The multi-dimensional analysis method development for KALIMER-600 using MARS-LMR CODE

In this study, KALIMER-600 (Korea Advanced Liquid Metal Reactor), originally designed by KAERI (Korea Atomic Energy Research Institute) is described and analyzed by MARS-LMRCODE in multi-dimension for analysis of PDRC (Passive Decay heat Removal Circuit) performance and pressure drop. The sodium circulates mainly by the force of natural convection during operation of SFR (Sodium-cooled Fast breeder Reactor). In this phenomenon, the pressure drop occurs in the pool by lots of reasons such as friction and gravity caused by the structures and shape of the sub-channels (wire-wrap, spacer grid and etc) in the core region. The important modeling features for the evaluation of natural circulation characteristics include a correct description of pressure drop and a heat transfer models for various situations. In this paper, the friction factor k for each control volume is estimated from the calculation results of CFD (Computational Fluid Dynamics). For validation, CFD results were compared with the previous experiment data and are applied to provide the necessary parameters for MARS-LMR CODE. With the aid of CFD results, MARS-LMR CODE is modified. The previous MARS-LMR CODE was constructed in one dimension giving a series of volumes and nodes. We have subdivided the UIS (Upper Internal Structure) into multi-dimensional shape and created 3-dimensional components for the parameters we are concerned about,to be more accurate in performing the analysis, to build more stable code, and to provide more reliable data. In previous study, KALIMER-600, which is consisted with a lot of components in RV (Reacot Vessel) such as IHX (Internal Heat Exchanger, DHX (Decay Heat Exchanger), UIS (Upper Internal Structure) and Pump,was analyzed by MARS CODE in 1 dimension. Therefore, it is not able to describe some phenomena. For example, some part of the hot sodium which has passed core is met UIS, IHX or Pump. Thus, the heated sodium flow is changed because of those. However, in 1 dimensional analysis, the heated sodium has one way to hot pool except consideration of structure factors. On the other hand, the hot pool is modified to 3 dimension pool and considered representative components included UIS in multi-dimension analysis. The effect and contribution of this multi-dimensional analysis method is that it can suggest a sound base for the safety and performance assessment to show more reliable analysis. In addition, this result will be useful to understand not only pressure drop but temperature and velocity distribution in the pool. The code is still under development. The hot pool in 3 dimension and the each components in 1 dimension do successfully input at code, whereas the junction of those parts are not accomplished. The connection of all components is only needed in the present