1、N288.6-12Environmental risk assessments at Class I nuclear facilities and uranium mines and millsLegal Notice for StandardsCanadian Standards Association (operating as “CSA Group”) develops standards through a consensus standards development process approved by the Standards Council of Canada. This
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17、suant to an applicable statute.This Standard was prepared by the Subcommittee on Environmental Risk Assessments at Class I Nuclear Facilities and Uranium Mines and Mills, under the jurisdiction of the Technical Committee on Environmental Management for Nuclear Facilities and the Nuclear Strategic St
18、eering Committee, and has been formally approved by the Technical Committee.Notes: (1) Use of the singular does not exclude the plural (and vice versa) when the sense allows.(2) Although the intended primary application of this Standard is stated in its Scope, it is important to note that it remains
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24、 in the subject line:(a) Standard designation (number);(b) relevant clause, table, and/or figure number;(c) wording of the proposed change; and(d) rationale for the change. 2012 CSA GroupEnvironmental risk assessments at Class Inuclear facilities and uranium mines and millsJune 2012 1N288.6-12Enviro
25、nmental risk assessments at Class I nuclear facilities and uranium mines and mills0Introduction0.1 Environmental risk assessment0.1.1 General0.1.1.1Environmental risk assessment (ERA) of nuclear facilities is a systematic process used to identify, quantify, and characterize the risk posed by contami
26、nants and physical stressors in the environment on biological receptors, including the magnitude and extent of the potential effects associated with a facility. Receptors should include humans as well as non-human biota (see Clause 0.5.3). Human receptors are addressed through a human health risk as
27、sessment (HHRA) and non-human biota are addressed through an ecological risk assessment (EcoRA).0.1.1.2An ERA should(a)identify and prioritize the contaminants and physical stressors of concern;(b) identify and prioritize the sources or points of release of the contaminants and physical stressors of
28、 concern;(c) identify and prioritize the potential receptors (human and non-human biota) of concern;(d) include a conceptual model of the environment representing the relationship between sources and receptors;(e) provide an assessment of the exposure to the contaminants and physical stressors of co
29、ncern (to be used with the benchmark value BV to assess the risk);(f) identify the BVs used to assess the potential effects of the contaminants and physical stressors of concern on the receptors;(g) provide an assessment of the environmental risk to receptors posed by the facility; and(h) identify a
30、nd, if possible, quantify the uncertainties in the assessment of the environmental risk.0.1.1.3The ERA approach takes into consideration the fact that many contaminants can be present simultaneously in several media such as food, air, water, soil, dust, or consumer products and that they can reach t
31、he receptors through multiple exposure pathways. An ERA can have both predictive and retrospective elements (as defined in Clause 3.1).0.1.2 Need for an ERAThe need to conduct an ERA arises from one or more of the following factors:(a) a desire for risk-based environmental management;(b) a desire to
32、 address stakeholder concerns about environmental protection; and(c) regulatory requirements for characterization of environmental risks.N288.6-12 2012 CSA Group2 June 20120.1.3 Human health risk assessment0.1.3.1Human health risk assessment (HHRA) focuses on the identification, quantification, and
33、characterization of the risks to individual human receptors resulting from exposure to contaminants and physical stressors released into the environment throughout the lifecycle of a nuclear facility. An HHRA can be completed as a component of an ERA or as a stand-alone assessment.0.1.3.2The objecti
34、ves of an HHRA are to evaluate the risks to relevant human receptors resulting from exposure to contaminants and stressors related to a site and its activities. Based on the results of the HHRA, further assessment and possible further action might be deemed necessary.0.1.4 Ecological risk assessment
35、0.1.4.1Ecological risk assessment (EcoRA) focuses on the identification, quantification, and characterization of the risks to ecological receptors resulting from exposure to contaminants and stressors released into the environment throughout the lifecycle of a nuclear facility. Ecological receptors
36、can include non-human biota at the individual, population, or community level (see Clause 7.2.3). An EcoRA can be completed as a component of an ERA or as a stand-alone assessment.0.1.4.2The objectives of an EcoRA are to evaluate the risks to relevant ecological receptors resulting from exposure to
37、contaminants and stressors related to a site and its activities. Based on the results of the EcoRA, further assessment and possible further action might be deemed necessary.0.1.5 Risk-based recommendationsThe end product of an ERA is a determination of the risk to human and non-human biota. This end
38、 product is the basis for risk-informed recommendations (e.g., risk control actions or remediation). The end product can also inform recommendations about monitoring to reduce uncertainty in the risk estimation. However, this Standard does not provide guidance on monitoring programs or risk manageme
39、nt decisions.0.2 Relationship to monitoring programs0.2.1 GeneralERAs provide the basis for the scope and complexity of monitoring programs, including effluent and environmental monitoring programs. Effluent monitoring programs and environmental monitoring programs are covered by CSA N288.5 and CSA
40、N288.4, respectively.0.2.2 Effluent monitoring programsAn ERA can provide input into an effluent monitoring program by identifying and prioritizing the specific radioactive and non-radioactive contaminants and physical stressors and the sources or release points from the nuclear facility or licensed
41、 activity. An ERA can contribute to the development of effluent objectives that can be the focus of monitoring programs. The effluent monitoring program can inform the ERA by providing the effluent characteristics used in estimating environmental exposure concentrations of contaminants.Note: Non-rad
42、ioactive contaminants include for example toxic, corrosive, or environmentally deleterious substances. 2012 CSA GroupEnvironmental risk assessments at Class Inuclear facilities and uranium mines and millsJune 2012 30.2.3 Environmental monitoring programsThe decision criteria for the scope and comple
43、xity of an environmental monitoring program (EMP) necessitate an understanding of the environmental risk posed by the facility (see CSA N288.4). The results of the ERA can be used to identify monitoring requirements for normal operating conditions (as defined in Clause 3.1). The EMP can inform the E
44、RA by providing the data on contaminant and receptor distribution for use in calibrating and validating the ERA models.0.3 Relationship to environmental assessmentThe ERA can be part of an environmental assessment (EA) report or any other document that contains the required information. An ERA is us
45、ually triggered during the EA process.Note: All references to ERAs in this Standard are intended to refer to any document that contains the required information.0.4 Levels of complexityThe nature and complexity of ERAs will vary according to the nature and complexity of the subject (site, scenario,
46、magnitude, facility, etc.). An ERA should follow a tiered approach starting from a broad evaluation using protective generic parameters and a high degree of conservatism and advancing towards more precise analysis involving site-specific, realistic parameters and less conservatism. Such a tiered app
47、roach facilitates early identification of potential issues. Lower-tier assessments are the least detailed. More detailed or higher-tier assessments may be conducted to determine whether an issue originates from overly conservative assumptions or parameters or is indicative of potential effects.0.5 B
48、asic concepts0.5.1 Radiation dose limits0.5.1.1 Dose limits for humansDose limits are radiation dose criteria set by regulatory agencies. In Canada, dose limits for members of the public and nuclear energy workers (NEWs) are set by the Canadian Nuclear Safety Commission (CNSC). Dose limits set by th
49、e CNSC are regulatory requirements and cannot be exceeded. For detailed information on radiation dose limits used in HHRAs, see Clause 6.4.5.0.5.1.2 Dose limits for non-human biotaCurrently, dose limits for non-human biota have not been set by the CNSC or other regulatory agencies in Canada. Various organizations such as the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR)
