E. RAST-K 3.0

The Recommended Publication for Citing
  1. Jiwon Choe, Sooyoung Choi, Peng Zhang, Jinsu Park, Wonkyeong Kim, Ho Cheol Shin, Hwan Soo Lee, Ji-Eun Jung, Deokjung Lee*, "Verification and validation of STREAM/RAST-K for PWR analysis," Nuclear Engineering and Technology, ISSN 1738-5733, https://doi.org/10.1016/j.net.2018.10.004 (2018)

The nodal diffusion code RAST-K is the second part of a conventional two-step approach code system, which is developed by UNIST CORE laboratory and sponsored by Korea Hydraulic & Nuclear Power Co. Ltd.. To achieve high accuracy of reactor analysis with affordable memory requirement and computing time, the pin-by-pin kernel is newly implemented in RAST-K v3. The neutron transport calculation is performed by solving pin-by-pin SP3 equation with axially unified nodal method. The pin-wise cross section data is corrected by SPH factor to preserve the accuracy of transport calculation. The depletion, TH feedback, and cross section feedback modules and user-supporting engineering features for convenience of reactor core design and analysis are extended from the sub-assembly to sub-pin level. The parallel computing capability is also applied to pin-by-pin kernel with high computing resources.

Physics Model


- Multi-group pin-wise SP3
- Assembly-wise CMFD acceleration - UNM for axial layer

XS model

- Eight-group group constants from STREAM2D
- Full / Hot case matrices
- Save micro XS for micro depletion
- XS functionalization with 3D/2D Lagrange interpolation
- XS correction using SPH factor with assembly DF

TH feedback

- Single phase formulation (no boiling) without momentum equation (constant pressure)
- 1D radial heat conduction
- Consider TCD with FRAPCON-4.0 correlation
- CTF Steam table (IAPWS industrial formulation 2008)

Fuel cycle analysis

- Micro-depletion for 22 actinides and 12 fission products
- Effective Gd approach
- CRAM depletion solver

Domain Decomposition

All processor need to have …
‒ Geometry information (all mapping index)
‒ Basic 3D information: macro XS, flux, power, psi, Tfuel, Tmod, BU, …
‒ Count node per same XS type
‒ Arrange node for each processor
‒ Then, each processor have only pin XS in 1 FA
DD for Depletion
‒ Same domain with XSFB
‒ Number density & micro XS & reaction rate
DD for TH
‒ Only radially decomposition to solve  axial heat convection
DD for neutronics (SP3, UNM, not for CMFD)
‒ Same with TH, but, including mesh in reflector assembly


- OPR1000 cycle 1 whole core depletion
- Critical boron concentration
- Peaking factor
- Pin power distribution