Radiation and Environmental Protection at the CNSC

Transcription

1 Radiation and Environmental Protection at the CNSC Patsy Thompson, Director General Rachel Lane, Radiation and Health Sciences Specialist Directorate of Environmental and Radiation Protection and Assessment, Canadian Nuclear Safety Commission Toronto Public Health Toronto, Ontario January 24, 2014 nuclearsafety.gc.ca

2 Content Overview of CNSC and DERPA Radiation protection overview CNSC Tritium Studies Project Tritium in Lake Ontario Tritium releases to Lake Ontario Tritium concentration trends in drinking water supply plants Recent health studies 2

3 The Canadian Nuclear Safety Commission Regulates the use of nuclear energy and materials to protect the health, safety and security of Canadians and the environment, and to implement Canada s international commitments on the peaceful use of nuclear energy 3

4 CNSC Regulates All Nuclear-Related Facilities and Activities Uranium fabricators and processing Nuclear power plants Radioactive waste management facilities Nuclear substance processing Industrial and medical applications Nuclear research and educational Export/import control Mines and mills Uranium fuel 4

5 Independent Commission Quasi-judicial administrative tribunal Reports to Parliament through Minister of Natural Resources Canada Commission proceedings are public and webcast Decision can only be reviewed by Federal Court 5

6 Organizational Chart of CNSC President Commission Members Executive Advisor Commission Secretariat Office of Audit, Evaluation & Ethics Legal Services Regulatory Operations Branch Technical Support Branch Regulatory Affairs Branch Corporate Services Branch 6

7 CNSC Structure The CNSC is a federal regulatory agency as well as an Independent Administrative Tribunal set up at arm s length from government with no ties to the nuclear industry The Commission consists of up to 7 permanent members appointed by the Governor in Council Heading the Commission is the President, who is designated by the Governor in Council as a permanent, full-time member The Commission, in the discharge of its work, is supported by over 800 scientific, technical and professional staff 7

8 Directorate of Environmental and Radiation Protection and Assessment (DERPA) Director General Administrative Assistant Planning Officer Lead Technical Advisor Environmental Risk Assessment Division Environmental Compliance & Laboratory Services Division Radiation and Health Sciences Division Environmental Assessment Division Radiation Protection Division 8

9 DERPA Mandate DERPA is the CNSC s centre of excellence for environmental assessment, geosciences, radiation protection, environmental protection and laboratory services DERPA s mission is to support the CNSC in its areas of professional and technical competence by: providing strategic direction and leadership contributing to the continuous improvement of CNSC s regulatory framework conducting and supporting licensing and compliance activities conducting public outreach activities and providing opportunity for stakeholder engagement supporting CNSC s international obligations and commitments 9

10 International Radiation Protection Framework The International Atomic Energy Agency (IAEA) works towards the safe, secure and peaceful uses of nuclear science and technology The International Commission on Radiological Protection (ICRP) is an advisory body providing recommendations and guidance on radiation protection The United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) assesses and reports on the levels and effects of exposure to ionizing radiation The CNSC reviews, participates in the development of, and follows international recommendations 10

11 Dose-response Models Many models have been proposed to explain how risk varies with radiation dose The CNSC applies the linearnon-threshold (LNT) model in its approach to radiation protection, as a prudent way to protect Canadians from radiation, keeping pace with its international peers 11

12 Dose-response and Radiation Risk The LNT is based on information from the strongest epidemiological studies of exposed populations (primarily the atomic bomb survivors) Accurate information on the health risks for atomic bomb survivors is only available at doses greater than ~100 msv radiation biology studies are used to extrapolate risk down to a dose of 0 msv International studies on large cohorts of nuclear energy workers and medically exposed populations generally support the radiation risk estimates from the atomic bomb survivor studies 12

13 CNSC Radiation Protection Framework LNT model used for radiation protection purposes to help set dose limits based on predicted risks for a given dose should not be used to predict cancer risk for few individuals or for low dose exposures Dose Limits (Radiation Protection Regulations) Members of the public Nuclear energy workers 1 msv per year 50 msv per year and 100 msv per five year dosimetry period Doses are typically well below regulatory limits 13

