TRANSIENT ANALYSIS OF A DETAILED THERMAL-HYDRAULIC MODEL OF A VVER-1000 CORE WITH THE SYSTEM CODE ATHLET
29th Symposium of AER on VVER Reactor Physics and Reactor Safety (2019, Energoland, Mochovce NPP, Slovakia)
reactor dynamics and safety analysis
Abstract
A new OECD/NEA benchmark entitled “Reactivity compensation with diluted boron by stepwise insertion of control rod cluster” is starting. This benchmark, based on high quality measurements performed at the NPP Rostov Unit 2, aims to validate and assess high fidelity multi-physics simulation code capabilities. The Benchmark is divided in two phases: assembly wise and pin-by-pin resolution of steady-state and transient multi-physics problems.
Multi-physics simulation requires the generation of few-group cross-sections. This task used to be done with deterministic lattice codes, but in the past few years the Monte-Carlo code SERPENT has demonstrate its ability to generate accurate few-group homogenized cross-section without approximations on the geometry.
Since whole core SERPENT models for production of such cross-section libraries would be computationally costly, models of each sub-assembly type in infinite radial lattice configurations have been created.
These cross-sections are then used to evaluate effective multiplication factors with PARCS for different core configurations. The results are compared with the reference SERPENT calculations. In the next step, an ATHLET (GRS in-house thermal-hydraulic system code) model with an assembly wise description of the core (i.e. one channel per fuel assembly) has been developed for coupled PARCS/ATHLET transients test calculations.
This paper describes in detail the models and techniques used for the generation of the few-group parameterized cross section libraries, the PARCS model and the ATHLET model. Additionally, transient simulations are presented, and their results are thoroughly analysed.