On Weapons Plutonium in the Arctic Environment (Thule, Greenland)

150 Pages·2002·3.55 MB·English

by  Mats Eriksson

Risł-R-1321(EN)

On Weapons Plutonium in the Arctic
Environment (Thule, Greenland)

Mats Eriksson

Risł National Laboratory, Roskilde, Denmark
April 2002
Risø–R–1321(EN)
On Weapons Plutonium in the Arctic
Environment (Thule, Greenland)
Mats Eriksson
Risø National Laboratory, Roskilde, Denmark
April 2002
Abstract
This thesis concerns a nuclear accident that occurred in the Thule (Pituffik)
area, NW Greenland in 1968, called the Thule accident. Results are based on dif-
ferent analytical techniques, i.e. gamma spectrometry, alpha spectrometry, ICP-
MS, SEM with EDX and different sediment models, i.e. (CRS, CIC). The scope
of the thesis is the study of hot particles. Studies on these have shown several
interesting features, e.g. that they carry most of the activity dispersed from the
accident, moreover, they have been very useful in the determination of the source
term for the Thule accident debris.
Paper I, is an overview of the results from the Thule-97 expedition. This pa-
per concerns the marine environment, i.e. water, sediment and benthic animals
in the Bylot Sound. The main conclusions are; that plutonium is not transported
fromthecontaminatedsedimentsintothesurfacewaterinthisshelfsea,thedebris
has been efficiently buried in the sediment to great depth as a result of biological
activity and transfer of plutonium to benthic biota is low.
Paper II, concludes that the resuspension of accident debris on land has been
limited and indications were, that americium has a faster transport mechanism
from the catchment area to lakes than plutonium and radio lead.
Paper III, is a method description of inventory calculation techniques in sedi-
ment with heterogeneous activity concentration, i.e. hot particles are present in
the samples. It is concluded that earlier inventory estimates have been under es-
timated and that the new inventory is about 3.8 kg (10 TBq) of 239,240Pu.
Paper IV, describes hot particle separation/identification techniques using real-
time digital image systems. These techniques are much faster than conventionally
used auto radiography and give the results in real time.
Paper V, is a study of single isolated hot particles. The most interesting result is
that the fission material in the weapons involved in the accident mostly consisted
of235U(about4timesmoreinmassthan239Pu).Thispaperconcludesthatthere
are at least two different source terms for the Thule accident debris. Another in-
teresting feature is that it seems like uranium is leaching from the particles faster
than plutonium and americium.
This thesis is submitted for the degree of Doctor of Philosophy, Department of
Radiation Physics at Lund University, Sweden.
Cover image: Hot Particle from the Thule sediment
ISBN 87–550–3006–8;
87–550–3007–6 (Internet)
ISSN 0106–2840
Print: Pitney Bowes Management Services Denmark A/S · 2002
Contents
Preface 6
1 Introduction 10
1.1 The Thule accident 11
1.2 Project Crested Ice 13
1.3 Radioecological surveys 14
1.3.1 Water 15
1.3.2 Sediments 15
1.3.3 Biota 16
1.3.4 Some thoughts concerning the early investigations 16
1.4 Aims of the studies in the present report 16
2 Methods 17
2.1 Sampling techniques 17
2.1.1 Water 17
2.1.2 Sediment 18
2.1.3 Biota 18
2.2 Radiochemical separation techniques 18
2.2.1 The use of tracers 18
2.2.2 Sub-sampling 19
2.2.3 Solubilisation 20
2.2.4 Concentration 20
2.2.5 Separation and purification 21
2.2.6 Source preparation 22
2.3 Detection and detection limits 22
2.3.1 Radiometric methods 22
2.3.2 Indirect measurements of 239,240Pu 24
2.3.3 Sediment dating techniques 24
2.3.4 Hot particle separation technique 25
2.3.5 Scanning Electron Microscope, SEM 25
2.3.6 Mass spectrometry 26
2.4 Statistics 27
2.4.1 Distribution functions 28
3 Results and Conclusions 28
3.1 Source term 28
3.2 Seawater 31
3.3 Sediments 31
3.4 Resuspension on land 33
3.5 Biota 34
4 Concluding Remarks and Future Research 34
Paper I 43
Paper II 63
Paper III 85
Risø–R–1321(EN) 3
Paper IV 113
Paper V 123
Publications not included in the thesis 144
4 Risø–R–1321(EN)

