irradiation modeling are reproduced with fair accuracy by means of CYRANO3 simulations. The results demonstrate the good ability of CYRANO3 to simulate P2M ramps. The melted radii and conditions of failure are well predicted. Calculated melted radius at ramp terminal Linear Heat Generation Rate (LHGR) is in good agreement with the experimental measurements performed after the experiments.
