The clean-up of land formerly held by the nuclear industry so that it may be "de-licensed" and used for other purposes is difficult and expensive. Even low-level contamination by radioactive isotopes can force the removal of many tonnes of soil before a site can be given a clean bill of health.
In the process environmental damage is caused and the vast quantity of soil must be safely stored somewhere for many years until its radioactivity drops to safe levels.
The answer to this problem may be growing in our own back yards, according to scientists at the University of the West of England in Bristol.
"The idea is that plants have the capacity to extract lots of inorganic chemicals from the soil using energy from sunlight - it's a solar-powered system for extracting minerals," explained Dr Neil Willey of the university's Centre for Research in Plant Sciences.
This process is called "phytoextraction". "We've been able to identify a branch on the evolutionary tree. Many of the plants that sit on this branch have an affinity for taking up radioactive isotopes."
The key innovation of Dr Willey's work is the development of a system for selecting the most suitable plants based on a new understanding of plant classification. Knowledge of the relationships between families of plants was turned upside down recently when new DNA analysis was introduced by botanists.
"There are 350,000 species of flowering plants alone. Up to now, the full biodiversity of plant species has not been used. This technique allows us systematically to select from these."
The uptake of metals from the surrounding soil by plants is controlled by proteins in the roots. Chemicals are released by the roots into the ground that help selected metals to dissolve. The metals are then absorbed as part of the plant's normal feeding process. Plants that are hungry for caesium are best for the decontamination of nuclear industry sites.
Once rooted in contaminated soil the plants can be left to draw in the isotopes along with the other nutrients. After a time they are cropped and stored, leaving the land safe for use.
"There are enormous contaminated land problems on a European scale," Dr Willey said. "There is a big drive for an eco-friendly solution involving an in-situ technique that doesn't disturb the soil."
Trials at Bradwell Nuclear Power Station on the Essex coast are under way in collaboration with British Nuclear Fuels Ltd to test out the team's new plant selection process. Varieties of sea beet (Beta Vulgaris), a relative of the humble beetroot, are being used.
The team is trying to optimise the harvesting of the sea beet to accelerate the clean-up rate. The harvested plants will still have to be stored until their radioactivity drops to safe levels but handling concentrated plant material is much easier than dealing with mounds of soil. "We are aiming at radioactive materials with relatively short half-lives of 60-90 years," Dr Willey said.
The potential for "soil scrubbing" using plants reaches further than the nuclear industry. The technique may open up a new form of recycling, Dr Willey said. "It may even be economically viable to recover certain metals such as cadmium and zinc from plants used in this way."
Dr Peter Foote is a research scientist with BAE Systems in Bristol. He is participating in the Media Fellowship programme of the British Association for the Advancement of Science.