Estimation of radiation risks under photonuclear production of 67Cu and 99Mo isotopes
The activated bremsstrahlung converter and isotopic target are the main sources of radiation hazard in the isotope production at electron accelerators. In experiments at the NSC KIPT accelerators KUT-30 and LU-40m, intended to produce 99Mo and 67Cu isotopes in the targets based on natural Mo and Zn,...
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| Цитувати: | Estimation of radiation risks under photonuclear production of 67Cu and 99Mo isotopes / M.I. Ayzatskiy, A.N. Dovbnya, A.Eh. Tenishev, A.V. Torgovkin, V.L. Uvarov, V.A. Shevchenko, B.I. Shramenko, D. Ehst // Вопросы атомной науки и техники. — 2010. — № 3. — С. 130-134. — Бібліогр.: 12 назв. — англ. |
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irk-123456789-170312011-02-19T12:03:46Z Estimation of radiation risks under photonuclear production of 67Cu and 99Mo isotopes Ayzatskiy, M.I. Dovbnya, A.N. Tenishev, A.Eh. Torgovkin, A.V. Uvarov, V.L. Shevchenko, V.A. Shramenko, B.I. Ehst, D. Применение ускорителей The activated bremsstrahlung converter and isotopic target are the main sources of radiation hazard in the isotope production at electron accelerators. In experiments at the NSC KIPT accelerators KUT-30 and LU-40m, intended to produce 99Mo and 67Cu isotopes in the targets based on natural Mo and Zn, the output devices were exposed to radiation. Induced activities of the tantalum converter, of targets and cooling water were measured. The exposure dose rates provided by each element and the activity decrease after the exposure were determined. Основными источниками радиационной опасности при производстве изотопов на ускорителе электронов являются активированные конвертер тормозного излучения и изотопная мишень. На ускорителях КУТ-30 и ЛУ-40М ННЦ ХФТИ проведено облучение экспериментальных выходных устройств для получения изотопов 99Мо и 67Сu в мишенях на основе природных Мо и Zn. Исследована наведенная активность конвертера из тантала, мишеней и охлаждающей воды. Определена мощность экспозиционной дозы, создаваемая каждым элементом, а также скорость ее снижения после облучения. Основними джерелами радіаційної небезпеки при виробництві ізотопів на прискорювачі електронів є активовані конвертер гальмівного випромінювання та ізотопна мішень. На прискорювачах КУТ-30 і ЛУ-40M ННЦ ХФТІ проведено опромінювання експериментальних вихідних пристроїв для отримання ізотопів 99Мо і 67Сu в мішенях на основі природних Мо і Zn. Досліджена наведена активність конвертера з танталу, мішеней і води, що охолоджує. Визначена потужність експозиційної дози, що створюється кожним елементом, а також швидкість її зниження після опромінення. 2010 Article Estimation of radiation risks under photonuclear production of 67Cu and 99Mo isotopes / M.I. Ayzatskiy, A.N. Dovbnya, A.Eh. Tenishev, A.V. Torgovkin, V.L. Uvarov, V.A. Shevchenko, B.I. Shramenko, D. Ehst // Вопросы атомной науки и техники. — 2010. — № 3. — С. 130-134. — Бібліогр.: 12 назв. — англ. 1562-6016 http://dspace.nbuv.gov.ua/handle/123456789/17031 en Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
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English |
| topic |
Применение ускорителей Применение ускорителей |
| spellingShingle |
Применение ускорителей Применение ускорителей Ayzatskiy, M.I. Dovbnya, A.N. Tenishev, A.Eh. Torgovkin, A.V. Uvarov, V.L. Shevchenko, V.A. Shramenko, B.I. Ehst, D. Estimation of radiation risks under photonuclear production of 67Cu and 99Mo isotopes |
| description |
The activated bremsstrahlung converter and isotopic target are the main sources of radiation hazard in the isotope production at electron accelerators. In experiments at the NSC KIPT accelerators KUT-30 and LU-40m, intended to produce 99Mo and 67Cu isotopes in the targets based on natural Mo and Zn, the output devices were exposed to radiation. Induced activities of the tantalum converter, of targets and cooling water were measured. The exposure dose rates provided by each element and the activity decrease after the exposure were determined. |
| format |
Article |
| author |
Ayzatskiy, M.I. Dovbnya, A.N. Tenishev, A.Eh. Torgovkin, A.V. Uvarov, V.L. Shevchenko, V.A. Shramenko, B.I. Ehst, D. |
| author_facet |
