Status of the IAEA Coordinated Research Project on HTGR Core Physics and Thermal Hydraulics Benchmarks (CRP-5)

High-temperature Gas-Cooled Reactor (HTGR) designs present special computational challenges related to their core physics and thermal-hydraulic characteristics. Neutron streaming and double heterogeneities are examples of the core physics challenges, while porous gas flow in a high temperature and high-burnup ceramic core, characterize some of the thermal-hydraulic challenges. In an effort to address such potential calculation uncertainties, computational benchmarks have been proposed in the framework of an IAEA Coordinated Research Project (CRP- 5) and results by several participating international institutes are used for the purpose of code-to-code as well as code-to-experiment comparisons. The benchmark problems cover areas such as core criticality, power and burnup distribution, safety analysis, decay heat removal and turbo-machinery performance. Experimental data have been made available by the HTTR of Japan, the HTR-10 of China, the ASTRA of Russia as well the Pebble Bed Micro Model (PBMM) facility of South Africa. This paper summarizes the status of this work. The results of finalized benchmarks will be presented. (author)