Application of nuclear-physics methods for studying the radionuclide transport in granite rocks
The results of studying the migration of ¹⁶⁹Yb as actinide-simulator in granite specimens in pristine state and preliminary irradiated with various γ-irradiation dose up to 3,0*10⁹ rad are represented and briefly discussed. Method of γ-spectrometry was used in order to determine the distribution of...
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| Cite this: | Application of nuclear-physics methods for studying the radionuclide transport in granite rocks / N.P. Dikiy, S.Yu. Sayenko, V.L. Uvarov, E.P. Shevyakova // Вопросы атомной науки и техники. — 2000. — № 2. — С. 54-57. — Бібліогр.: 9 назв. — англ. |
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| author | Dikiy, N.P. Sayenko, S.Yu. Uvarov, V.L. Shevyakova, E.P. |
| author_facet | Dikiy, N.P. Sayenko, S.Yu. Uvarov, V.L. Shevyakova, E.P. |
| citation_txt | Application of nuclear-physics methods for studying the radionuclide transport in granite rocks / N.P. Dikiy, S.Yu. Sayenko, V.L. Uvarov, E.P. Shevyakova // Вопросы атомной науки и техники. — 2000. — № 2. — С. 54-57. — Бібліогр.: 9 назв. — англ. |
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| description | The results of studying the migration of ¹⁶⁹Yb as actinide-simulator in granite specimens in pristine state and preliminary irradiated with various γ-irradiation dose up to 3,0*10⁹ rad are represented and briefly discussed. Method of γ-spectrometry was used in order to determine the distribution of γ-emitting tracer isotope ¹⁶⁹Yb in granite. Estimations based on analysis of ytterbium bulk distribution are given to determine the diffusion coefficients of radionuclides in granite rock.
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| first_indexed | 2025-11-27T19:45:47Z |
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A P P L I C A T I O N O F T H E N U C L E A R M E T H O D S
APPLICATION OF NUCLEAR-PHYSICS METHODS FOR STUDYING
THE RADIONUCLIDE TRANSPORT IN GRANITE ROCKS
N.P. Dikiy, S.Yu. Sayenko*, V.L. Uvarov, E.P. Shevyakova
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
The results of studying the migration of 169Yb as actinide-simulator in granite specimens in pristine state and pre-
liminary irradiated with various γ-irradiation dose up to 3,0*109 rad are represented and briefly discussed. Method of
γ-spectrometry was used in order to determine the distribution of γ-emitting tracer isotope 169Yb in granite. Estima-
tions based on analysis of ytterbium bulk distribution are given to determine the diffusion coefficients of radionu-
clides in granite rock.
PACS: 28.41.Kw
1. INTRODUCTION
It is known that geological disposal of radioactive
high-level wastes (HLW) or nuclear spent fuel will
eventually result in contact between groundwater and
the radioactive wastes upon failure of disposal metal
container (e.g. mechanical breach or metal corrosion).
Therefore, studying the mechanisms of radionuclides re-
lease from spent fuel and glass waste forms for HLW
upon contact with aqueous solutions is being urgent
now. These investigations usually include two direc-
tions: studying of oxidation and dissolution of speci-
mens of really used UO2-fuel or unirradiated chemical
analogue of spent fuel - SIMFUEL (simulator of fuel)
[1-5] and studying of radionuclide migration in natural
rocks intended as repository material for radioactive
waste disposal [6]. The main attention is paid to study-
ing the behaviour of long-lived radionuclides and, in the
first turn, actinides, e.g. U, Pu, Np, Am, Cm. It was
shown in particular, that the amount of leached actinides
in leach solution reduced when crushed granite was
present under dynamic leaching tests in deionized water
(Soxhlet method) and that concentration of radionu-
clides in solution is greatly influenced by sorption phe-
nomenon in present of granite [3,4].
The closest to direction of used methods is the work
of Japanese authors, describing the migration of ra-
dionuclides through granite of the local deposit [6]. Re-
searches included the study of radionuclide migration by
means of building penetration profiles of 233U in granite
during 58 and 252 days after contact with nitrate solu-
tion of uranium, containing 233U as tracer isotope and
simulator of actinides. Alpha-autoradiography was car-
ried out to obtain the distribution of uranium concentra-
tion in granite matrix. It was shown that 233U migration
depends both on the mineral composition of natural
granite (quartz, plagioclase, feldspar, biotite), and its in-
ternal structure, in particular, micro and macro porosity,
micro and macro cracks. The influence of external radia-
tion streams as well as absorbed doses on radionuclide
migration in granite is not investigated there.
