The ever increasing demand for low-cost energy is forcing many of our power stations to run well beyond their original design life. The safe extension of a power station's operating life requires new inspection techniques which must accurately detect creep damage and predict the remaining life of a component.
CreepImage, a project run by a group of European companies (Aimen, Dantec Dynamics, IKnowHow, Integrity NDT, Pro Optica and TWI) and funded by the Research Executive Agency (REA) of the European Commission is developing an optical inspection technique for long-term measurement and monitoring of creep deformation in engineering structures. The inspection process is particularly suited to the harsh operating conditions of a power station, where high temperatures and radiation often prevent the use of conventional inspection methods.
In this non-intrusive approach a high-temperature resistant grid pattern is superimposed on the surface of the component under test and a high-definition digital camera captures images of the grid over an extended period of time (typically 6-12 months). Digital image correlation (DIC) software then analyses the changes in the digital images to calculate the extent of creep deformation that has occurred. Finally, creep-life prognosis software, based on the MPC Omega methodology, predicts the remaining life of the component under test.
It will be possible to monitor the creep deformation both whilst a plant is in operation (via access windows set into a component's insulation), and during scheduled power plant outages, when component access is more straightforward. This will enable the power plant operator to closely monitor creep damage and make decisions regarding component replacement based upon up-to-date creep measurements.
Laboratory trials and on-site power station testing of the prototype system have demonstrated the feasibility of the inspection process. Additional validation work and long-term industrial trials are now required to convince industry of the merits of this new inspection process.
CreepImage will potentially help power plant operators to reduce risk by providing enhanced safety assurance, increase revenue by improving the availability of power plant, and optimise inspection scheduling thereby reducing costs.
To learn more about CreepImage, visit the project website at www.creepimage.eu or contact the Project Coordinator Jianxin Gao.
The CreepImage project has been managed and co-ordinated by TWI Ltd (UK). The research leading to these results has received funding from the European Union's Seventh Framework Programme managed by REA Research Executive Agency (FP7-SME-2011) under grant agreement No 284986.