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
October 2025
Nuclear Technology
September 2025
Fusion Science and Technology
Latest News
NNSA awards BWXT $1.5B defense fuels contract
The Department of Energy’s National Nuclear Security Administration has awarded BWX Technologies a contract valued at $1.5 billion to build a Domestic Uranium Enrichment Centrifuge Experiment (DUECE) pilot plant in Tennessee in support of the administration’s efforts to build out a domestic supply of unobligated enriched uranium for defense-related nuclear fuel.
Byoung Kyu Jeon, Cheol Ho Pyeon, Hyung Jin Shim
Nuclear Technology | Volume 191 | Number 2 | August 2015 | Pages 174-184
Technical Paper | Fission Reactors | doi.org/10.13182/NT14-83
Articles are hosted by Taylor and Francis Online.
Experiments on the isothermal temperature reactivity coefficient (ITRC) have been carried out at the light water–moderated core with or without a D2O tank in the Kyoto University Critical Assembly. The ITRC experiments are analyzed by a continuous-energy Monte Carlo (MC) neutron transport analysis code, McCARD. Through the temperature changes of H2O and D2O, effects of the coolant density changes in moderator and reflector regions and the microscopic cross-section variations on the ITRC are investigated by sensitivity analyses with the use of the MC adjoint-weighted perturbation method. An adjoint-weighted correlated sampling method for the stochastic mixing technique of cross-section libraries is devised to estimate the reactivity change from a perturbation of the thermal scattering cross sections due to the temperature change. From results of the MC perturbation analyses, it is clearly seen that the ITRCs of the two core configurations are dominated by a negative contribution of the number density change of hydrogen in the moderator region and a positive contribution of the thermal scattering cross-section change of hydrogen in the reflector region.
