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Nuclear Energy Conference & Expo (NECX)
September 8–11, 2025
Atlanta, GA|Atlanta Marriott Marquis
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Hash Hashemian: Visionary leadership
As Dr. Hashem M. “Hash” Hashemian prepares to step into his term as President of the American Nuclear Society, he is clear that he wants to make the most of this unique moment.
A groundswell in public approval of nuclear is finding a home in growing governmental support that is backed by a tailwind of technological innovation. “Now is a good time to be in nuclear,” Hashemian said, as he explained the criticality of this moment and what he hoped to accomplish as president.
Nicolas P. Leclaire, Jacques A. Anno, Gérard Courtois, Pascal Dannus, Gilles Poullot, Veronique Rouyer
Nuclear Technology | Volume 144 | Number 3 | December 2003 | Pages 303-323
Technical Paper | Reactor Safety | doi.org/10.13182/NT03-A3447
Articles are hosted by Taylor and Francis Online.
Up to now, criticality safety experts used density laws fitted on experimental data and applied them outside the measurement range. Depending on the case, such an approach could be wrong for nitrate solutions. Seven components are concerned: UO2(NO3)2, U(NO3)4, Pu(NO3)4, Pu(NO3)3, Th(NO3)4, Am(NO3)3, and HNO3. To obviate this problem, a new methodology based on the thermodynamic concept of mixtures of binary electrolytes solutions (one electrolyte + water) at constant water activity, a so-called "isopiestic" solution, has been developed by the Institute de Radioprotection et de Sûreté Nucléaire (IRSN) to calculate the nitrate solutions density. This paper presents its qualification by using criticality experiments. The theory and the implementation are also given.Qualification results of the uranyl and plutonium nitrate solutions show that the new density law (also called the isopiestic law) is in good agreement with the benchmarks. Thus, no bias is put into evidence for the uranium solutions, and a small negative bias equal to 0.2% is found for the plutonium solutions.Moreover, the isopiestic law corrects the observed 1% overestimation of keff due to the empirical IRSN Leroy and Jouan density law for uranium solutions and the observed 3.4% underestimation of keff due to the ARH-600 density law for plutonium solutions.The isopiestic density law has been implemented in CIGALES V2.0, the graphical user interface of the French criticality safety package CRISTAL that calculates the atom densities of nuclides (and writes the input file for CRISTAL computations).
