Development of Automated Scanners for Underwater and Under-Sodium Ultrasonic Imaging
This paper gives an overview of the development of automated scanners for underwater and under-sodium ultrasonic imaging of complex objects in two different scanning modes. The paper deals with the control instrumentation, mechanical movement, degrees of
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Abstract. This paper gives an overview of the development of automated scan‐ ners for underwater and under-sodium ultrasonic imaging of complex objects in two different scanning modes. The paper deals with the control instrumentation, mechanical movement, degrees of freedom and ultrasonic sensor deployed for the development of the automated scanner. Keywords: Underwater scanner system · XY raster scan plan · θ-Z scan plan · Under-sodium scanner · Automated scanner
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Introduction
Under-sodium viewing at high temperatures is an important requirement in sodium cooled fast reactors (SFR) for navigation during structural inspection. One of the major difficulties for in-service inspection and repair (ISI&R) deployment in SFR is the sodium environment [1]. As the sodium is opaque, ultrasonic inspection is the best suited method for carrying out ISI&R of the internal components of the reactor during shutdown period. The recent advances in electronics and digital processing techniques have signifi‐ cantly improved conventional ultrasonic imaging systems and allowed new and sophis‐ ticated scanning methods [2]. Haviceslice et al. [2] describes how and why ultrasonic pulse-echo approaches are of substantial aid in medical field. Voleisis et al. [3] focused on development of an ultrasonic imaging system for the Multi-purpose hybrid Research Reactor for High-tech Applications (MYRRHA). Focussed and unfocussed ultrasonic transducers of 5 MHz were used. Sylvia et al. [4] described the application of Under-sodium Ultrasonic Scanner (USUSS) for Prototype Fast Breeder Reactor (PFBR) to detect any protruded part above the core plenum before starting the fuel handling operation. Images were obtained using under-sodium transducer of 1 MHz frequency mounted on a mechanical scanner. Many demonstrated under-sodium viewing systems incorporate a single transducer with two scanning degrees of freedom (planar Cartesian coordinates in the XY plane) [5]. The XY raster scan plan provides constant angle perspective of the component. Imaging by XY scan plan requires complete coverage of the object. However, due to space constraints within a sodium cooled fast reactor (SFR), it may not always be © Springer Nature Singapore Pte Ltd. 2016 B. Vinod et al. (Eds.): ICAARS 2016, CCIS 627, pp. 109–117, 2016. DOI: 10.1007/978-981-10-2845-8_9
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possible to deploy an XY scanner which may pose limitation for imaging large areas. This demands the development of a scan plan which can enhance the ultrasonic scanning span under space constraints. Recently, Kumar et al. [6] have addressed the limitation posed by the conventional XY raster scan method due to the space constraints within the reactor and has shown the possibility of using θ-Z scan plan based approach for imaging of objects submerged in liquid medium. θ-Z scan plan is an alternative and this can easily be deployed even in constrained situations and still can cover large areas. In addition to this many demonstrated under-sodium viewing systems incorporate a single transducer
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