review of nea and wna reports protect – oslo 2008
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REVIEW OF NEA AND WNA REPORTS PROTECT – OSLO 2008. [email protected]. Reports reviewed. Scientific Issues and Emerging Challenges for Radiological Protection, OECD-NEA 2007 - PowerPoint PPT PresentationTRANSCRIPT
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Reports reviewed
• Scientific Issues and Emerging Challenges for Radiological Protection, OECD-NEA 2007
• Issues around radiological protection of the environment and its integration with protection of humans: promoting debate on the way forward. George Brownless, OECD, J Radiol Prot 2007
• Overview of Representative Ecological Risk Assessments Conducted for sites with Enhanced Radioactivity, SENES (for WNA) 2007
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OECD-NEA – Report Contents
• Possible Scientific issues and their Implications
• Challenges from Non-targeted and Delayed Effects
• Individual Sensitivity
• Epidemiology
• Challenges to the Concept of Dose as a Surrogate for Risk
• Possible Emerging Challenges in the Application of radiological Protection
• Radiological Protection in Medical Exposure
• Radiological Protection of the Environment
• Health Impacts of Radiological Terrorist Attacks
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Radiological Protection of the Environment
• There is international consensus on the need to protect the environment
• Research need to be well-targeted and aimed towards concrete results to assist policy makers
• Data published to date suggest that no significant harmful effects that could have put whole species at risk of promote irreversible balance between species have been observed for exposures below 1 mGy/day
• Lack of data for chronic exposure
• Requirement for compatibility with other areas of environmental protection
• Proposal for a International Network or “Observatory” for data and assessments
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Issues
• Need to demonstrate that the current system gives an adequate level of protection to the environment
• Linking measurement data to protection of the environment
• Identification of pertinent endpoints
• Models
• Fit-for-purpose approach
• Reference organism approach
• Pragmatic
• Simple
• Life-stage sensitivity
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“Today, under controlled practice and in normal operation of facilities, there seems to be not indication of any significant or visible harmful effect on the health of ecosystems that can be attributed to radiation. But given the complexity of the situation (e.g. natural background, relationships between individual and ecosystems, many simultaneous stresses), the research necessary to scientifically answer questions regarding the well-being of ecosystems must be well targeted and based upon the social choices at the international, national and local levels depending on the situation being considered” (p. 94)
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Brownless, 2007
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Two Concerns
1. “Lack of transparency of the current system. It is not immediately obvious how protecting humans gives good protection to the rest of the environment, since the system does not give any direct protection or means of measurement or comparison.
2. “Lack of comprehensiveness of the current system. Currently, radioactivity accumulated in the environment is only controlled insofar as humans are exposed to it. Therefore it is in principle possible that isolated, sensitive parts of the environment may be inadequately protected.”
p.392
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Three-banded Scheme
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“What should be measured?”
• Estimate generic dose rate per unit concentration values for reference ecosystems, organisms and radionuclides (eg. ERICA)
• Subject to periodic review
• Assumption that a limited set of organisms is representative of an ecosystem needs to be explored
• Information on background is desirable to give a sense of scale
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Conclusions – changes to the system of radiological protection
• Incorporate an explicit evaluation of potential environmental harm
• Incorporate a three-band scheme
• Issues
• Concentrations and doses
• The broad aim of environmental protection
• Sustainable development
• “…even if more is done to protect the environment, this should complement the current system, taking advantage of how it already acts to protect the environment, rather than solely consisting of additions to it.”
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SENES and WNA
• WNA Press Release, 2007
“Reassurance on environmental protection from nuclear site releases”
“ By examining the effects of ionising radiation in the environment, an independent expert overview has confirmed that both people and nature have been adequately protected from radioactive releases from all kinds of nuclear sites, old and new”
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SENES Report
Overview of Representative Ecological Risk assessments Conducted for Sites with Enhanced Radioactivity
• Uranium Mining Sites
• McArthur River, McClean Lake
• Nuclear Power Plants
• Pickering Generating System, Loire River
• Used Nuclear Fuel Reprocessing Plants
• La Hague, Marcoule, Sellafield
• Management and Disposal Sites
• Hanford, Bear Creek, Chalk River
• The Chernobyl Accident
• Sites involving NORM
• Komi, Oil and Gas Off-Shore Platforms
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Uranium Mining Sites
• McArthur River (EcoMetrix, 2005)• Methodology: IAEA/NCRP• Reference dose rates: 10 mGy/d aquatic organisms; 1
mGy/d terrestrial; wR alpha - 10 (40 for comparative purposes)
• Sensitive Ecological Receptor: duck• Duck (scaup) predicted to exceed benchmark in the area
near the discharge (ingestion of Po-210). Benthic invertebrate >10 mGy/d if wR alpha = 40; below if 10. Levels decrease quickly. No potentially significant effects in receiving environment
• McClean Lake (Cogema, 2004) • Methodology: IAEA/NCRP• Reference dose rates: 10 mGy/d aquatic organisms; 1
mGy/d terrestrial • Sensitive Ecological Receptor: Duck and muskrat• Reference dose rates exceeded only at upper bound within
immediate discharge area. No potentially significant effects in receiving environment
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Nuclear Power Plants
• Pickering Generating System (SENES, 2000; Wismer et al 2004)• Methodology: IAEA/NCRP• Reference dose rates: 10 mGy/d all aquatic biota and
terrestrial plants; 0.137 mGy/day for trumpeter swan, 1 mGy/d for other terrestrial biota; wR3 for tritium
• Sensitive Ecological Receptor: Earthworm, trumpeter swan• Conservative assessment showed potential effects on
earthworm and swan (tritium) Further investigations indicate that there are no significant ecological impacts from PNGS
• Loire (Beresford and Howard, 2005) • Methodology: FASSET
• Reference dose rates: 2.4 mGy/d, wR3 for tritium • Sensitive Ecological Receptor: Small terrestrial animals with
aquatic diet • Dose rates five orders of magnitude lower than those at
which effects have been reported. No potential effects on populations of non-human biota.
