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TRANSP: Deterministic Photon Transport with the Method of Characteristics

K Hadad

K Hadad1*, A Moghaddam1 , M NEmatollahi1 , H Porhemmat1 , (1) Shiraz University, Shiraz, Fars


SU-I-GPD-T-85 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall

Purpose: Development and implementation of a two-dimensional deterministic photon transport code called PTRANS in a heterogeneous media using the method of characteristic.

Methods: PTRANS is written in MATLAB environment to solve the linear Boltzmann photon transport equation in two-dimensional Cartesian geometries. The method of characteristics (MOC) as a deterministic method is employed to obtain the energy, space, and directional-dependent density fluxes. The level symmetric angular discretization approximation and analytic method applied for ray tracing in rectangular domain are used in PTRANS. Modular ray tracing as a flexible ray producer is implemented to cover heterogeneity of solution domain and also to decrease the overall calculation time. A special treatment is employed to obtain the order of Legendre expansion for efficient computational time. PTRANS could process coupled multi-group photon/electron cross sections provided by CEPXS or EPDL97 for a variety of materials and energies.

Results: PTRANS photon transport code is validate with EGSnrc Monte Carlo code. For comparing our 2-D with the 3-D Monte Carlo code, we expanded the 2-D plane in its normal direction so much that the boundary would have no effect on the solution domain. An isotropic fixed source with known energy (1 MeV) is considered. For validation of PTRANS, several benchmarks with variety of sources and field sizes to calculate the scalar flux and kerma were designed. For these benchmarks, scalar flux and kerma distribution by PTRANS 3 to 10 percent difference with Monte Carlo. The minimum difference is in the source region and with increasing distance from source, and a maximum of 10% occurs.

Conclusion: Due to highly paralyzing capability of MOC methods as well as our obtained results, TRANSP could be further developed and utilized as an accurate, time efficient and geometrically flexible code in radiation dosimetry.

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