Radiation protection of a complex of high-current distributed electron accelerators
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| Опубліковано в: : | Вопросы атомной науки и техники |
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| Дата: | 2001 |
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| Формат: | Стаття |
| Мова: | Англійська |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
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| Назва журналу: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Цитувати: | Radiation protection of a complex of high-current distributed electron accelerators / G.D. Pugachev, D.G. Pugachev, O.A. Repichov, V.S. Shestakova, A.V. Mazilov, T.A. Semenets // Вопросы атомной науки и техники. — 2001. — № 3. — С. 194-195. — Бібліогр.: 10 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859637998913585152 |
|---|---|
| author | Pugachev, G.D. Pugachev, D.G. Repichov, O.A. Shestakova, V.S. Mazilov, A.V. Semenets, T.A. |
| author_facet | Pugachev, G.D. Pugachev, D.G. Repichov, O.A. Shestakova, V.S. Mazilov, A.V. Semenets, T.A. |
| citation_txt | Radiation protection of a complex of high-current distributed electron accelerators / G.D. Pugachev, D.G. Pugachev, O.A. Repichov, V.S. Shestakova, A.V. Mazilov, T.A. Semenets // Вопросы атомной науки и техники. — 2001. — № 3. — С. 194-195. — Бібліогр.: 10 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| first_indexed | 2025-12-07T13:18:16Z |
| format | Article |
| fulltext |
RADIATION PROTECTION OF A COMPLEX OF HIGH-CURRENT
DISTRIBUTED ELECTRON ACCELERATORS
G.D. Pugachev, D.G. Pugachev, O.A. Repichov, V.S. Shestakova, A.V. Mazilov,
T.A. Semenets1
National Science Center “Kharkov Institute of Physics and Technology”, Ukraine
1 Kharkov National University of Radioelectronics, Ukraine
PACS numbers: 29.17.+w, 28.70.+y
Creation of several high-current distributed electron
accelerators for production of medical radionuclides on
the base of a linear electron accelerator LUE-2000 has
required to use maximally the available equipment,
premises and existing radiation shields [1]. Therefore, it
was necessary to perform calculations and to choose a
relevant variant for arrangement of distributed electron
accelerators.
In the process of isotope 99Mo production in en-
riched and not enriched targets the optimum electron en-
ergy is 25 MeV [2] and 40 MeV [3], respectively. In
connection with an opportunity to operate with acceler-
ated electron energies up to 100 MeV and currents up to
1 µA it was necessary to calculate the levels of radiation
for thick tantalum targets behind the existing shield of
the linear accelerator LUE-2000 for 25, 60 and
100 MeV. An absorber dose rate created by the
bremsstrahlung and neutrons was calculated in conform-
ity with normative documents and works of [4 - 6]. An
agreement between calculations and experimental data
at maximum energies of bremsstrahlung up to 25 MeV
[7] allows one to extend these calculations to higher
currents, and for higher energies of bremsstrahlung one
should perform additional calculations of attenuation
multiplicity as a function of the concrete thickness.
At present, the normative documents for attenuation
multiplicity of the absorbed dose of electron
bremsstrahlung are available only to 40 MeV [8]. We
have calculated the concrete thickness required for
shielding from the bremsstrahlung at different attenu-
ation multiplicities and electron energies up to 100 MeV
according to [8, 9]. As for concrete the critical electron
energy Ec is close to 40 MeV (by our calculations Ec =
41.5 MeV, and radiation length is 24.5 g/cm2) the data
of [5] on the shield thickness for the maximum energy
of bremsstrahlung 38 MeV can be used for any energy
more than 40 MeV with taking into account the multi-
plication factor and, consequently, the increase of the
absorbed dose rate. The multiplication factor in concrete
is determined using the data for electron-photon cas-
cades in lead at a primary electron energy of 100, 200,
400 and 1000 MeV [9]. The results obtained for E0 =
100 MeV are in accordance with the results of [10] and
are valid for the concrete thickness more than 2.5 radi-
ation lengths. The attenuation multiplicity for concrete
required for bremsstrahlung protection with a maximum
energy E0 is given in Table1.
Table 1
E0, MeV / Atten.multiplic. 10 102 103 104 105 106
38*( [5]) 57 105 150 197 241 287
60 60 108 153 200 244 290
100 66 114 159 206 250 296
200 97 145 190 237 281 327
400 104 152 197 244 288 334
1000 118 165 210 257 301 347
Table 2
E0 /Points A1 A2 A3 A4 A5 A6 A7 A8 A9 A10
25 MeV 1290 3.9 59.5 290 34.4 11.9 53.2 0.06 1.4 0.1
60 MeV 5580 18.6 279 1360 160 55 247 0.3 6.5 0.5
100 MeV 105 354 5250 25570 3.103 1050 4.7.103 5.8 123 8.5
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 194-195. 194
The results of calculations on the equivalent dose
rate beyond the existing concrete shield of 2 m for elec-
tron energies of 25, 60 and 100 MeV, a mean current of
1 mA and for a thick tantalum target are given in
Table 2 in µSv/h.
