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Wayne Oatway

Guidance on the assessment of exposure from land contaminated with heterogeneously distributed radioactive material. Wayne Oatway. Version 1. Contents. Background to the guidance Overview of the aims of the planned guidance

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Wayne Oatway

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  1. Guidance on the assessment of exposure from land contaminated with heterogeneously distributed radioactive material Wayne Oatway Version 1

  2. Contents • Background to the guidance • Overview of the aims of the planned guidance • Guidance was consulted on in 2011 with main feedback being received from: • HPA, EA, SEPA, ONR, UKAEA, NDA, DECC • Currently undergoing an internal review at HPA • Publish summer 2012

  3. Background – patchy contamination • Typically encountered in the UK at: • Industrial sites (NORM - slag, gas mantel production) • Nuclear licensed sites • Assessing radiological implications for redevelopment (planned exposure situation) • Assessments are relatively simple • Use of generic parameter values and models • Default dose coefficients • Scaling estimated exposure accounts for probability of encountering radioactivity

  4. Background – contamination by radioactive objects • Examples in the UK where contamination is by radioactive objects: • Beaches near the Dounreay and Sellafield nuclear sites • Foreshore at Dalgety Bay • Assessing radiological implications for remediation (existing exposure situation) • Assessments can be very complicated • More specific account of object characteristics eg size, solubility • Need to specifically assess the probability of encountering objects

  5. The need for guidance • Development of many assessment methodologies • Widespread contamination: W36 (HPA); RCLEA (Defra); ReCLAIM (NDA) • Contamination by radioactive objects: Approach used at Dounreay / Sellafield (HPA) • User guides on running models but little guidance on: • Selecting data to put into a model • Interpreting results from the model • Particularly where contamination is by discrete radioactive objects

  6. Guidance aims • Provide practical guidance on performing a radiological assessment of contaminated land • Tiered assessment • Defining assessment areas • Defining source term • Defining scenarios and pathways • Defining the representative person • Probability of encounter • Radiological protection interpretation of an assessment • Opinions of stakeholders

  7. Format of the guidance • Descriptive text • Key questions posed relating to aspects of that area of guidance • ‘check list’ of important points to consider

  8. Summary • Practical guidance on performing an assessment for heterogeneous contamination • Description of features that should be considered • Questions to guide the direction of an assessment • Discussion of how to interpret the results

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