In-Situ Test of High Temperature Pipes in Nuclear Power Plant (UltraHotTest) UltraHotTest is a unique new sensor system for assessing the condition of high temperature steam pipes used in nuclear power generation plant. Ageing nuclear plants are an increasing problem globally, with 75% of reactors in the last half of their design life and many plants subject to lifetime extension. A high degree of maintenance is required to keep the pipe-work of ageing plants operating safely. Pipe failures can be catastrophic and expensive (ca. £100M per event). Increasing safety and environmental regulation requires more frequent inspection to mitigate risks of unplanned failure or unsafe conditions. However, current inspection techniques are either inaccurate or only work at room temperature, thus requiring expensive shutdown (energy unavailability worth £1M per day) to perform the inspection. UltraHotTest will use a novel high temperature ultrasonic phased array (PA) probe combined with Time of Flight Diffraction (TOFD) to provide accurate and reliable flaw detection and monitoring up to 580°C, the maximum operating temperature of super-heated steam pipes in UK AGR power plant. This high temperature combined PATOFD system has been developed to an initial prototype stage and laboratory validated at 580°C (TRL6). The objective of this “First Of A Kind” (FOAK) project is to deploy the technology, for the first time, on super-heated steam pipes (SHSP) in a UK AGR power plant. The project will be conducted in two phases. Phase 1 will develop a detailed business plan for commercial deployment of the UltraHotTest system, demonstrating market viability of the system. Phase 2 will deliver the deployment at a UK AGR plant. This will entail the design and construction of high temperature phased array probes, system integration into a prototype suitable for installation on turbine steam supply pipe-work in operational power plant, and on-site services to conduct the deployment safely and with minimum disruption to plant operation. These FOAK trials will demonstrate customer benefits, paving the way for commercialisation of the technology. UltraHotTest will reduce the cost of nuclear electricity generation and improve its safety. It will improve the profitability of operators by reducing failures and downtime, saving the UK nuclear power industry £56M p.a. It has commercial potential to develop new revenues of £40M with a profit of £25M cumulative within 5 years, creating 75 new jobs for the SME led the consortium and ROI of 20:1.