South African Perspective for Radon in Dwellings and the Anticipated Regulatory Control Measures

Transcription

1 South African Perspective for Radon in Dwellings and the Anticipated Regulatory Control Measures John Pule and Wilcot Speelman NNR Regulatory Information Conference October 2016

2 DISCLAIMER The information presented is not an official record of the NNR; The NNR makes no warranties, whatsoever, either express or implied, concerning the accuracy, completeness, reliability, or suitability of the information. Neither does it warrant that use of the information is free of any claims of copyright infringement; The use of particular designations of countries or territories does not imply any judgment by the NNR as to the legal status of such countries or territories, of their authorities and institutions or of the delimitation of their boundaries; The mention of names of specific companies or products (whether or not indicated as registered) does not imply any intention to infringe proprietary rights, nor should it be construed as an endorsement or recommendation on the part of the NNR. 2

3 Talk Outline Background Summary from Epidemiological Studies International Reference Levels Concern about Indoor Radon Radon Exposure Scenarios Current National Situation Reference Levels Justification of the Approach Anticipated Legislative Changes Existing Exposure Situations Preparatory Activities Expected Challenges Way Forward 3

4 Background Radon is a naturally occurring radioactive gas Half-life days with progeny generating capacity Radon migrates from the soil into ambient and indoor air Radon builds up inside houses when it cannot disperse Radon progeny are electrically charged and can attach themselves to tiny dust particles in indoor air, can be inhaled with dust particles Inhaled atoms decay emitting alpha radiation - can cause DNA damage 4

5 Radon Entry Mechanisms 5 5

6 Summary from Studies Epidemiological studies confirm that radon increases the risk of lung cancer in the general population The proportion of all lung cancers linked to radon is estimated to lie between 3% and 14%, depending on the average radon concentration in the country and on the method of calculation (WHO) Radon is the second most important cause of lung cancer after smoking in many countries 6

7 Summary from Studies (cont d) There is no known threshold concentration below which radon exposure presents no risk Even low concentrations of radon can result in a small increase in the risk of lung cancer The majority of radon-induced lung cancers are caused by low and moderate radon concentrations rather than by high radon concentrations 7

8 Summary from Studies (cont d) Numerous countries do regulate radon either on a mandatory or advisory basis There is international shift towards stringent approach to indoor radon regulation From the above conclusions, clearly regulatory controls are necessary, however there are challenges to overcome Planned Exposure Situations are already authorised by the National Nuclear Regulator 8

9 Countries Regulating Radon Country Reference level (Existing dwelling) in Bq.m -3 Reference level (New dwelling) in Bq.m -3 Austria Belarus Czech Republic Denmark Finland Germany Greece Poland Russia Slovenia D. Sweden - 20 Switzerland A. USA Bq.m -3 including background B. UK Bq.m -3 Reference: Åkerblom G 9

10 Indoor Concern of Radon in RSA More than 100 years of gold mining in South Africa Radioactivity contamination of land during early years of mining due to lack of regulatory control Continuous deposition of radioactive dust from Tailings Storage Facilities (TSFs) Tailings material run-off onto land occupied by the public 10

11 Concern about Indoor Radon Mine waste readily accessible to the public and its possible use for construction (i.e. waste rock, tailings) Uranium prospecting and mining in the Karoo Certain geological formation can give rise to excess risk due to radon exposure (natural phenomena) e.g. Paarl in Western Cape Parts in Mpumalanga Resulting in possible exposure scenarios 11

12 Dwellings Proximity to TSFs 12

13 TSFs in Johannesburg Ref: Google Earth Images 13

14 Uranium Ore used in Construction 14

15 Typical Radon Exposure Situation Scenario 1: House built using radioactive uranium ore Beaufort West farm (Karoo) house foundation built from abandoned uranium ore stockpiles Average concentration : 476 Bq.m -3 ~ msv/a Maximum value: 536 Bq.m -3 ~ 13.5 msv/a Occupancy and habits dependent 15

16 Typical Radon Exposure Situation Scenario 2: Houses built on radon prone area Tshepisong Township in Soweto Average concentration : Bq.m -3, ~ 5.32 msv/a Highest value: Bq.m -3, ~ 43.5 msv/a Occupancy 16

17 Current National Situation Indoor radon exposure situations exist in South Africa, and may be very extensive (to be confirmed by studies) Not unique to South Africa (cases around the world) Current regulatory framework does not provide for regulatory control of radon in dwellings Hence the NNR must advise government accordingly on measures to be taken to assure protection of persons 17

