Neutronic model of a fusion neutron source
The MCNPX numerical code has been used to model a fusion neutron source based on a combined stellaratormirror trap. Calculation results for the neutron spectrum near the inner wall and radial leakage of neutrons through the mantle surface of the fusion neutron source are presented. С помощью програм...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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| Цитувати: | Neutronic model of a fusion neutron source / S.V. Chernitskiy, V.E. Moiseenko, O. Ågren, K. Noack, A. Abdullayev // Вопросы атомной науки и техники. — 2013. — № 1. — С. 61-63. — Бібліогр.: 8 назв. — англ. |
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Chernitskiy, S.V. Moiseenko, V.E. Ågren, O. Noack, K. Abdullayev, A. 2016-11-21T21:15:08Z 2016-11-21T21:15:08Z 2013 2013 Neutronic model of a fusion neutron source / S.V. Chernitskiy, V.E. Moiseenko, O. Ågren, K. Noack, A. Abdullayev // Вопросы атомной науки и техники. — 2013. — № 1. — С. 61-63. — Бібліогр.: 8 назв. — англ. 1562-6016 PACS: 52.55.Hc, 52.50.Dg https://nasplib.isofts.kiev.ua/handle/123456789/109240 The MCNPX numerical code has been used to model a fusion neutron source based on a combined stellaratormirror trap. Calculation results for the neutron spectrum near the inner wall and radial leakage of neutrons through the mantle surface of the fusion neutron source are presented. С помощью программы MCNPX разработана концепция термоядерного источника нейтронов на основе открытой ловушки. Представлены спектры нейтронов вблизи первой стенки, а также результаты расчетов радиальной утечки нейтронных потоков за пределы моделируемой системы. За допомогою програми MCNPX розроблена концепція термоядерного джерела нейтронів на основі відкритої пастки. Представлені спектри нейтронів поблизу першої стінки, а також результати розрахунків радіального витоку нейтронних потоків за межі модельованої системи. This work is supported in part by a grant from Swedish Institute. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники ИТЭР и приложения для термоядерного реактора Neutronic model of a fusion neutron source Нейтронная модель термоядерного источника нейтронов Нейтронна модель термоядерного джерела нейтронів Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Neutronic model of a fusion neutron source |
| spellingShingle |
Neutronic model of a fusion neutron source Chernitskiy, S.V. Moiseenko, V.E. Ågren, O. Noack, K. Abdullayev, A. ИТЭР и приложения для термоядерного реактора |
| title_short |
Neutronic model of a fusion neutron source |
| title_full |
Neutronic model of a fusion neutron source |
| title_fullStr |
Neutronic model of a fusion neutron source |
| title_full_unstemmed |
Neutronic model of a fusion neutron source |
| title_sort |
neutronic model of a fusion neutron source |
| author |
Chernitskiy, S.V. Moiseenko, V.E. Ågren, O. Noack, K. Abdullayev, A. |
| author_facet |
Chernitskiy, S.V. Moiseenko, V.E. Ågren, O. Noack, K. Abdullayev, A. |
| topic |
ИТЭР и приложения для термоядерного реактора |
| topic_facet |
ИТЭР и приложения для термоядерного реактора |
| publishDate |
2013 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Нейтронная модель термоядерного источника нейтронов Нейтронна модель термоядерного джерела нейтронів |
| description |
The MCNPX numerical code has been used to model a fusion neutron source based on a combined stellaratormirror trap. Calculation results for the neutron spectrum near the inner wall and radial leakage of neutrons through the mantle surface of the fusion neutron source are presented.
С помощью программы MCNPX разработана концепция термоядерного источника нейтронов на основе открытой ловушки. Представлены спектры нейтронов вблизи первой стенки, а также результаты расчетов радиальной утечки нейтронных потоков за пределы моделируемой системы.
