TY - GEN
T1 - Acceleration of shutdown dose rate Monte Carlo calculations using the Multi-Step cadis hybrid method
AU - Ibrahim, Ahmad M.
AU - Peplow, Douglas E.
AU - Grove, Robert E.
N1 - Publisher Copyright:
© Copyright (2015) by the American Nuclear Society.
PY - 2015
Y1 - 2015
N2 - Shutdown dose rate (SDDR) analysis requires (1) a neutron transport calculation to estimate space- and energy-dependent neutron fluxes, (2) an activation calculation to compute the distribution of radionuclide inventories and the associated photon sources, and (3) a photon transport calculation to estimate the final SDDR. In some applications, accurate full-scale Monte Carlo (MC) SDDR simulations are needed for immensely large systems that involve massive amounts of shielding materials with complex geometric arrangements. However, these simulations are impractical because accurate calculation of space- and energy-dependent neutron fluxes in these systems is difficult with the MC method even if global variance reduction techniques are used. This paper describes the Multi-Step Consistent Adjoint Driven Importance Sampling (MS-CADIS) hybrid MC/deterministic methodology that accelerates multi-step MC shielding calculations. MS-CADIS speeds up the SDDR neutron MC calculation using an importance function that represents the neutron importance to the final SDDR. Using a simplified example, preliminary results showed that the MS-CADIS method enhanced the efficiency of the SDDR neutron MC calculation by a factor of 550 compared to standard global variance reduction techniques, and that the efficiency enhancement compared to analog MC is higher than a factor of 10,000.
AB - Shutdown dose rate (SDDR) analysis requires (1) a neutron transport calculation to estimate space- and energy-dependent neutron fluxes, (2) an activation calculation to compute the distribution of radionuclide inventories and the associated photon sources, and (3) a photon transport calculation to estimate the final SDDR. In some applications, accurate full-scale Monte Carlo (MC) SDDR simulations are needed for immensely large systems that involve massive amounts of shielding materials with complex geometric arrangements. However, these simulations are impractical because accurate calculation of space- and energy-dependent neutron fluxes in these systems is difficult with the MC method even if global variance reduction techniques are used. This paper describes the Multi-Step Consistent Adjoint Driven Importance Sampling (MS-CADIS) hybrid MC/deterministic methodology that accelerates multi-step MC shielding calculations. MS-CADIS speeds up the SDDR neutron MC calculation using an importance function that represents the neutron importance to the final SDDR. Using a simplified example, preliminary results showed that the MS-CADIS method enhanced the efficiency of the SDDR neutron MC calculation by a factor of 550 compared to standard global variance reduction techniques, and that the efficiency enhancement compared to analog MC is higher than a factor of 10,000.
KW - Hybrid Monte Carlo/deterministic transport
KW - Multi-Step CADIS
KW - Multi-step shielding analysis
KW - Shutdown dose rate
UR - http://www.scopus.com/inward/record.url?scp=84949495011&partnerID=8YFLogxK
M3 - Conference contribution
AN - SCOPUS:84949495011
T3 - Mathematics and Computations, Supercomputing in Nuclear Applications and Monte Carlo International Conference, M and C+SNA+MC 2015
SP - 1819
EP - 1831
BT - Mathematics and Computations, Supercomputing in Nuclear Applications and Monte Carlo International Conference, M and C+SNA+MC 2015
PB - American Nuclear Society
T2 - Mathematics and Computations, Supercomputing in Nuclear Applications and Monte Carlo International Conference, M and C+SNA+MC 2015
Y2 - 19 April 2015 through 23 April 2015
ER -
