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
Education, Training & Workforce Development
The Education, Training & Workforce Development Division provides communication among the academic, industrial, and governmental communities through the exchange of views and information on matters related to education, training and workforce development in nuclear and radiological science, engineering, and technology. Industry leaders, education and training professionals, and interested students work together through Society-sponsored meetings and publications, to enrich their professional development, to educate the general public, and to advance nuclear and radiological science and engineering.
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
Apr 2024
Jan 2024
Latest Journal Issues
Nuclear Science and Engineering
May 2024
Nuclear Technology
Fusion Science and Technology
Latest News
Nicholas Tsoulfanidis—ANS member since 1969
We welcome ANS members who have careered in the community to submit their own Nuclear Legacy stories, so that the personal history of nuclear power can be captured. For information on submitting your stories, contact nucnews@ans.org.
As an undergraduate I studied physics at the University of Athens. I entered the university in 1955 after successfully passing a national exam (came up fourth in a field of about 700 candidates). Upon graduation and finishing my mandatory two-year military service, the plan was to teach physics either in a public high school or as a tutor for a private for-profit institution, preparing high school students for the national exam.
Francesco Ganda, Ehud Greenspan
Nuclear Science and Engineering | Volume 164 | Number 1 | January 2010 | Pages 1-32
Technical Paper | doi.org/10.13182/NSE08-64
Articles are hosted by Taylor and Francis Online.
A thorough investigation was performed to understand the physics behind the calculated trends in the reactivity coefficients of hydride-fueled pressurized water reactor cores. A two-step procedure was developed for this purpose: ranking the contribution to a reactivity coefficient of each of the system's constituents; investigating, for each of the more important constituents, the spectral reasons for their specific response to the temperature perturbation. This procedure was applied to understand (a) the difference in the beginning-of-life and end-of-life fuel temperature coefficient of reactivity (FTC) behavior of hydride- as compared to oxide-fueled cores; (b) the different effect integral fuel burnable absorber (IFBA) and erbium burnable poisons have on the FTC and coolant temperature coefficient of reactivity (CTC); (c) the effects on the FTC and CTC of inclusion of thorium hydride in the fuel; (d) the effects of plutonium on the FTC and CTC in hydride- as compared to oxide-fueled cores.It is found that the physics characteristics of hydride-fueled cores are fundamentally different from those of oxide-fueled cores as particularly manifested by the behavior of the FTC. In oxide-fueled cores the main phenomenon affecting the FTC is the well-known Doppler broadening of the fuel resonances. Hydride cores feature an additional unique phenomenon of spectral shift in the thermal energy range; it is the result of upscattering of the thermal neutrons due to the increase in the fuel hydrogen temperature. The interplay between the spectral shift and the shape of the low-energy cross sections of the fuel isotopes is responsible for the sometimes very different values of the calculated FTC for hydride- versus oxide-fueled cores and even for the same fuel type at different burnups. It is also concluded that fissile plutonium can have different effects on the FTC and, although the physics phenomena are quite different, on the CTC in hydride-fueled cores. If the plutonium is present in sufficiently large quantities, its effect can be negative, while if it is present in relatively small quantities, it is more likely to give a positive contribution. An additional finding is that the buildup of 135Xe makes the FTC less positive in hydride-fueled cores, while it has little effect on the FTC of oxide-fueled cores. Also concluded is that thorium-containing hydride fuel cores feature a smaller FTC than that of oxide-fueled cores. This is due to a harder neutron spectrum in the Th-containing hydride-fueled cores leading to a smaller spectral shift, combined with the buildup of 233U the contribution to the FTC of which in hydride-fueled cores is mostly negative.The insight gained through the analyses reported in this work facilitated the identification of an optimal, safe uranium-based hydride-fueled core design; it consists of U-ZrH1.6 fuel in which 25% (volumetric) of the ZrH1.6 is replaced by ThH2. Burnable poisons have to be used to compensate part of the excess reactivity; IFBA is the preferred choice.