Electron linac application for characterization and disposal of radioactive waste
Rapid development of nuclear engineering, medicine and radiation technologies is accompanied by increase of the radioactive waste (RAW) including long-lived ones. A RAW handling assumes their element content and activity analysis (characterization), compacting and disposal. This problem is of ultima...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
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| Cite this: | Electron linac application for characterization and disposal of radioactive waste / N.P. Dikiy, N.A. Dovbnya, S.Yu. Sayenko, V.L. Uvarov // Вопросы атомной науки и техники. — 2001. — № 3. — С. 178-180. — Бібліогр.: 8 назв. — англ. |
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| author | Dikiy, N.P. Dovbnya, N.A. Sayenko, S.Yu. Uvarov, V.L. |
| author_facet | Dikiy, N.P. Dovbnya, N.A. Sayenko, S.Yu. Uvarov, V.L. |
| citation_txt | Electron linac application for characterization and disposal of radioactive waste / N.P. Dikiy, N.A. Dovbnya, S.Yu. Sayenko, V.L. Uvarov // Вопросы атомной науки и техники. — 2001. — № 3. — С. 178-180. — Бібліогр.: 8 назв. — англ. |
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| description | Rapid development of nuclear engineering, medicine and radiation technologies is accompanied by increase of the radioactive waste (RAW) including long-lived ones. A RAW handling assumes their element content and activity analysis (characterization), compacting and disposal. This problem is of ultimate importance after shutdown of Chornobyl nuclear power plant Unit 4. The activity of the RAW inside the unit is estimated as much as 20 MCi (mainly on account of the Cs-137). These circumstances ensure a necessity of elaboration of the especial methods for express-analysis of large RAW fluxes. An immobilization of the long-lived radionuclides is entailed in turn with the problem of their localization into stable matrix as well as placing in resistive to radiation containers and geological structures. The report contains an overview of methods elaborated in NSC KIPT for RAW characterization and investigation using the bremsstrahlung of the high-current electron accelerator of radiation stability of the artificial and natural barriers for radionuclide immobilization.
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ELECTRON LINAC APPLICATION FOR CHARACTERIZATION AND
DISPOSAL OF RADIOACTIVE WASTE
N.P. Dikiy, N.A. Dovbnya, S.Yu. Sayenko, V.L. Uvarov
National Science Center “Kharkov Institute of Physics and Technology”,
61108, Kharkov, Ukraine
uvarov@kipt.kharkov.ua
Rapid development of nuclear engineering, medicine and radiation technologies is accompanied by increase of the
radioactive waste (RAW) including long-lived ones. A RAW handling assumes their element content and activity
analysis (characterization), compacting and disposal. This problem is of ultimate importance after shutdown of
Chornobyl nuclear power plant Unit 4. The activity of the RAW inside the unit is estimated as much as 20 MCi
(mainly on account of the Cs-137). These circumstances ensure a necessity of elaboration of the especial methods
for express-analysis of large RAW fluxes. An immobilization of the long-lived radionuclides is entailed in turn with
the problem of their localization into stable matrix as well as placing in resistive to radiation containers and geolo-
gical structures. The report contains an overview of methods elaborated in NSC KIPT for RAW characterization and
investigation using the bremsstrahlung of the high-current electron accelerator of radiation stability of the artificial
and natural barriers for radionuclide immobilization.
PACS numbers: 29.17.+w, 28.41.Kw
1 INTRODUCTION
Radioactive waste (RAW) management includes a
number of procedures. First of all it is RAW characteri-
zation i.e. determination of the amount, activity, ra-
dionuclide and element content etc. The available meth-
ods of RAW characterization are based either on analy-
sis of their inherent radiation (γ-, β-, α-spectrometry) or
on the profound radiochemical treatment of the samples
with an extraction of the corresponding analyzed frac-
tion for its further spectrometry. The shortcomings of
the first group methods are a relatively low accuracy
and a restriction to the analysis of only thin RAW layers
(particularly β- and α-active ones) as well as a small
number of identifiable elements. Second group methods
are devoid of these shortcomings. However they are
rather labor-consuming, expensive and low operative (a
duration of one radiochemical analysis is up to several
days). It is known that the activation method based on
secondary radiation of electron accelerators is widely
used at present for nondestructive express-analysis of
samples of ore and different materials [1], fission mate-
rials [2] and in other fields.
