The Advanced Thermal-hydraulic Test Loop for Accident Simulation (ATLAS) test facility was constructed with the aim of developing new safety concepts and performance verification of the APR1400 power plant. As a result, valuable large-scale integral effect test (IET) database has been generated and effectively utilized for the Domestic Standard Program (DSP) and the International Standard Program (ISP). Furthermore, due to the successful completion of the ISP-50, in which 14 organizations from 11 OECD countries participated, ATLAS has been recognized as one of the important IET facilities worldwide.
A follow up international project has been initiated since 2014 and continued to the second phase by OECD/NEA to use the ATLAS facility in providing additional experimental measurements for common safety issues relevant to PWR consisting of five topics related to beyond design basis accidents. The United Arab Emirates is one of the countries participating in this project with the goal of increasing the local human capabilities and the required know-how on safety analysis studies. To achieve this, FANR and Khalifa University are planning to cooperate in taking part of the ATLAS project to produce numerical predictions for the pre-test prediction and the post-test simulations. The pre-tests rely on only the specification of the experiment given by the operating agency (OA). The post-test simulation can be performed after acquiring experiment data from OA. The codes to be used for this numerical study are the system codes RELAP5 developed by the US Nuclear Regulatory Commission (NRC).
At the start of the project, the steady-state input deck of RELAP5/MOD3 for ATLAS facility is to be provided by the facility operating agency, KAERI, to all participants. Then, each participating agency has to generate its transient input in accordance with proposed experiment scenarios. It goes without saying that even if the steady-state input deck is readily provided, the generation of transient input is toughly dependent on experience and know-how of user groups. Additionally, the given steady-state inputs also need to be modified and some components have to be remodeled in order to cope with the newly proposed scenario. For this reason, each participating agency comes back with different results even though they are using the same safety analysis code.
As mentioned above, RELAP5 will be used for both pre-test and post-test numerical predictions. The symbolic nuclear analysis package (SNAP) will help the input preparation. The schedule of pre-test and post-test runs to be performed will follow the planned schedule by the OA. Preparation of input, running simulation, debugging process, interpretation of results, and all lessons learned will be consolidated as a training material for increasing local human capability on safety analysis.
Additionally, at least one local component will be selected from each proposed scenario to investigate the detailed thermal hydraulic phenomena using the CFD approach. Simulation results from RELAP5 will then be mutually compared and validated with the CFD predictions, to be conducted at Khalifa University, and with the experimental data from the ATLAS facility.