Project of a fast neutron target based on a 10 MeV 300 kW proton accelerator
Project of targets for high intense neutron source is proposed. The source is based on a proton continuous accelerator with the 10 MeV particle energy and up to 300 kW mean beam power. Problems of fabrication of these targets are discussed. Hot solid state and liquid target designs are considered. M...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
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| Zitieren: | Project of a fast neutron target based on a 10 MeV 300 kW proton accelerator / M.S. Avilov, K.V. Gubin, N.Kh. Kot, P.V. Logatchev, P.V. Martyshkin, S.N. Morozov, S.V. Shiyankov, A.A. Starostenko, A. Andrighetto, Y.W. Bao, L. Tecchio, Ya.Z. Kandiev, V.V. Plokhoi, S.I. Samarin // Вопросы атомной науки и техники. — 2001. — № 3. — С. 24-26. — англ. |
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irk-123456789-792212015-03-31T03:01:37Z Project of a fast neutron target based on a 10 MeV 300 kW proton accelerator Avilov, M.S. Gubin, K.V. Kot, N.Kh. Logatchev, P.V. Martyshkin, P.V. Morozov, S.N. Shiyankov, S.V. Starostenko, A.A. Andrighetto, A. Bao, Y.W. Tecchio, L. Kandiev, Ya.Z. Plokhoi, V.V. Samarin, S.I. Project of targets for high intense neutron source is proposed. The source is based on a proton continuous accelerator with the 10 MeV particle energy and up to 300 kW mean beam power. Problems of fabrication of these targets are discussed. Hot solid state and liquid target designs are considered. Maximum admissible target parameters are presented. Advantages and disadvantages of various types of target for neutron production are discussed. 2001 Article Project of a fast neutron target based on a 10 MeV 300 kW proton accelerator / M.S. Avilov, K.V. Gubin, N.Kh. Kot, P.V. Logatchev, P.V. Martyshkin, S.N. Morozov, S.V. Shiyankov, A.A. Starostenko, A. Andrighetto, Y.W. Bao, L. Tecchio, Ya.Z. Kandiev, V.V. Plokhoi, S.I. Samarin // Вопросы атомной науки и техники. — 2001. — № 3. — С. 24-26. — англ. 1562-6016 PACS numbers: 29.17.+w http://dspace.nbuv.gov.ua/handle/123456789/79221 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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DSpace DC |
| language |
English |
| description |
Project of targets for high intense neutron source is proposed. The source is based on a proton continuous accelerator with the 10 MeV particle energy and up to 300 kW mean beam power. Problems of fabrication of these targets are discussed. Hot solid state and liquid target designs are considered. Maximum admissible target parameters are presented. Advantages and disadvantages of various types of target for neutron production are discussed. |
| format |
Article |
| author |
Avilov, M.S. Gubin, K.V. Kot, N.Kh. Logatchev, P.V. Martyshkin, P.V. Morozov, S.N. Shiyankov, S.V. Starostenko, A.A. Andrighetto, A. Bao, Y.W. Tecchio, L. Kandiev, Ya.Z. Plokhoi, V.V. Samarin, S.I. |
| spellingShingle |
Avilov, M.S. Gubin, K.V. Kot, N.Kh. Logatchev, P.V. Martyshkin, P.V. Morozov, S.N. Shiyankov, S.V. Starostenko, A.A. Andrighetto, A. Bao, Y.W. Tecchio, L. Kandiev, Ya.Z. Plokhoi, V.V. Samarin, S.I. Project of a fast neutron target based on a 10 MeV 300 kW proton accelerator Вопросы атомной науки и техники |
| author_facet |
Avilov, M.S. Gubin, K.V. Kot, N.Kh. Logatchev, P.V. Martyshkin, P.V. Morozov, S.N. Shiyankov, S.V. Starostenko, A.A. Andrighetto, A. Bao, Y.W. Tecchio, L. Kandiev, Ya.Z. Plokhoi, V.V. Samarin, S.I. |
| author_sort |
Avilov, M.S. |
| title |
Project of a fast neutron target based on a 10 MeV 300 kW proton accelerator |
| title_short |
Project of a fast neutron target based on a 10 MeV 300 kW proton accelerator |
| title_full |
Project of a fast neutron target based on a 10 MeV 300 kW proton accelerator |
| title_fullStr |
Project of a fast neutron target based on a 10 MeV 300 kW proton accelerator |