Taking into account that a RAW sample activated
with high-energy braking photons emits a radiation that
is caused both by its inherent activity and initiated one
as a result of photonuclear reactions, then an analysis of
such a radiation gives quantitative information about the
radionuclide and element composition of the sample
without its destruction.
The next RAW management stage is their immobi-
lization and disposal in the steady geological structures.
This task calls elaboration of experimental prognostica-
tion methods for lasting (up to thousand years) conduct
of the disposal environment under complicated radiation
and corrosive conditions.
2 ACCELERATOR
2.1. For analysis of large amounts of RAW samples
by the γ-activation method and implementation of other
concomitant programs it is needed an electron accelera-
tor with a beam power up to 10 kW and a wide range of
particle energy regulation.
The complex LU-20 [3] designed at the “Accelera-
tor” R&D Prod. Est. of NSC KIPT satisfies these re-
quirements (see Table 1).
Table 1. Basic parameters of LU-20 Linac
Energy range, MeV 10...30
Pulse duration, µs 4
Maximum repetition rate, Hz 300
Maximum peak current, mA 1000
Maximum average current, µA 1000
Beam scanning frequency, Hz 3
Beam size at the accelerator exit, cm 2x30
Absorbed dose rate (electrons), Gy/h up to 4⋅107
Absorbed dose rate (braking
photons), Gy/h
up to 1⋅105
2.2. A necessary set of radiation forming and diag-
nostics devices has been developed for ensuring γ–acti-
vation analysis (Fig. 1).
Fig. 1. Schematic of the radiation forming and diag-
nostics devices.
An electron beam at the accelerator A exit is
scanned using the electromagnet SM. A continuous
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 178-180.
178
mailto:uvarov@kipt.kharkov.ua
beam current monitoring is carried out by the magne-
toinductive sensor MIS and linear beam coordination
using the beam position monitor BMP [4]. A converter
assembly C consists of a tantalum plate that is placed
into an aluminium casing and is cooled by running wa-
ter. The filter F (5 aluminium plates) absorbs the part of
the electron beam that passed the converter assembly. A
braking photon flux after filter F measuring typical di-
mensions 150×500 mm is controlled by a wide-aperture
ionization chamber IC-W [5]. The capsules with sam-
ples being analyzed are placed just behind the IC-W.
In case when the electron energy exceeds 10 MeV
an isotropic stream of photoneutrons is emitted from the
converter together with braking photons. These neutrons
can be used also in the framework of the problem under
consideration.
3 RAW ANALYSIS
A RAW sample investigated is irradiated as a rule
together with a sample of the standard isotope content.
A concentration of this isotope in the sample is deter-
mined by comparison of the induced γ-activity of each
sample along the lines corresponding to the given iso-
tope (taking into account the mass of the specimen).
As an example, Fig. 2, 3 show the induced γ-spec-
trum for two samples of materials of the destroyed
ChPP Unit 4: fragments of the reactor concrete shield
(Fig. 2) and lava-like fuel-containing mass (LFCM),
which was formed in under-reactor premises as a result
of the accident (Fig. 3).
400 800 1200 1600 2000
channel number
10
100
1000
10000
co
un
ts
ju
vl
Sc
47
U
237
K
43
Ca47
511
K
43
Cs132
K
40
Ni
57
Na
24
Ca47
Na
22
Zr89
Rb84
Mn54
Ca47
Fig. 2. Induced γ-activity spectrum of concrete sample.
400 800 1200 1600 2000
channel number
1
10
100
1000
10000
co
un
ts
ju
vl
U
237
Eu154
U
237
511
Cs137
K
40
Eu154
Eu154
Sr
89
Eu154
Eu
154
Cs
134
Fig. 3. Spectrum of activated LFCM sample.
The spectrum in Fig. 2 includes the U-237 line. This
isotope was generated in the sample under the activation
process in the 238U(γ,n)237U reaction. This example
demonstrates the ability of the γ-activation method to
analyze the elements the identification of which is im-
possible by means of a traditional spectrometry meth-
ods. The quantitative data obtained concerning the ele-
ment content in the samples allow to carry out a correla-
tion analysis as well.
Fig. 3 demonstrates also the ability of the γ-activa-
tion method in analysis of the samples having their own
activity of a different nature. So, apart the lines of γ-ra-
diating nuclides (Eu-154, Cs-137 and Cs-134) there are
shown the lines of U-237 and Sr-89. The last result is
especially important because the γ-radiating nuclide Sr-
89 is created as a consequence of the β-radiating Sr-90
activation. It is known that an analysis of the γ-radiating
nuclides is realized technically simpler and for more
thick RAW layers (up to 30 cm or so).
