Safety first

A British company is enabling nuclear plant manufacturers to make more efficient, cost-efficient components, without compromising on safety -precisely what the nuclear industry requires to fuel its resurgence.

Bristol-based VEQTER’s Deep Hole Drilling (DHD) Technique refines component manufacture by determining the exact residual stress acting on a component throughout its entire thickness. In doing so, integrity may be verified and the need to rely on conservative standards now decades old is removed.

According to VEQTER's Dr Ed Kingston, using the DHD technique means components no longer have to be over-engineered and oversized, reducing the amount of raw material needed, therefore minimising its cost and weight.

The result is that less infrastructure is needed to support the component (typically reactor pipelines and particularly the welds connecting the pipes), leading to a significant overall reduction in plant construction costs.

A University of Bristol spinout, VEQTER launched commercially last year, offering through-thickness residual stress measurements up to 500mm deep on components of any shape. Previously the best other stress measurement techniques could offer was 30mm using neutron diffraction. Prior to the commercial launch, DHD was researched at the University for over a decade by Professor David Smith and was joined by Kingston in 1998.

Originally developed to test component structural integrity, the UK nuclear industry (with the UK Engineering and Physical Sciences Research Council) funded Smith and Kingston's research. Within that industry DHD has been described as 'the principal method for measuring through-wall distributions of residual stress in components where the wall of the component exceeds 30mm' and VEQTER's DHD residual stress measurements have been used to help understand and support the safe operation of British nuclear plant.

While the technology is helping to assess and maintain the safe operation of the 63 reactors currently online or under construction in Japan, VEQTER is keen to deploy its technology globally as other economies increase nuclear interests or seek to extend the working life of existing plant.

France for example, plans to start renewing its 59 nuclear power stations in 2015, while most of the UK's existing plant will have reached the end of already extended working lives within twenty years.

South East Asia, particularly China, is increasing nuclear plant levels, while India has just received the go-ahead from the US to forge ahead with its own programme. Aiming to have at least one new reactor operational by 2010, US power companies also plan to extend plant life by 20 years. There are currently 118 plants operating in North America.

Given the global scale of nuclear plant build and maintenance, there's a growing market that can benefit from VEQTER's DHD technology. By working with organisations such as JNES, alongside big names such as Airbus and Rolls Royce, Kingston says nuclear companies are increasingly recognising the commercial value of a technique once seen only as a University research tool.

"They are beginning to appreciate that by working out what the actual stresses are and where they lie we also enable them to go through fewer processes to improve stress levels within the components," he says. "So for new plant, component designs can be more accurate and therefore the whole plant design less expensive. In existing plant our technology facilitates a reduction in the frequency and duration of downtime while verifying how long plant is safe to use."