Research highlights

• Reduced costly delays for dredging operations for a UK nuclear new-build at Hinkley Point C.
• Provided evidence supporting the expedited and safe return of tens of thousands of evacuated citizens to their homes after the disaster at the Fukushima Daiichi Nuclear Power Plant, Japan.
• Improved clean-up operations in the Fukushima catchment to prevent radiation leaks.
• Strengthened regulatory assessments by the Swedish and Finnish nuclear waste authorities (Posiva, SKB) concerning the safe storage of high-level radioactive waste of the next one million years.

Nuclear power contributes around 10% of the world's total electricity. In the coming decades, nuclear power - alongside renewable energy sources such as wind, hydro and solar power - is likely to play an important role in the transition to low-carbon societies.

It's important we understand how radioactive materials and nuclear waste are managed, protected and disposed of. Poor management of radioactive material could present considerable risk, not just to our own populations and ecologies, but to future generations.

Interdisciplinary teams of researchers at the University of Bristol are working to strengthen the public and environmental safety of nuclear energy, pioneering a range of novel technologies and methodologies in pursuit of this goal.

Mapping environmental radioactivity in the aftermath of disaster

On 11 March 2011 an earthquake struck east of Honshu, the largest island of Japan. The subsequent tsunami caused a devastating loss of life in the coastal region and critical damage to reactors at the Fukushima Daiichi Nuclear Power Plant.

In the post-disaster clean-up, a University of Bristol team, led by Professors David Richards and Tom Scott and Dr Peter Martin, joined forces with experts from Kyoto University to improve assessments of radioactivity levels across the fallout zone.

Previously, surveys of post-accident zones or compromised waste-storage sites had relied on either:

• High-altitude measurements from manned aircraft, which provide relatively poor spatial resolution
• On-foot surveys with hand-held radiation detectors which can risk the health of operators

As an alternative, the Bristol team designed and deployed a low-altitude unmanned aerial vehicle (UAV) fitted with a lightweight gamma-ray spectrometer.

Working autonomously, the UAV used pre-programmed waypoints and altitudes to map radiation intensity and chart the movement of radionuclides through the environment, relaying imaging of radioactive zones at higher spatial resolutions than ever before.

Working in collaboration with local authorities, this combination of technical engineering and geochemistry provided a powerful tool for assessing changes in radioactivity over time, aiding and evaluating the success of clean-up operations.

Months after the leak, mapping activity found a very low abundance of radioactive elements at most evacuated sites. This indicated safe regions around the plant and the data was used by local governments to support the repopulation.

Revolutionising global climate modelling

There are a quarter of a million metric tons of nuclear waste across the globe, most of which is at low levels of radioactivity. Nuclear waste can be hazardous to human health and potentially take thousands of years to break down. 

Many countries with nuclear power capability are assessing the safety of long-term storage for high-level radioactive waste.

Inefficient or defective long-term storage can have devastating environmental impacts, from large-scale leaks to compromised sub-surface water stores.

The integrity and safety of waste repositories is of paramount importance. Understanding how the world's changing climate may impact storage of nuclear waste, and negating said impacts presents a considerable challenge.

Professor Dan Lunt and his team developed a new approach to modelling the Earth's future climate, enabled by the supercomputing facilities of Bristol's Advanced Computing Research Centre.

Typical climate forecasts look 80-90 years ahead. For these short-term forecasts the main consideration is the global consideration of atmospheric CO2. However, for linger term projections Professor Lunt's team also considered how the Earth's orbit and the tilt of its axis change - these factors shift over time and will have a profound impact on future climate.

Over the course of five years of in-depth modelling, they created a 'statistical emulator' based on their multiple climate model simulations. This emulator approach allowed Professor Lunt and his team to forecast climate changes, including the potential advance and retreat of ice sheets such as Antarctica and Greenland. 

This provides insights on factors affecting the safety of nuclear waste storage facilities which could lead to the potential exposure of long-buried nuclear material.

To date, this work has informed regulatory assessment by the Swedish and Finnish nuclear waste authorities (SKB and Posiva, respectively).

A greener nuclear future

Our understanding of the potential of nuclear power and how we can manage its risks is continuously growing.

The University of Bristol's radioactivity research efforts have been transnational, interdisciplinary, and deeply collaborative. 

The network of specialisms involved is reflective of work across the South West Nuclear Hub - an alliance of academics, industry professionals and governmental representatives working to ensure nuclear power is a key pillar of low-carbon energy production.

This unique expertise and engagement with the nuclear industry has already led to international improvements in the management and storage of radioactive materials, helping to safeguard the health of future generations.