1. TE NORM and ALARA in the Florida Phosphate Industry
Brian Birky, Ph.D.
Florida Institute of Phosphate Research
Julian Hilton, D.Phil.
Oxford University
AleffGroup
Vaughn Astley, Ph.D.

2. NORM and ALARA in the Florida Phosphate Industry
Brian Birky, Ph.D.
Florida Institute of Phosphate Research
Julian Hilton, D.Phil.
Oxford University
AleffGroup
Vaughn Astley, Ph.D.

3. Today’s Presentation
Occupational dose studies by Florida Institute of Phosphate Research (FIPR)
ALARA / absolute dose considerations
The phosphogypsum issue: waste or asset
The gap between supposition and reality
Did the R drop out of ALARA?

4. The Phosphate Industry in Florida
> 6,000 directly employed
> 30,000 indirectly employed
Supplies 75% of US phosphate demand
Supplies 25% of world phosphate demand

5. FIPR Occupational Dose Studies
NORM Energy Spectrum
Industry specific dose conversion factors
Florida Phosphate Industry Dose Assessment
External dose
Inhalation dose
Inhalation Dose – Follow-up Studies

7. Central Florida NORM Distribution (Bq/kg)
Material
Process Stage
1400
Matrix
Mining
1430
1610
Clays
230
200
Sand
Beneficiation
1460
1350
Rock Concentrate
1100
<40
Phosphogypsum
Chemical Processing
Phosphoric Acid
170
2560
MAP/DAP
Fertilizer Products
>>1400
420
Scale
Waste

8. FIPR Study No.1 – Phosphate Industry Specific Dose Conversion Factors
Florida International University (funded by FIPR)
Examined External dose only
Method: Broad-energy germanium spectrometer in the field
Characterized NORM energy spectrum
Developed Roentgen-to-Rem DCFs

9. Phosphate Industry Specific Dose Conversion Factors (Cont.)
One-to-one conversion commonly used
Actual dose rate
40 to 45% of common survey meter readings in mR/hr
Doses estimated using survey meters are overestimated by up to 60%
Recyclable metals are buried instead of salvaged

10. FIPR Study No.2 - Results of the Phosphate Industry NORM Study
Doses were low
< 1 mSv/a
External dose was the big contributor
But, internal dose could drive the TEDE up an order of magnitude in some situations

11. FIPR Study No. 3 – Inhalation Doses in the Phosphate Industry
Actually two related studies
Particle size distributions by site areas
Chemistry and radioactivity by size fractions
Particle shapes and densities
Solubility of size fractions in lung fluid
ICRP-66 HRTM and LUDEP/IMBA codes

12. Research Procedure for Inhalation Dose Assessment
Air Sampling & Size distribution
Project 1
Project 2
(Cascade Impactor)
Determination of
particle size distribution
(Hi-Vol Sampler)
For analysis of density
and radioactivity
Particle Shape
Analysis
Element
Composition Analysis
Particle Density
Analysis
Radioactivity
Measurement
(SEM)
Determination of
particle shape factor
(EDXS)
Quantification of
elemental distribution
(Pycnometer)
Determination of
Particle density
(HPGe)
Determination of
Particle radioactivity
Effective Dose
Scaling Factors
Inhalation Dose
Assessment
Particle Solubility
In Lung Fluid
(IMBA, LUDEP)
Generation of effective
dose scaling factors
(IMBA, LUDEP)
Calculation of inhalation dose
w/o solubility data
(In-Vitro Test)
Radionuclide dissolution
fractions & rates
Risk Assessment to Workers
in the Phosphate Industry
Annual total effective dose calculation
Recommendation

13. Dissolution Rates of Phosphate
If radioactive element is present as a minor constituent of inhaled particles, absorption of the radionuclide to body fluids may be controlled by surrounding matrix rather than elemental form of the radionuclide. [ICRP 71]
Dissolution rate of surrounding matrix (phosphate)
Measurement of phosphate ion concentration in solution (IC)

14. Dissolution Rates of Phosphate (Cont.)

15. Dissolution Rate of Uranium

16. Dissolution Rate of Thorium

17. Dissolution Rate of Lead

18. TEDE Results for the Industry
Final reports from the University of Florida are due soon
Several are in various stages of publication
First is in the current issue of Health Physics
More to follow
Full FIPR publications will be posted on the web at

19. Where Do You Focus ALARA Resources?
You may reasonably choose:
To apply no further resources
Worker education
Time, Distance, Shielding
Proper use of dust masks
Dust suppression
Ventilation of rock tunnels

20. The Price of the Dropped R?

22. The Great Divide
The industry views phosphogypsum as a potentially useful by-product
Regulatory agencies view phosphogypsum as a waste that does not belong in commerce
Radium content
Radon potential

23. New Project: Stack Free by ’53?
Establish an authoritative database by country and by region of regulations and laws affecting the industry, and the extent to which such laws impact on commerce and trade
Evaluate potentially beneficial uses of phosphogypsum in construction and agriculture, including the use of phosphogypsum as a source of nutrients
Provide new information to policymakers on the safety aspects of phosphogypsum

24. Is it Economical to Use Phosphogypsum (PG)?
Will the PG be sold or given away?
Transportation costs will determine the distance PG can be delivered
Competitive sources of sulfur
Natural gypsum
Electric power, etc.
Engineer a desirable PG?

25. The Key Question
Is the practice of stacking phosphogypsum truly in keeping with ALARA as supposed, or is it really at odds with the ALARA philosophy?

26. What Data are Needed to Answer the Key Question?
Data in two categories
Risk to the public and environment from PG use
Standard pathway techniques
Risk avoided by the use of PG
Is this assessment done as easily?
Literature review in progress
Support from Rothamsted Research (UK)

27. Data Needed to Determine Risk from PG Use
PG characteristics
Radioactivity concentrations for radionuclides in PG by production site
Concentrations of heavy metals (Cd, Pb, Hg, etc.)
Data for Defined Application Scenarios

28. Data Needed to Determine Risk from PG Use (cont.)
For example: PG as a soil amendment
Application rates for optimum growth
Soil to plant transfer of radionuclides and metals
Accumulation and leaching
Conduct ingestion pathway analyses
Translate dose to risk

29. Data Needed to Determine Risk Avoided from PG Use
Improved nutrition
Estimate of increased life expectancy
Improved availability of foods
Lives saved

30. Data Needed to Determine Risk Avoided from PG Use (Cont.)
Decreased risk of stack failure
Estimate of failure rate and environmental damage
Decreased discharge of PG to the environment
Estimate of long-term effects

31. Data Needed to Determine Risk Avoided from PG Use (Cont.)
Benefits from other uses
Road beds
All are difficult to quantify

32. Regulatory Practice and ALARA
USEPA – If the maximally exposed hypothetical individual exceeds a risk of 1E-04, the practice is not acceptable
Is this keeping with the ALARA philosophy if the vast majority of the population will enjoy a decreased risk of detriment and mortality as a result?

33. Regulatory Practice and ALARA
If the health risks from radiation are surpassed by decreasing societal health risks from other causes, and economic considerations for both industry and the public are favorable, then doses are as low as practical and optimization is achieved

34. Two Questions Remain
Do you protect the unlikely hypothetical maximum individual at the expense of the more numerous and realistic individuals?
Is it reasonable to reinstate reasonableness in the adjudication of risk – ALAA, or ALARA?

35. Is this reasonable?