| title_full_unstemmed |
Project of a fast neutron target based on a 10 MeV 300 kW proton accelerator |
| title_sort |
project of a fast neutron target based on a 10 mev 300 kw proton accelerator |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2001 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/79221 |
| citation_txt |
Project of a fast neutron target based on a 10 MeV 300 kW proton accelerator / M.S. Avilov, K.V. Gubin, N.Kh. Kot, P.V. Logatchev, P.V. Martyshkin, S.N. Morozov, S.V. Shiyankov, A.A. Starostenko, A. Andrighetto, Y.W. Bao, L. Tecchio, Ya.Z. Kandiev, V.V. Plokhoi, S.I. Samarin // Вопросы атомной науки и техники. — 2001. — № 3. — С. 24-26. — англ. |
| series |
Вопросы атомной науки и техники |
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2025-07-06T03:16:28Z |
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| fulltext |
PROJECT OF A FAST NEUTRON TARGET BASED ON A 10 MEV
300 KW PROTON ACCELERATOR
M.S. Avilov, K.V. Gubin, N.Kh. Kot, P.V. Logatchev, P.V. Martyshkin,
S.N. Morozov, S.V. Shiyankov, A.A. Starostenko, A. Andrighetto1, Y.W. Bao1,
L. Tecchio1, Ya.Z. Kandiev2, V.V. Plokhoi2, S.I. Samarin2
Budker Institute of Nuclear Physics, 11, Ac. Lavrentiev Ave, Novosibirsk, 630090, Russia
1Laboratori Nazionali di Legnaro, Istituto Nazionale di Fisica Nucleare (LNL-INFN),
Via Romea 4 - 35020 Legnaro (Padova) Italy
2Russian Federal Nuclear Center Russian Research Institute of Technical Physics,
13 Vasiliev St, Snezhinsk, 456770, Russia
Project of targets for high intense neutron source is proposed. The source is based on a proton continuous accelera-
tor with the 10 MeV particle energy and up to 300 kW mean beam power. Problems of fabrication of these targets
are discussed. Hot solid state and liquid target designs are considered. Maximum admissible target parameters are
presented. Advantages and disadvantages of various types of target for neutron production are discussed.
PACS numbers: 29.17.+w
1 INTRODUCTION
The low-energy proton beam of small transverse size
(∼ 1 cm) and high mean beam power causes a high den-
sity of energy deposition in a small volume of the target.
The typical stopping length for protons of 10 MeV ener-
gy occurs to be less than 1 mm for some materials.
The main problem for target irradiated with the
high-power beam is a heat removal from the active tar-
get area. This problem may be solved by the target sur-
face extension for solid targets, or by use of liquid metal
as a target operational substance. If the proton beam size
can be increased in diameter up to 10 cm or more, it
seems reasonable to use the stationary solid state target
for neutron production. Otherwise, the rotated or liquid
metal targets should be used.
Another serious problem is to choose the proper tar-
get material. The following materials have high neutron
production ratio: 13C, boron compounds, lithium, beryl-
lium.
2 STATIONARY BERYLLIUM TARGET
When the proton beam size is rather large, the sta-
tionary beryllium target can be used for high neutron
flux production. The layout of this target is presented in
Fig. 1.
To avoid a target surface overheating, it is reason-
able to produce the target of a conical shape that effec-
tively extends its active area. This target is cooled by
liquid agent, for example, water or liquid metal. In the
latter case the size of the target should be essentially re-
duced. Parameters of the target cooled both by water
and sodium - potassium alloy are presented in Table 1.
The beam has a gaussian shape with σr=3.5 cm.
Fig. 1. Layout of the conical target with liquid agent
cooling. 1 – operational layer, 2 – intermediate lay-
er of liquid metal, 3 – conical backing with cooling
channels, 4 – vacuum chamber, 5 – inlets and out-
lets of cooling channels, 6 – neutron beam output
window, 7 – primary beam, 8 - collimator.
