Application of ecological risk assessment to establish non-human environmental protection at nuclear generating stations in Ontario, Canada

Abstract

A screening ecological risk assessment was performed for regulatory compliance at three Ontario nuclear generating station sites to establish design requirements for a routine contaminant monitoring program and to address the need for non-contaminant stressor management Site specific assessments went beyond traditional contaminant risk assessment to include stressors associated with land-use change, cooling water systems and site storm water runoff Valued terrestrial and aquatic ecosystem components were selected from species lists after stakeholder consultation, and contaminants of concern were selected based on their relative loadings, and with respect to regulatory and literature-based benchmarks Predictive modeling was used to estimate chemical and radionuclide exposures and likelihood of effects Adverse effects on individual biota were predicted for aqueous emissions of chlorine and storm water but not for radionuclides Retrospective analyses of past field monitoring were used to determine likelihood of effects from non-contaminant stressors Individual-level adverse effects were observed for fish losses from cooling water withdrawal Depending on the site and the biological species, either beneficial or adverse effects from thermal discharge and land-use change were observed Followup studies include monitoring, laboratory study, computer modeling and mitigation Field monitoring will generate more precise species-level estimates of intake fish losses, magnitude of fish response to thermal discharge and chlorine concentrations in near-field discharge waters Laboratory study is determining the effectiveness of intake fish loss mitigation technology Computer fish population models are being used to design field studies and interpret individual level effects Mitigation includes storm water controls and habitat biodiversity management projects to offset past losses from site development and construction Routine contaminant monitoring is planned to collect necessary information to verify site specific risk assessment model predictions and confirm model parameters and assumptions The updated contaminant risk assessment models will be used to adjust site monitoring programs (author)