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.
Division Spotlight
Fusion Energy
This division promotes the development and timely introduction of fusion energy as a sustainable energy source with favorable economic, environmental, and safety attributes. The division cooperates with other organizations on common issues of multidisciplinary fusion science and technology, conducts professional meetings, and disseminates technical information in support of these goals. Members focus on the assessment and resolution of critical developmental issues for practical fusion energy applications.
Meeting Spotlight
2024 ANS Annual Conference
June 16–19, 2024
Las Vegas, NV|Mandalay Bay Resort and Casino
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
May 2024
Jan 2024
Latest Journal Issues
Nuclear Science and Engineering
June 2024
Nuclear Technology
Fusion Science and Technology
Latest News
Congress receives NRC report on unusual events
The Nuclear Regulatory Commission has published its annual report to Congress for fiscal year 2023 on abnormal occurrences involving medical and industrial uses of radioactive material.
The report, which was announced by the NRC on May 3, is available on the NRC website.
J. T. Mihalczo, J. J. Lynn, J. R. Taylor
Nuclear Science and Engineering | Volume 130 | Number 1 | September 1998 | Pages 153-163
Technical Paper | doi.org/10.13182/NSE96-121
Articles are hosted by Taylor and Francis Online.
The reactivity worth of a central void region in the Oak Ridge National Laboratory (ORNL) unmoderated and unreflected uranium (93.20 wt% 235U) metal sphere was obtained by replacement measurements in a small (0.460-cm-diam) central spherical region in this 3.4420-in.-radius sphere. The measured central void region worth was 9.165 ± 0.023 ¢ using the delayed neutron parameters of Keepin, Wimett, and Zeigler to obtain the reactivity from the measured stable reactor periods. This value is slightly larger than measurements for GODIVA I with larger cylindrical samples of uranium (93.70 wt% 235U) in the center: 135.50 ± 0.12 ¢/mol for GODIVA I and 138.05 ± 0.34 ¢/mol for the ORNL sphere measurements. The difference could be due to sample size effect. The central worth was also calculated by neutron transport theory methods to be 6.02 ± 0.01 × 10-4 k. The measured and calculated values are related by the effective delayed neutron fraction. The value of the effective delayed neutron fraction obtained in this way from the ORNL sphere is 0.00657 ± 0.00002, which is in excellent agreement with that obtained from GODIVA I measurements, where the effective delayed neutron fraction was determined as the increment between delayed and prompt criticality and was 0.0066. From these ORNL measurements, using the delayed neutron parameters of ENDF-B/VI to obtain the reactivity from the stable reactor period measurements, the central void worth is 7.984 ± 0.021 ¢, and the inferred effective delayed neutron fraction is 0.00754. These values are 14.2% higher than those obtained from use of the Keepin, Wimett, and Zeigler delayed neutron data and produce a value of effective delayed neutron fraction in disagreement with GODIVA I measurements, thus questioning the usefulness of the six-group delayed neutron parameters (fast fission) of uranium from ENDF-B/VI for obtaining the reactivity from the measured reactor period using the Inhour equation.