2.1.1

Core Science

Core Science is focused on pushing the boundaries of nuclear science, building NNL’s technical reputation and delivering knowledge and capabilities for our stakeholders.

Our 12 Core Science areas

Our Core Science themes provide a platform for innovative and scientifically challenging work for our scientists, of which risk taking – but with a fail-fast approach – is a necessary component.

Advanced Recycling Isotope Separations (ARIS)

Environmental Radiochemistry


Post Irradiation Evaluation (PIE) & Materials Performance

Reactor Chemistry (& Corrosion)


Advanced Fuels

Thermal Treatment


Nuclear Safety

Structural Integrity


Decontamination Science

Health and Nuclear Medicine


Reactor Technology

Irradiated Fuel Characterisation

In addition to three new areas of science added this year, five of the 12 are heading to ‘world class’ and four have already been independently peer reviewed as such.

Not only does this work stimulate creativity and fresh thinking amongst our people, but the technologies developed through Core Science contribute directly to our commercial activities. The programmes therefore return extremely good value for money in relation to the level of investment they require.

Our core areas of science are also fundamentally important to our current and future Strategic Research programmes. It is through the technical advances that have been made in Advanced Fuels and ARIS, for example, that we have been able to deliver our pioneering Advanced Fuel Cycle Programme (AFCP) on behalf of BEIS.

Developing our national capabilities through Materials Performance

Nassia Tzelepi has over 15 years’ experience in the nuclear industry and is a Fellow in Graphite Technology at NNL.

“Materials Performance is one of our Core Science areas at NNL and is made up of three key parts – Metals and Alloys, Spent Fuel Storage and Graphite Technology. Whilst each of these areas is distinct, they all aim to develop a mechanistic understanding of the behaviours of the different materials being studied and help us deliver on our ambitions in Clean Energy and Environmental Restoration.

I work specifically in Graphite Technology which involves supporting the operation of existing reactors and the development of new ones, as well as assisting graphite decommissioning. For reactors in the UK, graphite acts both as a moderator in the nuclear reaction and forms the structural material of the reactor core itself. The UK has been operating graphite-moderated reactors commercially longer than any other country in the world, so our expertise in the field is unparalleled.

To ensure our work is always at the cutting edge, we collaborate with experts in academia and with universities across the country, often welcoming PhD students and researchers into our laboratories. This provides those outside NNL with the opportunity to work in an industrial environment, as well as giving our people the chance to tap into a wider pool of knowledge and enhance their own technical abilities.

Likewise, through our participation in ASTM International, which is the organisation that provides the standards and the test methods for measuring graphite samples, we have formed strong partnerships with laboratories across the world. These include Idaho National Laboratory and Oak Ridge National Laboratory in the US, and NRG in the Netherlands.

As we look to the future, our main aim in Graphite Technology is to support the next generation of nuclear reactors and ensure we accelerate the decommissioning of our existing ones in a safe and cost-effective manner. For over 60 years, NNL has been the only provider of post-irradiation examination campaigns of reactor graphite in the UK, which means we are perfectly positioned to apply our extensive experience to new areas of nuclear energy.”

“To ensure our work is always at the cutting edge, we collaborate with experts in academia and with universities across the country, often welcoming PhD students and researchers into our laboratories.”

Nassia Tzelepi Fellow in Graphite Technology at NNL

The future of Core Science

By 2026, we want all 12 of our Core Science areas to be independently reviewed as, or on the way to being, ‘world class’.

To help us achieve this, we will deliver a series of engagement programmes that line up with each of our Core Science areas. This will involve communicating much more broadly – both across NNL and externally – to engage the very best in our sector, and continuing to provide the wider research community with access to our specialist facilities.

2.1.2 Innovation