За допомогою програми MCNPX розроблена концепція термоядерного джерела нейтронів на основі відкритої пастки. Представлені спектри нейтронів поблизу першої стінки, а також результати розрахунків радіального витоку нейтронних потоків за межі модельованої системи.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/109240 |
| citation_txt |
Neutronic model of a fusion neutron source / S.V. Chernitskiy, V.E. Moiseenko, O. Ågren, K. Noack, A. Abdullayev // Вопросы атомной науки и техники. — 2013. — № 1. — С. 61-63. — Бібліогр.: 8 назв. — англ. |
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ISSN 1562-6016. ВАНТ. 2013. №1(83) 61
NEUTRONIC MODEL OF A FUSION NEUTRON SOURCE
S.V. Chernitskiy 1, V.E. Moiseenko 2, O. Ågren 3, K. Noack 3, A. Abdullayev1
1“Nuclear Fuel Cycle” Science and Technology Establishment, NSC “Kharkov Institute of
Physics and Technology”, Kharkov, Ukraine;
2Institute of Plasma Physics NSC ‘‘Kharkov Institute of Physics and Technology”,
Kharkov, Ukraine;
3Uppsala University, Ångström Laboratory, Uppsala, Sweden
The MCNPX numerical code has been used to model a fusion neutron source based on a combined stellarator-
mirror trap. Calculation results for the neutron spectrum near the inner wall and radial leakage of neutrons through
the mantle surface of the fusion neutron source are presented.
PACS: 52.55.Hc, 52.50.Dg
INTRODUCTION
Powerful sources of fusion neutrons with energies
~ 14 MeV are of particular interest to test suitability of
materials for use in a fusion reactor. Developing
materials for fusion reactors has long been recognized
as a problem nearly as difficult and important as plasma
confinement, but it has received only a fraction of the
attention. The neutron flux in a fusion reactor is
expected to be about 100 times higher than in existing
pressurized water reactors. Each atom in the blanket of a
fusion reactor is expected to be hit by a neutron and
displaced about a hundred times before the material is
replaced. Furthermore the high-energy neutrons will
produce hydrogen and helium in various nuclear
reactions that tends to form bubbles at grain boundaries
and result in swelling, blistering or embrittlement. One
also prefers to choose materials which primary
components and admixtures, after neutron, exposure do
not result in long-lived radioactive waste. And also, the
mechanical forces and temperatures are large, and the
cyclic variations add to the difficulties to find suitable
materials.
Realistic material tests ought to expose samples to
neutron fluxes of a similar level for a similar period of
time as those expected in a fusion power plant.
MODEL OF A FUSION NEUTRON SOURCE
In this research, the neutronics of a fusion neutron
source is studied. The fusion neutron source consists of
a magnetic trap for plasma confinement at which fusion
neutrons are generated. The magnetic trap is of a
combined type: it is a toroidal stellarator with an
embedded magnetic mirror with lower magnetic field
[1]. The stellarator part is for confinement of warm
dense deuterium target plasma. Hot tritium sloshing
tritium ions are confined at the mirror part of the device.
At this part the plasma column is straight. It is
surrounded by a cylindrically symmetrical shield.
The hot minority tritium ions are sustained in the
plasma by neutral beam injection (NBI). The NBI is
normal to the magnetic field and targets plasma just
near the main part (Fig. 1). The sloshing ions bounce
inside the magnetic mirror and fusion neutrons are
generated there. Some fusion neutrons are generated
outside the main part near the injection point. There is a
need of protection from these neutrons.
The purpose is to calculate the neutron spectrum near
the first wall of the installation, where will be a neutron
irradiation facility in special volumes, and compute
leakage of neutrons through the mantle surface of the
model.
CALCULATION MODEL
The model has a cylindrical symmetry with a
horizontal axis. Its radial and axial structure is shown in
Fig. 1. The vacuum chamber contains the D-T plasmas
which supplies the fusion neutrons. The inner radius of
the vacuum chamber is 0.5 m. The space between
plasma and the first wall is reserved for the irradiation
specimens. The first wall thickness is 3 cm. The
thickness of the buffer (LBE) is 15 cm and the shield
thickness is 20 cm. The LBE [2] was assumed to be a
mixture of 44.5 wt.% lead and 55.5 wt.% bismuth. The
shield contains a 60:40 vol.% mixture of the stainless
steel alloy S30467 type 304B7 [3,4] with water. The
steel contains 1.75 wt.% of natural boron. The total
length of the main part of the model is 4 m.
The ends of the neutron irradiation zone are
surrounded by a vessels filled with borated water to
absorb the outcoming neutrons. The water slows down
the neutrons and boron then absorbs slow neutrons.
Boron has an exactly stable isotope B10 which absorbs
neutrons very efficiently: the absorption cross section of
thermal neutrons is about 4000 barn. As a result of
neutron absorption by boron-10 the excited nucleus B11
is formed, which immediately decays into the nucleus
Li7 and the alpha-particle.
The concentration of boron in the water was taken
10 g/kg. The isotopical content is B10 - 20 % and B11 -
80 %. The part with borated water has a length of 2 m at
both sides of the main part and a thickness is of 35 cm.
