Modular High Temperature Gas Cooled Reactor Safety Design

The CRP will investigate and make proposals on modular high temperature gas cooled reactor (HTGR) safety design criteria. It is expected that these criteria would refer to light water reactor safety standards (e.g. Safety of Nuclear Power Plants: Design (IAEA Safety Standards Series No. SSR-2/1, Vienna, 2012)), and the deterministic and risk-informed safety design standards under development for existing and planned HTGRs worldwide that apply to the wide spectrum of design basis and beyond design basis events. The CRP would also take into account the effect of the Fukushima Daiichi accident, clarifying the safety requirements and safety evaluation criteria for design extension conditions, especially those events that can affect multiple reactor modules or are dependent on the application (such as process heat or hydrogen production) on the plant site. The logical flow of criteria is from the fundamental inherent safety characteristics of modular HTGRs and associated expected performance characteristics, to the safety functions required to ensure those characteristics, and finally to specific criteria related to those functions. The initial focus will be on the criteria for a specific HTGR concept (e.g. steam cycle) but other concepts (e.g. gas turbine and process heat) will also be looked at. Both prismatic and pebble bed modular HTGR designs will be considered. Several publications and presentations were identified as important input to the CRP and will be used as the point of departure. The results of the CRP will be documented in an IAEA Technical Document (TECDOC) to be made available to the entire HTGR community. The CRP could also provide technical information for future separate activities on the development of IAEA safety standards for HTGRs with the cooperation of the IAEA Department of Nuclear Safety and Security.