Design, construction and operation of a graphite irradiation creep facility

Abstract Representative irradiated graphite properties are essential for the successful design, licensing and long term operation of a graphite moderated reactor. These properties are acquired from irradiation programs that are executed in different Materials Test Reactors around the world. Recently, the Nuclear Research and consultancy Group (NRG) has completed a graphite irradiation creep program by the name ACCENT to support long term operation of Advanced Gas-cooled Reactors in the UK. In a series of 4 irradiation steps, paired graphite specimens are irradiated at a temperature of 440 °C under loaded and non-loaded conditions. By using a modular design with pressurized bellows, a load of 5 or 10 MPa is applied to the specimens. Characterization of the graphite specimens is performed before, between and after the irradiation steps to generate graphite property curves in a range of 0 to 14 DPA. This paper describes the different design, construction and operational aspects of graphite irradiation (creep) facilities that are fundamental to successfully acquire representative irradiation data. It will be demonstrated how these different aspects are controlled for the ACCENT graphite irradiation creep facility.