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Reprocessing Plants
• La Hague (SENES, 2000)
• Methodology: IAEA/NCRP
• Reference dose rates: 10 mSv/d aquatic; wR sensitivity analysis
• Sensitive Ecological Receptor: Crustaceans and molluscs
• Marine biota dose rates 2-3 orders of magnitude below lowest benchmark. No potential effects expected on marine biota
• Sellafield (Beresford and Howard, 2005)
• Methodology: FASSET
• Reference dose rates: 2.4 mGy/d, ( perhaps 0.1 - 10 mGy/d) wR3 for tritium; 10 alpha
• Sensitive Ecological Receptor: Snails and small mammals
• When compared to FRED database, doses received by all organism groups were below the levels at which significant effects would be seen (1 mGy/h). No effects in snails and small mammals. No potential health effects on non-human biota are expected in the vicinity of the Sellafield site.
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Reprocessing Plants
• Marcoule (St Pierre et al, 1999)
• Methodology: IAEA/NCRP
• Reference dose rates: 10 mSv/d aquatic; 2.4 mGy/d endemic population
• Sensitive Ecological Receptor: Molluscs and fish eating birds
• Maximum predicted dose rates more than a factor of 40 below reference dose rates. No potential effects expected.
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Waste Disposal Sites
• Hanford (Antonio, Domotor, Higley and Tiller, 2003)
• Methodology: DOE Graded Approach
• Reference dose rates: 10 mGy/d aquatic; and 1 mGy/d terrestrial wR alpha 20
• Sensitive Ecological Receptor: Riparian mammal
• No effects expected in Columbia River.
• Beer Creek (Jones and Scofield, 2003)
• Methodology: DOE Graded Approach
• Reference dose rates: 1 mGy/d terrestrial; wR alpha 20
• Sensitive Ecological Receptor: Mouse
• No effects expected.
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Waste Disposal Sites
• Chalk river (EcoMetrix, 2005)
• Methodology: IAEA/NCRP
• Reference dose rates: 1 mGy/d all non-human biota
• Sensitive Ecological Receptor: Riparian animals, water shrews and herons
• Initial calculations indicated potential for effects on some biota in inland aquatic sites (water shrews and blue herons > 1 mGy/d) and within confines of small waste management facilities (Woodchuck 50 mGy/d). Doses unlikely to lead to significant effects at the population level
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NORM
• Komi (Beresford and Howard, 2005)
• Methodology: FASSET
• Reference dose rates: 2.4 - 24 mGy/d
• Sensitive Ecological Receptor: Rodents, soil invertebrates, grasses
• Effects on biota observed at small contaminated sites. Plants and animals in other areas containing naturally elevetaed levels of radionuclides have adapted.
• Oil and Gas Off-Shore Platforms (Beresford and Howard, 2005)
• Methodology: FASSET
• Reference dose rates: 2.4 - 24 mGy/d
• Sensitive Ecological Receptor: Crustaceans and molluscs
• No effects expected.
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Conclusions (SENES)
• “The potential for effects on non-human biota due to exposures arising from the controlled releases of radionuclides from nuclear fuel cycles is low and well below reference dose rates
• Similarly, the potential for effects on non-human biota arising from exposure arising from the controlled releases of radionuclides from NORM sites is low and well below reference dose rates
• For radioactive waste management and disposal sites, although higher doses can be sometimes found in the immediate proximity of radioactive wastes within the site boundaries, further away from the source of radioactivity or beyond the site boundaries, dose rates are below the reference dose rates, and
• Populations of biota exposed to very high levels of radiation, arising from major accidents such as the Chernobyl accident, seem likely to recover within a reasonably short period once the source of exposure is significantly reduced or removed”
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Conclusions
• “The representative ERAs considered in this review show that the application of the current system of radiological protection, which includes a variety of standards protective practices for containing radioactive sources, controlling and limiting radioactive releases to the environment, and protecting people, have in fact also provided an adequate level of protection to populations of non-human biota.” SENES p 4-2
• “This overview provides reassurance against the concern expressed in this decade by part of the international expert community, which suggested that the environment may not have been adequately protected from exposure to ionising radiation and that the system of radiological protection was incomplete.” WNA Press Release
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Three-banded Scheme
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Overlapping Issues
• Thresholds, benchmarks, targets, …
• Model compatibility - derivation of “dose rate to unit concentrations for reference ecosystems”
• Robustness of the ICRP statement
• Broad principles and aim of protection
• Applicability of reference organisms.
• More data and applications (assessment, optimisation, justification, …)