Identification of Origin of Actinides in Environmental Samples with Radioanalytical Technologies

2010. 10. 5

Myung Ho Lee, Jong Ho Park, Kyuseok Song

Nuclear Chemistry Research Division, KAERI

International Workshop on Nuclear Forensics following on Nuclear Security Summit, 5-6 October 2010, JAEA, Japan

1. Introduction, definitions: Nuclear forensics related with

environmental radioanalytical chemistry

2. Analytical methods: Radiometric method, Mass Spec.

method

3. Test cases (Fallout site, Nuclear fuel facilities, Weapon missile

site) : Determination of Pu and U isotopes ratios in

environmental samples

4. Summary

Outlines

Alexander Litvinenko was a former officer of the Russian Federal Security Service, FSB and KGB, who escaped prosecution in Russia and received political asylum in the United Kingdom. He authored two books, "Blowing up Russia: Terror from within" and "Lubyanka Criminal Group", where he accused the Russian secret services of staging Russian apartment bombings and other terrorism acts to bring Vladimir Putin to power.On 1 November 2006, Litvinenko suddenly fell ill and was hospitalized. He died three weeks later, becoming the first confirmed victim of lethal polonium-210-induced acute radiation syndrome. According to doctors, "Litvinenko'smurder represents an ominous landmark: the beginning of an era of nuclear terrorism".Litvinenko's allegations about the misdeeds of the Federal Security Service of Russia (FSB) and his public deathbed accusations that Russian president Vladimir Putin was behind his unusual malady resulted in worldwide media coverage (From TELEGRAPH, UK)

Nuclear terrorism ; illicit trafficking of nuclear materials

What is Nuclear Forensics?

Technical means by which unknown nuclear materials are characterized and interpreted

Characterization relies on radioanalytical and materials science techniques

Interpretation requires an understanding of relevant nuclear and chemical processes

Both chemical signatures and isotopic signatures provide useful clues

Nuclear forensics is similar to environmental radiochemistryNatural geochemical cyclesContaminant fate & transport

Environmental Radiochemistry vs. Nuclear Forensics:Similar approaches, different questions

From environmental radiochemistry

- Natural vs. anthropogenic radioactivity?- What is the source of the contamination?- What is the best approach for remediation?

From nuclear forensics

- What part of the nuclear fuel cycle does the signature represent?

- How old is the unknown material?- What is the origin of the material?

Analytical techniques for nuclear fingerprinting

Bulk analysis

Single particle(micron size)

Radiometric method(α,β,γmeasurement)

Sequential extraction method

Mass Spec. method(ICP-MS, TIMS, SIMS)

Isotopic signature Chemical signature

Nuclide Type Energy Half-life 239Pu α 5.15 MeV 24,390 y Undiscrimin-

ating by alpha spectrometry

240Pu α 5.17 MeV 6,580 y

238Pu α 5.49 MeV 86.4 yInterference

by 238U

241Pu β 21 keV 14.4 yDecay to

241Am 241Am α 5.49 MeV 458 y244Cm α 5.81 MeV 18.9 y

242Cm α 6.11 MeV 163 d

235U α 4.40 MeV 7.1E+8 yNuclear fuel

(1-90%)

238U α 4.32 MeV 4.5E+9 y

234U α 4.77 MeV 2.5E+5 y

6.07

6.07

6.11

242Cm

5.76

5.81

244Cm

5.44

5.48

241Am

5.23

5.28

243Am

5.46

5.50

238Pu

5.10

,5.1

25.

16

239,240Pu

4.86

4.90

242Pu

5.26

5.32

232U

4.72

4.77

234U

4.26

4.32

238U

4.37

4.40

235U

4.58

Energy (MeV)

Emitt

ing

ratio

of a

lpha

nuc

lides

Physical properties for alpha emitting nuclides

Request on radiochemical analysisfor identifying origin of unknown nuclear material

Reliable Fast Cheap(repeatability, accuracy) (Analytical time) (Analytical cost )

- numerous samples- accidental

- independent ofvariation in matrices

- concentration of nuclides

- numerous samples

Request on radioanalytical methods for nuclear forensic

TIMS or MC-ICP-MS

Radiochemical separation

Purification of Pu, UExtraction chromatography

Sample pretreatment

- Ashing sample (500 oC, 8-10 h)- Muffle furnace

Alpha spectrometer

-Volume reduction-Organics removal

Acid treatment

Sourcepreparation

Determination procedure for actinides in environmental samples

Determination of Pu, U and Am/Cm isotopes

UTEVA resin- 0.01M HCl

U fraction

- Added tracers (242Pu, 243Am, 232U/233U)

