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The Recommended Publication for Citing

  1.  Sooyoung Choi, Deokjung Lee*, “Three-Dimensional Method of Characteristics/Diamond-Difference Transport Analysis Method in STREAM for Whole-core Neutron Transport Calculation”, Comput. Phys. Commun.,
  2.  Sooyoung Choi, Changho Lee, Deokjung Lee, “Resonance Treatment using Pin-Based Pointwise Energy Slowing-Down Method,” J. Comput. Phys., 330: 134-155.  (2017)


 A neutron transport analysis code, STREAM (Steady state and Transient REactor Analysis code with Method of Characteristics), has been developed to perform a whole LWR core calculation with the direct transport analysis method and the two-step method. Numerous advanced features, especially resonance treatment methods, have been developed and implemented in the STREAM code for higher accuracy and performance. STREAM with the advanced methods has order of ~100 pcm accuracy in LWR analyses. STREAM has capabilities to analyze the whole LWR core through the two-step (with PARCS or RAST-K 2.0) method and direct transport method (2-D and 3-D).


Direct 3D core design
– 3D MOC-DD method
– Hybrid MPI/OPENMP parallelization
– Thermal expansion
– Fuel assembly shuffling/refueling
– Thermal-hydraulics (TH) feedback
– Equilibrium Xe feedback & Critical boron concentration search

– Gamma contribution to power with gamma transport
– STREAM 3D coupled with CTF/FRAPCON

Multi-group Cross-Section Generation
– Pin-based pointwise energy slowing-down method
– Equivalence theory for structure material
– Resonance upscattering correction
– Enhanced neutron current method
– Resonance interference factor library method (option)
– Inflow transport correction

Transport Solver
– Method of Characteristics
– T-Y optimum quadrature sets
– Assembly modular ray tracing method
– Direct neutron path linking method
–  P0~P5 scattering source treatment
– Coarse mesh finite difference acceleration

– Matrix exponential method
– Chebyshev rational approximation method
– Chain with ~1400 isotopes
– Predictor/corrector

3D whole core modeling


Functions for multi-cycle simulation


Core benchmark

- BEAVRS HFP simulation

- OPR1000 HFP cycle N & N+1, APR1400 cycle N
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Multi-physics coupling with CTF/FRAPCON

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