14 Radiation Dose in Perspective Canadian Nuclear Safety Commission 14

15 Tritium Overview Tritium is a radioactive form of hydrogen that occurs naturally and is also a by-product of nuclear reactor and tritium processing facilities operations Tritium exposure can pose a health risk if it is ingested (drinking water, food), inhaled or absorbed through the skin in large quantities CNSC regulates releases of tritium to ensure the health and safety of workers and the public, and the protection of the environment Part of the CNSC s mandate is to provide objective scientific, technical and regulatory information to the public on nuclear-related health and safety 15

16 CNSC Tritium Studies January 2007 the Commission directed CNSC staff to: initiate research studies on tritium releases in Canada study and evaluate tritium processing facilities against international practices following this request, CNSC staff launched several research activities under the umbrella of the «Tritium Studies» project this study had the goal of enhancing the information available to guide regulatory oversight of tritium processing and tritium releases in Canada 16

17 CNSC Tritium Studies: Key Objectives Assemble data on tritium releases in Canada Investigate the fate of tritium releases to the atmosphere Review engineering controls for facilities that produce or handle tritium Assess the health risk to workers and the public from exposure to tritium 17

18 Results Adequate provision has been made through existing regulatory mechanisms for the protection of health and safety of Canadians related to tritium exposures Effective controls are now uniformly in place in the Canadian nuclear industry as a result of compliance enforcement actions Tritium management of routine operational releases is now following best practices internationally Releases are currently as low as reasonably achievable (ALARA) and close to the minimum practically achievable 18

19 Results (cont d) Conservative regulatory approaches combined with strict controls on releases are being used Gaps do exist in tritium environmental science, but they are not significant for people or the biosphere at current low levels of exposure this has clearly been shown by a thorough assessment of the health risks of tritium 19

20 Publications Seven CNSC public reports plus a Synthesis Report - Journal article: Thompson et al. (2011), Radioprotection, 46(4): Standards and Guidelines for Tritium in Drinking Water 2. Tritium Releases and Dose Consequences in Canada in Investigation of the Environmental Fate of Tritium in the Atmosphere 4. Evaluation of Facilities Handling Tritium 5. Health Effects, Dosimetry and Radiological Protection of Tritium 6. Tritium Activity in Garden Produce from Pembroke in 2007 and Dose to the Public * Tritium in Soils and Vegetation (to be published) 20

21 Background Levels of Tritium in Ontario Drinking Water Location Q1 Q2 Q3 Q4 Bq/L ± 2σ Bq/L ± 2σ Bq/L ± 2σ Bq/L ± 2σ Bancroft (Clarke Lake) <MDL <MDL <MDL No sample Belleville (Bay of Quinte) 3.79 <MDL <MDL No sample Cobourg (Lake Ontario) 4.80 <MDL <MDL No sample Brockville (WSP) <MDL <MDL <MDL <MDL Burlington (WSP) <MDL Goderich (WSP) <MDL <MDL <MDL Kingston (WSP) <MDL <MDL <MDL London (WSP) <MDL <MDL Niagara Falls (WSP) <MDL <MDL <MDL North Bay <MDL <MDL <MDL <MDL Orangeville <MDL <MDL <MDL <MDL Parry Sound <MDL <MDL Sarnia <MDL <MDL St. Catherines <MDL <MDL <MDL <MDL Sudbury <MDL <MDL <MDL <MDL Thunder Bay <MDL <MDL <MDL <MDL Windsor <MDL <MDL <MDL Minimum Detection Level

22 Annual Measured Tritium Concentrations from Drinking Water Supply Plants Surrounding the Darlington and Pickering NPPs Annual Tritium Concentrations in from Drinking Water Supply Plants (Bq/L) NPP Water Supply Plant O. DWQO Darlington Bowmanville WSP Darlington Newcastle WSP Darlington Oshawa WSP Pickering Ajax WSP Pickering Pickering Scarborough F. J. Horgan WSP (Scarborough) Toronto R.C. Harris WSP (Toronto) Pickering Whitby WSP Concentrations are significantly lower than Ontario DWQO Annual averages vary from roughly 4-6 Bq/L 22

