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The spark of the Super: Teller–Ulam and the birth of the H-bomb—rivalry, credit, and legacy at 75 years
In early 1951, Los Alamos scientists Edward Teller and Stanislaw Ulam devised a breakthrough that would lead to the hydrogen bomb [1]. Their design gave the United States an initial advantage in the Cold War, though comparable progress was soon achieved independently in the Soviet Union and the United Kingdom.
YuGwon Jo, Nam Zin Cho
Nuclear Science and Engineering | Volume 189 | Number 1 | January 2018 | Pages 26-40
Technical Paper | doi.org/10.1080/00295639.2017.1373517
Articles are hosted by Taylor and Francis Online.
In the three-dimensional (3-D) continuous-energy whole-core reactor analysis, the partial current–based coarse mesh finite difference (p-CMFD) feedback was applied to the Monte Carlo (MC) k-eigenvalue problem simulation for both inactive and active iterations (cycles). To reduce the stochastic errors in the p-CMFD parameters and their biases due to the ratio-type estimators, the first-in-first-out (FIFO) accumulation scheme was introduced in the MC/p-CMFD procedure. The MC/p-CMFD procedure was tested on a typical pressurized water reactor 3-D continuous-energy whole-core problem while varying the FIFO queue lengths and the results were compared with the conventional power iteration. The Shannon entropy analysis showed that MC/p-CMFD accelerates the convergence of the fission source distributions and mitigates the spatial clustering phenomenon. The real variance analysis also showed that MC/p-CMFD reduces the interiteration correlation, leading to the most real variance reduction in the local MC tallies at the optimum queue length (L = 5). It was also shown that a nontrivial bias was introduced by the p-CMFD feedback, especially for the global tally (keff) with L = 1. However, the bias decreased as the tally bin size became smaller and it was effectively reduced by increasing the queue length (L ≥ 5). In conclusion, the MC/p-CMFD procedure showed promising capability for 3-D continuous-energy whole-core reactor analysis by MC simulation.