Public Release: 

Cambridge team explore power of thorium for improved nuclear design

Engineering and Physical Sciences Research Council

The UK is playing a key role in an international project to develop a radical new type of nuclear power station that is safer, more cost-effective, compact, quicker and less disruptive to build than any previously constructed.

Funded by the Engineering and Physical Sciences Research Council (EPSRC), as part of the RCUK Energy Programme, a team at the University of Cambridge is exploring whether the element thorium could help to meet the new design's fuel needs. As well as being three to four times more abundant than uranium, thorium could potentially produce electricity more fuel efficiently and therefore more cheaply.

The aim of the overall project, initiated by the US Department of Energy and led by Georgia Institute of Technology, is to design a power plant whose size would be reduced and safety enhanced by breaking with convention and integrating the main heat exchangers inside the secure pressure vessel where the nuclear reactions take place. This innovation gives the design its name: Integral Inherently Safe Light Water Reactor (I2S-LWR).

Dr Geoff Parks, who is leading the Cambridge team, says: "The fact that we are part of such a pioneering international project not only reflects the UK's enduring reputation in nuclear science and engineering - it also provides a platform for the UK to develop a new suite of relevant, globally marketable skills for the years and decades ahead. If all goes to plan, construction of the first I2S-LWRs could begin in around 10 years, making deployment of nuclear power more practical, more cost-effective and more publicly acceptable worldwide."

The I2S-LWR, which could also be constructed off-site, module by module, and then quickly assembled on site, would be suitable for deployment worldwide. In this country, it could contribute to a new era of nuclear power that helps the UK meet its carbon reduction targets and energy security objectives; no new nuclear power station has been built here since Sizewell B began generating in 1995. With a power rating of around 1GW, the output from the I2S-LWR would be comparable with Sizewell B's 1.2GW rating, but the station should be significantly less costly in real terms.

The EPSRC-funded part of the project will help the UK reinvigorate its technical expertise in civil nuclear power and attract a new generation of engineers and scientists to the field. Expertise of this kind will be crucial to securing the UK's nuclear future but has significantly diminished during the 20 year 'nuclear hibernation' where no new nuclear power stations have come on stream.

The Cambridge team will focus on how thorium, which can be converted into the isotope uranium-233, could be used alongside uranium silicide to fuel the I2S-LWR. The team will assess the question not just from the perspective of fundamental nuclear reactor physics but also in terms of the scope to achieve high fuel-to-power conversion efficiency and to recycle spent nuclear fuel - key issues impacting the cost-effectiveness of the thorium fuel option.


For media enquiries contact:

Dr Geoff Parks, Reader in Nuclear Engineering, University of Cambridge, Tel: 01223 748553, E-mail:;

For images contact the EPSRC Press Office, Tel: 01793 444 404, e-mail:

Image 1: A visualisation of the I2S-LWR pressure vessel and contents.
Image 2: A 3D printed model of the I2S-LWR pressure vessel and contents.
Image 3: A schematic of the I2S-LWR concept.
Credit images to the Georgia Institute of Technology

Notes to Editors:

The 3.5-year project, 'Integral Inherently Safe Light Water Reactor (I2S-LWR)' GOW EP/K033611/1, has received around £279,000 in EPSRC funding and is due to run until January 2017.

For more information on the overall international project, see

The I2S-LWR would be a type of pressurised water reactor (PWR), a technology well-established around the world. Examples include Sizewell B power station on the Suffolk coast.

In a PWR, heat is taken away from the nuclear core by a primary coolant and then transferred to a secondary coolant which is raised to steam. This steam is then used to drive turbines and generate electricity.

Nuclear power currently produces around one-sixth of the UK's electricity. Most existing nuclear power stations in this country are scheduled to close by 2023. The Coalition Government's vision is that nuclear power should continue to play an important role in the UK's energy mix, with energy companies building new power stations subject to the normal planning process and without public subsidy.

Conventionally, nuclear power stations use uranium oxide as their main fuel. Uranium silicide's higher density and better thermal conductivity mean it could potentially deliver superior power production performance, resulting in lower-cost electricity.

The Engineering and Physical Sciences Research Council (EPSRC) is the UK's main agency for funding research in engineering and the physical sciences. EPSRC invests around £800 million a year in research and postgraduate training, to help the nation handle the next generation of technological change. The areas covered range from information technology to structural engineering, and mathematics to materials science. This research forms the basis for future economic development in the UK and improvements for everyone's health, lifestyle and culture. EPSRC works alongside other Research Councils with responsibility for other areas of research. The Research Councils work collectively on issues of common concern via Research Councils UK.

The Research Councils UK (RCUK) Energy Programme

The Research Councils UK Energy Programme led by EPSRC aims to position the UK to meet its energy and environmental targets and policy goals through world-class research and training. The Energy programme is investing more than £625 million in research and skills to pioneer a low carbon future. This builds on an investment of £839 million over the past eight years.

The Energy Programme brings together the work of EPSRC and that of the Biotechnology and Biological Sciences Research Council (BBSRC), the Economic and Social Research Council (ESRC), the Natural Environment Research Council (NERC), and the Science and Technology Facilities Council (STFC).

About the University of Cambridge

The mission of the University of Cambridge is to contribute to society through the pursuit of education, learning and research at the highest international levels of excellence. To date, 90 affiliates of the University have won the Nobel Prize.

Founded in 1209, the University comprises 31 autonomous Colleges, which admit undergraduates and provide small-group tuition, and 150 departments, faculties and institutions.

Cambridge is a global university. Its 19,000 student body includes 3,700 international students from 120 countries. Cambridge researchers collaborate with colleagues worldwide, and the University has established larger-scale partnerships in Asia, Africa and America.

The University sits at the heart of one of the world's largest technology clusters. The 'Cambridge Phenomenon' has created 1,500 hi-tech companies, 14 of them valued at over US$1 billion and two at over US$10 billion. Cambridge promotes the interface between academia and business, and has a global reputation for innovation.

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