Radiation performances of a high current deuteron linac channel
The results of numerical simulation of spatial and time performances of the radiation field, which is produced by the induced activity in high-current deuteron linac elements, are given. Наведено результати чисельного моделювання просторових і часових характеристик радіаційного поля, що створюєтьс...
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Demchenko, P.O. Gussev, Ye.V. Shulika, M.G. Sotnikov, V.V. Voronko, V.A. 2015-03-31T19:22:06Z 2015-03-31T19:22:06Z 2004 Radiation performances of a high current deuteron linac channel / P.O. Demchenko, Ye.V. Gussev, M.G. Shulika, V.V. Sotnikov, V.A. Voronko // Вопросы атомной науки и техники. — 2004. — № 2. — С. 183-185. — Бібліогр.: 12 назв. — англ. 1562-6016 PACS: 29.17.+w, 29.27.-a https://nasplib.isofts.kiev.ua/handle/123456789/79391 The results of numerical simulation of spatial and time performances of the radiation field, which is produced by the induced activity in high-current deuteron linac elements, are given. Наведено результати чисельного моделювання просторових і часових характеристик радіаційного поля, що створюється наведеною активністю елементів сильнострумового прискорювача дейтронів. Приведены результаты численного моделирования пространственных и временных характеристик радиационного поля, создаваемого наведенной активностью в элементах сильноточного линейного ускорителя дейтронов. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Применение ускоренных пучков Radiation performances of a high current deuteron linac channel Радіаційні характеристики каналу сильнострумового прискорювача дейтронів Радиационные характеристики канала сильноточного линейного ускорителя дейтронов Article published earlier |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
| title |
Radiation performances of a high current deuteron linac channel |
| spellingShingle |
Radiation performances of a high current deuteron linac channel Demchenko, P.O. Gussev, Ye.V. Shulika, M.G. Sotnikov, V.V. Voronko, V.A. Применение ускоренных пучков |
| title_short |
Radiation performances of a high current deuteron linac channel |
| title_full |
Radiation performances of a high current deuteron linac channel |
| title_fullStr |
Radiation performances of a high current deuteron linac channel |
| title_full_unstemmed |
Radiation performances of a high current deuteron linac channel |
| title_sort |
radiation performances of a high current deuteron linac channel |
| author |
Demchenko, P.O. Gussev, Ye.V. Shulika, M.G. Sotnikov, V.V. Voronko, V.A. |
| author_facet |
Demchenko, P.O. Gussev, Ye.V. Shulika, M.G. Sotnikov, V.V. Voronko, V.A. |
| topic |
Применение ускоренных пучков |
| topic_facet |
Применение ускоренных пучков |
| publishDate |
2004 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Радіаційні характеристики каналу сильнострумового прискорювача дейтронів Радиационные характеристики канала сильноточного линейного ускорителя дейтронов |
| description |
The results of numerical simulation of spatial and time performances of the radiation field, which is produced by
the induced activity in high-current deuteron linac elements, are given.
Наведено результати чисельного моделювання просторових і часових характеристик радіаційного поля,
що створюється наведеною активністю елементів сильнострумового прискорювача дейтронів.
Приведены результаты численного моделирования пространственных и временных характеристик радиационного поля, создаваемого наведенной активностью в элементах сильноточного линейного ускорителя
дейтронов.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/79391 |
| citation_txt |
Radiation performances of a high current deuteron linac channel / P.O. Demchenko, Ye.V. Gussev, M.G. Shulika, V.V. Sotnikov, V.A. Voronko // Вопросы атомной науки и техники. — 2004. — № 2. — С. 183-185. — Бібліогр.: 12 назв. — англ. |
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2025-11-25T20:39:25Z |
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2025-11-25T20:39:25Z |
| _version_ |
1850525540597891072 |
| fulltext |
RADIATION PERFORMANCES OF A HIGH CURRENT DEUTERON
LINAC CHANNEL
P.O. Demchenko, Ye.V. Gussev, M.G. Shulika, V.V. Sotnikov, V.A. Voronko
National Science Center "Kharkov Institute of Physics and Technology", Institute of Plasma
Electronics and New Methods of Acceleration, Kharkov, Ukraine
E-mail: demchenko@kipt.kharkov.ua
The results of numerical simulation of spatial and time performances of the radiation field, which is produced by
the induced activity in high-current deuteron linac elements, are given.
PACS: 29.17.+w, 29.27.-a
1. INTRODUCTION
One of ion accelerator applications is production of
radioisotopes used in medicine, biology, and industry.
About 90% of radiological diagnostic examinations in
medicine are based on the usage of technetium-99m rа-
dionuclide, which is generated as a result of decay of a
parent radioisotope (generator) of molybdenum-99. The
basic method of 99Mo production is the irradiation of
high-enriched uranium-235 targets by neutrons in a nu-
clear reactor, and the subsequent chemical 99Mo extrac-
tion from high radioactive uranium fission products [1].