The intermediate layer of sodium-potassium alloy is
used in order to decrease the thermo-mechanical stress
in target elements. Maximum stress for the target cooled
by water is 10.8∙107 Pa, and maximum temperature of
beryllium should be 2000C.
Table 1. Parameters of the fixed beryllium target
Water Na – K
alloy
Target length, m 0.9 0.4
Max. cone radius, m 0.06 0.06
Number of cooling channels 89 39
Coolant consumption, lpm 339 292
Max. coolant velocity, m/s 22 27
For the target cooled by the Na – K alloy the maxi-
mum stress is 25∙107 Pa and maximum temperature of
beryllium is 350ºC.
3 ROTATING TARGET
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 24-26.
24
A serious drawback of the target presented above is
its large size and, as a result, a low density of neutron
flux. When the beam size is rather small, the rotating
13C or boron compound based target seems to be the
most attractive. These materials stand well the high tem-
perature, and coolant is not required, since target cool-
ing is carried out by thermal radiation.
The target layout is shown in Fig. 2. The target rep-
resents the rotating titanium disk with the diameter ap-
proximately 1-1.5 m. The disk rim is assembled from
graphite or B4C plates. Plate thickness is about 2 mm
(stopping length of 10 MeV protons in graphite and
boron carbide is about 0.7 mm), width – 1-2 cm, length
– 10-12 cm. The disk is set on the shaft 5 cm in diame-
ter.
Fig. 2. Layout of rotating target.
Target rotation is carried out with a frequency of
30-50 Hz and transferred to the vacuum chamber via a
magnetic clutch. The dissipation of heat is carried out in
two water-cooled semi-circle aluminum channels. Chan-
nels have two gaps: operating one for incident beam,
and technical one for temperature measurements
(bolometer). A graphite collimator, which also acts as a
beam position monitor, is placed opposite to the target.
Behind the target the special graphite plate is placed for
chamber protection and converter damage indication.
The whole device is positioned inside the radiation
shielding.
Fig. 3. Temperature distribution over the carbon
plate irradiated by gaussian proton beam with σ
=1 cm.
Result of simulation of temperature distribution over
the MPG-class graphite plate irradiated by 300 kW
gaussian proton beam is shown in Fig.3. The target di-
ameter is 1 m. The front surface of the target is hotter
than the rear one, and the highest temperature is ob-
served near the point with maximum power deposition.
Highest temperature does not exceed 20500C. The maxi-
mum termo-mechanical stress is about 107 Pa, that is 2 –
4 times less than the ultimate stress for graphite.
Another material suitable for intense neutron flux
production is boron carbide. The production ratio for
this material is higher than for carbon. Otherwise, the
thermal conductivity of boron carbide is less than the
one of carbon. As a result the temperature of the target
hot area is 30% higher than for carbon target.
Fig. 4. Highest temperature of boron carbide and
carbon targets for various beam sizes vs. cyclic mo-
tion amplitude.
The maximum temperature of boron carbide and car-
bon targets for various beam size is shown in Fig. 4.
Points correspond to the maximum temperature of car-
bon target at a beam size of 0.5 cm, 1 cm, 1.25 cm (top
to bottom). The most reliable temperature of the target
seems to be 2000O – 2100OC. To decrease the tempera-
ture to this value, the effective target area has to be ex-
tended by the cyclic motion of the target axis in vertical
direction. The acceptable temperature value is reached
when the motion amplitude is 2.5 – 3 cm.
The maximum thermomechanical stress of boron
carbide target is about 108 Pa that is 500 times less than
its ultimate stress.
4 LIQUID METAL TARGET
The target where the hot area is removed from the
active zone is based on the liquid lithium technology
and usually represents a liquid lithium jet. Such a target
requires large consumption of liquid lithium. In this pa-
per the alternative type of target is proposed. Liquid
lithium is contained in a special tank - liquid lithium
container (LLC), its sketch is shown in Fig 5.
To avoid the local overheating, the liquid lithium has
to be mixed up intensively. As a result, high-tempera-
ture liquid lithium layers are mixed up with low-temper-
ature layers. The typical mixing size is approximately a
few spot sizes of proton beam. By this way, the liquid
lithium mean temperature is maintained fixed except the
area, located directly under the proton beam.
