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2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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U.K., Japan to extend decommissioning partnership
The U.K.’s Sellafield Ltd. and Japan’s Tokyo Electric Power Company have pledge to continue to work together for up to an additional 10 years, extending a cooperative agreement begun in 2014 following the 2011 tsunami that resulted in the irreparable damage of TEPCO’s Fukushima Daiichi plant.
D. A. Knoll, H. Park, Kord Smith
Nuclear Science and Engineering | Volume 167 | Number 2 | February 2011 | Pages 122-132
Technical Paper | doi.org/10.13182/NSE09-75
Articles are hosted by Taylor and Francis Online.
The use of the Jacobian-free Newton-Krylov (JFNK) method within the context of nonlinear diffusion acceleration (NDA) of source iteration is explored. The JFNK method is a synergistic combination of Newton's method as the nonlinear solver and Krylov methods as the linear solver. JFNK methods do not form or store the Jacobian matrix, and Newton's method is executed via probing the nonlinear discrete function to approximate the required matrix-vector products. Current application of NDA relies upon a fixed-point, or Picard, iteration to resolve the nonlinearity. We show that the JFNK method can be used to replace this Picard iteration with a Newton iteration. The Picard linearization is retained as a preconditioner. We show that the resulting JFNK-NDA capability provides benefit in some regimes. Furthermore, we study the effects of a two-grid approach, and the required intergrid transfers when the higher-order transport method is solved on a fine mesh compared to the low-order acceleration problem.