To exclude the problems with usage of nuclear reac-
tors [1], the alternative methods for producing
99Mo-99mTс have been offered, which are based on an ap-
plication both electron accelerators [1,2] and ion ones
[3,4]. In particular, for production of 99Mo in commer-
cial amount in a paper [4] it was offered to use a high-
current deuteron linac with the output energy of
W=14 MeV and average current of I=1 mA. If the accel-
erator operation time factor is 70%, the total 99Mo pro-
duction has to be about 1000 Ci/yr, when thin foils from
natural molybdenum are used as targets.
The essential accelerator performance is its radioac-
tive purity that is needed for the accelerator mainte-
nance. As the radiation purity criterion it is considered
that the equivalent dose rate at a distance of 1 m from an
accelerator axis should not exceed permissible dose rate
Kp in 1 hour after the accelerator switch off (radiation
cooling time) and after its long-term operation (activa-
tion time) [5]. In Ukraine for the personal, in correspon-
dence with the recommendation ICRP (International
Commission on Radiological Protection), the annual
dose limit is Dp=20 mZv. As the personal work time is
tp=1700 h/yr that corresponds to the permissible dose
rate of Kp=11.2 µZv/h [6].
The purpose of the present work is the simulation of
radiation field produced by induced activity in high-cur-
rent deuteron linac elements for different activation and
cooling times and finding on this basis of beam current
losses dI/dz along the accelerating channel satisfying to
radiation purity requirements (z is a longitudinal coordi-
nate along the accelerator).
2. THE INDUCED ACTIVITY GENERATION
The proposed deuteron linac [4] consists of an initial
section with radio frequency quadrupole focusing
(RFQ) of length 4.7 m and output deuteron energy of
W1=2 MeV, and two Н-cavity sections with the modi-
fied alternative phase focusing (MAPF), which lengths
are 3.14 m and 3.8 m, and the output energies of
W2=6.4 MeV and W3=14 MeV respectively. Between
sections the magnetic quadrupole lenses are situated for
matching of beam phase space characteristics with the
sectional performances. The total accelerator length is
14 m. The deuteron energy W1 of the RFQ-section is
taken below than the threshold of activation reactions.
Therefore the beam losses in the section are not limited
by the purity requirements.
The accelerating channel of MAPF1 and MAPF2
sections represents a set of copper drift tubes with aper-
ture radii varying from 1 cm at MAPF1 inlet up to
2.9 cm at MAPF2 output. The drift tubes are mounted in
a copper cylindrical cavity with the diameter of 40 cm,
and the wall thickness of 1 mm. Every MAPF section is
situated in a cylindrical vacuum liner of 12Х18Н10Т
stainless steel with 89 cm in diameter and the wall
thickness of 10 mm.
The linac activation is caused by nuclear reactions,
which arise when accelerated deuterons are bombarding
the drift tube surfaces. Accelerator activation processes
would be divided in 3 groups.
1. Deuteron activation of drift tube surfaces as a re-
sult of reactions with nuclei of natural copper iso-
topes of 63,65Cu. The generated rаdionuclides dis-
tributed in thin layer of l≤0.3 mm which is less
than the path length in copper of deuterons with
energy of W3=14 MeV.
2. Activation of drift tube volume by the secondary
fast neutrons, which result from
63,65Cu (d, xn)-channels of nuclear reactions, when
the deuterons are bombarding the copper drift
tubes.
3. Activation of the vacuum liner by secondary fast
neutrons, which were not absorbed by the copper
drift tubes.
Activation of the cavity walls by fast secondary neu-
trons would not be taken into account owing to the
small wall thickness.
For definition of nuclear reaction channels and their
cross-sections for deuterons in copper drift tubes, and
the secondary neutrons in drift tubes and in the liner,
and also γ-rays energies, which are emitted by rаdionu-
clide decay, decay constants, and γ-ray quantum yields
were used both the published data [7,9-11] and evaluat-
ed neutron data ENDF/B-VI and experimental nuclear
data EXFOR libraries of Brookhaven National Labora-
tory of USA. The isotope abundance ratios of copper
___________________________________________________________
PROBLEMS OF ATOMIC SIENCE AND TECHNOLOGY. 2004. № 2.
Series: Nuclear Physics Investigations (43), p.183-185. 183
mailto:demchenko@kipt.kharkov.ua
and multicomponent alloy of the liner have been deter-
mined using Ref. [8].