18 Current National Situation (cont d) It is appropriate for South Africa to include in its regulatory framework existing exposures, including indoor radon Definition: existing exposure situation means a situation of exposure that already exists when a decision on the need for control needs to be taken. Existing exposure situations include exposure to natural background radiation that is amenable to control; exposure due to residual radioactive material that arose from past practices that were never subject to regulatory control Question: What reference levels of radon concentrations will be introduced? 18

19 Reference Levels (i) Reference Level (RL) as Radon Concentration 200 Bq.m -3 Lower bound reference level Comments and Possible Actions Radon concentration should be kept below 200 Bq.m -3 Existing houses should implement moderate and inexpensive mitigation measures to reduce radon to below 200 Bq.m -3 with measures such as o Increase of ventilation in the house (more windows, keep windows open, install airbricks, install simple extraction fans, etc.) All new houses including those in radon prone areas should comply with radon levels below 200 Bq.m -3 o Ensure that building materials do not contain elevated radium content leading to elevated radon concentration 19

20 Reference Levels (ii) Reference Level (RL) as Radon Concentration 300 Bq.m -3 Upper bound reference level Comments and Possible Actions Reduce radon concentrations to below 300 Bq.m -3 and ensure optimisation Educate the public Install active radon reduction equipment Building pressurization Increase ventilation rate Increase natural ventilation (i.e. fit more windows, open windows, install airbricks, etc.). Ensure that building materials for all new dwellings is not contaminated with radium Prohibition of using mining waste for construction 20

21 Justification of the Approach Provide optimisation targets for various exposure situations (lower and higher radon concentrations) Alignment to international recommendations Advisory approach, hence compliance with the RL should be achievable without excessive cost There is no defined safe level (threshold) for radon, so keep it as low as reasonably achievable (optimise) 21

22 Anticipated Legislative Changes Currently the NNR Act and Regulations are being revised to include existing exposures as well Indoor radon is included in the draft regulations In future The NNR will advise government to include mandatory radon measurements in housing regulations and building codes Control must be at level of housing regulation 22

23 Anticipated Legislative Changes It will be proposed for indoor radon to be controlled at local government level Amendment of local government legislation will be necessary to accommodate the change. Local government should require that radon measurements are performed and should strictly control the developments in areas classified as radon prone and prevent the usage of contaminated building materials for construction Introduction of Rn (222 and 220) to Exclusion Levels applicability 23

24 Existing Exposure Situations Reference Levels applicable to the representative person in the range of 1 20 msv (feasibility in controlling the situation) Public Exposure Due to Indoor Radon (Draft Regulations) not exceed an average of 300 Bq.m -3 Persons or organisations responsible for the planning, implementation and verification of radon protection measures shall ensure that: Priority to reduce radon activity concentrations of 222 Rn shall be assigned Reduction to level at which is optimised 24

25 Preparatory activities The general extent of indoor radon problem across the country must be investigated to identify radon prone areas. Investigations of certain areas will be prioritised. Implementation of controls will only be in areas identified as radon prone areas Solicit funding for implementation of appropriate corrective measures. i.e. government, other relevant parties, etc. 25

26 Preparatory activities Public education and communication programme must be launched on the risk associated with radon exposures in dwellings: To educate local government and its relevant employees To get public support and buy-in (stakeholder engagement) Improve on chances of success of the project 26

27 Expected Challenges The National Nuclear Regulator does not have capacity to oversee the implementation of controls for each affected household due to limited footprint: Large numbers expected, may be widespread across the country Households may not have sufficient funds to implement the necessary corrective actions: Most houses likely to be affected are low cost housing due to their proximity to mining areas. Owners unable to cover the costs Government funding may be limited or deferred 27

28 Way Forward a) Propose a national study to identify radon prone areas b) Update legislation and regulations to include radon in dwellings c) Engage local government departments on incorporation of radon in dwellings in their building codes and its regulatory control d) Educate the public on risks due to radon exposure 28

29 The End Thank You Wilcot Speelman - Senior Specialist: Environment & Radiation Protection National Nuclear Regulator South Africa Eco Glades 2 Block G, 420 Witch Hazel Avenue, Highveld, Centurion PO Box 7106 Centurion, 0046 c: +27 (0) t: +27 (0) f:+27 (0) e: wjspeelman@nnr.co.za I w: