1. Gamma Dose Reduction for
Underground Diamond Drillers
Dr Cameron Lawrence
Superintendent Radiation & Occupational Hygiene
Olympic Dam

2. Radiation & Occupational Hygiene Department 2010 Slide 2
Disclaimer
Reliance on Third Party Information
The views expressed here contain information that has been derived from publicly available sources that have not been
independently verified. No representation or warranty is made as to the accuracy, completeness or reliability of the
information. This presentation should not be relied upon as a recommendation or forecast by BHP Billiton.
Forward Looking Statements
This presentation includes forward-looking statements within the meaning of the U.S. Securities Litigation Reform Act of
1995 regarding future events and the future financial performance of BHP Billiton. These forward-looking statements are
not guarantees or predictions of future performance, and involve known and unknown risks, uncertainties and other factors,
many of which are beyond our control, and which may cause actual results to differ materially from those expressed in the
statements contained in this presentation. For more detail on those risks, you should refer to the sections of our annual
report on Form 20-F for the year ended 30 June 2009 entitled “Risk factors”, “Forward looking statements” and “Operating
and financial review and prospects” filed with the U.S. Securities and Exchange Commission.
No Offer of Securities
Nothing in this release should be construed as either an offer to sell or a solicitation of an offer to buy or sell BHP Billiton
securities in any jurisdiction.

3. Radiation & Occupational Hygiene Department 2010 Slide 3
Olympic Dam
• Large underground mining operation
and processing plant for multi-mineral
resource
• Copper, Uranium, Gold & Silver
• Fourth largest copper mineral
resource
• Fourth largest gold mineral resource
• Largest uranium mineral resource

4. Radiation & Occupational Hygiene Department 2010 Slide 4
Underground Operations
• Over 300 km of developed underground tunnels
• Workshops, offices, crib rooms and stores
• Mining occurs using open stopes
• Ore removed from bottom of stopes and transported to ore handling system
• 2 underground ore handling systems including crushing and haulage
• Whenan and Clark crushers and shafts

5. Radiation & Occupational Hygiene Department 2010 Slide 5
Radiation Monitoring Methods – Mine
• Radon Decay Products
• Borak grab sampling method used
• Monitoring program defines locations requiring sampling
• Ventilation department perform pre entry and ongoing inspections,
data captured
• Airway averages determined and doses calculated by linking to
timesheet location information
• Radioactive Dust
• Minor pathway underground due to low ore grade, ~0.2 mSv/a
• Workgroups sampled according to program using standard dust
monitoring equipment
• Total alpha count and radioactive dust concentration determined
• Workgroup averages calculated and doses applied depending on
timesheet information
• Gamma
• All designated and selected non designated employees wear TLD
badges attached to personal cap lamps
• Individual doses from TLD results, workgroup averages applied for
missing badges
• Pre entry gamma surveys performed
• Electronic monitoring programs in place using gamma watches and
dosicards

6. Radiation & Occupational Hygiene Department 2010 Slide 6
Average Mine Radiation Exposures FY09
• Exposure pathways
• 57% from radon decay products
• 38% from gamma radiation
• 5% from dust
0
1
2
3
4
5
6
Backfill
C
orefarm
D
evelopm
entD
iam
ond
D
rilling
Electricians
Fitters
M
ine
Surface
O
re
H
andling
Production
Charging
Production
Drilling
R
aise
D
rilling
Services
Work Group
Dose(mSv)
Airborne Dust (mSv) Radon Decay Products (mSv) Gamma (mSv)

7. Radiation & Occupational Hygiene Department 2010 Slide 7
Diamond Drilling Operations
• Independent contractor operates 4
diamond drill rigs underground
• Diamond drilling program is used to
determine ore resources and future
stoping operations
• Drill rigs can be established at a site
for up to 3 months
• Diamond drilling delivers core to the
on site core processing facility for
analysis preparation

8. Radiation & Occupational Hygiene Department 2010 Slide 8
Potential Gamma Exposures
• Site may be located in a mineralised area
and have elevated gamma levels
• Localised mineralisation possible in walls, floor
and/or roof
• Cuttings produced from drilling operations
can give off high gamma levels
• >100 Sv/h historically recorded at some sites
• Water seepage causing salt crystallisation
around drill holes can concentrate
radionuclides
• Core handling activities
• High grade core recorded at >100 Sv/h

9. Radiation & Occupational Hygiene Department 2010 Slide 9
Controls for Gamma Dose Reduction
• Diamond Drill Rig sites gamma surveyed prior to set up
• In FY08 internal limits for the requirement of shotcrete at these sites was reduced from 8
Sv/h to 6 Sv/h
• In FY08 ground control methods at Olympic Dam were changed
• This resulted in shotcrete being more widely used as a ground support tool

10. Radiation & Occupational Hygiene Department 2010 Slide 10
Controls for Gamma Dose Reduction
• Diamond Drill sites were being set up with more focus on good
housekeeping
• Shotcrete, road base and drainage became common at all rig sites
• Previously shotcrete was only used if gamma levels required it
• Previously metal boxes around controls (TARDIS) were the only
engineering control for dose reduction
• Some sites had poor drainage resulting in accumulation of cuttings around
drill rigs
• Core storage segregation at rig sites

11. Radiation & Occupational Hygiene Department 2010 Slide 11
Site Setup

12. Radiation & Occupational Hygiene Department 2010 Slide 12
Site Setup
Drainage channel to remove cuttings
Metal control box to reduce exposure

13. Radiation & Occupational Hygiene Department 2010 Slide 13
Historical Average Exposures for Diamond
Drillers
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
18.0
20.0
Jul04-Jun05 Jul05-Jun06 Jul06-Jun07 Jul07-Jun08 Jul08-Jun09
Period
Dose(mSv)
Dust RDP Gamma MAX Total Dose(mSv)

14. Radiation & Occupational Hygiene Department 2010 Slide 14
Average Gamma Exposures for Diamond
Drillers
0.0
1.0
2.0
3.0
4.0
5.0
6.0
Jul04-Jun05 Jul05-Jun06 Jul06-Jun07 Jul07-Jun08 Jul08-Jun09
Year
GammaDose(mSv)
Average Maximum
• Current rolling average for Diamond Drillers gamma exposure is 1.0 mSv
(April 2009 – April 2010)

15. Radiation & Occupational Hygiene Department 2010 Slide 15
Conclusion
• Site decision to change ground control methods has reduced gamma
exposures to all work groups
• Shotcrete readily applied throughout all areas of the underground operation
• Focus on site set up for Diamond Drillers
• Use of concrete pads, metal boxes, shotcrete and drainage channels
• Segregation of core
• Education about the importance of good housekeeping at rig sites
• Drainage channels hosed out twice a shift
• Average gamma dose reduction of 43% for Diamond Drilling workgroup

16. Radiation & Occupational Hygiene Department 2010 Slide 16
Questions?
? ?