The accelerating section model, which was used for
calculations of induced activity dose rate, is shown in
Fig.1. It was supposed that the linear density of
deuteron beam losses dI/dz is a constant along the accel-
erating channel. Since the drift tube diameters are essen-
tially less than the distance from a channel element dz0
to a view point P(r,z), Fig.1, it is possible to consider
the source of γ-rays, emitted by the i- rаdionuclide de-
cay in the drift tubes as linear one with linear activity
Ach(z). The linear activity Ach(z) is the function of z-coor-
dinate, owing to monotonous deuteron energy growth
along the channel.
It was also supposed, that the activity uniformly dis-
tributed over the liner azimuth, and linear activity of the
liner ALi(z) depends only on the longitudinal z-coordi-
nate.
As γ–rays are emitted isotropically by a rаdionuclide
of the i-kind, and if the radiation absorption is neglected
in drift tubes and the liner, then the dose rate in P(r z)
point, produced by activations of drift tubes of Kchi(r,z)
and the liner of KLi(r,z) may be presented as [12]:
∫ +−
Γ=
L
chi
iich
rzz
A
zrK
dzz
0
22
0
00
)(
)(
),(
δ , (1)
∫ −++−+−
Γ= δ
L
Li
iLi
RrRrzzzz
zA
zrK
dz
0
22
0
22
0
22
0
4
0
00
2 )()()()(
)(
),( , (2)
where Γδ i is the air kerma constant for the i-radionuclide
[12], L is the accelerating section length. The integrand
in (2) is the dose rate produced by a liner elementary
ring of R0 radius and dz0 length, Fig.1.
The total dose rate K(r,z) is the sum of partial dose
rates produced by all i-radioisotopes, generated in drift
tubes and the liner:
( ) ( ) ( )∑ +=
i
Lichi
zrKzrKzrK ,,, . (3)
The linear activity A(d)
chi(z), generated by the drift
tube deuteron bombarding, is given by the expression:
( ) ( )( )[ ] )exp()exp(//)()(
ciaiii
d
chi ttdzdIWBzA λ−λ−−λ= 1 , (4)
where Bi(W) is the i-rаdionuclide yield due to deuteron
reactions with copper [10], W=W(z) is the deuteron en-
ergy, λi is the i-rаdionuclide decay constant [9], ta is the
activation time, tc is the radiation cooling time.
To define the activation of drift tubes ( )zA n
chi
)( and
the liner ( )zA n
Li
)( by the secondary neutrons it is neces-
sary to know the distribution of neutron source strength
Sn(z) (n/s m) along the accelerator. If one considers that
the neutron source is linear one and is located along the
system axis, then the source strength Sn(z) is:
( ) ( )∑ λ=
i
iin WBipdzdIzS /)/( , (5)
where the summing is made over all Bi(W) yields for re-
actions of 63,65Cu(d,n) and 63,65Cu(d,2n); pi=1 or 2 ac-
cordingly for (d,n) or (d,2n) reactions. Then the drift
tubes linear activity ( )zA n
chi
)( will be given as:
( ) [ ] )exp()exp()()(
ciai
i
sciinn
chi ttdzS
A
NzA λ−λ−−
λ
ρ ησ= 10 , (6)
where N0 is the Avogadro number, A is the copper mass
number, ρ is the copper density, ηi is the abundance ra-
tio of the i-kind isotope in copper, σi is the activation
cross-section of this isotope by neutrons, dsc is the mean
neutron scattering length in copper.
Since the neutron source strength Sn(z) is known, it
is possible to calculate the liner linear activity of
( )zA n
Li
)( , produced by the secondary neutron irradiation.
For that the total neutron flux through the liner elemen-
tary ring, Fig.1, irradiated by the linear neutron source
Sn(z) of L length, was calculated.
The neutron activation cross-sections σi(En) are
functions of neutron energy En. In the present work the
energy distribution of the fast neutrons, generated in
Cu(d,xn) reactions, was not examined. For linac activa-
tion calculations the maximal σi values for the neutron
energy range of 0,1≤En≤20 МэВ have been used (upper
estimation). The integrals (1) and (2) had been taken nu-
merically.
3. RESULTS OF SIMULATION
The dose rate map of the radiation field, produced
by induced activity of the linac in tc=1 h after its switch
off, and for the activation time ta=1 yr, is shown in
Fig. 2. The equivalent dose rate isolines K(r, z)=const
are normalized (%) to the dose rate Kc in the critical
point Pc(1 m; 13,65 m), located 1 m apart from the ac-
celerator axis (z=0 corresponds to the RFQ-section in-
put). In this point the dose rate Kc is maximal one. As it
follows from Fig.2, for the constant beam losses dI/dz
along the channel, the maximal dose rate area is at the
end of the accelerator. It is caused by the growth of rа-
dionuclide yields Bi(W) with increasing of deuteron en-
ergy W(z) and opening additional channels of radioiso-
tope generation.
