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The division was organized to promote the advancement of knowledge of the use of particle accelerator technologies for nuclear and other applications. It focuses on production of neutrons and other particles, utilization of these particles for scientific or industrial purposes, such as the production or destruction of radionuclides significant to energy, medicine, defense or other endeavors, as well as imaging and diagnostics.
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Remembering Charles E. Till
Charles E. Till
Charles E. Till, an ANS member since 1963 and Fellow since 1987, passed away on March 22 at the age of 89. He earned bachelor’s and master’s degrees from the University of Saskatchewan and a Ph.D. in nuclear engineering from Imperial College, University of London. Till initially worked for the Civilian Atomic Power Department of the Canadian General Electric Company, where he was the physicist in charge of the startup of the first prototype CANDU reactor in Canada.
Till joined Argonne National Laboratory in 1963 in the Applied Physics Division, where he worked as an experimentalist in the Fast Critical Experiments program. He then moved to additional positions of increasing responsibility, becoming division director in 1973. Under his leadership, the Applied Physics Division established itself as one of the elite reactor physics organizations in the world. Both the experimental (critical experiments and nuclear data measurements) and nuclear analysis methods work were internationally recognized. Till led Argonne’s participation in the International Nuclear Fuel Cycle Evaluation (INFCE), and he was the lead U.S. delegate to INFCE Working Group 5, Fast Breeders.
Yuichi Niibori, Joonhong Ahn, Hitoshi Mimura
Nuclear Technology | Volume 175 | Number 3 | September 2011 | Pages 641-651
Technical Paper | NURETH-13 Special / Radioactive Waste Management and Disposal | doi.org/10.13182/NT11-A12512
Articles are hosted by Taylor and Francis Online.
Relative permeability kr is a practical tool to describe two-phase flow in the performance assessment of a geological disposal system of radioactive waste. So far, to avoid thermal alteration of an engineered barrier system such as bentonite, the maximum temperature in the conceptual design of a Japanese geological disposal system has been limited to <373 K. However, for a limited time period, even if the temperature exceeds 373 K or the boiling point at the underground level, the robustness of the system is expected to be sufficient. An upward revision of the permissible maximum temperature would reduce the total space of the repository and would result in more effective use of the space. Therefore, when two-phase flow is also considered, a more reliable estimate of the thermal impact on the repository system is needed.In general, the fluid flow velocities of two phases are described by Darcy's law including the relative permeabilities defined as the functions of liquid-water saturation (or steam saturation), e.g., Corey's equations. However, such saturation (e.g., liquid-water saturation Sw) is not always uniformly distributed in the grid cells of the numerical implementation. In this study, the uncertainty of kr due to the distribution of Sw was examined by using various kinds of probability density functions (pdf's). The results suggest that the apparent kr value can be numerically described by the arithmetic mean, the standard deviation, and the skewness of Sw. (In other words, the apparent value of kr does not depend on the types of pdf's.) Since the value of Sw is in the range of 0 to 1, the standard deviation and the skewness are limited. Therefore, the apparent values of kr also are in a limited range. Using the Lagrange multiplier method, this study examined the ranges of the kr value for each arithmetic mean of saturation Swa. Furthermore, by considering both the frequency distribution and the spatial distribution of saturation, this study quantitatively shows the degree of uncertainty of relative-permeability curves. These curves can explain the scattered data of two-phase-flow experiments.