Mineral Sands Mining in Victoria

Transcription

1 Mineral Sands Mining in Victoria Iluka Douglas Mine Radon Monitoring and Community Engagement Morrie Facci Radiation Team Victorian Department of Health and Human Services

2 Presentation Outline Iluka Resources - Murray Basin operations including Douglas Mine Radon monitoring at the Douglas Mine site Community engagement by DHHS Dose Assessment for the Douglas Mine site

3 Iluka s Murray Basin Operations Image courtesy of Iluka Resources Limited

4 Iluka s Douglas Mine During Operation Pit 23 Images courtesy of Iluka Resources Limited

5 Iluka Mineral Sands Processing (pre 2009) DOUGLAS MINE MINERAL SEPARATION PLANT (MSP) Heavy mineral concentrate (HMC) Zircon TiO 2 HAMILTON 140:1 MIX QUARTZ SAND, CLAY, ETC. WASTE BY-PRODUCT (INCLUDING MONAZITE)

6 Iluka s Douglas Mine Mineral sands mining, primary concentration, and disposal of mineral separation plant (MSP) waste by-product were undertaken at the Douglas Mine since 2005 in accordance with: a mining regulator approved Mine Work Plan a DHHS approved Radiation Management Plan (RMP) The Department of Economic Development, Jobs, Transport and Resources (DEDJTR)

7 Iluka s Douglas Mine Mining and primary concentration at Douglas concluded in early 2012 but MSP waste by-product disposal is on-going (Pit 23) The HMC is currently sourced from mines other than Douglas (inside and outside of Victoria) Concern was expressed about the mining activities by a few members of the local community

8 Douglas Mine Site - Pit 23 Images courtesy of Iluka Resources Limited

9 Mineral Separation Plant at Hamilton Image courtesy of Iluka Resources Limited

10 Radon Measurement 2004 to 2007 Iluka s RMP specifies a radiation monitoring program that includes measurement of radon concentration in air (Bq/m 3 ) Iluka Resources consistently measured <12 Bq/m 3 (MDL) at four locations around the site during 2004 to 2007 using Landauer track-etch monitors (3 and 6 month periods) Radon monitoring ceased with DHHS approval in 2007 Image courtesy of Iluka Resources Limited

11 Radon Measurement 2014 to 2015 Iluka Resources consistently measured 12 Bq/m 3 or slightly above in Pit 23 using Landauer track-etch monitors during Oct 14 Jun 15 (3 month monitoring periods) A local landcare group measured levels of 28, 45, 47 and 62 Bq/m 3 at four sites adjacent to mine site using ARPANSA track-etch monitors (Jan - May 2015) Average concentration of radon in Australian homes is about 10 Bq/m³ (about 90 Sv per year assuming 1760 hours exposure per year) ARPANSA recommends an action level of 200 Bq/m³ for households

12 Radon Measurement - DHHS DHHS initiated a 12 month radon motoring programme to investigate this inconsistency: Track-etch monitoring using both Landauer and ARPANSA monitors Real-time monitoring using a Durridge RAD7 monitor

13 Radon Measurement Locations PIT 23 7

14 DHHS Track-etch Radon Monitoring ARPANSA monitors: Radon diffuses through gap between screw-on lid and base of container Detection element CR-39 (allyl diglycol carbonate) Etched with NaOH Manual reading of tracks

15 DHHS Track-etch Radon Monitoring Landauer monitors: Detector sealed in film-foil bag before use and covered with a metallic adhesive label after use Detection element CR-39 Etched with NaOH Detector analysis performed using image scanner at Landuer s C-NRPP accredited laboratory Canadian National Radon Proficiency Program is a certification program designed to establish guidelines for training professionals in radon services Image courtesy of Landauer

16 DHHS Track-etch Radon Monitoring Track-etch monitors placed inside weather-proof canisters and attached to star pickets at a height of about 1.5 metres No significant difference between measurements with track-etch monitors inside vs. outside weather-proof canisters

17 DHHS Track-etch Radon Monitoring ARPANSA track-etch monitors: 3 month: 20 to 59 Bq/m 3 ± 20% in 8 locations around the mine site 6 month: Bq/m 3 ± 20% in 8 locations around the mine site (49 Bq/m 3 ± 20% at one location immediately adjacent to mine site) Landauer track-etch monitors (3 months): 12 Bq/m 3 (9 locations at mine site) 15 ± 4 Bq/m 3 and 14 ± 4 Bq/m 3 at 2 locations at mine site

18 Radon Track Etch Results Same Location 3 MONTH MONITORING PERIOD

19 Real-time Monitoring RAD7 draws air in through desiccant for about 5 minutes Radon progeny attracted to a solid-state detector (alpha spectrometer) by E-field RAD7 detects alphas from radon progeny in manufacturer-defined energy windows for remainder of monitoring period Output Bq/m 3

20 Real-time Monitoring AIR DRAWN IN ALPHAS DETECTED CYCLE CYCLE CYCLE RUN RAD7 readout: Results (Bq/m 3 ) for each cycle Average of cycles as run average

21 Real-time Monitoring Run Averages VARIOUS LOCATIONS (DIFFERENT IN EACH TABLE) AROUND MINE SITE October 2015 Rn Concentration (Bq/m 3 ) January 2016 Rn Concentration (Bq/m 3 ) May 2016 Rn Concentration (Bq/m 3 ) Measurements over hours; one 2 day run ( ) Weighted mean of all results ± 0.4 Bq/m 3

22 Real-time Monitoring 23.4 Bq/m 3 maximum reading of real-time monitor Exposure hrs/year (UNSCEAR hrs/year) Breathing rate m 3 /hour Equilibrium factor for outdoor exposure Effective Dose = 0.69 msv The radon concentrations measured may well be just natural background levels

23 Radon Monitoring - Comparisons ARPANSA LANDAUER RAD Bq/m 3 ± 20% Generally 12 Bq/m ± 0.4 Bq/m 3

24 Radon Monitoring - Conclusions Measuring radon concentrations at low levels can be challenging DHHS radon monitoring results: Support those obtained by Iluka Demonstrate no discernible change from pre-mining concentrations Radiation doses to members of the public from radon will be well below 1 msv

25 Community Engagement Community updates on radon monitoring programme published on DHHS web site Radon monitoring results presented at quarterly Environmental Review Committee meetings for the Douglas Mine Approval process for continuation of current MSP waste by-products disposal also occurring in the background. As part of the approval process DHHS attended a number of government sponsored information sessions

26 Radiation Dose from All Exposure Pathways External Radiation ~0 msv/y Contamination of Groundwater ~0 msv/y Radon 0.02 msv/y Surface Water ~0 msv/y Radioactive Dust msv/y Foodstuffs msv/y Heavy minerals are highly insoluble

27 Radiation Dose from All Exposure Pathways DHHS has concluded that: The radiation dose to the critical group from all exposure pathways during by-product disposal in Pit 23 will be about 0.08 msv, well below the annual radiation dose limit for members of the public of 1 msv The radiation dose to the critical group from all exposure pathways after rehabilitation is effectively zero

28 Radiation Dose from All Exposure Pathways DHHS conclusion based on: 1. DHHS modelling (using internationally accepted methods) of total effective dose from the various exposure pathways 2. Radiation measurement programme by Iluka required by DHHS 3. DHHS radon monitoring programme 4. Expert radiological and hydrogeological reports submission-hrcc-epa-iluka-resources-limited-applications

29 Acknowledgements ARPANSA SGS ARS Landauer Durridge Radon Instrumentation Iluka Resources To receive this publication in an accessible format phone (03) or State of Victoria, Department of Health and Human Services September 2016.