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2025 ANS Winter Conference & Expo
November 9–12, 2025
Washington, DC|Washington Hilton
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NNSA awards BWXT $1.5B defense fuels contract
The Department of Energy’s National Nuclear Security Administration has awarded BWX Technologies a contract valued at $1.5 billion to build a Domestic Uranium Enrichment Centrifuge Experiment (DUECE) pilot plant in Tennessee in support of the administration’s efforts to build out a domestic supply of unobligated enriched uranium for defense-related nuclear fuel.
E. E. Lewis, G. Palmiotti
Nuclear Science and Engineering | Volume 126 | Number 1 | May 1997 | Pages 48-58
Technical Paper | doi.org/10.13182/NSE97-A24456
Articles are hosted by Taylor and Francis Online.
The multigroup simplified spherical harmonics equations with anisotropic scattering are derived from a variational principle that preserves nodal balance. The resulting equations are discretized using a Ritz procedure with spatial trial functions that are complete polynomials within the nodes and on the interfaces. The resulting equations are cast in a response matrix form and incorporated as an option of the variational nodal spherical harmonics code VARIANT. Fixed source and multigroup eigenvalue calculations are performed on benchmark problems. The accuracy and computational efficiency of spherical harmonic and simplified spherical harmonic approximations are compared, and the compensating effects of spatial and angular truncation errors are examined. The results indicate that in most situations, simplified and standard spherical harmonics results of the same order are in close agreement, while the use of simplified spherical harmonics substantially reduces computing costs.