ANS is committed to advancing, fostering, and promoting the development and application of nuclear sciences and technologies to benefit society.
Explore the many uses for nuclear science and its impact on energy, the environment, healthcare, food, and more.
Explore membership for yourself or for your organization.
Conference Spotlight
2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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!
Latest Magazine Issues
Sep 2025
Jan 2025
Latest Journal Issues
Nuclear Science and Engineering
September 2025
Nuclear Technology
Fusion Science and Technology
October 2025
Latest News
IAEA report confirms safety of discharged Fukushima water
An International Atomic Energy Agency task force has confirmed that the discharge of treated water from Japan’s Fukushima Daiichi nuclear power plant is proceeding in line with international safety standards. The task force’s findings were published in the agency’s fourth report since Tokyo Electric Power Company (TEPCO) began discharging Fukushima’s treated and diluted water in August 2023.
More information can be found on the IAEA’s Fukushima Daiichi ALPS Treated Water Discharge web page.
J. T. Wajima, H. Yamamoto, H. Kikuchi, T. Ohnishi, S. Kobayashi
Nuclear Science and Engineering | Volume 31 | Number 1 | January 1968 | Pages 19-31
Technical Paper | doi.org/10.13182/NSE68-A18004
Articles are hosted by Taylor and Francis Online.
The microparameters including the thermal-neutron disadvantage factor, DF, the epi- to sub-Cd neutron capture ratio in 238U, ρ28, the epi- to sub-Cd fission ratio in 235U, δ25, and the ratio of the epi-Cd 238U fission to the sub-Cd 235U fission, δ28, were measured in the Ozenji Critical Facility for a seven-rod clustered nuclear superheat fuel element. The factors f, p, and ϵ were derived therefrom and the effect of 235U epithermal fissions on the neutron multiplication factor was observed to be 1.5% Δk/k. Flooding changed the individual factors f, p, and ϵ by amounts corresponding to −6.8% Δk/k, +4.7% Δk/k, and −2.9% Δk/k, respectively, yielding an overall change of −5.1% Δk/k. The maximum discrepancies between measurement and calculation are 1 to 3% for DF, ρ28 , δ25, and δ28; 0.3% Δk/k for f, p, and ϵ; and 0.4% Δk/k for the infinite multiplication factor. The calculation of the effects of flooding on f, p, ϵ, and the infinite multiplication factor agrees with the experiment to within 0.3 to 0.4% Δk/k. When performing the cell calculations, care was taken to determine how to cylinderize the unit cell to perform the one-dimensional calculations with the THERMOS code, how to select the value of the L factor to be used in the JUPITER code (modified MUFT) and how to incorporate the heterogeneous effect of fast fissions.
