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Fixing the barriers: How new policies can make U.S. nuclear exports competitive again
The United States has a strong marketplace of ideas on future civil nuclear technology. President Trump wants to see 10 large reactors under construction by 2030 and has discussed making $80 billion available for that objective. Evolutionary small modular reactors based on light water reactor technology are on the market now, and the Tennessee Valley Authority expects a construction permit for a project at its Clinch River Site later this year.
Z. J. Bergstrom, M. A. Cusentino, B. D. Wirth
Fusion Science and Technology | Volume 71 | Number 1 | January 2017 | Pages 122-135
Technical Note | doi.org/10.13182/FST16-121
Articles are hosted by Taylor and Francis Online.
Fusion reactor materials experience high ion fluxes and operating temperatures, which will ultimately produce subsurface helium and hydrogen bubbles in the tungsten divertor that can cause surface degradation and impact core plasma performance. Molecular dynamics simulations have been used to evaluate the behavior of hydrogen and helium near a 2-nm bubble or void below a tungsten surface as a function of surface orientation, temperature, gas atom concentration, initial hydrogen distribution, and depth below the surface. A clear tendency for hydrogen to segregate to the bubble-matrix interface is observed in these simulations, regardless of the initial spatial distribution of the hydrogen or simulation parameters. This segregation is due in part to a local minimum in the hydrogen energy at the periphery of the bubble. Further work is required to fully characterize the mechanism of this behavior and to assess the quantities of hydrogen in the bubble and at the bubble periphery.