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
Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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
September 2025
Nuclear Technology
Fusion Science and Technology
August 2025
Latest News
From operator to entrepreneur: David Garcia applies outage management lessons
David Garcia
If ComEd’s Zion plant in northern Illinois hadn’t closed in 1998, David Garcia might still be there, where he got his start in nuclear power as an operator at age 24.
But in his ninth year working there, Zion closed, and Garcia moved on to a series of new roles—including at Wisconsin’s Point Beach plant, the corporate offices of Minnesota’s Xcel Energy, and on the supplier side at PaR Nuclear—into an on-the-job education that he augmented with degrees in business and divinity that he sought later in life.
Garcia started his own company—Waymaker Resource Group—in 2014. Recently, Waymaker has been supporting Holtec’s restart project at the Palisades plant with staffing and analysis. Palisades sits almost exactly due east of the fully decommissioned Zion site on the other side of Lake Michigan and is poised to operate again after what amounts to an extended outage of more than three years. Holtec also plans to build more reactors at the same site.
For Garcia, the takeaway is clear: “This industry is not going away. Nuclear power and the adjacent industries that support nuclear power—and clean energy, period—are going to be needed for decades upon decades.”
In July, Garcia talked with Nuclear News staff writer Susan Gallier about his career and what he has learned about running successful outages and other projects.
T. E. Dudley, M. R. Mendelson, N. E. Holden
Nuclear Science and Engineering | Volume 30 | Number 3 | December 1967 | Pages 328-339
Technical Paper | doi.org/10.13182/NSE67-A18396
Articles are hosted by Taylor and Francis Online.
A reasonable physical model for the slowing down of gamma rays in infinite media is presented, and a method of numerical solution is described. Equilibrium energy spectra due to a fission source of gamma rays are shown for water, aluminum, iron, zirconium, and lead. In addition, energy spectra in aluminum, iron, and lead, due to the corresponding (n, γ) source in each metal, are presented. The use of infinite medium calculations to obtain a lower energy cutoff for a gamma heating problem is suggested. It is shown that for the case of a fission source, essentially all of the source energy is absorbed above 0.05 MeV in the materials studied, except in the case of water where approximately three percent of the energy is absorbed below 0.05 MeV. The infinite medium spectra are used to average absorption and slowing down cross sections for fuel materials and metals, and the resulting group constants are compared with similar calculations using a fission-source spectrum as a weighting function. Large differences are noted in many instances. Calculations of spatial energy deposition in simple model problems indicate that such differences in group constants can lead to local errors of significant magnitude.
