Design, construction and operation of a graphite irradiation creep facility

• Published in: Nuclear engineering and design 2020-08, Vol.364, p.110588, Article 110588
• Main Authors: van Staveren, T.O., Davies, M.A., Knol, S., de Koning, A.J.
• Format: Article
• Language: English
• Subjects: Bellows; Construction; Consultancy services; Creep (materials); Gas cooled reactors; Graphite; Irradiation; Long term; Materials testing; Modular design; Nuclear reactors; Nuclear research; Reactors
• ISSN: 0029-5493; 1872-759X
• DOI: 10.1016/j.nucengdes.2020.110588

•Creep data is provided by test reactors to design and manage graphite moderated reactors.•Parameters to be controlled for creep irradiation are: temperature, load and neutron dose.•Design considerations to meet targets for irradiation parameters are explained.•Application of considerations is demonstrated by the ACCENT graphite creep irradiation program.•Creep strain is measured on graphite specimens irradiated at 440 °C to high doses.•ACCENT graphite measurements agree with model predictions for creep and recovery. 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.