Ayzatskiy, M.I. Dovbnya, A.N. Tenishev, A.Eh. Torgovkin, A.V. Uvarov, V.L. Shevchenko, V.A. Shramenko, B.I. Ehst, D. |
| author_sort |
Ayzatskiy, M.I. |
| title |
Estimation of radiation risks under photonuclear production of 67Cu and 99Mo isotopes |
| title_short |
Estimation of radiation risks under photonuclear production of 67Cu and 99Mo isotopes |
| title_full |
Estimation of radiation risks under photonuclear production of 67Cu and 99Mo isotopes |
| title_fullStr |
Estimation of radiation risks under photonuclear production of 67Cu and 99Mo isotopes |
| title_full_unstemmed |
Estimation of radiation risks under photonuclear production of 67Cu and 99Mo isotopes |
| title_sort |
estimation of radiation risks under photonuclear production of 67cu and 99mo isotopes |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2010 |
| topic_facet |
Применение ускорителей |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/17031 |
| citation_txt |
Estimation of radiation risks under photonuclear production of 67Cu and 99Mo isotopes / M.I. Ayzatskiy, A.N. Dovbnya, A.Eh. Tenishev, A.V. Torgovkin, V.L. Uvarov, V.A. Shevchenko, B.I. Shramenko, D. Ehst // Вопросы атомной науки и техники. — 2010. — № 3. — С. 130-134. — Бібліогр.: 12 назв. — англ. |
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____________________________________________________________
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2010. № 3.
Series: Nuclear Physics Investigations (54), p.130-134.
130
ESTIMATION OF RADIATION RISKS UNDER PHOTONUCLEAR
PRODUCTION OF 67Cu AND 99Mo ISOTOPES
M.I. Ayzatskiy, A.N. Dovbnya, A.Eh. Tenishev, A.V. Torgovkin, V.L. Uvarov,
V.A. Shevchenko, B.I. Shramenko, D. Ehst1
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine;
1Argonne National Laboratory, USA
E-mail: bshram@kipt.kharkov.ua
The activated bremsstrahlung converter and isotopic target are the main sources of radiation hazard in the iso-
tope production at electron accelerators. In experiments at the NSC KIPT accelerators KUT-30 and LU-40m, in-
tended to produce 99Mo and 67Cu isotopes in the targets based on natural Mo and Zn, the output devices were ex-
posed to radiation. Induced activities of the tantalum converter, of targets and cooling water were measured. The
exposure dose rates provided by each element and the activity decrease after the exposure were determined.
PACS: 06.60.Mr, 07.85.-m, 07.88+y, 81.30.Hd, 81.70.Jb
1. INTRODUCTION
The 99Mo and 67Cu isotopes range among the most
demandable in nuclear medicine. Thus, the world produc-
tion of 99Mo, which is the generator of the basic diagnos-
tic radionuclide 99mTc, currently exceeds 300 000 Ci per
annum and is practically all-based on 235U fission in nu-
clear reactors [1]. This method provides the high-yield
production of 99Mo and a high specific activity (up to
104 Ci/g), but leads to a great amount of radioactive
waste [2]. The technology using the radiative capture
reaction 98Mo(n,γ)99Mo appears to be safer [3]. However,
in this case the yield and specific activity of the target
turn out to be a few orders of magnitude lower, and be-
sides, the method also calls for the use of a nuclear reac-
tor. Taking into account the ecological effects of reactor
technologies as well as the problem of fissile material
nonproliferation, it becomes currently central to create
alternative methods of 99Mo production, one of them be-
ing the photonuclear method [4].
In turn, the 67Cu isotope is considered as a most prom-
ising beta-emitter for radioimmunotherapy [5]. At present
it is mainly produced at high-current proton accelerators
through the use of the 68Zn(p,2p)67Cu reaction. The reali-
zation of the process also involves the production of a
considerable quantity of “hot” impurities [6].
As preliminary studies have shown, the production
of the mentioned radionuclides by the 100Mo(γ,n)99Mo
and 68Zn(γ,p)67Cu reactions can provide the yield of
desired isotopes, which is comparable with that pro-
vided by other technologies, but with a substantially less
quantity of radioactive waste produced [7, 8]. In this
case, the high-current electron accelerator is an essen-
tially more reliable, safe and inexpensive device than
the nuclear reactor or the heavy-particle accelerator with
the same beam energy and intensity.
