Advancing dispersion modelling of radioactivity releases resulting from increasingly frequent Chernobyl Exclusion Zone (ChEZ) wildfire events.

The April 2020 fires that ravaged the Chernobyl Exclusion Zone (ChEZ) were the most extensive to have ever occurred – burning large areas of heavily contaminated land that could have released significant quantities of radioactive material across the whole of Europe. Unfortunately, owing to the lack of appropriate forest management in the zone these fires are becoming increasingly common – representing a near-annual occurrence. This increase in fire events occurs alongside the growing number of tourists visiting the ChEZ, reaching over 100,000 in 2019 – and expected to grow further still since the hit television mini-series on the accident. Consequently, to protect local and global populations, it is now more important than ever to accurately underpin predictions and scientific models of the radiation release from future fires originating from the heavily radiologically contaminated ChEZ by advancing not only our understanding of radioactive aerosol formation associated with such fire events, but also the dispersion (plume) modelling of the radioactivity release that is vastly different to ‘traditional’ dispersion events/models.  

The Aims and Objectives of this project, supported by the Met Office, are: 

– Utilise and improve upon existing radiometric mapping data (both airborne and ground-based) to provide a well calibrated radiation distribution model of various environments and fuel sources/reservoirs that comprise the ChEZ. 

– Collect and subsequently analyse aerosol particulate samples obtained using in-field sampling techniques, as well as utilising prior aerosol sampling undertaken by the ChEZ authorities. 

– Conduct advanced X-ray and electron microscopy analysis on the collected ash particulates to determine particle size, shape and mass distribution to determine Cs and Sr speciation and material evolution/state post-fire event. 

– Conduct laboratory based Cs and Sr release experiments on samples of red forest silver birch and pine trees to determine release fractions as a function of temperature and first duration. This would also be conducted for grasses and other organic matter to ascertain the release fractions of such volatile radioactive species during simulated wildfire conditions. This combustion analysis will permit for the mechanism of Cs and Sr release to be invoked – for examples, whether associated with solid particulate material or bonded onto sulphate or other fine-scale aerosol particles. 

– Examine the role (and mobility) of fine particles of actinides elements (associated with fuel debris particles) to understand their capacity for resuspension and aerosol transportation during wildfire incidents of varying severities and fuel consumption.  

– Working with Met Office scientists refine the source information and particle characteristics for radioactive materials released by fire in the Met Office’s dispersion model, NAME (Numerical Atmospheric-dispersion Modelling Environment). Use this updated source information carry out NAME simulations for fires in the ChEZ and compare with observations of gamma dose or air concentration. 

As the UK Met Office is often called upon to provide scientific advice in the event of the release of radioactive material during fires in the ChEZ. This advice is currently limited by the ability to estimate the quantity and characteristics of the material released in the fire. This PhD studentship would help to more effectively characterise the source term and the particle characteristics in NAME; especially with regards to release fractions. This would improve the accuracy of the predictions for fire events involving radioactive materials. 

This project is available through the EPSRC Aerosol Science CDT programme. Please find out more and apply through our website: https://www.aerosol-cdt.ac.uk/

We also encourage you to make an informal enquiries to Dr. Peter Martin ([email protected]) if you have any queries or would like to discuss details of the project.