Maintaining the structural health of prestressed concrete nuclear containments is a key element in ensuring nuclear reactors are capable of meeting their safety requirements. This paper discusses the attachment, fabrication and characterisation of optical fibre strain sensors suitable for the prestress monitoring of irradiated steel prestressing tendons. The all-metal fabrication and welding process allowed the instrumented strand to simultaneously monitor and apply stresses up to 1300 MPa (80% of steel's ultimate tensile strength). There were no adverse effects to the strand's mechanical properties or integrity. After sensor relaxation through cyclic stress treatment, strain transfer between the optical fibre sensors and the strand remained at 69%. The fibre strain sensors could also withstand the non-axial forces induced as the strand was deflected around a 4.5 m bend radius. Further development of this technology has the potential to augment current prestress monitoring practices, allowing distributed measurements of short- and long-term prestress losses in nuclear prestressed-concrete vessels.
Bibliographical noteNOTICE: this is the author’s version of a work that was accepted for publication in Nuclear engineering and design. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Perry, M, Yan, Z, Sun, Z, Zhang, L, Niewczas, P & Johnston, M, 'High stress monitoring of prestressing tendons in nuclear concrete vessels using fibre-optic sensors' Nuclear engineering and design, vol.268 (2014) DOI http://dx.doi.org/10.1016/j.nucengdes.2013.12.038
Funding: EPSRC and EDF Energy Nuclear Generation, Ltd