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Assessment tools. A number of ‘approaches’ documented & available and being used/developed in-house e.g. 15 models/approaches participated within the IAEA EMRAS Biota Working group (although ranged from dose or transfer models through to more complete assessment tools). Assessment tools.
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Assessment tools • A number of ‘approaches’ documented & available and being used/developed in-house • e.g. 15 models/approaches participated within the IAEA EMRAS Biota Working group (although ranged from dose or transfer models through to more complete assessment tools)
Assessment tools • Software for some tools freely available • including RESRAD-Biota (implementation of USDOE Graded Approach); ERICA Tool; England & Wales EA R&D128 • Many approaches use a tiered assessment structure (in common with other areas of risk assessments) • simple initial screening through to more refined assessments
Initial screening tier: Tier 1 • Designed to be simple and conservative • User only needs to input media activity concentrations • Aim - to enable sites of negligible concern to be identified and removed from need for further assessment – with a high degree of confidence • Envisaged that most sites will only need this level of assessment [i.e. ‘be screened out’]
Tier 1 • Media concentrations are compared to predefined concentrations (EMCLs or BCGs) = concentration giving rise to screening dose rate (to most limiting organism)
Tier 1 – conservative • Maximum measured or modelled media activity concentrations advised as input • Transfer parameters used to derive EMCL/BCG are maximums or 95th percentiles • Habitat assumptions (e.g. RESRAD-Biota terrestrial animal surrounded by soil) • Dose conversion coefficients (RESRAD-Biota) progeny with half-lives <100 year included; external exposure organism assumed to be very small; internal exposure organisms assumed to be large)
Higher tier assessments USDOE graded approach Use same dose rate
Higher tier assessments ERICA
Regulatory action level(s) RQ>1 Taxonomic screening levels Taxonomic screening levels RQ>1 Generic screening level PROTECT benchmarks & tiered assessments Highest level tier (risk characterisation) PROTECT benchmarks Middle level tiers (site specific/user defined inputs) Initial screening tier (highly conservative) Assessment frameworks