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Conference Spotlight
2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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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!
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Empowering the next generation: ANS’s newest book focuses on careers in nuclear energy
A new career guide for the nuclear energy industry is now available: The Nuclear Empowered Workforce by Earnestine Johnson. Drawing on more than 30 years of experience across 16 nuclear facilities, Johnson offers a practical, insightful look into some of the many career paths available in commercial nuclear power. To mark the release, Johnson sat down with Nuclear News for a wide-ranging conversation about her career, her motivation for writing the book, and her advice for the next generation of nuclear professionals.
When Johnson began her career at engineering services company Stone & Webster, she entered a field still reeling from the effects of the Three Mile Island incident in 1979, nearly 15 years earlier. Her hiring cohort was the first group of new engineering graduates the company had brought on since TMI, a reflection of the industry-wide pause in nuclear construction. Her first long-term assignment—at the Millstone site in Waterford, Conn., helping resolve design issues stemming from TMI—marked the beginning of a long and varied career that spanned positions across the country.
Hiroshi Motoda
Nuclear Science and Engineering | Volume 46 | Number 1 | October 1971 | Pages 88-111
Technical Paper | doi.org/10.13182/NSE71-A22338
Articles are hosted by Taylor and Francis Online.
A generalized treatment for investigating the effects of various refueling schemes on the optimal control rod programming that maximizes the average burnup of discharged fuels in a two-region, radially one-dimensional light water moderated nuclear reactor is presented and applied to a boiling water reactor having uranium fuel of a single 235U enrichment. It is assumed that the refueling scheme has reached an equilibrium fuel cycle, and the analysis by burnup space is applied, which helps in interpreting geometrically the coupled effect of the control rod programming and the fuel burnup by the trajectory drawn in this space. Three refueling schemes are considered: parallel, series out-in, and series in-out. Scatter loading is assumed in each region and the batch number and volume fraction of each region are varied as the refueling parameters. Fuel management and poison management constitute a hierarchy relation, and the effect of the refueling schemes on burnup maximization or enrichment minimization is several times greater than that of the control rod programmings. However, the policy of the optimal control rod programming strongly depends on the refueling scheme. The power density of the inner region should be as high as possible for out-in scheme (inner high policy) and vice versa for in-out scheme (outer high policy). However, either policy can be optimal, depending on the refueling parameters for parallel schemes, and in some cases the optimal control rod programming is not unique (degenerate policy). Optimal control rod programming increases the discharge burnup or decreases the enrichment of the feed fuels by about 0 to 4% over the conventional constant power shape operation. The difference is mainly determined by the reactor design and the refueling scheme. Optimal refueling should be chosen from among parallel schemes, which have much larger freedom than series schemes.
