ANALYTICAL METHODS FOR OBTAINIG„FINGERPRINTS“ OF NUCLEAR MATERIALS IN ILLICIT TRAFICKING: A CASE OF HIGH
ENRICHED URANIUM SEIZED IN PRAGUE IN 1994
A REVIEW
Miloš BERAN, František SUS *
Nuclear Physics Institute, Czech Academy of Sciences
250 68 Rez near Prague, Czech Republic
Nuclear Research Institute Rez plc *
250 68 Rez near Prague
Czech Republic
From the newspaper article in The Prague Post:
Outer and inner packaging of the seized material:
The Certificate as attached to the Material:
After the event, the International Technical Working Group
(ITWG) for assisting to state and international safety offices
and agencies in suppresing an illicit nuclear trafficking, was
established in a short series of international meetings:
• International Conference on Nuclear Smuggling Forensic Analysis,
LLNL, Livermore (U.S.A)
November 7-9, 1995
• First Meeting of the Nuclear Smuggling International Technical
Working Group, ITU, Karlsruhe (Germany)
January 31-February 1, 1996
• International Workshop on Nuclear Material Illicit Trafficking,
Institute of Physics and Power Ingeneering, Obninsk (Russia)
December 2-4, 1996
Basic analytical methods recommended by ITWG for forensic analyses of seized illicit nuclear material to
attribute its origin and possible use:
• High resolution gamma (for detection of enriched U-235 and/orPu) and alpha spectrometry
• Potentiometric oxidation-reduction titration to determine stoichiometric composition (U-content) of material
• Mass spectrometric methods for determination of isotopic com-position, e.g. ID-TI-MS, GD-MS or ICP-MS ( determination of enrichment, impurities, …)
• Optical and electron (scanning or transmision) microscopy fordetermination of structure and microstructure
• X-ray diffraction analysis (homogeneity of material)
• Determination of age of material from ratio of some generic radionuclide pairs ( e.g. U-235/Pa/231, U-232/Th-228,Pu-239/U-235, Pu-240/U/236,… )
SELECTED ANALYTICAL RESULTS FOR THE
MATERIAL SEIZED IN PRAGUE IN
DECEMBER, 1994
Mass Spectrometric (TI-MS) Determination of Isotopic Composition of the Material
Test Parameter Batch A Batch B
U-content (wt. %) 86,799 +- 0,001 86,735 +- 0,001
IC-NRI 232 U
232 U
234 U
235 U
236 U
238 U
<0,000002
< 0,000002
1,0781 +- 0,0003
87,731 +- 0,046
0,2108 +- 0,0001
10,9797 +- 0,004
<0,000002
<0,000002
1,0778 +- 0,0004
87,737 +- 0,035
0,2102 +- 0,0004
10,9438 +- 0,004
IC-ITU
(comparison in
collaboration)
234 U
235 U
236 U
238 U
1,078 +- 0,070
87,766 +- 0,046
0,210 +- 0,00
10,946 +- 0,046
Determination of Trace Impurities by ICP-MS
Test Element Batch A Batch B
Impurities (μg/g)
IC-MS
Elan 6000
(without
chem.
separation)
Ag
Al
Ba
Be
Cd
Cr
Cu
Fe
Li
Mg
Mn
Mo
Ni
Pb
Sb
Sn
Sr
Th
Ti
V
W
Zr
0,19
7,8
0,65
0,005
0,015
8,9
1,25
58,5
0,03
10,4
0,91
3,2
2,9
4,1
0,010
0,70
0,45
0,22
0,82
0,14
0,39
18,6
0,15
8,5
0,49
0,004
0,018
9,5
1,15
65,4
0,04
12,0
1,05
2,8
3,5
3,2
0,018
0,82
0,55
0,26
0,99
0,19
0,46
16,1
Radionuclide Impurities
Method Spike Isotope Batch A Batch B Unit
AS-ID 236Pu 239+ 240Pu < 1 < 1 (Bq/g)
ICP-
MS
99mTc 99Tc < 0,02 < 0,02 (Bq/g)
Age Determination
Pair of
isotopes Spike
Batch A
(year)
Batch B
(year)
234U- 230Th
235U- 231Pa
228Th
237Np
26,9
25,6
27,3
26,4
Appearance of Samples in Optical Microscope
Structure of the Material
Pictures of material by scanning electron microscopy
C o n c l u s i o n s:
• The material seized in Prague in December 1994 was according to high resolution gamma spectrometry, potentiometric titration and mass spectrometric measurement high enriched UO2 (87,7 % of 235U)
• The material consisted of irregular porous particles (size under1 mm) with microcrystal structure according to scanning electron microscopy
• Very low content of radionuclide (99Tc, 239+240Pu) and chemical impurities (excepting traces of common construction materials of production equipment – Fe, Cr, Al and Zr) vere found in the material
• According to determination of „age“, 26-27 years elapsed from last retreatment (separation or purification) of the material to the moment of analysis
C o n c l u s i o n s:
• High chemical reactivity (e.g easy solubility in mineral acids) suggests the material to be an intermediate product for production of other products in nuclear technology
• The described case represent a most significant seizure of weapon utilizable illicit shipment of nuclear matererial
• Radioanalytical chemistry can provide tools to retrace illicit nuclear shipment to its source, supposing that nuclear material database exists