Here we analyze the main sources of radiation haz-
ards and estimate their level at different stages of pho-
tonuclear production of 99Mo and 67Cu isotopes.
2. RADIATION SOURCES
AT PHOTONUCLEAR PRODUCTION
OF ISOTOPES
The basis for the technology under consideration is
the activation of the isotopic target by means of high-
energy bremsstrahlung resulting from accelerated elec-
tron beam conversion. The process can be realized di-
rectly in the target itself or in a separate device–
converter placed between the exit window of the accel-
erator and the target. The last variant is more preferable,
because it provides a high specific activity of the target,
and also makes it possible to reduce the radiation power
absorbed in the target [9].
The converter generally corresponds to one or sev-
eral plates, which are made from the material having a
high atomic number (e.g., Ta, W or Pb) and are cooled
with a flowing water [10]. So, in the general case, the
output devices of the electron accelerator operated in the
mode of isotope production include the exit window
with tandem converter and target units behind it.
The exit window of the high-current electron accel-
erator usually consists of two thin foils (Al or Ti), be-
tween which water is circulated. The contribution of this
unit to the radiation hazard can be neglected in the esti-
mation.
On interaction of accelerated electrons with the con-
verter, owing to (γ,n) reactions, apart from bremsstrah-
lung, a quasi-isotropic photoneutron flux is generated.
For example, the main reactions that occur in the W
converter are 182W(γ,n)181W and 186W(γ,n)185W, in the
Ta converter this is the reaction 181Ta(γ,n)180Ta, etc. In
other words, in the process of target activation the con-
verter unit is the source of mixed high-intensity γ,n-
radiation [11]. On completion of the activation, the ra-
diation hazard is mainly contributed by the residual ac-
tivity of the converter and the target. In this case, their
dose rates and the activity decrease are determined by
the activation mode and the element composition of the
devices.
3. DOSE CHARACTERISTICS
OF RESIDUAL ACTIVITY OF OUTPUT
67Cu-PRODUCTION DEVICES
3.1. EXPERIMENTAL CONDITIONS
For experimental estimation of the radiation back-
ground at photonuclear production of the 67Cu isotope, a
target device shown in Fig.1 has been used. It includes a
stainless steel casing with a thin entrance window. In-
side the casing, there is a four-plate Ta converter, each
plate being 1 mm thick. In the process of irradiation the
mailto:bshram@kipt.kharkov.ua
converter is cooled by water (the total thickness of wa-
ter spacings is 5 mm). Behind the converter, there is a
Ti capsule, ~ 52.3 g in weight, which accommodates the
isotopic target. The capsule is sealed with a stainless
steel cap, ~ 10.5 g in weight. Directly in front of the
converter and immediately behind it there were placed
two sets of Ø40mm foils (Mo, Ni, Sn) to measure the
electron beam profile (Mo1, Ni1, Sn1) and the
bremsstrahlung profile (Mo2, Ni2, Sn2) by the photonu-
clear converter technique [12].
e-
Mo1
Ni1
Sn1
Mo2
Ni2
Sn2
Ta
Znwater
water
plug,ss
capsule,Ti
Fig.1. Target device design
To determine the contribution to the radiation back-
ground from each target element (Zn, Ti, stainless
steel), the following technique was used. Two similar Ti
capsules were taken. The first capsule housed 18 Zn
discs (Ø=20 mm, h=1 mm), and also 3 molybdenum
foils (Ø=20 mm, δ=0.1 mm) at the beginning of the as-
sembly (Mo-1), in its middle (Mo-10) and at the end
(Mo-18). This approach enables one to determine the
“utilization factor” of bremsstrahlung that is in contact
with the Mo foil and Zn disc having the number i ac-
cording to the activity ratio AMo-i/AMo2 (see Fig.1).
In the second capsule, an Al cylinder (Ø=20 mm,
h=19 mm) was put instead of zinc. Under the same ex-
posure conditions of each capsule, this permitted us to
estimate the zinc contribution to the residual activity of
both the target and the casing for two variants (Ti or Al)
of target casing fabrication. The targets were activated
at the accelerator LU-40m operated in the 56 MeV,
5 μA mode. Each capsule was irradiated for 1 hour.
