Article

Anisotropic scattering in the variational nodal simplified spherical harmonics formulation

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Under the assumption of isotropic scattering, the simplified spherical harmonics method (SP{sub N}) was recently formulated in variational nodal form and implemented successfully as an option of the VARIANT code. The authors here remove the isotopic scattering restriction. The variational nodal form of the SPN approximation is formulated and implemented with both within-group and group-to-group anisotropic scattering. Results are presented for a model problem previously utilized with the standard P{sub N} variational nodal method.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... The replacement allows for the even-parity quantities to become functions of three spatial dimensions. (Lewis and Palmiotti 1996) The inclusion of simplified spherical harmonics greatly reduces the computing time for the model at a cost of reduced accuracy. For the benchmark case, the model was run with and without simplified spherical harmonics. ...
... The replacement allows for the evenparity quantities to become functions of three spatial dimensions. (Lewis and Palmiotti, 1996) The inclusion of simplified spherical harmonics greatly reduces the computing time for the model at a cost of reduced accuracy. For the benchmark case, the model was run with and without simplified spherical harmonics. ...
Article
Full-text available
Significant research is currently being performed whereby fast reactor cores have been designed to burn transuranic materials reducing the volume and long-term radiotoxicity of spent nuclear fuel. These core and depletion models depend on various computer codes. This research used MCNPX 2.6.0 and ERANOS 2.1 to model a standard 250 MW Advanced Burner Test Reactor (ABTR) core. The intent was to benchmark criticality and burnup results from a stochastic Monte Carlo code and a deterministic depletion code using a standard ABTR model created by Argonne National Laboratory. Because each of these codes solves the transport and burnup problem differently, there is a need to benchmark the core models in order to verify results and identify root causes for significant differences in results between codes. Flux calculations in ERANOS were performed using diffusion theory, Legendre polynomial approximations (using the VARIANT module) and discrete ordinates methods. The k-effective for the higher order transport models remained within 1000 pcm of the MCNPX model. The difference between the total heavy nuclide mass balance in ERANOS using the various flux calculations and the MCNPX depletion model was less than 0.4% out to a burnup of 1095 days (67.45 GWd/MTHM). The percent delta between the codes as a fraction of the fissioned mass was 1.34%. For the isotopes with large concentrations, such as 238U and 239Pu, the mass differences were 0.38% and 0.01% respectively. The mass difference for 241Am was also small at 0.42%. Notable isotopes in small quantities with larger mass differences were 242Am, 242Cm, 243Cm and 246Cm where differences ranged from 0.1 to 0.2% after 26 days and increased to 11–136% at 1095 days.
ResearchGate has not been able to resolve any references for this publication.