RWMAC's Advice to Ministers on the Restoration of the UKAEA Dounreay Nuclear Site

8. Contaminated land remediation

8.1 The Contaminated Ground Decommissioning Plan - Volume 7 of the DSRP - sets out UKAEA's proposed strategy and arrangements for the characterisation, control, and remediation of contaminated land, both on and off the Dounreay site.

8.2 The Plan is structured so as to allow the results of investigations to be continually assessed and evaluated, and emerging recommendations to be implemented, on a prioritised basis, to form the management programme for contaminated ground. This process is termed the "sentencing" of contaminated areas. For on-site contamination, the system of zones is used for predicting conditions at the end of the decommissioning and "care and maintenance" (300 years) phases.

8.3 The Plan also addresses the environmental risk associated with contaminated land liabilities, their potential impact on the closure of the site, and waste arisings from remediation schemes. The issue of offshore contamination by the "Dounreay particles" is considered separately (see section 9 of this report). There is a summary of the relevant legislation and of UKAEA's management structure associated with the control and remediation of contaminated areas. The contaminated ground programme accords with UKAEA decommissioning policy for Dounreay.

8.4 Again, RWMAC wishes to emphasis that UKAEA has had to produce the Plan in the absence of clear Government policy and standards for the remediation of radioactively contaminated land. In these circumstances, UKAEA has chosen to use the Substances of Low Activity (SoLA) Exemption Order (EO) figure, 0.4Bq/g, as the level of contamination that can be left in place. UKAEA acknowledges that, for activity concentration above this level, it will have to consult the regulators on the precise manner in which the contamination is to be dealt with.

8.5 RWMAC sees a number of problems in use of the SoLA values as a criterion in this exercise. First, use of the SoLA values has not been formally accepted as Government policy. Hence, UKAEA could proceed in this way and its planning could ultimately be rendered invalid by the emergence of an alternative policy. Second, RWMAC's view, and that apparently emerging from ongoing Safegrounds work (a project managed by the Environment Council, involving a wide variety of stakeholders, focussing on the remediation of nuclear sites), is that the current RSA93 and EO framework is inappropriate for dealing with radioactively contaminated land. Last, RWMAC believes there is a need for radionuclide-specific clean up criteria that are linked to risk considerations. The Committee therefore again calls for the Government to develop a comprehensive policy for dealing with radioactively contaminated land. This must include interpretation of the "no danger" criterion for nuclear site delicensing under the Nuclear Installations Act 1965. In light of these problems, RWMAC continues to see it important for Government to move forward to develop a comprehensive radioactively contaminated land policy as soon as is reasonably possible.

8.6 Other than this, RWMAC finds the Contaminated Ground Decommissioning Plan to be generally acceptable and sensible. The Plan covers controlled burial, use of physical barriers, and on-site engineered containment. Again, RWMAC makes the point that, ultimately, it may prove impossible to return all parts of large nuclear sites to their pre-existing state, except in the very long term, or, possibly, at all. It may also prove impossible to justify moving large amounts of relatively lowly contaminated material from one site to another, either in terms of the radiation detriment this might give rise to, or cost.