3.2. MEASUREMENTS AND RESULTS
Thirty minutes after the end of irradiation of the first
capsule (with zinc) the exposure dose rate (EDR) of the
residual activity of the target device was measured. At a
distance of 0.5 m the EDR was measured to be
200 mR/h, while the EDR of the capsule with zinc,
taken out of the target device, was found to be
189 mR/h at the same distance. Thus, the capsule with
zinc appears the main dose contributor of the target de-
vice.
In the following 7 days the EDRL of the capsule with
zinc was measured at distances of L cm that provided
the correspondence of the measured dose rate to the
operative range of the dosimeter-radiometer. The meas-
ured values were reduced to the standard distance
L=10 cm by the formula:
EDR10 = EDRL(L/10)2 ,
and were also normalized to the average beam current
value of 1 μA and the exposure time of one hour (Fig.2).
After irradiation of the second capsule at the same con-
ditions, it was extracted from the target device and dis-
assembled into components (Ti casing, cap and Al cyl-
inder). Then, with the use of the same technique, dose
rate measurements were performed for each component
(Fig.3).
The comparison between the data in Figs.2 and 3
shows that immediately after EOB the capsule with zinc
mainly contributes to the EDR of the target device.
0,01 0,1 1 10
0,1
1
10
100
1000
ED
R
10
m
R
/h
/(m
kA
*h
)
Time after irradiation, day
Fig.2. Exposure dose rate (EDR10) of the capsule with
zinc versus time after EOB (day)
0,01 0,1 1
1E-3
0,01
0,1
1
10
100
Ti
StSteel
AlED
R
10
m
R
/h
/(m
kA
*h
)
Time after irradiation, day
Fig.3. Exposure dose rates (EDR10) of capsule
components versus time after EOB (day)
In this case, the radiation background within the first
2-3 hours after the irradiation is determined by compara-
tively short-lived isotopes Zn-63 and Zn-62 having the
half-lives of 38 min and 9.3 hour, respectively. During
the first day the main activity of the target is created by
Zn-69m and Cu-67 isotopes; then in the following ~ 7
days, it is Cu-67 and Zn-65 that present the main dose-
producing factor, and later - only Zn-65 (T1/2=243 days).
The EDR is contributed by Sc-46, Sc-47 and Sc-48
isotopes (for the Ti capsule), Ni-56, Ni-57, Co-57 and
Co-58 isotopes (for the stainless steel cap), and by iso-
topes produced on the impurities (Si, Mg, etc.) for the
Al target. If within 2 or 3 hours after irradiation the
EDR of the Zn-filled capsule is more than order of
magnitude higher than the total EDR of other capsule
elements, then in a day of “cooling”, their EDR values
appear comparable.
131
The present data enable one to choose the optimum
regime of irradiated target handling, and also to predict
dose characteristics of a similar target device activated
at other conditions. D.Ehst has independently calculated
the EDR10 variations after irradiation of a similar Zn-
containing capsule and its separate components for elec-
tron energy of 55 MeV and compared the results with
the experimental data (see Figs.2 and 3) reduced to a
beam current of 31.8 μA (this corresponding to the RPI
(USA) accelerator conditions) and 1 hour of exposure.
The obtained results are presented in Fig.4.
1
10
100
1000
10000
0.01 0.1 1 10 100
Time after irradiation (d)
Ex
po
su
re
(m
R
/h
)
Fig.4. Calculated EDR10
versus time after EOB (in days)
under RPI conditions: a – Zn-containing capsule,
b – capsule components (Ti+cap). ∆ – experiment
(see Figs.2, 3); □, ◊ – calculation of D. Ehst
(□ – upper limit of estimates, ◊ – lower limit of estimates)
As it follows from Fig.4, the measured and calcu-
lated EDR10 of the activated Zn-containing capsule and
its components are in fair agreement.