_____________
* Corresponding author: e-mail: sayenko@kipt.kharkov.ua
It is known, that in case the spent fuel container fails,
i.e. after a storage time less than 500 years, the radiation
field surrounding the fuel will be constituted essentially
by γ-radiation, but after storage time ≥ 500 years - by
α-particles [7]. So, granite, in cases of abnormal destruc-
tion of the metal container after storage time ≤ 500 years
in the first turn will be influenced mainly by γ-irradia-
tion. Actinides dissolved from spent fuel or HLW will
interact with granite rock, differing from intact natural
granite rock by changing the structure and composition
on account of magnitude of absorbed γ-dose.
The study of granites of Korostenian deposit from
the Ukrainian crystalline shield is of most interest now
because it is located near the "Shelter" unit and is being
considered as a perspective place for disposal of long-
lived radioactive wastes in Ukraine [8].
Here the results of the first experiments on investiga-
tion of the transport of 169Yb in pristine and γ-irradiated
(up to doses about 109 rad) granite are presented.
2. CONDITIONS OF EXPERIMENT
A piece of Korostenian granite was cut into a test
specimens in the form of blocks with the sizes of
10x10 mm in cross section and 30 mm in length. Each
block was covered with shellac adhesive besides one
surface.
Following steps realized studying the migration of
radionuclides as actinide simulators into granite matrix.
Pellets of Yb2O3 were irradiated by bremsstrahlung ob-
tained in Electron Linear Accelerator (ELA). In the
course of irradiation the tracer 169Yb-isotope was pro-
duced in accordance with reaction: 168Yb (n,γ) 169Yb
(half-decay period T1/2 = 30,7 days). Mass of ytterbium
oxide pellet after irradiation was 0,1 g. Then the pellet
was dissolved in concentrated HCl acid with the volume
of 0,2 ml and finally the solution with pH = 1,8 was pre-
pared. Obtained solution (with the volume of about
40 ml) was transferred into thermoresistance flask sup-
plied with reverse motion refrigerator. Experimental
granite blocks were placed inside flask. The flask was
being heated by water steam within 32 hours. Then each
of granite blocks was being washed in distillated water
54 ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2000, № 2.
Серия: Ядерно-физические исследования (36), с. 54-57.
within 24 hours and dried out at 60°C in the drying box.
Then layers were removed by means of precision grind-
ing of the uncovered surface of block (to escape the loss
of tracer). The thickness of removed layers varied from
2 µm to 50 µm. Material of the removed layer was used
for γ-spectrometry with the Ge(Li)-detector. 169Yb gam-
ma-intensity was measured within 20 min.
Studying of the radionuclide migration was being
made on granite specimens in both natural pristine and
γ-irradiated state. Irradiation has been carried out up to
magnitudes of absorbed dose 0,3∗109, 1,0∗109 and 3,0∗
109 rad, exposure times were respectively 7, 21 and
60 days. Realization of these severe conditions may be
of greater interest to estimate chemical and radiation sta-
bility of granite matrix under conditions of radioactive
waste disposal. The selected range of absorbed doses
corresponds to some international standards on tests of
radiation strength of protective materials of geological
repositories (in particular, materials to be exposed to ab-
sorbed doses ranging from 105 to 1010 rad).
3. IRRADIATION TECHNIQUE
To realize the conditions of external γ-irradiation ef-
fect of the granite specimens, the bremsstrahlung of the
ELA was used. Scheme of irradiation is shown on
Fig. 1.
Fig. 1. Scheme of γ-irradiation in electron accelera-
tor: e- -electrons, n-neutrons, 1 -electron accelerator, 2
- Ta-converter, 3 - filter for electrons and neutrons, 4 -
granite specimen.
