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Fusion Science and Technology
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In transition: Commercializing fusion power
Commercial fusion power is closer than ever. There are now around 30 U.S. fusion companies, several of which claim to be on track to connect to the grid as early as the 2030s.
Tokamak and laser inertial confinement approaches benefit from decades of research at facilities such as the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory and ITER, with alternative concepts including stellarator, magnetic mirror, and Z-pinch confinement also making notable progress as private and government funding for fusion increases.
Raymond J. Juzaitis
Nuclear Science and Engineering | Volume 80 | Number 3 | March 1982 | Pages 424-447
Technical Paper | doi.org/10.13182/NSE82-A19829
Articles are hosted by Taylor and Francis Online.
A deterministic analysis of the computational cost associated with geometric splitting/Russian roulette in Monte Carlo radiation transport calculations is presented. Appropriate integro-differential equations (based on the theory of Monte Carlo errors) are developed for the first and second moments of the tally as well as for the expected value of time per particle history, given that splitting with Russian roulette takes place at one or more internal surfaces of the geometry. The equations are solved using a standard Sn solution technique, allowing for the prediction of computer cost (formulated as the product of sample variance and time per particle history) associated with a given set of splitting parameters. Extensive numerical results relating to the transport model chosen for study (namely, particle transmission through a semi-infinite slab shield composed of an isotropically scattering medium) are presented. Optimum splitting surface locations and splitting ratios are determined. Single-surface results indicate that the threshold slab thickness for which any splitting becomes cost effective varies from ∼2 to >7 mean-free-paths, depending on the degree of scattering in the medium. When splitting is cost effective, it is so over a wide range of surface locations. Benefits of such an analysis are particularly noteworthy for transport problems in which splitting is apt to be extensively employed (e.g., deep-penetration calculations).