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Neutron Transport Models and Methods for HZETRN and Coupling to Low Energy Light Ion TransportExposure estimates inside space vehicles, surface habitats, and high altitude aircraft exposed to space radiation are highly influenced by secondary neutron production. The deterministic transport code HZETRN has been identified as a reliable and efficient tool for such studies, but improvements to the underlying transport models and numerical methods are still necessary. In this paper, the forward-backward (FB) and directionally coupled forward-backward (DC) neutron transport models are derived, numerical methods for the FB model are reviewed, and a computationally efficient numerical solution is presented for the DC model. Both models are compared to the Monte Carlo codes HETCHEDS and FLUKA, and the DC model is shown to agree closely with the Monte Carlo results. Finally, it is found in the development of either model that the decoupling of low energy neutrons from the light ion (A<4) transport procedure adversely affects low energy light ion fluence spectra and exposure quantities. A first order correction is presented to resolve the problem, and it is shown to be both accurate and efficient.
Document ID
20090012421
Acquisition Source
Langley Research Center
Document Type
Conference Paper
Authors
Blattnig, S.R.
(NASA Langley Research Center Hampton, VA, United States)
Slaba, T.C.
(Old Dominion Univ. Norfolk, VA, United States)
Heinbockel, J.H.
(Old Dominion Univ. Norfolk, VA, United States)
Date Acquired
August 24, 2013
Publication Date
June 29, 2008
Subject Category
Space Radiation
Report/Patent Number
LF-6655
ICES-2008-01-2162
Meeting Information
Meeting: 38th International Conference on Environmental Systems (ICES)
Location: California
Country: United States
Start Date: June 29, 2008
End Date: July 3, 2008
Sponsors: Society of Automotive Engineers, Inc.
Funding Number(s)
CONTRACT_GRANT: NNL06AA14A
Distribution Limits
Public
Copyright
Other

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