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2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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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.
Nagafumi Aihara, Nobuo Fukumura, Hiroyuki Kadotani, Yuuki Hachiya
Nuclear Science and Engineering | Volume 109 | Number 2 | October 1991 | Pages 158-170
Technical Paper | doi.org/10.13182/NSE91-A28515
Articles are hosted by Taylor and Francis Online.
The effect on reactivity of changes in the coolant levels in the pressure tubes of a pressure-tube heavy water reactor is experimentally studied to clarify the effect of an axial coolant void fraction distribution. The coolant void fraction distribution is simulated by stepwise changes in the coolant levels in the Deuterium Critical Assembly (DCA). The reactivity is measured for a 25.0-cm-pitch square-lattice core with a positive coolant void reactivity. The reactivity changes resulting from changes in the coolant levels are measured as changes in the critical heavy water levels. The axial distribution of the thermal neutron flux is also measured by the copper activation method. In these measurements, the critical heavy water levels show a sinuous curve having a maximum and a minimum, and a positive reactivity larger than those of both the 0% and the 100% void uniform cores is introduced at certain coolant levels by stepwise changes in the coolant levels. An experimental analysis is performed with the coupled WIMS-ATR/CITATION code system, whose analytical method was established through DCA critical experiments. Agreement between experiment and analysis is fairly good. Furthermore, the peculiar reactivity behavior resulting from changes in the coolant levels is analyzed using a simplified model to take note of typical reactor physics parameters. It is clarified that this anomalous phenomenon is caused by the combined effect of the flattened S curve change in the thermal neutron absorption and the even flatter S curve change in the neutron leakage caused by the changes in the coolant levels. Useful information is obtained regarding reactivity behavior with an axial coolant void fraction distribution.