The spectrum in Fig. 4 corresponds to the activated
U-238 dioxide water solution (with concentration
30 mg U-238/l). These data show that the γ-activation
method can be used also for the analysis of liquid RAW
with identification limit no more then 2 µg U-238 /l.
400 800 1200 1600 2000
channel number
1
10
100
1000
10000
co
un
ts
ju
vl
Sc47
U
237
511
Ca
47
Na
22
Zr
89
237U Kα
Fig. 4. γ-spectrum of the activated U-238 water so-
lution.
4 INVESTIGATION OF MATERIALS
FOR RAW DISPOSAL
It is known that during lasting disposal of the high-
level RAW or nuclear spent fuel a situation can arise
when the RAW immobilization matrix (including geo-
logical structure) will contact with ground water. Thus a
structure of “RAW-water-geological barrier” type origi-
nates. A radionuclide transport in such a structure deter-
mines a reliability of the RAW disposal. Besides, such
transport depends on the absorbed dose of radiation
from the RAW estimated as much as 108 Gy during dis-
posal period.
For research of radionuclide transport processes the
granite samples (that is considered as a perspective en-
vironment for disposal of long-lived RAW) were select-
ed. A piece of granite was cut into the specimens in the
form of blocks with the size of 10x10 mm in cross-sec-
tion and 30 mm in thickness. Each block was covered
with epoxy except for 10x10 surface.
Isotope Yb-169 was used as a γ-radiating nuclide-
tracer which is analogous to actinides in its chemical
properties. For this nuclide production under reac-
179
tion 168Yb(n, γ)169Yb the pellets of stable 168Yb2O3 were
irradiated with photoneutrons. Then the pellet was dis-
solved in concentrated HCl acid (0.2 ml) and finally the
aqueous solution with pH=1.8 was prepared.
The solution obtained (40 ml) together with the sam-
ple irradiated up to the given dose value (3⋅106...3⋅107
Gy) were placed into the thermostable flask. The latter
was heated with the water steam during 32 hours.
Then each specimen was washed in distillate water
during 24 hours and dried out at 60°C in the drying box.
Further the layers (2...50 µm) from the free surface of
the specimen were removed by means of precision
grinding. Material of the removed layers was used for
γ-spectrometry with the Ge(Li)-detector. Typical spec-
trum of the material removed of the sample, irradiated
with braking photons of LU-20 accelerator up to the
dose value 3 107 Gy is shown in Fig. 5. Spatial distribu-
tion of Yb-169 concentration within depth of the speci-
men is demonstrated in Fig.6. These results allowed to
determine a dose dependence of the radionuclide diffu-
sion as well as to find out its mechanism [7].
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. 5. γ-spectrum of irradiated granite (3⋅107 Gy).
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. 6. Distribution of Yb-169 into granite:
a – irradiated (3⋅107 Gy);
b – pristine state (granite with pegmatite structure);
c - pristine state (granite with uniform grain structure).
5 COMPUTER SIMULATION
A method of the computer simulation based onthe
standardized code GEANT (or other like it) can be used
for optimization of the sample irradiation conditions,
isotope generation modelling as well as for investigation
of metrological characteristics of the measuring sensors
under their interaction with radiation. Such code allows
to calculate these parameters with appropriate accuracy
(not less than 10%) considering real composition of the
radiation forming systems as well as of the irradiated
object [8].
6 CONCLUSIONS
1. High-current electron accelerator with the energy
range 10...30 MeV allows to solve effectively different
problems of radioactive waste management, in particu-
lar, operative analysis of the nuclide and element con-
tent of the RAW using the γ-activation method without
destruction of samples.
This method provides also an ability of distant-read-
ing analysis under automatic operation. Such facility is
important for large amount of samples to be analyzed,
for example, when extracting the RAW from Chernobyl
power plant unit 4.
2. A powerful (∼10 kW) electron accelerator is compa-
rable, by its absorbed dose rate ability, with the Co-60
source having the activity up to 1 MCi. This circum-
stance as well as a possibility to control the upper limit
of the braking photons spectrum allow to use linacs for
research of radiation and chemical stability of materials
intended for immobilization and disposal of RAW. The
radionuclides produced directly at linac can be used as
tracers in these investigations.
3. A linac provides the radiation of different intensity
and nature (accelerated electrons, bremsstrahlung and
photoneutrons) that gives a possibility of radiation test
of materials within the wide range of their operation
conditions.
