University: Imperial College London Supervisors: Dr Frederic Cegla and Dr J. Corcoran

There is concern that rapid temperature changes in the primary cooling circuit of reactors can induce thermal fatigue that can be detrimental to the overall life of components in the primary circuit. It is therefore desirable to monitor the number and magnitude of cross wall temperature changes in these components so that one can better estimate the magnitude and number of stress cycles that a component experience. These parameters can then be used in structural integrity assessments to predict the overall life of the components.

The Imperial NDE group has recently performed a RCNDE feasibility study that has shown that internal pipe wall temperature can be estimated from through thickness time of flight ultrasound measurements that are combined with an external resistance temperature detector (RTD) measurement and a simple heat transfer model of the pipe wall. It was shown that for 50mm thick mild steel components and a temperature step of 15°C across the wall (inside temperature 15°C above the outside temperature, where the transducers are installed) the inside temperature could be determined to within 2°C of an independent RTD measurement. This project aims to build on the outcomes of the feasibility study to enable real-time monitoring of temperature wall gradients in primary circuit components under realistic conditions (up to 350°C) and using the information to perform structural integrity assessments.

The academic and practical challenges for the project will be:

  • Design and implement a sensor system that will withstand the operating temperatures (350°C) and will perform repeatable high SNR and repeatable time of flight measurements on realistic components.
  • Investigate the effect of rapid cyclical temperature changes on the sensitivity of the method and the accuracy to which the initial temperature distribution throughout the component needs to be known and how errors accumulate.
  • Determine the effectiveness of using the ultrasonically monitored temperature information to estimate thermally induced stress levels and fatigue life predictions.

Funding: 

This studentship covers fees at the home/EU rate, a stipend of £16877 per annum and the full technical and professional training programme as part of the FIND CDT