Qualification of remote automated ultrasonic inspection of an austenitic pipe weld

Demonstration of inspection capability is an essential input to any safety cases which are reliant upon non-destructive inspection to detect and size defects in components or structures. This paper describes a recent specific example of how Nuclear Electric has demonstrated the capability of a remote automated ultrasonic inspection on its Advanced Gas Cooled Reactor plant. Following the discovery of a small leak in a 300mm diameter austenitic steam tube there was an urgent requirement to develop a capability for inspecting all similar welds and to provide a demonstration of capability of the inspection. The first part of the paper describes the inspection requirements, the ultrasonic techniques used and the procedure and equipment which was developed. The second part describes how the capability was demonstrated: all the evidence to support the capability was embodied in a technical justification which was prepared under contract by the AEA Technology Inspection Validation Centre (IVC). The technical justification included a combination of theoretical evidence and practical evidence from open and blind test block trials together with experience of inspection of other similar components. Within a period of less than two months from initial request, an inspection capability had been developed and justified and was then successfully deployed on-site.