Download Intro_RAST-K 2.0
The Recommended Publication for Citing
Introduction
The RAST-K v2, a novel nodal diffusion code, was
developed at the Ulsan National Institute of Science and Technology
(UNIST) for designing the cores of pressurized water reactors (PWR) and
performing analyses with high accuracy and computational performance by
adopting state-of-the-art calculation models and various engineering
features. It is a three-dimensional multi-group nodal diffusion code
developed for the steady and transient states using microscopic
cross-sections generated by the STREAM code for 37 isotopes. A depletion
chain containing 22 actinides and 15 fission products and burnable
absorbers was solved using the Chebyshev rational approximation method. A
simplified one-dimensional single-channel thermal-hydraulic calculation
was performed with various values for the thermal conductivity.
Advanced features such as burnup adaptation and CRUD modeling
capabilities are implemented for the multi-cycle analysis of commercial
reactor power plants. The performance of RAST-K v2 has been validated
with the measured data of PWRs operating in Korea. Furthermore, RAST-K
v2 has been coupled with a sub-channel code (CTF), fuel performance code
(FRAPCON), and water chemistry code for multiphysics analyses.
Physics ModelNeutronics – Assembly-wise Unified Nodal Method (UNM)
– CMFD acceleration
– Wielandt shift
XS model – Two-group group constants from STREAM2D
– Full / Hot case matrices
– Save micro XS for micro depletion
– XS functionalization with 3D/2D Lagrange interpolation
TH feedback – Single phase formulation (no boiling) without momentum equation (constant pressure)
– Equivalent pin model
– 1D radial heat conduction
– Consider TCD with FRAPCON-4.0 correlation
– CTF Steam table (IAPWS industrial formulation 2008)
– Consider TCD with FRAPCON-4.0 correlation
Fuel cycle analysis – Micro-depletion for 22 actinides and 12 fission products
– Effective Gd approach
– CRAM depletion solver
Engineering Features– Multi-cycle calculation (shuffling, rotation)
– Jump-in approach
– Pin power reconstruction
– Branch calculation
– Restart folding/unfolding
– DNB calculation
– Critical search
– Cycle length search
– B-10 depletion
– Cycle length search
– Overhaul period
– Cycle length search
– Mass flow rate search
– Print design parameter (mini-RSAC) for nuclear design
– Mass flow rate search
– In-core/Ex-core detector signal calculation
– FRAPCON/FRAPTRAN/VIPRE/CUPID input generation
– Source term calculation and decay heat analysis
– FRAPCON/FRAPTRAN/VIPRE/CUPID input generation
– Simple CRUD modeling
– Burnup adaptation
Verification and ValidationRAST-K v2 has been verified and validated using the
operation history of Korean PWRs. A total of 114 cycles of 13 reactor
cores, including the OPR-1000, APR-1400, Westinghouse 2-loop reactor
(WH-2L), and Westinghouse 3-loop reactor (WH-3L) were employed for the
core follow calculation. The core depletion calculation results are
compared with the results obtained from commercial nuclear design code
and measurement data for the verification and validation of the
steady-state depletion capability of the RAST-K v2.
Multi-Physics CouplingHigh-fidelity multi-physics systemRAST-K v2 is coupled with CTF and FRAPCON to perform high-fidelity core depletion calculations. As CTF is a TH subchannel analysis code, its channel-centered model is changed to the pin-centered model to ensure consistency during coupling. The pin power information from the RAST-K v2 pin power reconstruction function is transferred to CTF and FRAPCON as input variables. The CTF solutions, such as the coolant temperature and pressure, are transferred to FRAPCON as a boundary condition for solving the heat conduction equation. Next, the coolant temperature from CTF and fuel temperature from FRAPCON are merged into node-wise information from pin-wise information and transferred to RAST-K v2 for cross-section feedback. For the multi-cycle calculation, the restart capability of FRAPCON is implemented by developing an interface program called FRAPI.
AOA analysisTo track the effect of CRUD deposition during core depletion, RAST-K v2 is coupled with the subchannel TH code VIPRE and water chemistry code BOA. The input file of VIPRE is automatically generated based on the node power distribution, which is calculated from RAST-K v2. After simulating VIPRE and BOA, the output file of BOA, which includes the CRUD thickness and boron mass in the CRUD, is read by RAST-K v2. The boron mass in the CRUD is used for the cross-section feedback, and the CRUD thickness is used to correct the increment in the fuel temperature. Owing to the absence of the source codes of VIPRE and BOA, the coupling is performed by handling the input and output files. It is possible to track the ASI by employing BOA during the AOA. Hence, the Nth cycle depletion can be initiated by predicting the depletion history of the fuel in the (N − 1)th cycle.
|
4. Code Development >