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
Nuclear Installations Safety
Devoted specifically to the safety of nuclear installations and the health and safety of the public, this division seeks a better understanding of the role of safety in the design, construction and operation of nuclear installation facilities. The division also promotes engineering and scientific technology advancement associated with the safety of such facilities.
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
Developing a new regulatory framework for advanced reactors: Update on Part 53
White
The American Nuclear Society’s Risk-informed, Performance-based Principles and Policy Committee (RP3C) on March 29 held another presentation in its monthly Community of Practice (CoP) series. The presenter, Patrick White with the Nuclear Innovation Alliance (NIA), talked about the current status of efforts to develop a new regulatory framework for advanced reactors—known as 10 CFR Part 53 or simply Part 53. White serves as the research director of the NIA, where he leads their research as well as analysis-based stakeholder and policymaker engagement and education. White’s March 29 presentation is publicly available on YouTube and at ANS’s publication platform Nuclear Science and Technology Open Research (NSTOR).
RP3C chair N. Prasad Kadambi opened the CoP with brief introductory remarks about the RP3C before he welcomed White as the session’s presenter.
White covered three main topics: the history of the existing regulatory frameworks for new reactors, progress to date on the development of the Part 53 rule for advanced reactors, and the current status and next steps for the Part 53 rulemaking process.
Justin M. Pounders, Farzad Rahnema
Nuclear Science and Engineering | Volume 163 | Number 3 | November 2009 | Pages 243-262
Technical Paper | doi.org/10.13182/NSE163-243
Articles are hosted by Taylor and Francis Online.
The definition of the multigroup diffusion coefficient for reactor physics problems is not unique; rather, it is based on limiting approximations made to the Boltzmann transport equation. In this paper, we present several new diffusion closures in an attempt to gain increased accuracy over the standard P1-based diffusion theory. First, the Levermore-Pomraning flux-limited diffusion theory is applied to reactor physics problems both in its original form and in a new modified form that makes the methodology more robust with respect to the energy variable. Additionally, two novel definitions of the diffusion coefficient are introduced that permit a neutron flux that is greater than first order in angle. These various diffusion theories are completed by developing consistent boundary conditions for each case. Diffusion theory solutions are computed for each unique closure and are compared against transport theory analytically for a simple half-space problem and numerically for a suite of simplified one-dimensional reactor problems. Conclusions and observations are made for each diffusion method in terms of its underlying assumptions and accuracy of the benchmark solutions.