The beam of electrons with energy of 20 MeV while
going through converter (tantalum) generates the stream
of γ-quantums, i.e. bremsstrahlung. Neutrons, which ap-
pear in converter (γ + 181Ta →180Ta + 1n0) have isotropic
distribution. The further placed system of filters (alu-
minium and paraffin) allows to reduce the electron and
neutron components of the radiation beam, obtaining
practically pure stream of γ-qauntums with average (by
spectrum) magnitude of energy 2,0-2,3 MeV. The maxi-
mum magnitude of absorbed dose rate corresponds to
~ 106 rad/h. The similar scheme of irradiation is realized
to get γ-emitting tracers on the base of 169Yb used for
γ-spectroscopy. The process of irradiation for this pur-
pose was carried out up to the absorbed dose of 108 rad.
4. ANALYTICAL METHODS
Crystal-optical analysis with using of polarized mi-
croscopes and immersion liquids was done to study the
crystalline structure of granite matrices before and after
tests. Morphology of grains, grain sizes, grain boundary
states and the extent of modification of internal structure
were investigated.
5. RESULTS AND DISCUSSION
Characteristic γ-spectrums of tracer isotope 169Yb in
removed layers are shown in Fig. 2 and Fig. 3. It should
be noted, that both spectrums are different in most ex-
tent due to appearance of gamma-activity lines of 84Rb
and 47Ca, which is connected with induced activity of
specimens during irradiation by bremsstrahlung. Thick-
ness of removed layer regarded to Fig. 2 was about 2 µ
m. However, that was insufficient for measuring of in-
duced activity in irradiated specimens. Therefore, fur-
ther the layers with thickness more than 2 µm (i.e. 50 µ
m) were used with simultaneous measuring of their
γ-spectrums.
500 1000 1500
channel number
2
5
2
5
2
5
1
10
100
co
un
ts
511 keV
Yb
169
Fig. 2. Typical γ-spectrum of natural granite.
55
500 1000 1500
channel number
2
5
2
5
2
5
2
5
1
10
100
1000
co
un
ts
84 Ca
47
Rb
511 keV
Yb
169
Fig. 3. Typical γ-spectrum of irradiated granite (dose 3,0*109 rad).
The absolute magnitudes of ytterbium concentrations
on each removed layer of pristine and irradiated speci-
mens were determined by calibrated measurements of
γ-spectrums with the use of 137Cs as standard γ-emitted
source. The maximum magnitude of ytterbium concen-
tration was determined as 3,0∗1020 at/cm3 that corre-
sponded to the first layer (i.e. thickness 50 µm) of block
irradiated up to external dose of 3,0∗109 rad (Fig. 4.).
0 200 400
depth, m
0.01
0.10
1.00
10.00
co
nc
en
tra
tio
n,
*
10
at
/c
m
20
3
µ
c
b
a
Fig. 4. 169Yb concentration in specimens of granite; a - irradiated by dose of 3,0∗109 rad,
b - pristine state with pegmatite structure, c - pristine state with uniform grain structure.
Curves of ytterbium concentration on various speci-
mens of granite blocks are shown in Fig. 4 as function of
matrix depth. To explain character of the curves, one
can give the following arguments. The total diffusant
mass in a body matrix is known to be determined by
both grain volume diffusion and grain boundary diffu-
sion. The grain boundary diffusion is usually of impor-
tance for natural minerals [9]. Besides this, structure de-
fects (pores, cracks) may also enhance the penetration of
diffusant inside the matrix. This means that the diffusant
enters the rock matrix far from the surface mainly along
grain boundaries (under absence of obvious micro or
macro defects). The both processes of volume grain and
grain boundary diffusion may be described by the fol-
lowing two equations, respectively (1) and (2) [9]:
−⋅= Dt
x
Dt
CtxC 4exp
2
),(
2
0
π , (1)
C - tracer concentration;
C0- initial tracer concentration;
D - diffusion coefficient;
x - distance from specimen surface.
⋅=
Dt
xerfcCtxC
2
),(
0
, (2)
where
( ) duuxerfc
x
∫
−⋅−=
0
2exp21
π
,
Dt
xu
2
= .
Based on the above-mentioned explanation, analysis
of concentration profiles presented on Fig. 3 was carried
out. Two characteristic regions of 0-60 µm and
60-400 µm were revealed. The first one is in a good
agreement with classic grain volume diffusion (penetra-
tion inside the bulk of grains). It was determined by
crystal-optical analysis that the grains of minerals, form-
ing the granite rock, i.e. plagioclase and feldspars were
exposed to interaction with tracer solution to a greater
extent than grains of quartz. This may be explained by
taking into consideration that in the natural granite rock
56
the quantity of microcracks in plagioclase and feldspars
is higher than that in quartz.
