Nuclear plans for Brexit

Materials World magazine
29 Oct 2018

As the UK continues on its difficult path towards Brexit in March 2019, there is little said so far about European collaborative research and how this might continue with UK participation post-Brexit. Kevin Mottershead, Mark Chatterton and John Sharples describe some of these activities in nuclear research.

To maintain state-of-the-art capabilities, all high level consultancies need to invest in research and development (R&D). In this respect, Wood Nuclear is fortunate in that, in addition to its own R&D investment programmes, it receives contracts from clients to actually undertake R&D for them. As will be seen, despite some challenges, the European Commission’s (EC) Horizon2020 projects provide a means of enhancing R&D for both Wood Nuclear and its R&D funding clients. Wood Nuclear is presently involved in four materials performance focused Horizon2020 projects, in collaboration with other European partners. Before we examine the advantages and challenges of participation, we should first introduce the four projects and Wood Nuclear’s involvement.

Understanding fatigue

Increasing safety in NPPs by Covering gaps in Environmental Fatigue Assessment (INCEFA+) began work in July 2015 – although the consortium had been working together on an in-kind basis since 2013. The project, which attracts €2.5m of funding over five years from the EC, has 16 participant organisations. This project’s focus is on creation of new environmental fatigue data aimed at improving understanding of fatigue sensitivity to three common parameters of interest, namely, effects of surface finish, hold time and mean stress. The ultimate objective for the project is creation of assessment rules able to predict fatigue lives more consistent with plant experience than is the case for present American Society of Mechanical Engineers and USA Nuclear Regulatory Commission guidance.

The project aims to reduce assessment conservatism through creation of more reliable consistent data than has hitherto been done. This is being achieved through all partners working to an agreed testing protocol and using mainly common material specimens all prepared in the same facility. Detailed material and specimen characterisation data have been created to help understand data outliers. Wood Nuclear is the coordinating organisation leading this project.

Materials ageing

Another project, safe long term operation of light water reactors based on improved understanding of radiation effects in nuclear structural materials – SOTERIA, a Euratom Research and Training Programme – began work in September 2015, building on many years of collaboration for consortium members within previous projects. This project comprises 23 organisations, and is funded with €5m over four years from the EC. It is developing understanding of ageing phenomena in reactor pressure vessel steels and reactor internals. Experiments are being performed to explore flux, fluence, and environmental effects, as well as effects of metallurgical heterogeneities and on materials ageing behaviours. Modelling tools are being developed to assess structural components, based on the developed understanding. Wood Nuclear manages the work package focused on irradiation-assisted stress corrosion cracking (IASCC), and also participates in the modelling of reactor pressure vessel material embrittlement and irradiation-assisted stress corrosion cracking.

Developing guidelines

The Mitigating Environmental Assisted Cracking Through Optimisation Of Surface Condition (MEACTOS) project started in September 2017 and will run for four years. The EC supports the project with €2.5m in funding, in which 16 organisations participate. This project will quantify the effect of various surface and treatment techniques on the EAC behaviour of nuclear primary circuit structural materials, with the objective of developing practical guidelines suitable for incorporation in nuclear design and manufacturing codes. Stress corrosion cracking (SCC) testing is being done using specimens with a variety of surface finishes. Significant demonstration of novel surface finishes being developed to mitigate against SCC is included in the test programme.  Wood Nuclear contributes SCC testing to the project.

Model pipelines

The Advanced Structural Integrity Assessment Tools for Safe Long Term Operation (ATLAS+) project began in June 2017 and will run for four years, over which 19 organisations collaborate with €4m EC funding. Five different large-scale experiments are planned to generate data for validation of advanced modelling tools for application to nuclear piping systems and associated components. Modelling tool development is focussed on simulation and assessment of weld residual stresses and prediction of large ductile tearing.  Assessment of safety margins using probabilistic methods is also being explored.  Wood Nuclear leads
the development of residual stress profiles through modelling simulation, and in the use of leak-before-break assessment tools for long-term operation.

The INCEFA+, SOTERIA, MEACTOS and ALPHA+ projects, which have all received funding from the Euratom Research and Training Programme 2014-2018, address very different aspects of materials performance. However, key to their success in attracting support and our participation is their relevance to knowledge gaps for two of Wood Nuclear’s main UK customers. This support is necessary because without it, commercial consultancy organisations, such as Wood would find it difficult to participate in these programmes. The problem for commercial consultancy organisations is that the Horizon2020 materials-focused projects Wood Nuclear participates in only fund 25% overheads and therefore, for many commercial consultancy organisations, funding of total costs is not complete.