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 25-26.
25
Fig. 5. Sketch of liquid lithium container. 1– inci-
dent proton beam, 2– cooling channels, 3 – liquid
lithium, 4 – mixed-up device, 5 – container wall,
6 - preliminary heating device.
High melting point of lithium (190OC) disables the
use of water as a cooling agent, so liquid metals should
be used as a heat carrier. After lithium is melted inside
the tank, liquid metal should be loaded inside the cool-
ing contour.
Liquid metal coolant selection is defined by its melt-
ing point. Melting temperature has to be as low as possi-
ble, not higher than 30 – 40OC. Low melting tempera-
ture allows to decrease the mean operation temperature
of liquid lithium, because the efficiency of LLC de-
pends directly on the temperature difference between
container wall and heat carrier. So, the higher the tem-
perature difference is, the stronger the heat transfer
should be. The mean lithium temperature should not ex-
ceed 300–350OC, otherwise its strong evaporation takes
place.
Since lithium is rather active chemical element, the
corrosion resistance of material in liquid lithium envi-
ronment strongly depends on admixtures content in it.
Low carbon stainless steel stands well in liquid lithium
environment and has rather high thermal conductivity
(90 W/m∙K against, for example, titanium, whose ther-
mal conductivity does not exceed 20 W/m∙K).
Only a few metals with a low melting temperature
can be used as liquid metal heat carriers. Examples are
sodium or potassium. These metals, however, have
melting points around 100 OC. Sodium-potassium alloy,
which is applied in nuclear reactors, has lower than pure
sodium or potassium melting temperature - down to
-12.50C. So, this material has been suggested to use as a
liquid metal heat carrier.
Table 2. Main results of lithium container heat estima-
tion
Cooling channel diameter
Heat carrier speed
Maximum pressure differential in the
channel
Total heat-carrier consumption
1 cm
2.3 m/s
0.03 at
2.2 lps
Lithium mean temperature
Container internal surface temperature
Cooling channel wall temperature
Heat carrier initial temperature
230OC
213OC
184OC
30OC
The estimation of thermomechanical stress shows
that the overheat of the container wall should not exceed
120OC for steel as a wall material.
Main results of LLC heat estimation are presented in
Table 2.
5 CONCLUSION
The advantages and disadvantages for each type of
neutron production target are summarized in Table 3.
Some of these items require additional study.
Various neutron target types may be used for various
applications, for example, BNCT, radioactive ion beam
production, material science application.
Table 3. Comparison of various target types.
Advantages Disadvantages
Stationary beryllium target
• absence of mechani-
cal motion;
• in the case of water
cooling - no expen-
sive materials;
• ability to use a num-
ber of materials for
neutron production.
• large source size;
cooling channels are
positioned so close to
working area;
• cooling agent is
under the beam;
• technology of
working material
deposition on the
backing needs
careful study.
Rotating carbon target
• radiation as an inter-
mediate heat carrier;
• reliability and sim-
plicity of design;
• target destruction
does not lead to dis-
astrous effects for
the accelerator;
• material annealing at
high temperatures
eliminates radiation
defects and reduces
mechanical stress;
• high rate of by-prod-
ucts diffusion from
graphite at high tem-
peratures;
• the use of two rotat-
ing targets allows to
reduce the thermal
stress at small trans-
verse beam size, and
the length of carbon
plates at large beam
size.
• limited lifetime
due to carbon
evaporation;
• high cost of mate-
rial (13С);
• if use glassy car-
bon – complexity
of plate treatment;
• power extraction
limit 200 W/cm2,
thus the maximum
proton beam power
should not exceed
300 kW;
• target thickness
grows with the
beam energy raise.
Liquid Lithium Container
• ability to receive the
high power beam;
• no beam energy lim-
it;
• low velocity of liq-
uid metal heat carri-
er.
• Intense evapora-
tion at temperature
higher than
400 − 450 OC;
• Careful control of
lithium tempera-
ture is required;
• Vertical or inclined
proton beam.
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