Curves of profiles for natural unirradiated granite
blocks (b, c, Fig. 4) are satisfactorily described by
Eq. (1). Magnitudes of diffusion coefficients were 1,4∗
10-15 and 1,09∗10-15 m2/s respectively. On the other
hand, curve of ytterbium concentration profile regarded
to granite block irradiated to dose of 3,0∗109 rad is dif-
ferent from profiles regarded to natural pristine blocks.
In this case, the characteristic profile view of irradiated
block (a, Fig. 4) cannot be described by grain volume
diffusion because Eq. (1) does not correspond to ob-
tained experimental results. This can be explained by
microstructure changes and accumulation of micro de-
fects (pores, cracks) occurred under action of irradia-
tion. Therefore, diffusion of ytterbium into deep granite
block with depth up to 60 µm occurs mainly on these
microdeffects. To achieve mathematical accordance, the
correct coefficients in Eq. (1) for estimating diffusion
coefficients were introduced. Average magnitude of yt-
terbium diffusion coefficient on depth from surface
0-60 µm for specimen of irradiated block was 3,2∗
10-15 m2/s.
In the range 60-400 µm the concentration profiles
for all specimens (both pristine and irradiated) have sim-
ilar nature, connected with grain boundary diffusion,
which is described quite precisely by Eq. (2). It is note-
worthy that in irradiated granite specimens up to doses
more than 1,0∗109 rad, the diffusion coefficient is
10-12 m2/s that is higher than for classic grain boundary
diffusion. Based on the results of crystal-optical analy-
sis, one may suppose that it is connected with the modi-
fication of grains and change of condition of grain
boundaries during irradiation.
6. CONCLUSION
The methods to study radionuclide (actinide simula-
tors) migration under conditions simulating the situation
of destruction of metal disposal container in the geologi-
cal repository for spent fuel, further interaction of spent
fuel with groundwater and transport of leached actinides
into environmental geological medium are proposed. To
create the simulated γ-irradiation on the side of nuclear
spent fuel, the bremsstrahlung of electron accelerator is
used.
Penetration profiles of 169Yb (as actinide simulator)
in specimens of natural granite rocks were obtained with
the use of nuclear-physics methods. Diffusion character-
istics for Yb-isotopes were estimated from the concen-
tration profiles, taking into consideration the microstruc-
ture of granite rock. The observed diffusion coefficients
for ytterbium were: for the depth 0-60 µm - about
1,09-1,4∗10-15 m2/s concerning unirradiated specimens
and 3,2∗10-12 m2/s as to irradiated specimens; for the
depth 60-400 µm - about 1,0-1,2∗10-8 m2/s that is practi-
cally same for both kinds of the specimens.
The radiation streams are shown to influence the
process of radionuclide migration in granite on account
of both changing of internal structure of rock matrix
during irradiation and enhancing of grain volume diffu-
sion. The magnitude of characteristic dose of γ-irradia-
tion (3,0∗109 rad), which is a reason for evident, in-
creasing of radionuclide transport was determined. As
such magnitudes of irradiation dose by spent fuel in real
situation are hardly possible, the release of actinides on
account of their transport in granite rocks will be deter-
mined first of all by the structure of natural granite.
ACKNOWLEDGEMENTS
This work has been carried out in the framework of
STCU Project 1580.
The authors are grateful to Dr. Hj. Matzke (Institute
for Transuranium Elements, Karlsruhe, Germany) for
helpful discussions of research program. Special thanks
are due to Prof. A.N. Dovbnya for his advice and con-
tinuos interest in all aspects of this work. Thanks are due
to Dr. E.P. Medvedeva for her assistance in diffusion
studies and Mr. Yu.V. Lyazhko for his help in computer
calculations.
REFERENCES
1. R.S. Forsyth, L.O. Werme. Spent fuel corrosion
and dissolution // J. Nucl. Mater. 1992, v. 190, p. 3.
2. J. Bruno, I. Casas and A. Sandino. Static and dy-
namic SIMFUEL dissolution studies under oxic con-
ditions // J. Nucl. Mater. 1992, v. 190, p. 61.
3. J.P. Glatz et al. // J. Nucl. Mater. 1995, v. 223,
p. 84.
