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ORNL is managed by UT-Battelle, LLC for the US Department of Energy
Development of Revised Radioanalytical Procedure for 210Po in Urine
and more…
Dosimetry Services Group
Oak Ridge National Laboratory
Hiromu Kurosaki
22
In Vitro Radiobioassay Program at ORNL• Routine Analyses – 24 Hour Void Urine– PAS (Personal Air Sampler) Filters for 227Ac
• Incident (Emergency) Analyses– Urine, Fecal, etc.
• Analytes of Interest– Alpha (225Ac, 241Am, 243Am, 242Cm, 244Cm, 248Cm, 252Cf, 237Np,
210Po, 238Pu, 239Pu, 242Pu, 244Pu, 226Ra, 228Th, 229Th, 230Th, 232Th, 232U, 234U, 235U, 238U)
– Beta (227Ac, 249Bk, 14C, 36Cl, 3H, 63Ni, 241Pu, 35S, 89/90Sr, 99Tc)– Gamma Emitters– ICP-MS (235U, 238U, Ratio)
33
Auto Deposition onto Ag/Cu/Ni Disks
• Simple and Quick
HEAT
44
Auto Deposition onto Ni Disks
24 Hour Urine(1.5 – 2 L)
Aliquot of 100 mL
Auto Deposition4 Hours
AlphaSpectrometry
Acidify with HCL
HEAT
55
0
10
20
30
40
50
60
70
80
90
100
4400 4600 4800 5000 5200 5400Energy keV
Auto Deposition onto Ni Disks
• Simple and Quick
• Poor Ni disks resolution– ROI setting difficulty
209Po
210Po
66
0
10
20
30
40
50
60
70
80
90
100
4400 4500 4600 4700 4800 4900 5000 5100 5200 5300 5400Energy keV
Setting ROI automatically is difficult.
209Po 210Po
ROI
77
Auto Deposition onto Ni Disks
• Simple and Quick
• Poor Ni disks resolution– ROI setting difficulty
• Sub-sampling required– Another source of uncertainty
88
How would you take sub-sample from these ?
Precipitate
99
We tried three sampling methods for 238U.
Supernate From the Bottom Entire Sample
1. Take 25 mL from the top2. Take 25 mL from the bottom3. Take remaining entire sample (950 mL)
1 2 3
1010
238U Activity: 3 > 1
y = 0.4188x
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04
Sub-
Sam
ple
/ dp
m/L
Entire Sample / dpm/L
1
3
1:1 line
1111
238U Activity: 2 > 3 > 1
y = 0.4188x
0
0.005
0.01
0.015
0.02
0.025
0.03
0.035
0.04
0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04
Sub-
Sam
ple
/ dp
m/L
Entire Sample / dpm/L
2
1
3
1:1 line
1212
Another Source of Uncertainty
• Sub-sampling uncertainty can be critical.– Good Sub-sampling procedure is necessary.
• Or process entire samples.– Eliminates sub-sampling uncertainty.– Provides better detection limit.
1313
Auto Deposition onto Ni Disks
• Simple and Quick
• Poor Ni disks resolution– ROI setting difficulty
• Sub-sampling required– Another source of uncertainty
• Sequential analysis difficult– Extraction chromatography makes it easy!
1414
Po Analysis with Separation
Entire Urineor Sub-sample
Pre-Concentration
Ce-OH Precipitation
AlphaSpectrometry
3M HCl
Po fraction
SR
8M HNO3
1515
After Column Separation, Takes < 30 Minutes
TRU
Po
Add Ce Carrier
Add H2O2
Add pH Indicator
Elute
Filter
Adjust pH
1616
Sequential Analysis Possible
3M HCl
SRTR
UDG
A
Pu/Np/Th/U
Am/Cm/Cf
Po/Sr
Entire Urineor Sub-sample
Pre-Concentration
1717
Fe may Follow Po
Entire Urineor Sub-sample
Pre-Concentration
Ce-OH Precipitation
AlphaSpectrometry
3M HCl
Po fraction
SR
8M HNO3
Fe
1818
TRU Removes Fe upon Po Elution
Entire Urineor Sub-sample
Pre-Concentration
Ce-OH Precipitation
AlphaSpectrometry
3M HCl
TRU
SR
8M HNO3
FePo fraction
1919
0
50
100
150
200
250
4400 4500 4600 4700 4800 4900 5000 5100 5200 5300 5400Energy keV
Sharper Peak, Greater RecoveryRecovery range:
EXC + Ce-OH70 – 90 %
Auto-Deposition30 – 60%Ce-OH ppt
Auto-Deposition
209Po 210Po
2020
Who cares about accurate alpha detector efficiency?
• If alpha tracer is used, efficiency cancels.
• It only affects recovery calculation.
• But beta tracers (234Th and 239Np) are used at ORNL
• So correct detector efficiency is required.
2121
How do we calculate efficiency?
• Use NIST traceable source (Electroplated)
• Are the efficiencies the same for ED and PPT?
Disk Filter
2222
242Pu
1
239Pu
Filter
2
Filter
Alpha Spec
How do you calculate efficiency of PPT?
Ce-OH ppt
Ce-OH ppt
242Pu
239+242Pu
2323
0
100
200
300
400
500
600
700
800
900
4700 4800 4900 5000 5100 5200 5300Energy / keV
Pu on Filter #1
0
20
40
60
80
100
120
4700 4800 4900 5000 5100 5200 5300Energy keV
Pu in Filtrate (Filter #2)
242Pu
242Pu
239Pu
Added 242Pu
242Pu left in filtrate (Calculated from filter #2)
242Pu on filter #1
minus
Should be equivalent to
1 2
2424
0
100
200
300
400
500
600
700
800
900
4700 4800 4900 5000 5100 5200 5300Energy / keV
Pu on Filter #1
0
20
40
60
80
100
120
4700 4800 4900 5000 5100 5200 5300Energy keV
Pu in Filtrate (Filter #2)
242Pu
242Pu
239Pu
Added 242Pu
242Pu left in filtrate (Calculated from filter #2)
242Pu on filter #1
minus
Should be equivalent to
1 2
ED > PPT ?
2525
Summary
• The new 210Po procedure provides– Sharper Peak– Greater Recovery– No Sub-Sampling Uncertainty– Sequential Analysis
• How are you handling efficiency of micro-precipitation?
2626
Acknowledgement
• Group Leader (Dosimetry)– Govind Rao
• Radiobioassay Lab– April Tucker– Kim Johnson– John Keaton Jr.– Michelle Kinnebrew– Pam McConkey– Jamie Daum– Hayden Nelson
• Counting Room– Joe Conner– Susan Lambert