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.
M. M. R. Williams, Edward W. Larsen
Nuclear Science and Engineering | Volume 139 | Number 1 | September 2001 | Pages 66-77
Technical Paper | doi.org/10.13182/NSE01-A2222
Articles are hosted by Taylor and Francis Online.
The majority of earlier work on neutron transport in spatially random media has relied on special models of the random process, closure techniques or perturbation theory. The purpose of the present paper is to further develop a technique, which employs the source-sink method and simulation, and which in principle leads to exact probability distributions, to assess the accuracy of such approximate methods. To this end, we also use perturbation theory, and extend it to eigenvalue problems thereby enabling random fluctuations in reactivity to be studied and some measures of their statistical properties to be calculated. We have found, by comparing results for the variance in the reactivity fluctuations with essentially exact values, that the perturbation method is an accurate way to deal with stochastic equations and is far more efficient numerically than the more exact simulation method.