The Multi-Step CADIS method for shutdown dose rate calculations and uncertainty propagation

Journal Article · Tue Dec 01 00:00:00 EST 2015 · Nuclear Technology

DOI:https://doi.org/10.13182/NT15-1· OSTI ID:1245347

Ibrahim, Ahmad M. ^[1]; Peplow, Douglas E. ^[1]; Grove, Robert E. ^[1]; Peterson, Joshua L. ^[1]; Johnson, Seth R. ^[1]

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1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Shutdown dose rate (SDDR) analysis requires (a) a neutron transport calculation to estimate neutron flux fields, (b) an activation calculation to compute radionuclide inventories and associated photon sources, and (c) a photon transport calculation to estimate final SDDR. In some applications, accurate full-scale Monte Carlo (MC) SDDR simulations are needed for very large systems with massive amounts of shielding materials. However, these simulations are impractical because calculation of space- and energy-dependent neutron fluxes throughout the structural materials is needed to estimate distribution of radioisotopes causing the SDDR. Biasing the neutron MC calculation using an importance function is not simple because it is difficult to explicitly express the response function, which depends on subsequent computational steps. Furthermore, the typical SDDR calculations do not consider how uncertainties in MC neutron calculation impact SDDR uncertainty, even though MC neutron calculation uncertainties usually dominate SDDR uncertainty.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Laboratory Directed Research and Development (LDRD) Program
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1245347
• Journal Information: Nuclear Technology, Vol. 192, Issue 3; ISSN 0029-5450
• Publisher: American Nuclear Society (ANS)
• Country of Publication: United States
• Language: English

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