23 Historical Tritium For Lake Ontario background from lake model is 1.6 Bq/L 23

24 Annual Tritium Releases to Lake Ontario Annual Tritium Oxide Released to Lake Ontario (Bq/year) NPP DRL Darlington NPP 3.90E E E E E E+18 Pickering NPP 4.50E E E E E E+17 Orders of magnitude lower than the derived release limits Decreasing trends have been observed since

25 Health Effects, Dosimetry and Radiological Protection of Tritium The study s objectives were to: Conduct an independent review of scientific literature to assess the health risks to workers and the public from exposures to tritium Assess Canadian and international dosimetry practices for tritium intakes Review the current approaches for limiting exposure to tritium 25

26 Health Effects, Dosimetry and Radiological Protection of Tritium Tritium beta radiation is about 1.4 times more effective in causing biological effects than x-rays and 2.2 times more effective than gamma rays The radiation weighting factor of 1 in the current ICRP radiation protection framework has not decreased the level of protection afforded to workers or members of the public tritium exposures very low and well below doses at which an increased risk of cancer has been observed 26

27 Health Effects, Dosimetry and Radiological Protection of Tritium Current dosimetry and biokinetic models for assessing dose are acceptable for radiation protection purposes Studies have shown that tritium exposures at current levels in Canada are highly unlikely to cause adverse health effects Canada s current regulatory framework has effectively controlled tritium exposures 27

28 Canadian Nuclear Energy Workers In 2005, a 15-country study of nuclear workers reported significantly increased radiation-related risks of all cancers excluding leukemia, with Canadian data a major factor behind the pooled results An earlier Canadian study, based on the same data, found very different results This apparent discrepancy in the results between the Canadian and the 15-country studies attracted considerable attention and questions A review of the Canadian data and a reanalysis of the revised cohort helped to explain the unexpected findings and provided revised risk estimates 28

29 Canadian Nuclear Energy Workers There was no evidence of radiation risk for 42, 228 workers employed by the NPPs and post-1964 AECL workers A significant dose-response for solid cancer was identified with 3,088 early ( ) AECL workers having a significant increase in risk There was no evidence of increased risk from tritium exposure All workers had mortality lower than the general population The significantly increased risks for early AECL workers are most likely due to the incomplete transfer of historical dose data to the National Dose Registry (NDR) Further investigation of this group of early AECL workers is necessary to ensure accuracy and completeness of radiation dose records in the NDR 29

30 RADICON Radiation and Incidence of Cancer Around Ontario Nuclear Power Plants from 1990 to 2008 study (the "RADICON" study) Determine the radiation doses to members of the public living within 25 km of the Pickering, Darlington and Bruce NPPs from 1985 to 2008 Compare cancer rates among these populations with the general Ontario population from 1990 to

31 RADICON Public radiation doses resulting from the operation of the NPPs are 100 to 1,000 times lower than natural background radiation No evidence of childhood leukemia clusters around the three Ontario NPPs All cancers for all age groups are well within the natural variation of the disease in Ontario Thus, radiation is not a plausible explanation for any excess cancers observed within 25 km of any Ontario NPP 31

32 Recent Third Party Research Leukemia in young children in the vicinity of British nuclear power plants: a case-control study (Bithell et al., 2013) A recent British case-control study found that young children who were born or live near a NPP from 1962 to 2007 do not have a greater risk of developing childhood leukemia or non-hodgkin lymphoma The results draw the same conclusions as those in the RADICON Study 32

33 Recent Third Party Research Estimating cancer risk in relation to tritium exposure from routine operation of a nuclear-generating station in Pickering, Ontario (Wanigaratne et al., 2013) A recent study by Cancer Care Ontario found that tritium was not associated with an increased risk of radiationsensitive cancers in Pickering, Ontario It is important because it isolates tritium-specific dose data It increases our understanding of cancer risks and lowlevel tritium exposure 33

34 nuclearsafety.gc.ca facebook.com/canadiannuclearsafetycommission youtube.ca/cnscccsn CCSN 2013