Recent Advances in the Recovery and
Purification of Actinium Isotopes
E. P. Horwtiz1, D. R. McAlister1 and J.T. Harvey2
1PG
Research Foundation, Inc. Lisle, IL
2Northstar Medical Radioisotopes, Madison, WI
National Meeting of the ACS, Spring 2012
San Diego, CA
The Chemistry of the Actinide and Transactinide Elements
500
Pu
400
Pages
300
200
Th
100
Ac
0
Pa U
Np
Am
Cm Bk
Cf
Es Fm-Lr
Sources of Actinium Isotopes
233U
1.6 x 105 y
229Th
235U
7.3 x 103 y
7.1 x 108 y
231Th
225Ra
231Pa
26 h
3.2 x 104 y
227Ac
10.0 d
227Th
22 y
14.8 d
225Ac
18.7 d
223Ra
11.7 d
Decay of Actinium-225
225Ac
10.0 d
5.6 – 5.8 MeV
221Fr
4.8 m
6.1 – 6.3 MeV
217At
32 ms
213Bi
7.067 MeV
45.6 m
213Po
4.2 ms
2%
213Tl
209Pb
2.2 m
8.375 MeV
Charge to Radius Ratio for
Selected Trivalent Cations
Element
Effective Ionic
Radius (CN = 6)
Charge to
Radius Ratio
Ac3+
1.12Å
2.68
La3+
1.03Å
2.91
Ce3+
1.01Å
2.97
Pu3+
1.00Å
3.00
Am3+
0.975Å
3.08
Extractants
O
O
O P OH
O
P
OH
O
HEH[EHP]
HDEHP
3(HY)2 + M3+ ↔ M(HY2)3 + 3H+
O
R N
R
O
O
N R
R
3TODGA + M3+ + 3NO3- ↔ M(TODGA)3(NO3)3
Selectivity of HDEHP and HEH[EHP]
10
7
10
6
10
5
10
4
10
3
HDEHP
HEH[EHP]
Y
Lu
k' Relative to La on LN2 = 1
Yb
10
Tm
Ho
Dy
Am
Eu
Sm
Ac
1
10
0
Ce
Y
Tb
2
10
Er
Pr Nd
La
Gd
Pm
Am
Ac
10
-1
56
58
60
62
64
Z
66
68
70
72
Selectivity of TODGA
10
5
Er
10
4
Tb
Sm Eu
Am
10
3
Tm
Lu
Gd
2
Pm
Am
10
Ho
Pm
Dy
Gd
Nd
Ho Tm Lu
Pr
Tb
Er Yb
Ce
Dy
La
Eu
Ac
k' 10
Yb
1
Pr
Sm
Nd
Ce
Ac
10
0
La
0.05 M HNO3
0.50 M HNO3
10
-1
56 58 60 62 64 66 68 70 72
Z
Y
Y
k’ Ac from HNO3 on TODGA and HDEHP Resins
10
4
HDEHP
10
3
TODGA
10
2
10
1
10
0
k'
10
-1
10
-2
10
-1
10
0
[HNO3], M
10
1
ppm/mL vs. Bed Volumes of Eluate
o
Slurry Packed 25-53 mm LN Resin, Preconditioned with 0.50 M (Na,H)OAc, 50(1) C
10
10
2
Load
0.50 M
(Na,H)OAc
pH = 4.5
1
Eluant
0.10 M
HNO3
225
Strip
4.0 M
HNO3
Ac
1 mg Ce
1 mg Pr
1 mg Nd
ppm La, Ce, Pr, Nd
2 225
cpm/mL (10 ) Ac
1 mg La
10
0
10
-1
10
-2
Background
10
-3
0
5
10
Flow Rate = 5 mL/min
Column diameter = 1.1 cm
2
= 5.3 mL/cm /min
Column length = 21.0 cm
= 3.8 min/Bed Volume Column volume = 20.0 mL
Pressure = 8 psi
LN lot # LF12013
 = 2.8 (Ac/La)
15
20
Bed Volumes
25
30
35
Ac-225 Sources
ORNL-150mCi Th-229 (on-going; ~600mCi Ac-225 annually
INL-27MT LWBR fuel; ~14MT unirradiated + ~13MT “lightly
irradiated” (~5000mCi/month Ac-225)
Chemical Separation of Th-229 from existing U-233 stocks
(~6000mCi/month Ac-225)
Cyclotron Production via Ra-226(p,2n)Ac-225
(~200mCi/month/cyclotron)
Photonuclear transmutation via Ra-226(g,n)Ra-225Ac-225
(~400mCi/month/LINAC)
Reactor production of Th-229; Ra-226Th-229 or Th228(n,g)Th-229
High Energy Proton Spallation of Th-232 (~10,000mCi/month)
Spallation
Lighter
Nuclide
1p
1
232
90 Th
1n
0
High energy protons strip neutrons and fragments from
thorium forming lighter nuclides.
Fragments can also combine with thorium to form
heavier nuclides.
Light Nuclides Formed by Spallation of Thorium
Target with Protons
90Th
230, 228, 227, 226
63Eu
147, 146
89Ac
227, 225
61Pm
148m
88Ra
225, 223
58Ce
144, 141, 139
84Po
210, 209, 208, 206
56Ba
140, 133, 131
82Pb
210
39Y
88
70Yb
169
38Sr
90, 85
64Gd
153, 148, 146
21Sc
46
Heavy Nuclides Formed by Spallation of Thorium
Target with Protons
91Pa
233, 231, 230
92U
233, 232, 230
Target Dissolution
Physical
De-cladding
Cu clad target
(0.127 cm Cu)
35g Th Metal
(2.3 x 1.0 x 1.3 cm)
Dissolve in minimum volume
of 7M HNO3 + 0.1M HF
(~100mL)
Adjust to 4M HNO3,
Add Boric acid
SX Process
DA[AP]
U(VI) and Tetravalent Actinide Selective Extractant
O
C5H11O
C5H11O
P
C5H11
Diamyl amylphosphonate (DA[AP])
Th4+ + 4NO3- + 2E ↔ Th(NO3)4∙2E
UO22+ + 2NO3- + 2E ↔ UO2(NO3)2∙2E
Ac, Ra no significant extraction
Tandem Column System for the rapid Extraction
and Purification of Ac-225
Raffinate from
SX Process
3M HNO3
Th, Pa, U
Ra, Ac, Ln, Y, Sc, Po
Y, Sc, Ln(Z>Pm), Po
To Recycle
Ac, La-Pm
Ra, Sr
La-Pm
Ac
Spallation Yields of Actinium Isotopes
(5.9x1016 protons on 30g Th-232)
Isotope
Half-life
89Ac-225
10 d
89Ac-226
29 h
89Ac-227
22 y
Atoms
uCi
7.7 x 1013
1.7 x 103
N/A
7.3 x 1013
N/A
2.0
Acknowledgement
The authors wish to thank
Del Bowers and George Vandegrift, CST Division,
Argonne National Laboratory, for their help in
processing the irradiated Th target.
The authors also wish to thank Vivian Sullivan of
Argonne National Laboratory for her assistance with the
analysis of sample fractions by gamma spectroscopy