4. V.V. Rondinella, Hj. Matzke. Leaching of SIM-
FUEL in simulated granitic water: comparison to re-
sults in demineralized water // J. Nucl. Mater. 1996,
v. 238, p. 44.
5. Hj. Matzke. Radiation damage-enhanced dissolu-
tion of UO2 in water // J. Nucl. Mater. 1992, v. 190,
p. 101.
6. K. Idemitsu et al. Primary diffusion path of urani-
um (IV) in laboratory scale water-saturated Inada
granite // Proceedings of Intern. Conf. on Rad. Waste
Manag. And Environm. Remediation, Prague, Sept.
1993, v. 1, p. 207-212.
7. V.V. Rondinella, Hj. Matzke, J. Cobos, T. Wiss.
α-Radiolysis and α-radiation Damage Effects on UO2
Dissolution under Spent Fuel Storage Conditions //
Proceedings of MRS Symp., Nov. 1998, Boston,
USA.
8. Z.M. Deconik et al. Investigation of possibility of
radioactive waste disposal in deep geological forma-
tions (in Ukrainian) // Bulletin of ecological state of
Chernobyl zone, 1999, v. 13, p. 64-66.
9. I. Kaur, W. Gust. Fundamentals of Grain and In-
terphase Boundary Diffusion // 1989, Ziegler Press,
Stuttgart.
57
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
ACKNOWLEDGEMENTS
REFERENCES
|
| id | nasplib_isofts_kiev_ua-123456789-82492 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-11-27T19:45:47Z |
| publishDate | 2000 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Dikiy, N.P. Sayenko, S.Yu. Uvarov, V.L. Shevyakova, E.P. 2015-05-31T19:33:44Z 2015-05-31T19:33:44Z 2000 Application of nuclear-physics methods for studying the radionuclide transport in granite rocks / N.P. Dikiy, S.Yu. Sayenko, V.L. Uvarov, E.P. Shevyakova // Вопросы атомной науки и техники. — 2000. — № 2. — С. 54-57. — Бібліогр.: 9 назв. — англ. 1562-6016 PACS: 28.41.Kw https://nasplib.isofts.kiev.ua/handle/123456789/82492 The results of studying the migration of ¹⁶⁹Yb as actinide-simulator in granite specimens in pristine state and preliminary irradiated with various γ-irradiation dose up to 3,0*10⁹ rad are represented and briefly discussed. Method of γ-spectrometry was used in order to determine the distribution of γ-emitting tracer isotope ¹⁶⁹Yb in granite. Estimations based on analysis of ytterbium bulk distribution are given to determine the diffusion coefficients of radionuclides in granite rock. This work has been carried out in the framework of STCU Project 1580. The authors are grateful to Dr. Hj. Matzke (Institute for Transuranium Elements, Karlsruhe, Germany) for helpful discussions of research program. Special thanks are due to Prof. A.N. Dovbnya for his advice and continuos interest in all aspects of this work. Thanks are due to Dr. E.P. Medvedeva for her assistance in diffusion studies and Mr. Yu.V. Lyazhko for his help in computer calculation. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Application of the nuclear methods Application of nuclear-physics methods for studying the radionuclide transport in granite rocks Применение ядерно-физических методов для изучения транспорта радионуклидов в гранитных породах Article published earlier |
| spellingShingle | Application of nuclear-physics methods for studying the radionuclide transport in granite rocks Dikiy, N.P. Sayenko, S.Yu. Uvarov, V.L. Shevyakova, E.P. Application of the nuclear methods |
| title | Application of nuclear-physics methods for studying the radionuclide transport in granite rocks |
| title_alt | Применение ядерно-физических методов для изучения транспорта радионуклидов в гранитных породах |
| title_full | Application of nuclear-physics methods for studying the radionuclide transport in granite rocks |
| title_fullStr | Application of nuclear-physics methods for studying the radionuclide transport in granite rocks |
| title_full_unstemmed | Application of nuclear-physics methods for studying the radionuclide transport in granite rocks |
| title_short | Application of nuclear-physics methods for studying the radionuclide transport in granite rocks |
| title_sort | application of nuclear-physics methods for studying the radionuclide transport in granite rocks |
| topic | Application of the nuclear methods |
| topic_facet | Application of the nuclear methods |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/82492 |
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