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Division Spotlight
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
Conference on Nuclear Training and Education: A Biennial International Forum (CONTE 2025)
February 3–6, 2025
Amelia Island, FL|Omni Amelia Island Resort
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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Latest News
US, Korea sign MOU for nuclear cooperation
The U.S. departments of Energy and State have signed a memorandum of understanding with the Republic of Korea’s ministries of Trade, Industry and Energy and of Foreign Affairs for the two nations to partner on nuclear exports and cooperation.
Masao Yamanaka, Cheol Ho Pyeon, Tsuyoshi Misawa
Nuclear Science and Engineering | Volume 184 | Number 4 | December 2016 | Pages 551-560
Technical Paper | doi.org/10.13182/NSE15-107
Articles are hosted by Taylor and Francis Online.
In an accelerator-driven system (ADS), the effective delayed neutron fraction βeff is required for subcriticality measurements in order to convert measured reactivity in dollar units into pcm units. Here, an alternative calculation methodology with source-dependent reaction rates is proposed to estimate the subcriticality (pcm units) with an external neutron source for the newly defined parameter βRRsource . In the proposed methodology, the parameter is obtained by the k-ratio method with reaction rates considering the external neutron source (fixed-source calculation) and is compared with that obtained by the eigenvalue calculations (MCNP6.1). To investigate its applicability to the estimation of subcriticality, subcriticality measurements by the extrapolated area ratio method are carried out in the experiments in ADS at the Kyoto University Critical Assembly, with the variation of subcriticality (pcm units) and the spectrum of the external neutron source. Then, βRRsource is estimated by the proposed methodology with MCNPX-2.5.0. The measured subcriticality with the use of βRRsource obtained by the fixed-source calculations shows good agreement with that obtained by the different measurement methodology and MCNPX-2.5.0. Through the subcriticality estimation, the applicability of the proposed methodology is confirmed for different subcriticality levels and the spectrum of the external neutron source.
