Radiological and Emergency Management Aspects of Non-Nuclear Waste Disposal Installations

Transcription

1 Radiological and Emergency Management Aspects of Non-Nuclear Waste Disposal Installations Ciara McMahon NEA Workshop, 2 May 2017

2 You are responsible for this waste disposal site

3 Individuals and populations in the future should be afforded at least the same level of protection as the current generation ICRP, 1998

4 You are responsible for this waste disposal site

5 Disposal Options Specific Landfill Near Surface Geological Disposal Borehole Disposal Emplacement in cavern/vault /silo Burial

6 Justification Optimisation Dose Limits Radiological Protection

7 Justification Waste disposal should be part of overall justification of practice/activity If not included, BAT and optimisation are first step Justification should be periodically reviewed over lifetime of activity

8 Optimisation: ALARA Doses to workers and public Land Use Economic Radiological Number of People Exposed Technical Viability Prob. of exposure Safety & Security Societal (costs/benefits) Doses to biota Other Env Impacts

9 Iterative, systematic, transparent process Optimisation of protection Best under prevailing circumstances (socioeconomic) Optimised for all time frames (incl. postoperational) Assess doses/risks for likely and less-likely events (design-basis) Very unlikely and extreme disruptive events (beyond design-basis) taken into account Reduce possibility of inadvertent human intrusion Best available techniques (BAT)

10 Operational Phase ost-operational Dose limits Workers: 20 msv/y; Public: 1 msv/y (general dose limits) Oversight: Direct to Indirect Dose/Health Detriment Workers: 20 msv/y Public: Dose constraint: 0.3 msv/y Risk constraints for workers and public Oversight: Indirect to None Potential exposures: risk constraint (Public: 1x10-5 /yr) Future doses? Knowledge of future dose/detriment Future habits?

11 Source: UK Strategy for the management of solid low level radioactive waste from the non-nuclear industry Disposal of solid LLW and VLLW, and potential exposure scenarios Discharges to air Direct exposure and inhalation air Contamination in air deposited on land Dust from day to day operations Exposure from direct irradiation from surface of land Ingestion of crops/animals Ash and air pollution control residues (VLLW) To landfill Combustible LLW/VLLW to incinerators Exposure due to reuse/recycling of incinerator residues Ingestion of drinking water Reuse/recycling Non combustible LLW/VLLW to landfill

12 Role for collective dose? Exposure of population as a whole Who is the exposed population? How far in time? Use for comparing options for waste management Part of optimisation process

13 Over-sight post-closure At what point can oversight be lifted (or lightened)? Trivial dose of µsv/y? 300 µsv/y for exemption of NORM? Inadvertent human intrusion <1 msv/y? Monitoring and surveillance post-closure demonstrated system working as designed? For how long? Early failure of barriers possible or important (radiologically)? Post-closure: environmental doses (biota) may prevail need for continued oversight? If there was an accident what would consequences be?

14 Human Intrusion example scenario Doses to people? Contamination of land? Loss of barrier Dust Groundwater Land reuse Drill scales

15 Human Intrusion Scenarios (doses to people around site) >20 msv/y Consider alternate waste disposal options 1-20 msv/y <1 msv/y Reduce probability of intrusion/limit consequences Consider if further efforts to reduce probability of intrusion/limit consequences warranted

16 Emergency!

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19 Emergency preparedness Fire Any event requiring evacuation (operational) Other Hazardous materials event Explosions (gas etc) Severe weather Landslide Flooding High winds Aircraft crash Dam inundation Meteorite strike Sudden coastal erosion Roof collapse (e.g., snow) Protests Intruders Terrorism

20 Planning for emergencies Operational phase: As for other nuclear/ radiological facilities Operator plans with regulatory oversight and coordination/ support of local emergency response Protection of workers, public, food/water Arrangements for mobilisation and coordination: Protective actions Assessment Monitoring Information Termination of emergency and recovery efforts

21 Planning for emergencies Post-Operational phase: Detection of emergency? Responders? Awareness of radiological risks? Who does the planning? Can oversight be lifted if an emergency could cause dose >1mSv? What likelihood? Perceived harm?

22 Final thought: What does a dose limit signify to you? Engineer Guideline for design and build Regulator/Public Authority Basis for decision-making about licensing, regulation Public Indicator of threat Media Indicator of news value (where exceeded) Source: ENTRIA Project, Kalmback and Rohlig (2016) JRP 36