Next generation composite materials for extreme environments in nuclear fusion power reactors
Lead Research Organisation:
Imperial College London
Department Name: Materials
Abstract
Nuclear fusion, if harnessed, could provide almost limitless carbon free energy. It could also
resolve issues of proliferation and long-lived radioactive waste that have prevented nuclear
fission from becoming more wide spread. In order for nuclear fusion to avoid the production
of long-lived radioisotopes only materials with low activation properties can be used in
components that will undergo neutron irradiation. This greatly limits materials choices,
providing some unique challenges for materials scientists. One such challenge is to find a
material that is suitable for shielding the superconducting magnetic components from
neutrons produced in the reactor. It is crucial that these components are not irradiated by
neutrons as neutron-induced heating or irradiation damage would seriously impact reactor
efficiency and lifetime. A shielding material is therefore required that has excellent neutron
stopping properties whilst not becoming highly active. It must also be mechanically stable at
elevated temperatures and withstand large amounts of helium production. One material that
has recently shown promise for this application is tungsten carbide, although its postirradiation
mechanical properties are little studied. Whilst the wide use of cemented
tungsten carbides has led to extensive research in these materials, the properties of
binderless tungsten carbide remain less understood. Tungsten carbide without a metal matrix
has often been overlooked due to its lower fracture toughness leading to its poor wear
resistance. This makes it an undesirable material in many engineering applications. It does,
however, have superior chemical and thermal stability as well as hardness and sputtering
resistance. Since the latter properties are undoubtedly more useful in a neutron
shielding application than wear resistance, research on the binderless compound is needed.
The overall objective of this thesis work is therefore to examine the changes in
properties caused by irradiation. Before this can be achieved, however, its mechanical
behaviour in the un-irradiated state must be properly understood. This project will aim to
explore this goal, with a focus on elevated temperatures.
resolve issues of proliferation and long-lived radioactive waste that have prevented nuclear
fission from becoming more wide spread. In order for nuclear fusion to avoid the production
of long-lived radioisotopes only materials with low activation properties can be used in
components that will undergo neutron irradiation. This greatly limits materials choices,
providing some unique challenges for materials scientists. One such challenge is to find a
material that is suitable for shielding the superconducting magnetic components from
neutrons produced in the reactor. It is crucial that these components are not irradiated by
neutrons as neutron-induced heating or irradiation damage would seriously impact reactor
efficiency and lifetime. A shielding material is therefore required that has excellent neutron
stopping properties whilst not becoming highly active. It must also be mechanically stable at
elevated temperatures and withstand large amounts of helium production. One material that
has recently shown promise for this application is tungsten carbide, although its postirradiation
mechanical properties are little studied. Whilst the wide use of cemented
tungsten carbides has led to extensive research in these materials, the properties of
binderless tungsten carbide remain less understood. Tungsten carbide without a metal matrix
has often been overlooked due to its lower fracture toughness leading to its poor wear
resistance. This makes it an undesirable material in many engineering applications. It does,
however, have superior chemical and thermal stability as well as hardness and sputtering
resistance. Since the latter properties are undoubtedly more useful in a neutron
shielding application than wear resistance, research on the binderless compound is needed.
The overall objective of this thesis work is therefore to examine the changes in
properties caused by irradiation. Before this can be achieved, however, its mechanical
behaviour in the un-irradiated state must be properly understood. This project will aim to
explore this goal, with a focus on elevated temperatures.
Planned Impact
The number of PhD level nuclear graduates in the UK remains small and despite the creation of a Nuclear EngD programme in 2008 it is considerably lower than the industry's need. The Imperial Cambridge Open Centre for Doctoral Training (ICO CDT) will deliver high impact research of enormous value to a range of companies while at the same time producing nuclear researchers trained to be internationally excellent and global thinking who can eventually assume leadership positions in industry, regulatory bodies, academia or Government. The aim of the ICO CDT is to train a cohort of PhDs of international quality prepared to operate in the global nuclear business and technology arena, and to deliver high-impact research. The ICO CDT will build on current industrial links including with larger companies such as EdF, EdF Energy, Horizon, AWE, Rolls-Royce, Westinghouse and Atkins and SME's such as Tokamak Solutions. We will look to develop new and improved links with other companies including in civil construction such as Laing O'Rourke, mining companies who may build any UK repository and component manufacturing companies through the Nuclear Advanced Manufacturing Research Centre (NAMRC). In addition, involvement of SME's down the supply chain in envisaged. Successful outcomes of the student research projects will ensure the UK is able to build the reactors to retain its nuclear capability providing baseload electricity to UK industry and domestic markets ensuring UK plc stays open for business! These projects will also enable the UKs nuclear industry to remain at the forefront of the global nuclear renaissance and to contribute key technologies in areas which offer potentially lucrative international opportunities including in Small Modular Reactors, lifetime extensive, decommissioning and clean up, and waste disposal technology.
In particular, we will aim at increasing our already strong international collaborations with e.g. universities and research centres in the USA (MIT, Florida, Berkeley, Michigan universities, Idaho National Lab, PNNL, SRNL), France (Limoges U, Ecole Centrale Paris, CEA, Areva), China (Tsinghua) and India (Bhabha ARC). All of these international links will benefit the UK by providing potential leaders with vision and knowledge of world leading research. In addition, we plan to be inclusive of other UK universities with a nuclear interest, involving non ICO academics in mentoring students, serving on the Management Board, in joint PhD projects and in Summer Schools, Workshops and other events.
Other beneficiaries will include the regulators such as the Office of Nuclear Regulation and the Environment Agency and various policy making Government departments including DECC, the FCO and BIS who are in dire need of nuclear-trained employees. Having the DECC and FCO Chief Scientific Advisor's (Dave Mackay and Robin Grimes) on the Advisory Board will help in this respect.
A key aspect of the research training will be that of communicating nuclear topics to the public and media and making sure that the nuclear debate is sensible and underpinned by sound science. All students will receive media training and as a result the wider public will benefit from improved communication and understanding of nuclear issues.
In particular, we will aim at increasing our already strong international collaborations with e.g. universities and research centres in the USA (MIT, Florida, Berkeley, Michigan universities, Idaho National Lab, PNNL, SRNL), France (Limoges U, Ecole Centrale Paris, CEA, Areva), China (Tsinghua) and India (Bhabha ARC). All of these international links will benefit the UK by providing potential leaders with vision and knowledge of world leading research. In addition, we plan to be inclusive of other UK universities with a nuclear interest, involving non ICO academics in mentoring students, serving on the Management Board, in joint PhD projects and in Summer Schools, Workshops and other events.
Other beneficiaries will include the regulators such as the Office of Nuclear Regulation and the Environment Agency and various policy making Government departments including DECC, the FCO and BIS who are in dire need of nuclear-trained employees. Having the DECC and FCO Chief Scientific Advisor's (Dave Mackay and Robin Grimes) on the Advisory Board will help in this respect.
A key aspect of the research training will be that of communicating nuclear topics to the public and media and making sure that the nuclear debate is sensible and underpinned by sound science. All students will receive media training and as a result the wider public will benefit from improved communication and understanding of nuclear issues.