Dissolve samples (8 M HNO3 solution)

- 0.36M HCl- 0.01M HFPu fractionAnion exchange resin

(Dowex, NO-3 form)

α-spectrometry

α-spectrometry

DGA(or TRU) resin

Anion exchange resin (1M HNO3/93% CH3OH)

Am/Cm frac. α-spectrometry- 0.5M HCl

- 0.25M HCl

TIMS(ICP-MS)

TIMS(ICP-MS)

TIMS(ICP-MS)

Determination of Pu isotopes

L S C(Liquid Scintill. Counter)

Pu-241

Scintillation coctailElectrodeposition

A S(Alpha Spectrometer)

Pu-238, Pu-239,240 Pu-239, Pu-240

ICP-MS,TIMS

Extraction chromatography

Ashed Sample Material

Dissolved Sample Material

PULSER

PREAMPLIFIER

DETECTORBIAS SUPPLY

AMPLIFIER

OSCILLOSCOPE

MCA SYSTEM

Source

Surface-BarrierDetector

VACUUM CHAMBER0 200 400 600 800 1000

0

100

200

300

400

500

600

242Pu 238Pu

239,240Pu

Cou

nts

/ Cha

nnel

Channel

Measurement of Pu, Am and U isotopes by AP

Decay time (ns)

Alpha(Pu-239,240,Pu-238); 200 – 300 ns

Beta(Pu-241); 1 – 2 ns

PSA level

200 400 600 800 10000

50

100

150

242Pu, 239,240Pu, 238Pu

241Pu

Cou

nts

/ Cha

nnel

Channel

Measurement of Pu-241 by LSC

10 Bq m-2

100 Bq m-2

126o 128o 130o

126o 128o 126o

36o36o

38o 38o

34o34o

ForestArableHillVolcanic ash

China40o N

124o E

32o N

130o E

Test case # 1 : Cumulative deposition of Pu-239,240 in South Korea(M. H. Lee et al., J. Environ. Radioact. 41, 99, 1998)

1. Geographical location- Forest > Grassland > Arable

2. Organic matter content- Association of radionuclides with organic substancesdue to its large cation exchange capacity

3. Rainfall- Precipitation scavenging effect

4. Clay content- Increased surface area and the greater adsorptioncapacity

Parameters affecting deposition of fallout Pu isotopes

Pu-238/Pu-239,240

Pu-241/Pu-239,240

In this study 0.040 3.76Worldwide

fallout0.037 3 ~ 8

Chernobylfallout

0.47 85

Activity ratios of Pu isotopes

H4 H5 H6 F1 F2 F3 F4 F5 F6 F7 F8 F9 V1 V2 V30.00

0.06

0.12

0.18

0.24

0.30

0.36

fallout value

240 Pu

/239 Pu

ato

mic

ratio

(m/z

)Sampling points

238.5 239.0 239.5 240.0 240.50

200

400

600

800

1000

1200

1400

1600

1800

Ion

co

un

ts /

ch

an

ne

l

Mass number (m/z)

Measurement of Pu-239 and Pu-240 by ICP-MS

Atomic ratio of Pu-240/Pu-239 : 0.158 ~ 0.224 (average; 0.183)

Test case # 2 : Activity concentrations of U isotopes around nuclear fuel facilities, Korea (M. H. Lee et al., J. Radioanal. Nucl. Chem, 249, 215, 2001)

N

DS-1 DS-2DS-3 DS-4

DS-5 DS-6

Taejon

Km

10 2 3

US

Hanaro Reactor

Fuel Fabrication(HWR, LWR)

H-1

H-2

H-3

H-4

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

US DS-1 DS-2 DS-3 DS-4 DS-5 DS-60

20

40

60

80

Con

cent

ratio

n of

238 U

in s

urfa

ce w

ater

, mB

q/L

Sampling sites Natural level

Activity concentration of U in the stream

Act

ivity

rat

io o

f 234 U

/238 U

U-1 D-1 D-2 D-3 D-4 D-5 D-6 H-1 H-2 H-3 H-40

1

2

3

4

Natural level

Ato

mic

pe

rce

nta

ge

of 2

35 U

, %

Sampling site

0

500

1000

1500

2000

0

100

200

300

400

Enriched UO2 powder (3.5 %)

