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 ANS Annual Conference
May 31–June 3, 2026
Denver, CO|Sheraton Denver
Latest Magazine Issues
Mar 2026
Jul 2025
Latest Journal Issues
Nuclear Science and Engineering
March 2026
Nuclear Technology
February 2026
Fusion Science and Technology
April 2026
Latest News
NRC approves TerraPower construction permit
Today, the Nuclear Regulatory Commission announced that it has approved TerraPower’s construction permit application for Kemmerer Unit 1, the company’s first deployment of Natrium, its flagship sodium fast reactor.
This approval is a significant milestone on three fronts. For TerraPower, it represents another step forward in demonstrating its technology. For the Department of Energy, it reflects progress (despite delays) for the Advanced Reactor Demonstration Program (ARDP). For the NRC, it is the first approval granted to a commercial reactor in nearly a decade—and the first approval of a commercial non–light water reactor in more than 40 years.
Gilles J. Youinou
Nuclear Technology | Volume 198 | Number 2 | May 2017 | Pages 202-216
Technical Paper | doi.org/10.1080/00295450.2017.1305191
Articles are hosted by Taylor and Francis Online.
This paper presents the results of a neutronics analysis related to the homogeneous recycling of different mixtures of transuranic elements (transuranics) (TRU) in pressurized water reactors (PWRs) loaded with mixed oxide (MOX) fuel using enriched uranium instead of depleted uranium (UenrO2-TRUO2, i.e., MOX-EU). It also addresses an often, if not always, overlooked aspect related to the recycling of TRU in PWRs, namely, the use of reprocessed uranium. From a neutronics point of view, it is possible to multirecycle the entirety of the plutonium with or without neptunium and americium in a PWR fleet using MOX-EU fuel in between one-third and two-thirds of the fleet. Recycling neptunium and americium with plutonium significantly decreases the decay heat of the waste stream between 100 to 1000 years compared to that of an open fuel cycle or when only plutonium is recycled. The uranium present in MOX-EU used fuel still contains a significant amount of 235U, and recycling it makes a major difference in the natural uranium needs. For example, at equilibrium, a PWR fleet recycling its plutonium, neptunium, and americium in MOX-EU needs 28% more natural uranium than a reference UO2 open cycle fleet generating the same energy if the reprocessed uranium is not recycled and 19% less if the reprocessed uranium is recycled back in the reactors, i.e., a 47% difference. Reenriching the reprocessed uranium is not necessary.