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
2026 Nuclear Energy Conference & Expo (NECX)
August 24–27, 2026
Dallas, TX|Hilton Anatole
Latest Magazine Issues
Jul 2026
Jan 2026
2026
Latest Journal Issues
Nuclear Science and Engineering
August 2026
Nuclear Technology
July 2026
Fusion Science and Technology
Latest News
The deadline arrives: Checking in on the Reactor Pilot Program
On May 23, 2025, President Trump signed Executive Order 14301, “Reforming Nuclear Reactor Testing at the DOE,” which instructed the Department of Energy to create a Reactor Pilot Program (RPP)—a new system in which companies could pursue DOE authorization to build and test their first-of-a-kind nuclear technologies. EO 14301 set an ambitious goal for that program: three reactors achieving criticality by July 4, 2026.
Margaret A. Marshall
Nuclear Science and Engineering | Volume 178 | Number 4 | December 2014 | Pages 479-495
Technical Paper | doi.org/10.13182/NSE14-43
Articles are hosted by Taylor and Francis Online.
A series of small, compact critical assembly experiments was completed from 1962 to 1965 at Oak Ridge National Laboratory's Critical Experiments Facility in support of the Medium-Power Reactor Experiments program. Initial experiments, performed in November and December 1962, consisted of a core of unmoderated stainless steel tubes surrounded by a graphite reflector. Later experiments included beryllium-reflected assemblies with the fuel in a 1.506-cm triangular lattice and in seven-tube clusters. Once the critical configurations had been achieved, various measurements of reactivity, relative axial and radial activation rates of 235U, and cadmium ratios were performed. The critical configurations, the cadmium ratio, and activation rate measurements for the beryllium-reflected 1.506-cm-array critical configuration have been evaluated and are described in this paper. It was found that these measurements are acceptable as benchmark experiments and have been included in the International Handbook of Evaluated Reactor Physics Benchmark Experiments and the International Handbook of Evaluated Criticality Safety Benchmark Experiments.