234U

235U

4.44

238U

4.20 4.77

Cou

nts/

chan

nel

Energy, MeV

Sediment in D-1

232U

234U

235U

238U

Cou

nts/

Cha

nnel

4.77 5.324.444.20

Energy, MeV

Atomic percentage of U-235 around nuclear fuel facilities

♦BOMARC facility (occupies 218 acres)operated from `60 to `72

♦An explosion and fire occurred BOMARC Missile Shelter 204 onJune 7, 1960

♦Plutonium fragments from the warhead were spread over an area surrounding the launcher

♦Air forces deactivated in 1972s ♦Air Force finally began a program to

clean up the radioactive contaminationof the BOMARC site between 1992 to2002

Test case # 3 : Activity concentrations of Pu isotopes around missile site, USA (M. H. Lee, Sue B. Clark, Environ. Sci. Technol. 39, 5512, 2005)

BOMARC (Boeing Michigan Aeronautical Research Center, NEW JERSEY, USA)

Particle size Pu-239,240 Pu-238 Pu-241 Am-241

(µm) (Bq/g) (Bq/g) (Bq/g) (Bq/g)

75– 47 6.34±0.42 0.11±0.008 15.28±0.98 1.08±0.17

147–250 2.23±0.30 0.049±0.006 4.50±0.62 0.40±0.07

250–350 1.46±0.08 0.038±0.002 2.54±0.39 0.22±0.03

350–425 0.67±0.07 0.022±0.003 0.92±0.12 0.16±0.01

425–600 0.42±0.05 0.010±0.001 0.67±0.10 0.09±0.01

Activity concentrations of actinides with particle size in missile site

75-47 147-250 250-350 350-425 425-6000

1

2

3

4

5

6

7

Activ

ity c

once

ntra

tion,

Bq/

g

Particle size, µm

: 239,240Pu : 241Am

241PuTf:14.35 y

241AmTf: 458 y

237Np

Am is more mobile than plutonium in the environment ?

Theoretical value of Activity of Am for 43 y

(2003 y-1960 y)

APu-241 at 43 years ago; 15.28 (Bq/g) x

Exp (0.693x43/14.35) = 147.3 Bq/g

AAm = λAmNAm = λAm / (λAm - λPu) APu

(e-λPut - e-λAmt), NAm0 = 0

= (0.693/458) / (0.693/458- 0.693/14.4)

* 147.3 (Bq/g) * (e–0.693/14.4*43 - e–0.693/458*43)

= 3.87 Bq/g (calculated value)

≠ 1.11 Bq/g (measured value)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.50.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

241Am in the BOMARC soil

241Am grown from 241Pu standard solution

Mea

sure

d ac

tivity

con

cent

ratio

n

Calculated activity concentration

Age determination of Am-241 produced from Pu-241

Particle size Atomic ratio

(µm) (Pu-240 / Pu-239)

75– 47 0.0567 ± 0.0009

147–250 0.0588 ± 0.0017

250–350 0.0571 ± 0.0014

350–425 0.0559 ± 0.0013

425–600 0.0594 ± 0.00100 20 40 60 80

0.0

0.1

0.2

0.3

0.4

Weapons grade Pu

Nuclear weapons test

Nuclear fuel reprocess plants

Chernobyl fallout

240 Pu

/239 Pu

(ato

mic

ratio

)

241Pu/239,240Pu (activity ratio)BOMARC Thule

Atomic ratio of Pu-240/Pu-239 in missile site

0.0 0.1 0.2 0.3 0.4 0.5

Nuclear fuel reprocess

Global fallout

Weapons grade Pu

Chernobyl

Sellafield

Nuclear weapons test

Chinese test(26th)

Thule(Greenland)

BOMARC

85

25

15

11

5.5

3.0

Activ

ity ra

tio of

24

1 Pu/ 23

9,240 P

u

Activity(atomic) ratio of 238Pu/239,240Pu( ) and 240Pu/239Pu( )

Activity (atomic) ratios of Pu isotopes emitted from different sources

1. Application of radioanalytical techniques (radiometric, mass

spectrometric method) to environmental samples

2. Update of reference databases for “nuclear fingerprinting”

- activity and atomic ratios of Pu isotopes in soil samples

(Korea Peninsular)

- activity and atomic ratios of U isotopes in environmental

samples (Nuclear fuel facilities)

- activity and atomic ratios of Pu and Am isotopes (age

determination) in soil samples (BOMARC Missile site)

3. Identification of origin of unknown nuclear material comparing

reference data from set-up databases

Summary

NuChem. Research Division

Thank you for your attention !!!