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The objectives of MSTD are: promote the advancement of materials science in Nuclear Science Technology; support the multidisciplines which constitute it; encourage research by providing a forum for the presentation, exchange, and documentation of relevant information; promote the interaction and communication among its members; and recognize and reward its members for significant contributions to the field of materials science in nuclear technology.
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The ongoing effort to convert the world’s research reactors
The Ghana Research Reactor-1, located in Accra, Ghana, was converted from HEU fuel to LEU in 2017. Photo: Argonne National Laboratory
In late 2018, Nigeria’s sole operating nuclear research reactor, NIRR-1, switched to a safer uranium fuel. Coming just 18 months on the heels of a celebrated conversion in Ghana, the NIRR-1 reboot passed without much fanfare. However, the switch marked an important global milestone: NIRR-1 was the last of Africa’s 11 operating research reactors to run on high-enriched uranium fuel.
The 40-year effort to make research reactors safer and more secure by replacing HEU fuel with low-enriched uranium is marked by a succession of quiet but immeasurably significant milestones like these. Before Africa, a team of engineers from many organizations, including the U.S. Department of Energy’s Argonne National Laboratory, concluded its conversion work in South America and Australia. Worldwide, 71 reactors in nearly 40 countries have undergone conversions to LEU, defined as less than 20 percent uranium-235. Another 31 research reactors have been permanently shut down.
Bryce K. Y. Matsuo, Mark Anderson, Devesh Ranjan
Nuclear Science and Engineering | Volume 176 | Number 2 | February 2014 | Pages 138-153
Technical Paper | dx.doi.org/10.13182/NSE12-85
Articles are hosted by Taylor and Francis Online.
Geometrical effects on the local heat transfer coefficient (HTC) and pressure drop for supercritical carbon dioxide in printed-circuit heat exchangers are numerically quantified. Combinations of different operating pressures (7.5 to 10.2 MPa), mass fluxes [326 to 762 kg/(m2⋅s)], and the enhanced wall treatment k-ε and shear stress transport k-ω turbulence models are investigated using a finite-volume framework. Three different channel geometries are used: a nonchamfered zig-zag (ideal case), a chamfered zig-zag (prototype case), and an airfoil (ideal case). The simulations are compared with experimental results and empirical correlations. A new correlation is developed based on the numerical data obtained and published experimental data for the zig-zag channels. The results show that the local HTC increases with an increase in operating pressure or an increase in mass flux for each channel. The HTC of the zig-zag channel is found to be approximately 2.5 times that of the airfoil; however, the pressure drop is 4.0 to 8.3 times higher. Based on these results, the area goodness ratios of the nonchamfered and chamfered zig-zag channels are respectively 2.65 and 1.57 times larger than that of the airfoil.