The spatial distribution of reduced dose rate
K(r,z)/Kc, Fig.2, does not depend on the beam linear
losses dI/dz, and is the important radiation characteris-
r
0 z
R0
z0
P(r,z)
1
2
dz0
r
z L
Fig.1. Model of accelerating section for simulation of induced activity dose rate: 1- accelerating channel of drift
tubes, 2- vacuum liner
184
tics of the accelerator. The absolute value of dose rate
K(r,z,ta,tc) depends on the times of activation ta, and
cooling tc, and is proportional to the beam losses dI/dz.
In Fig.3 the dose rates Kc in the critical point Pc, re-
duced to the beam losses dI/dz are given as the function
of cooling time tc, and for different activation time ta.
For the short activation time ta the equilibrium con-
centration is achieved for short-lived rаdionuclides.
Therefore the activity decreases quickly after the accel-
erator switch off (ta=1 h), Fig.3. For long activation time
the essential contributions in the total activity give the
long-lived rаdionuclides, which activity decreases slow-
ly with growth of cooling time tc.
On the base of the dependences, Figs.2 and 3, the
equivalent dose rate would be calculated in any space
point, and for different activation ta and cooling tc times,
and beam losses dI/dz. In particular, from Figs. 2 and 3
it follows that the dose rate Kc in the critical point Pc
will not exceed the permissible dose rate Kp=11.2 µZv/h
through tc=1 hour after the accelerator switch off, if the
beam losses dI/dz≤3.7⋅10-8 A/m, and long continuous
linac operation (ta≥1 yr).
In conclusion it needs to mark, that the main contri-
bution to the dose rate gives the copper drift tube activa-
tion by deuterons. In Fig.4 the dose rate distributions
along the line, which is parallel to the accelerator axis
and crosses the critical point Pc, (line AB, Fig.2) are
shown, which are produced by: drift tube deuteron acti-
vation - 1, drift tube neutron activation - 2, liner neutron
activation - 3 and the total dose rate - 4. As it follows
from Fig. 4, the contribution to the total dose rate of ac-
celerator activation by the secondary neutrons does not
exceed 17 %.
REFERENCES
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tem of 99mTc Production Based on Distributed Elec-
tron Accelerators and Thermal Separation // Nucle-
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2. N.P. Dikiy, A.N. Dovbnya, V.L. Uvarov. Develop-
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3. P.A. Demchenko, V.A. Voronko, V.Ya. Migalenya
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4. P.A. Demchenko, Ye.V. Gussev, M.G. Shulika. A
Channel of High Current Deuteron Linac with Low
Radiation Losses // Problems of Atomic Science
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___________________________________________________________
PROBLEMS OF ATOMIC SIENCE AND TECHNOLOGY. 2004. № 2.
Series: Nuclear Physics Investigations (43), p.183-185.
Fig. 2. Dose rate map of activated deuteron linac for ta=1 year and tc=1 hour
Fig. 3. Dependence of equivalent dose rate reduced to beam losses on cooling time tc and for different activation
time ta in the critical point Pc
Fig. 4. Dose rate distributions along accelerator apart 1 m from axis: 1 – drift tube deuteron activation, 2 – drift
tube neutron activation, 3 - liner neutron activation, 4 – total
185
12. V.F. Kozlov. Spravochnik po radiatsionnoj be-
zopasnosti. M.: Energoatomizdat, 1987, p.191 (in
Russian).
РАДИАЦИОННЫЕ ХАРАКТЕРИСТИКИ КАНАЛА СИЛЬНОТОЧНОГО ЛИНЕЙНОГО УСКОРИ-
ТЕЛЯ ДЕЙТРОНОВ
В.А. Воронко, Е.В. Гусев, П.А. Демченко, В.В. Сотников, Н.Г. Шулика
Приведены результаты численного моделирования пространственных и временных характеристик радиа-
ционного поля, создаваемого наведенной активностью в элементах сильноточного линейного ускорителя
дейтронов.
РАДІАЦІЙНІ ХАРАКТЕРИСТИКИ КАНАЛУ СИЛЬНОСТРУМОВОГО ПРИСКОРЮВАЧА ДЕЙ-
ТРОНІВ
В.О. Воронко, Є.В. Гусєв, П.О. Демченко, В.В. Сотніков, М.Г. Шуліка
Наведено результати чисельного моделювання просторових і часових характеристик радіаційного поля,
що створюється наведеною активністю елементів сильнострумового прискорювача дейтронів.
186
В.А. Воронко, Е.В. Гусев, П.А. Демченко, В.В. Сотников, Н.Г. Шулика
В.О. Воронко, Є.В. Гусєв, П.О. Демченко, В.В. Сотніков, М.Г. Шуліка
|