Safety and Environment Assessment of ARIES-AT

ARIES-AT is a 1000 MWe conceptual fusion power plant design with a very low projected cost of electricity. The design contains many innovative features to improve both the physics and engineering performance of the system. From the safety and environmental perspective, there is greater depth to the overall analysis than in past ARIES studies. For ARIES-AT, the overall spectrum of off-normal events to be examined has been broadened. They include conventional loss of coolant and loss of flow events, an ex-vessel loss of coolant, and in-vessel off-normal events that mobilize in-vessel inventories (e.g. tritium and tokamak dust) and bypass primary confinement such as a Loss of Vacuum and an in-vessel loss of coolant with bypass. This broader examination of accidents improves the robustness of the design from the safety perspective and gives additional confidence that the facility can meet the no-evacuation requirement. We also provide a systematic assessment of the design to address key safety functions such as confinement, decay heat removal, and chemical energy control. In the area of waste management, waste is classified by both the volume of the component and its hazard. In comparison to previous ARIES designs, the overall waste volume is less because of the compact design. I. BACKGROUND AND OBJECTIVES The DOE Fusion Safety Standard was developed in 1996 to enumerate the safety requirements and to provide corresponding safety guidance related to the hazards associated with D-T magnetic fusion facilities. Two fusion-specific requirements that were developed are: § The need for an off-site evacuation plan shall be avoided § Wastes, especially high-level radioactive wastes, shall be minimized The ARIES program has adopted these last two requirements for their design studies. These stringent requirements have impacts in terms of materials selection and design decisions, and were adopted to demonstrate the safety and environmental potential of fusion power. The no-evacuation requirement translates into a dose limit of 10 mSv (1 rem) in a worst case accident. The waste minimization requirement is currently interpreted in the ARIES context as requiring that all waste meet current US low-level waste (Class C or better) disposal requirements. In this paper, we evaluate the ARIES-AT design against these requirements. II. RADIOLOGICAL INVENTORIES AND RELEASE LIMITS The major radiological inventories in the ARIES-AT design are tritium and activation products in plasma facing components, in structural materials and in the coolant. We present the major inventories and the corresponding release limits to meet the no-evacuation limit.