RICHARD KIMBER,* FRANCIS R. LIVENS AND JONATHAN R. LLOYD

ABSTRACT

The widespread spread use of nuclear materials over the past 60 years has lead to anthropogenic release of radionuclides into the environment. The release of such contaminants is currently of great public concern and scientific interest worldwide. Contamination has arisen on sites involved in both military and civilian uses of nuclear material through leakages, spills, controlled discharges and munitions use. The management of this nuclear legacy is a global priority as governments seek to decommission and reclaim land contaminated by the use of nuclear facilities. The scale of contamination presents a serious financial burden with the cleanup of US sites expected to cost up to a trillion dollars. In the UK, the problem exists on a smaller but significant scale with associated cleanup costs estimated to be in the order of £100 billion. A wide range of disciplines are required to understand the behaviour of radionuclides and co­contaminants in these contaminated environments in order for effective remediation techniques to be utilised. Potential remediation strategies cover a range of biological, chemical and physical methods which can be used to treat the complex contamination scenarios found at nuclear sites. A number of these remediation techniques have been trialled at several sites managed by the United States Department of Energy with some success in treating radionuclide contamination.

* Corresponding author

Issues in Environmental Science and Technology, 32 Nuclear Power and the Environment Edited by R. E. Hester and R. M. Harrison © Royal Society of Chemistry 2011

Published by the Royal Society of Chemistry, www. rsc. org

The industrial production of nuclear materials and their subsequent use, both militarily and civilian, since the 1940s has left behind a legacy of contamination and hazardous waste. Management of this legacy is now a global priority as many governments seek to decommission and reclaim land once used by their nuclear facilities. However, the storage and disposal of contaminated equip­ment and spent nuclear material, compounded with the widespread dispersion of radionuclides and co-contaminants at these sites makes this a challenging and expensive undertaking.

Many former nuclear facilities were shut down at the end of the Cold War in the 1990s as the demand for nuclear weapon production decreased. These sites are now the focus of remediation, decommissioning and decontamination efforts for governments and agencies worldwide. Substantial quantities of land, groundwater, and equipment have been contaminated by the former operations of these sites, the details of which will be discussed in this chapter. A number of sites which are still in operation, often dealing with the reprocessing of nuclear material, are also the focus of ongoing remediation efforts. Contamination issues have arisen from various sources including accidental release, the con­trolled discharge of nuclear waste and the use of radionuclide-containing munitions. The accidental release of radionuclides can occur through the leakage and spills of radioactive material, as well as from incidents (such as explosions) which have occurred on site. Off site contamination is a concern in cases where both on site accidents and natural transport processes have spread radionuclides further afield. Hydraulic flow presents an ongoing problem for the containment of on site contaminants as groundwater plumes threaten to spread contamination to aquifers used in the irrigation of crops or for public drinking water. For this reason, the mobility of radionuclides, heavy metals and toxic organics is a key factor in determining the risk that each contaminant presents to the environment and general public. Understanding the mechanisms which affect contaminant mobility is therefore vital in developing effective remediation strategies. Numerous techniques are available for treating con­taminated land and groundwater, generally falling under either biological (bioremediation) or chemical processes. This chapter will outline some of the key techniques available, along with their associated advantages and disadvantages. A number of key case studies relating to former nuclear facilities will also be discussed where a variety of techniques have been applied in field scale studies.