The commercial challenges are then further compounded by many projects being proposed for only partial funding of the total costs plus 25% overheads. This usually occurs because funds applied for are constrained by expectations of what is available, and are often then insufficient to fund the work necessary to meet the research objectives. Thus, for many Horizon2020 projects, it is necessary for participants to supply matching funding.

For national research laboratories this can come from national funded programmes, whereas for commercial consultancy organisations, it typically comes from customers who see value in the project’s objectives. So to begin with, we have determined that the incentive for participating in Horizon2020 projects is not financial. It is also true that the administrative challenges of managing matching funds and partially recovered overheads should not be underestimated. Neither is it always easy to balance national interests against those of projects, leading to sometimes energetic exchanges of views between partners.

Gearing up

So, with the difficulties just described, why would anybody want to participate in a Horizon2020 project? The answer has already been suggested, and it can be labelled gearing. Through a willingness to devote partial funding, Wood Nuclear and its customers gain some significant benefits. Firstly, there is simply the access to results of relevant research from the whole project consortium. For a well-focused project such gearing of volume has, for one of the current projects, been estimated to be a factor 10 by one of Wood Nuclear’s customers. Secondly, the projects provide for sharing of expertise between partners, so that best practice is disseminated within each consortium. Thirdly, the projects provide opportunity to showcase an organisation’s capabilities to a wide audience – in fact the audience can be far wider than just the project consortium, since dissemination of Horizon2020 projects is a key requirement at project specific international workshops, and through participation in respected international conferences. Finally, through energetic and passionate discussion between leading experts, ideas are challenged and refined far more than would be likely within an individual organisation. Some specific examples of these benefits for each of the current projects are outlined here.

The creation of more than 200 high-quality, high consistency data points from INCEFA+ offers the potential for a European agreed response to existing US sourced environmental fatigue methodologies and their application to several issues of common interest in Europe. Such consensus would be much more difficult to achieve without the project. Neither would it be easy to achieve consistency of materials, material conditions, nor testing practices without the project. So far, in this project, it has been notable just how variable testing practices were between partners, and how much standardisation of best practice has now been achieved through cooperative sharing
of experience.

Detailed mechanistic understanding of irradiation damage to materials, and its effects on damage susceptibilities, requires the bringing together of a large range of modelling and testing capabilities. No single organisation possesses all of the required skills. However, by bringing them together, the SOTERIA project enables a genuinely multi-disciplinary approach. Individual partners also benefit from influence of, and access to work in institutions with valuable unique capabilities. For example, Wood Nuclear does not have neutron-irradiated materials testing capability but others in the consortium do. Similarly, Wood Nuclear holds unique statistical modelling capabilities that the rest of the consortium value.

Likewise, the MEACTOS project also brings together multiple disciplines and capabilities. Firstly, testing for stress corrosion cracking susceptibility is notoriously difficult to do reliably, and within practical laboratory timescales. The need to accelerate timescales to achieve cracking must be balanced against the potential pitfalls of results that bear no resemblance to anything that could occur on plant after several decades. Furthermore, it is well known that there can be significant statistical variability in surface properties achieved for apparently very similar machining specifications. The combining of testing, material characterisation and machining capabilities into one project provides a team well able to deal with such challenges far better than any one organisation could do on its own.

ATLAS+ also brings together a unique combination of complementary skills and experience. For this project the skills brought together comprise multi-scale materials testing, modelling and assessment of residual stress, understanding of advanced assessment tools for leak-before-break prediction, and application of probabilistic approaches to determine safety margins. As with the other projects, the combining of skills creates a capability that far exceeds that of any single participant.

So, despite some significant financial and administrative challenges, and occasionally challenges balancing national concerns against those for projects, these research initiatives really do bring very significant advantages to Wood Nuclear and its customers. Arguably, the benefits extend beyond to the wider United Kingdom by virtue of showcasing UK capabilities internationally, and thereby encouraging overseas organisations to seek further collaboration and investment in work sourced in the UK. It should also be noted that the projects are also exciting to work on and provide excellent career opportunities for new UK materials scientists.

To conclude, during a period when news concentrates on European disharmony, it is a welcome diversion to be reminded that, at least in the materials performance world, the entente cordiale continue – at least most of the time. There is definitely a strong case for such collaboration to continue post-Brexit, however it is funded.