4. MEASUREMENT
OF DOSE CHARACTERISTICS
OF 99Mo PRODUCTION DEVICES
4.1. TARGET COMPOSITIONS
AND IRRADIATION CONDITIONS
To measure the radiation background of photonu-
clear 99Mo production devices, two Mo targets of natu-
ral composition, each weighing 65.07 g, were used. The
target was an assembly of 10 discs, each being ~ 2 mm
in thickness and 19 mm in diameter. The target was
placed directly behind the converter consisting of four
interspaced 1-mm thick tantalum plates. During irradia-
tion the converter and the target were cooled with water
at a flow rate of 10 l/min. Molybdenum foils-witnesses
of diameter 19 mm were inserted between the Mo discs
in the target (Mo-19(1)…Mo-19(10)). In front of the
target, there were placed Ø40 mm Mo and Sn foils-
witnesses. They were used to determine the
bremsstrahlung beam profile (see Fig.2). In addition,
measurements of activities AMo-19(1)…AMo-19(10) enable
one to determine the bremsstrahlung intensity variation
in depth of the target.
The two targets were irradiated in the accelerator
KUT-30 at operating conditions of (36 MeV, 260 μA),
one target for 10 min. and the other − for 60 min.
4.2. DOSE CHARACTERISTICS OF RESIDUAL
TARGET-DEVICE ACTIVITIES
After 10 minutes after turn-off of the accelerator op-
erated for 10 minutes, the dose rate at the distance
L=1m from the target device was measured to be
6800 μSv/h (≈680 mR/h), that on the standard distance
L=10 cm basis being 68 R/h. This EDR is formed by the
residual activities of the converter, the target and the
remaining equipment. After irradiation, the two Mo
targets were extracted from the target device for do-
simetric measurements. Thus, in 10 min after irradia-
tion, the EDR10 of the first target was 32.2 R/h, and in a
day it decreased by a factor of 370. In the following
period of 1 to 8.8 days the two targets showed a similar
fall-off in the EDR due to the decay of Mo-99 isotope.
Fig.5 shows the EDR10 of the second target as a function
of time after irradiation.
High EDR levels of Mo targets of natural composi-
tion at the first hours after irradiation are due to 97 Nb
isotope (T1/2=72 min). A further EDR decrease is de-
termined by the decay of the desired isotope 99Mo
(T1/2=66 hours).
Fig.6 shows the EDR versus time after EOB for the
Ta converter. The dose rate is mainly determined by the
isotopes 180Ta (T1/2=8.12 h) and 182Ta (T1/2=115 days).
Fig.5. Target-device dose rate versus time after
irradiation (day)
Fig.6. Ta-converter dose rate versus time after
irradiation (day)
The converter activity in 4.5 days after irradiation
and on was mainly due to 182Ta resulting from the radia-
tive capture reaction 181Ta(n,γ)182Ta. In particular, in
9 days after 10-hour exposure of the Ta converter to the
beam having an average current of 240 μA at an elec-
tron energy of 36 MeV the EDR at distance of 0.5 m
made up 5.4 mR/h. With long exposure of the Ta con-
verter the EDR value will increase practically linearly
with time. This fact limits the use of Ta as a converter
material in photonuclear production of isotopes.
In realization of the present technology for different
periods of target activation it is of interest to make a
forecast of the ratio of the desired isotope activity to the
EDR provided by the target device. The knowledge of
generated partial activities of desired (67Cu or 99Mo) and
accompanying (62Zn, 63Zn, 69mZn or 97Nb) isotopes
makes it possible to calculate the target EDR for any
activation period. Thus Table 1 lists the measured spe-
cific activities A of the 67 Cu and 99Mo isotopes (reduced
to the irradiation termination), the corresponding EDR
values of natural Mo and Zn targets (normalized to 1 g
of target weight), and also, the predicted values of the
parameters after 24 and 48 hours of irradiation, respec-
tively. It can be seen that the A/EDR ratio substantially
increases with increasing time of exposure.
132
133
Table 2 gives the predicted activities of 67Cu and
99Mo isotopes, reduced to the termination of irradiation
in the (36 MeV, 100 μA) mode, and also, the corre-
sponding EDR values for enriched 68Zn (100%) and
100Mo (100%) targets, 40 and 60 g in weight, respec-
tively, at different time of exposure.
