9: Current capabilities and lessons for practice

Aims of the section

This section brings together a summary of the key differences between the characterisation of nuclear-licensed or defence sites and the characterisation of "conventional" sites. Three case studies of characterisations are presented, with lessons for practice drawn from each one. The SAFEGROUNDS Learning Network would be pleased to consider further case studies for inclusion in a later edition of this guidance.

Finally, this section summarises the key points from the best practice guidance and indicates some areas where future technological or process developments have the potential to improve current best practice.

Current capabilities

This best practice guidance has summarised current best practice for the investigation of nuclear-licensed sites and defence sites. Many of the project management and legislative issues are specific to such sites, although the general technical approach and characterisation techniques have broader application to potentially radioactively contaminated land.

Most of the site characterisation technologies described in this guidance are conventional and well established. Many have been used extensively for the characterisation of chemically contaminated land and will be familiar to most readers. The technologies and instruments that may be less familiar are those concerned with the measurement of radioactivity. However, these are all conventional health physics equipment, with a long record of successful use.

The key differences between the characterisation of nuclear-licensed and defence sites and the characterisation of 'conventional' contaminated sites are summarised below:

• nuclear-licensed and defence sites have a more complex regulatory regime. There is a need for site characterisation on such sites to satisfy a number of regulators, who regulate under different legislation and who may have different perspectives on the management of contaminated land
• because of the different regulatory regimes, the required endpoints of site characterisation on nuclear-licensed and defence site and on 'conventional' contaminated sites may be different
• there will be greater client involvement on nuclear-licensed sites, primarily driven by nuclear site licence requirements
• site characterisation on nuclear-licensed sites and defence sites will have a higher public profile, because of the potential presence of radioactive contamination. Effective communication with stakeholders (typically a wider group than would be the case for characterisation of 'conventionally' contaminated sites) is essential
• radioactive contamination is potentially present at all nuclear-licensed sites and defence sites. Best practice for characterisation of such sites is that Radiation Protection Advisers and Radiation Protection Supervisors are appointed to provide advice to the employer on compliance with the Ionising Radiations Regulations 1999 and with the Radioactive Substances Act 1993. Note that there is a requirement under IRR 1999 to appoint RPAs and RPSs if working with ionising radiations (i.e. if radioactive contamination is encountered)
• waste minimisation is a key issue on nuclear-licensed sites. There may be requirements for waste segregation, to ensure arisings of radioactive wastes are minimised
• on nuclear licensed sites, there is a requirement for long-term storage of records. This may influence the extent to which electronic collection and storage of data is used.

Case studies

Case studies, which demonstrate current practice for the characterisation of nuclear-licensed and defence sites, are presented in the full text of the guidance. In each case study, some or all of the following information is presented.

• Description of the site
• Driver for the site characterisation
• Outline of the scope of characterisation (e.g. desk study, non-intrusive surveys etc.)
• Health, safety and environmental issues
• Derivation of the preliminary conceptual model and link with the design of subsequent parts of the site investigation
• Areas of the site characterisation that are considered to represent good practice
• Outcome of site characterisation and use of data in decision making
• Lessons learned.

Possible future improvements to site characterisation best practice

This final section of the document describes areas where there is potential for technological or process developments to improve best practice for characterising nuclear-licensed sites and defence sites.

In future, greater use will probably be made of rapid, on-site techniques for quantifying levels of radioactivity. This development will minimise the need for off-site transport of radioactively contaminated samples. Similarly, more use will probably be made of in-field instrumentation for quantifying concentrations of chemical contaminants in soils and waters. Portable X-ray fluorescence (XRF) and gas chromatography (GC) is already commonly used in the USA, and is becoming more widely used in the UK. There is also potential for wider use of plants as indirect indicators of soil or water contamination.

Ecotoxicological testing offers a potentially better way to determine directly the impact of contamination on ecosystems. However, at present such testing cannot relate observed harm to a particular component in the contaminated soil or water. In future, ecotoxicological testing via DNA and genetic markers may enable the impact of specific contaminants on ecosytems to be directly measured.

The need to minimise waste production on nuclear-licensed sites may result in the wider use of invasive sampling technologies that reduce or eliminate wastes. Coupling of advanced sampling techniques with in-situ contaminant measurement will further reduce production of wastes. In general, there will probably be a greater need to minimise the overall environmental impact of a site characterisation programme, which will also influence the production of wastes and the types of equipment used during the programme.

In the future, there will probably be improved use of statistical methods for designing and interpreting site characterisation surveys. This will enable the level of confidence in the conclusions drawn from the survey to be better expressed. The use of statistical methods, together with use of better decision-making tools, will ensure that sufficient data to reach the required end point is collected, and that the collection of unnecessary data is minimised.

Finally, there is the need for a better understanding of potential interactions between radioactive and chemical contaminants in the environment. UK and international radioactive waste management R&D clearly demonstrates the potential enhanced mobilisation of some radionuclides, particularly actinides, with certain organic complexants. Further, enhanced transport of radionuclides associated with colloidal material has also been demonstrated. There is a need for further research in this area specifically targeted on contaminated land, and for the results from this research to be used in remediation decisions for such land.