Many countries across the globe are looking to nuclear power as a potential low carbon solution to energy generation. However, although nuclear power is an attractive alternative to fossil fuels, it remains costly to build reactors and requires the highest manufacturing standards.
To maximise output from investments nuclear operators are looking to extend the operational lives of their reactors. But how do components cope with prolonged exposure to the high pressure, high temperature nuclear environment?
Researchers at The University of Manchester are using a combination of experimental methods combined with computer simulations to identify how specific weld techniques and parameters can reduce internal stresses and strains within the materials that make up the weld. These stresses can affect the overall performance of reactor components and limit their durability.
The EPSRC-funded New Nuclear Manufacturing (NNUMAN) programme, led by the University's Dalton Nuclear Institute, is driving efforts to optimise welding techniques. For example, researchers are looking at how various types of weld affect the materials within the weld and how this in turn can affect the way the materials survive long-term exposure to the nuclear coolant.
“The challenge”, says Dr Neil Irvine, NNUMAN Programme Manager, “is to ensure that improved weld techniques are developed and used to produce components at reduced cost but with improved lifetimes.”
So far research shows that the answer may well lie not in traditional, triangular-shaped welds but in narrower, parallel-sided welds. Smaller gaps between the joined materials require less weld metal and narrower joints also reduce the range and, perhaps, the magnitude of residual stresses in components which is likely to increase their operational life.
“This is really exciting for our industry partners,” comments Dr Irvine. “Our partners are looking closely at our research and how it might be used to optimise the welds in their reactors.”
Alongside this welding work, early research on machining methods by project partners the Nuclear Advanced Manufacturing Research Centre (Nuclear AMRC) also shows promise. Techniques such as assisted machining and mobile machining, using small robots, can significantly reduce production times whilst maintaining the quality of the components produced. International reactor vendors and manufacturing organisations have been quick to show interest in the work of NNUMAN.
The NNUMAN programme also incorporates projects in the areas of near-net shape manufacture, fuel manufacture and product performance testing.
Dr Irvine concludes: “Our work is helping to shape manufacturing techniques for the next generation of nuclear reactors. We are giving the UK a real advantage in an industry which is growing across the globe.”
Principal Investigator: Professor Michael Preuss
Dates: October 2012 – September 2017
Research centre: Dalton Nuclear Institute
Department: Department of Materials
Our work is shaping the manufacture of the next generation of nuclear reactors