Table 1
Reduced yields of 67Cu 99Mo, target EDRs
Time
of ex-
posure,
hours
A - desired-
isotope specific
activity,
μCi/g·100μA·h
Target
EDR10,
mR/h·g
A/EDR10
of the target,
μCi/
g·100μA·h/m
R/h·g
67Cu
1 68 6,50 10,4
24 1500 83,53 17,9
48 2530 110,79 22,8
99Mo
1 271 51,37 5,27
24 5810 212,87 27,3
48 10320 295,1 34,9
Table 2
Activity and EDR10 of enriched targets
Time of
exposure,
hours
Desired isotope
activity,
Ci
Target
EDR10,
R/h
67Cu
1 0,0144 0,08
24 0,318 1,77
48 0,538 2,98
99Mo
1 0,169 3,08
24 3,63 65,88
48 6,45 117,02
5. COOLING WATER ACTIVATION
To estimate the activity of water that cools the target
device, its 100 ml aliquot was taken 30 min after the
irradiation of Mo was completed.
The gamma-spectrometry analysis has indicated the
presence of 24Na and 99Mo isotopes in the water. This
can be attributed to their leaching from structural ele-
ments, and also to activation of water impurities. The
isotope 15O was not detected, because by the measure-
ment time it had fully decayed.
CONCLUSIONS
1. The undertaken experiments have indicated the
main background radiation sources of target devices for
67Cu and 99Mo/99mTc isotope production. The measured
EDRs are given in universal units (mR/h/(μA·h) and are
reduced to the standard distance from the radiation
source. This enables one to predict the radiation envi-
ronment in the neighborhood of the target device at dif-
ferent modes of its irradiation. The comparison between
our experimental data and the calculations by D. Ehst
(USA) for the RPI accelerator conditions shows their
good agreement.
2. As regards the ratio of the desired isotope (67Cu
and 99Mo) activity to the EDR of natural-composition
targets, the modes of exposure for much more than 1h
are preferred, because in this case the activities of more
short-lived impurity isotopes (62Zn, 63Zn and 97Nb) get
saturated.
3. The use of enriched 68Zn- and 100Mo-based targets
not only increases the yield of the desired isotopes 67Cu
and 99Mo/99mTc, but also substantially reduces the EDR
of the targets just after EOB.
4. Of the structural materials considered, the radia-
tion background criterion points to Al (without Fe and
Mn impurities) as most preferable. At the same time, the
exposure of Al in contact with water may be accompa-
nied by the formation of a great amount of Al2O3.
ACKNOWLEDGEMENTS
The authors express gratitude to G.D. Pugachev and
A.V. Mazilov for their valuable advices.
The work has been done partially due STCU grant
#P228.
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Статья поступила в редакцию 07.09.2009 г.
ОЦЕНКА РАДИАЦИОННЫХ РИСКОВ ПРИ ФОТОЯДЕРНОМ ПРОИЗВОДСТВЕ
ИЗОТОПОВ 67Сu И 99Мо
Н.И. Айзацкий, А.Н. Довбня, А.Э. Тенишев, А.В. Торговкин, В.Л. Уваров, В.А. Шевченко, Б.И. Шраменко,
D. Ehst
Основными источниками радиационной опасности при производстве изотопов на ускорителе электронов
являются активированные конвертер тормозного излучения и изотопная мишень. На ускорителях КУТ-30 и
ЛУ-40М ННЦ ХФТИ проведено облучение экспериментальных выходных устройств для получения изото-
пов 99Мо и 67Сu в мишенях на основе природных Мо и Zn. Исследована наведенная активность конвертера
из тантала, мишеней и охлаждающей воды. Определена мощность экспозиционной дозы, создаваемая каж-
дым элементом, а также скорость ее снижения после облучения.
ОЦІНКА РАДІАЦІЙНИХ РИЗИКІВ ПРИ ФОТОЯДЕРНОМУ ВИРОБНИЦТВІ
ІЗОТОПІВ 67Сu І 99Мо
М.І. Айзацький, А.М. Довбня, А.Е. Тєнішев, О.В. Торговкін, В.Л. Уваров, В.А. Шевченко, Б.І. Шраменко,
D. Ehst
Основними джерелами радіаційної небезпеки при виробництві ізотопів на прискорювачі електронів є ак-
тивовані конвертер гальмівного випромінювання та ізотопна мішень. На прискорювачах КУТ-30 і ЛУ-40M
ННЦ ХФТІ проведено опромінювання експериментальних вихідних пристроїв для отримання ізотопів 99Мо і
67Сu в мішенях на основі природних Мо і Zn. Досліджена наведена активність конвертера з танталу, мішеней
і води, що охолоджує. Визначена потужність експозиційної дози, що створюється кожним елементом, а та-
кож швидкість її зниження після опромінення.
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