The neutron flow in points A1 and A7 (not served
rooms) at the electron energy E0=100 MeV and the
mean current 1 mA will be equal to 1.6.102 and 4.4 neut-
rons/(cm2.s). In the rest points it will be less than 1 neut-
rons/(cm2.s). At energy of accelerated electrons up to
1 mA the existing shield provides a required level of ra-
diation safety. In the case of operation with energies up
to 100 MeV and a current of 1 mA there is a possibility
to install a local lead shield (11 cm) or to add on the
outside concrete blocks of 1m thick that can decrease
the radiation level by a factor of 100. So, radiation con-
ditions for operation of electron accelerators with en-
ergy up to 100 MeV in the rooms adjacent to the bunker
are determined by gamma-radiation being formed when
electron beam interacts with the targets having a high
atomic number. Neutrons do not give an appreciable
contribution into the equivalent dose rate behind the
shield even during operation with the target made of
heavy materials. It should be noted that at electron ener-
gies up to 100 MeV for radiation angles up to 90° the
shield thickness is determined by the bremsstrahlung
dose rate and for angles larger than 90° it is determined
by the neutron radiation dose rate. At electron energies
higher than 100 MeV already beginning from angles of
∼ 30° the shield thickness will be determined by the
neutron radiation from quasi-deuteron mechanism, and
above 200 MeV also by a pi-meson mechanism of neut-
ron formation.
Taking into account a great demand for 99Tc, real
and guaranteed providing of medical establishments
with 99Mo one should have as the minimum two acce-
lerators for 99Tc production. Therefore, it was decided to
create once more LUE-25 (No 2) in the space of 25-26
sections in the LUE-2000 bunker. For safety of works
conducted, it was necessary to install a radiation shield
on the accelerator under construction (LUE-10 and
LUE-25 (No 1) being in operation) in the LUE-2000
bunker. Arrangement of this shield is shown in Fig. 1.
Fig. 1. Arrangement of the concrete shield against radiation of the accelerators LUE-25 (No 1) and
(No 2) (cross-section of the accelerator LUE-2000 in the plane passing through the accelerator axis in
parallels to its base. 1, 2 - accelerators LUE-25 No 1 and No 2; 3 - concrete radiation shield of acceler-
ator N1; 4, 5 - walls of the labyrinth for the scattered radiation protection of accelerator No2; 6 - ladder
for entrance into the bunker of accelerator N2; 7 - existing concrete shield of LUE-2000. SI and Si
1 - re-
flecting surfaces. R1 – distance from the target of accelerator N2 to the reflecting surface S1.
To calculate the thickness of the concrete shield in-
stalled in the space of 23 section we have used experiment-
al data on the absorbed dose rate behind the aluminium tar-
get at maximum operating beam parameters. It was
2.104 Gy m2/h. The contribution of LUE-10 into the ad-
sorbed dose rate is less than 1%. To provide the radiation
level of 12 µSv/h the required thickness of the concrete
shield is 2.5 m. Taking into account the existing shield be-
ing equivalent to a lead layer of 6 cm and very severe re-
quirements to shield dimensions we have constructed a
concrete shield of 1.8 m in thickness. The equivalent dose
rate in the course of accelerator operation measured experi-
mentally in different points just behind the shield 3 was
from 4 to 9 µSv/h. The level of neutron radiation did not
exceed 1 neutrons/(cm2 s).
Arrangement and parameters of the accelerator LUE-25
#2 under construction are similar to those of the existing
accelerator #1. Therefore, we do not expect the problems
related with the direct radiation protection. Considering
that it was convenient to make the access into the room of
the new accelerator through the top shield which can be
opened, and that there was not a massive shielding access-
door we constructed the labyrinth for scattered radiation
protection. The labyrinth walls were 1.2 m thick. The lay-
out of the labyrinth at the accelerator LUE-25 (#2) is
shown in Fig. 1. As basic reflecting surfaces we have chose
surfaces S1 and S1
1. The absorbed dose rate at surfaces S1
and S1
1 from the radiation of LUE-25 is 2.5 Gy/h. The cal-
culation shows that contribution into the equivalent dose
rate created by the scattered radiation at the bunker en-
trance of LUE-25 (#2) in the not served space at a level of
the shield surface will be not higher than 1.5 µSv/h.
So, the shield constructed, engineering and arrange-
ment actions ensure the level of absorbed dose rate less
than a maximum permissible one.
The authors are grateful to I.I.Shapoval for the help in
paper preparation.
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| id | nasplib_isofts_kiev_ua-123456789-79274 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T13:18:16Z |
| publishDate | 2001 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Pugachev, G.D. Pugachev, D.G. Repichov, O.A. Shestakova, V.S. Mazilov, A.V. Semenets, T.A. 2015-03-30T08:55:00Z 2015-03-30T08:55:00Z 2001 Radiation protection of a complex of high-current distributed electron accelerators / G.D. Pugachev, D.G. Pugachev, O.A. Repichov, V.S. Shestakova, A.V. Mazilov, T.A. Semenets // Вопросы атомной науки и техники. — 2001. — № 3. — С. 194-195. — Бібліогр.: 10 назв. — англ. 1562-6016 PACS nambers: 29.17.+w, 28.70.+y https://nasplib.isofts.kiev.ua/handle/123456789/79274 The authors are grateful to I.I.Shapoval for the help in paper preparation. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Radiation protection of a complex of high-current distributed electron accelerators Радиационная защита комплекса сильноточных технологических ускорителей электронов Article published earlier |
| spellingShingle | Radiation protection of a complex of high-current distributed electron accelerators Pugachev, G.D. Pugachev, D.G. Repichov, O.A. Shestakova, V.S. Mazilov, A.V. Semenets, T.A. |
| title | Radiation protection of a complex of high-current distributed electron accelerators |
| title_alt | Радиационная защита комплекса сильноточных технологических ускорителей электронов |
| title_full | Radiation protection of a complex of high-current distributed electron accelerators |
| title_fullStr | Radiation protection of a complex of high-current distributed electron accelerators |
| title_full_unstemmed | Radiation protection of a complex of high-current distributed electron accelerators |
| title_short | Radiation protection of a complex of high-current distributed electron accelerators |
| title_sort | radiation protection of a complex of high-current distributed electron accelerators |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79274 |
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