Work is supported by STCU under contract N 1580.
REFERENCES
1 Toms M. Elaine. Photonuclear Activation Analysis
with Ge(Li) Detector. Nav. Res. Lab., USA, Rep.
7554, 1973.
2 T.Gozani et al. Measurement of Prompt and De-
layed Neutrons from Photofission // ANS Trans.
1968, v. 11, p. 659.
3 A.N.Dovbnya et al. Electron Linacs Based Radia-
tion Facilities of Ukrainian National Science Center
“KIPT” // Bul. of the Amer. Phys. Soc. 1997, v. 42,
N 3, p. 1391.
4 V.L.Uvarov, V.N.Boriskin et al. Calibration of
Electron Beam Measuring in Technological Linacs
// Proc. of ICALEPS’99, Trieste, Italy, 1999.
5 A.A.Butenko, S.P.Karasyov et al. Technological
Measuring Channel for Bremsstrahlung Monitoring
// Problems of Atomic Science and Technology. Is-
sue: Nuclear-Physics Research (35). 1999, v. 4,
p. 49.
6 A.Borovoi. Post-Accident Management of De-
stroyed Fuel from Chernobyl: Technologies Used
and Lessons Learned // IAEA. 1990, p. 15.
7 N.P.Dikiy, S.Yu.Sayenko, V.L.Uvarov, E.P.-
Shevyakova. Application of Nuclear-Physics Meth-
ods for Studying the Radionuclide Transport in
Granite Rocks // Problems of Atomic Science and
Technology. Issue: Nuclear-Physics Research (36),
2000, v. 2, p. 54. (in Russian).
8 S.P.Karasyov, S.V.Maryokhin, V.L.Uvarov et al.
On Computer Modelling of Primary Transducers in
Electron Radiation. Diagnostics // Proc. of
EPAC’98, Stockholm, June 1998, p. 134.
180
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| id | nasplib_isofts_kiev_ua-123456789-79252 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T18:49:47Z |
| publishDate | 2001 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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| spelling | Dikiy, N.P. Dovbnya, N.A. Sayenko, S.Yu. Uvarov, V.L. 2015-03-30T07:49:18Z 2015-03-30T07:49:18Z 2001 Electron linac application for characterization and disposal of radioactive waste / N.P. Dikiy, N.A. Dovbnya, S.Yu. Sayenko, V.L. Uvarov // Вопросы атомной науки и техники. — 2001. — № 3. — С. 178-180. — Бібліогр.: 8 назв. — англ. 1562-6016 PACS numbers: 29.17.+w, 28.41.Kw https://nasplib.isofts.kiev.ua/handle/123456789/79252 Rapid development of nuclear engineering, medicine and radiation technologies is accompanied by increase of the radioactive waste (RAW) including long-lived ones. A RAW handling assumes their element content and activity analysis (characterization), compacting and disposal. This problem is of ultimate importance after shutdown of Chornobyl nuclear power plant Unit 4. The activity of the RAW inside the unit is estimated as much as 20 MCi (mainly on account of the Cs-137). These circumstances ensure a necessity of elaboration of the especial methods for express-analysis of large RAW fluxes. An immobilization of the long-lived radionuclides is entailed in turn with the problem of their localization into stable matrix as well as placing in resistive to radiation containers and geological structures. The report contains an overview of methods elaborated in NSC KIPT for RAW characterization and investigation using the bremsstrahlung of the high-current electron accelerator of radiation stability of the artificial and natural barriers for radionuclide immobilization. Work is supported by STCU under contract N 1580. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Electron linac application for characterization and disposal of radioactive waste Применение линейного ускорителя электронов для определения характеристик и захоронения радиоактивных отходов Article published earlier |
| spellingShingle | Electron linac application for characterization and disposal of radioactive waste Dikiy, N.P. Dovbnya, N.A. Sayenko, S.Yu. Uvarov, V.L. |
| title | Electron linac application for characterization and disposal of radioactive waste |
| title_alt | Применение линейного ускорителя электронов для определения характеристик и захоронения радиоактивных отходов |
| title_full | Electron linac application for characterization and disposal of radioactive waste |
| title_fullStr | Electron linac application for characterization and disposal of radioactive waste |
| title_full_unstemmed | Electron linac application for characterization and disposal of radioactive waste |
| title_short | Electron linac application for characterization and disposal of radioactive waste |
| title_sort | electron linac application for characterization and disposal of radioactive waste |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79252 |
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