Pressure tube replica imaging system for PHWR reactors based on optical coherence tomography

•Development of a custom built non-contact 3D profiling system for pressure tube replicas.•Fiber based FD-OCT configuration was used to design and develop the system.•Inner surface replicas of pressure tube with flaws were obtained using replica tool.•3D surface profile of replicas with various flaws were imaged by the system. This paper describes a 3D profiling system for surface profiling of replicas obtained from pressure tube (PT) of PHWR/CANDU type reactors. This system is based on Optical Coherence Tomography (OCT) technique. Fiber based Fourier domain OCT configuration was used to design and develop the system considering the potential application of imaging radioactive PT replica samples. The sample scanning assembly of the system has been custom designed considering the cylindrical nature of PT replicas. Replica of inner surface of pressure tube was obtained on a replica plate using a custom built replica tool. Three PT replicas of non-radioactive pressure tubes with various flaws were obtained in different conditions. These replicas were imaged in 3D for identification and quantification of the flaws. This 3D profiling system termed as ‘PT replica imaging system’ is a promising tool which can be useful in periodic inspection of pressure tubes for safe operation of nuclear reactor.