Preface
This thesis reports the results of a Ph.D study on radionuclides originating from
the Thule Accident. The work was carried out in the period from March 1998
to March 2002 as a joint venture between the Radiation Research Department,
RisøNationalLaboratory,Denmark,andDepartmentofRadiationPhysics,Lund
University, Sweden. The thesis includes and summarizes the five articles outlined
below.
I. DahlgaardH,ErikssonM.,IlusE.,RyanT.,McMahonC.A.andNielsenS.P.:
Plutonium in the marine environment at Thule, NW-Greenland after a nu-
clear weapons accident
In: ”Plutonium in the environment”, Ed. Kudo A., Elsevier, Oxford, UK,
15-30, 2001.
II. Eriksson M., Holm E., Roos P. and Dahlgaard H.:
Flux of 238,239,240Pu, 241Am, 137Cs and 210Pb to High Arctic Lakes in the
Thule District (Greenland)
Journal of Environmental Radioactivity, submitted (19 pp) 2001.
III. Eriksson M.:
PlutoniumInventoryCalculationsinSedimentswhenHotParticlesarePresent
Manuscript, (25 pp), 2002.
IV. Eriksson M., Ljunggren K. and Hindorf C.:
Plutoniumhotparticleseparationtechniquesusingreal-timedigitalimagesys-
tems
Nuclear Instruments and Methods in Physics Research, A, in press (6 pp),
2002.
V. Eriksson M., Roos P., Dahlgaard H., Lindahl P. and Holm E.:
Isotopic ratios in Thule hot particles, source term of the Thule debris
Manuscript, (18 pp), 2002.
PapersIandIVarereprintedwithpermissionfromtheElsevierScienceLtd,UK.
I wish to thank my superb supervisors Henning Dahlgaard and Elis Holm!
Moreover, I would like to thank my family, friends, colleges and coauthors, and
especially:
Per Roos, Claus Andersen, Miranda Keith-Roach, Karen Mandrup, Pearl Baade-
Pedersen, Jytte Clausen, Lis V. Kristensen, Sven P. Nielsen, Radiation Research
Department, Risø National Laboratory, Denmark
PatricLindahl,Torbjo¨nGa¨fvert,EdvinJohansson,ThomasHjerpe,MathiasLeisvik,
Ronnie Wirestam, Kaj Ljunggren, Cecilia Hindorf, Birgitta Roos, Gertie Johans-
son, Birgit Amilon, Christer Samuelsson, Carin Ling˚ardh, Christoffer Ellmark,
PeterMannfolk,JuanRioseco,DepatmentofRadiationPhysics,LundUniversity,
Sweden
Rolf Odselius, Electron Microscopy Unit, Lund University, Sweden
Erkki Ilus, STUK, Finland
Tom Ryan (Radiological Protection Institute of Ireland), Ciara McMahon, Luis
Le´on-Vintro´ (Dept. of Experimental Physics, University College Dublin), Ireland
Deborah H Oughton, Lindis Skipperud, Brit Salbu, Agricultural University of
Norway
John Norton Smith, Bedford Institute of Oceanography, Dartmouth, Canada
The NKS BOK-2 groupe
6 Risø–R–1321(EN)
This work was supported by grants from The Danish Research Agency (Min-
istry of Research, Denmark, former The Danish Research Academy), The Royal
Physiographic Society in Lund, Sweden, Dancea (Danish Co-operation for Envi-
ronment in the Arctic), EC contract number FI4P–CT95–0035(ARMARA), NKS
(Nordic nuclear safety research) framework program BOK-2.
Risø–R–1321(EN) 7
”Tack, ni svenska vakttorn.
Med Plutonium tvingar vi dansken p˚a kn¨a.
H¨ar – Danmark ...
Utskitet av kalk och vatten
Da¨r – Sverige ...
Hugget i Granit ...”
Dr. Stig Helmer (Ernst Hugo Ja¨reg˚ard)
i Lars von Triers film Riget
To my lovely Pia and Julliana!
8 Risø–R–1321(EN)