At the right side of the main part, openings with square
79 cm2 are made to provide access to the plasma for the
neutral beam (see Fig. 1, inlet hole for neutral beam
injection).
In the calculation model, the volumetric source of
neutrons is represented by a number of cylindrical
volumes of radius 10 cm and with a total length of 4 m.
At every source point, the fusion neutrons were emitted
with a fixed kinetic energy of 14.1 MeV and isotropic
velocity distribution.
62 ISSN 1562-6016. ВАНТ. 2013. №1(83)
Fig. 1. Radial and axial structures of the neutron source model
The intensity distribution along the length of the neutron
source [5], which was used in the MCNPX model, is
shown in Fig. 2. The total number of the particles
emitted by the source is normalized to unity.
Fig. 2. Intensity distribution of the source neutrons for
Einj=300 keV
RESULTS OF CALCULATIONS
The MCNPX numerical code has been used for
neutron calculations. Calculation results for the leakage
of neutrons through the mantle surface of the model are
presented below. Calculations were performed for two
coolants – LBE and Na. Neutron leakage, normalized
per fusion neutron, through the separate surfaces see
(see Fig. 1) is:
coolant – LBE
• Surface 6: 0.0147± 0.5 %
• Surface 7: 0.0351± 0.5 %
• Surface 8: 0.0263± 0.5 %
coolant – Na
• Surface 6: 0.026 ± 0.5 %
• Surface 7: 9.54 ×10-3 ± 0.5 %
• Surface 8: 0.0369 ± 0.5 %.
As seen from the above results, radial leakage of
neutrons is sufficiently small. The estimates predict that
the energy released with neutrons from the fusion
neutron source to outer space is 4.2×10-17 Ws with LBE
and 5.9×10-17 Ws with Na per fusion source neutron.
This power loading should be considered in the
calculation of the cooling requirements for the magnetic
coils of the stellarator-mirror magnetic trap.
Flux of neutrons at the first wall of main part of the
model equal 2×1014 and 1×1014 cm-2s-1 using as coolant
LBE and Na, respectively, for a fusion neutron source
with intensity 3×1018 neutrons per second [1].
In Fig. 3,a,c shows the spectrum of neutrons at the
first wall of the main part of the model, using as
coolants LBE and Na, respectively. Fig. 3,b,d shows the
average along the entire length of the model spectrum of
neutrons at the first wall. As can be seen from the
graphs, the neutron spectrum depends significantly on
the coolant material. In the range of 0.8…1.0 MeV, an
increase of the neutron flux through the first wall is
observed, which can be explained by the reaction (n,
2n), for example Pb207(n,2n)Pb206. The peak at 14 MeV
is due to the fusion neutrons from the plasma source.
This spectrum is different from the spectrum
computed for the powerful neutron source IFMIF
(International Fusion Material Irradiation Facility) [6,
7]. The IFMIF requirement of 250 mA of deuteron
beam current delivered to the lithium target (7.5 %-Li6
and 92.5 %-Li7) will be met by two 125 mA beams,
with energy of 40 MeV for the accelerator modules. A
continuous 155 mA deuteron beam is extracted from the
ion source at 95 keV. The IFMIF ion injector has to
provide excellent beam quality, sufficiently high beam
current and high operational availability. In developing
a source model for the Li(d,xn) reaction, there are three
possible routes: Li7(d,2n)Be7; Li7(d,n)Be8; Li6(d, n)Be7.
The neutrons with energies up to 55 MeV are
irradiated.. The IFMIF/test cell spectra are smoothed
functions of neutron energy without a prominent peaks
at 14 MeV and 15...25 % of the total flux is distributed
throughout the high energy domain. The majority of the
flux (between 75 and 80 %) has energy below 14 MeV.
Thus, the spectrum is noticeably different from that of a
fusion reactor, with the most important difference being
the high energy tail of the IFMIF flux.
The Russian Federation is actively developing a
fusion neutron source based on a spherical tokamak for
burning transuranic elements and for breeding the fuel
isotops 239Pu and 233U from 238U and 232Th, respectively
[8].
ISSN 1562-6016. ВАНТ. 2013. №1(83) 63
Fig. 3. Energy group fluxes averaged over the first wall
CONCLUSIONS
By means of neutron transport calculations a
principal design for fusion neutron source has been
devised. The calculations were carried out with the
Monte Carlo code MCNPX.
Neutrons outflux and neutron spectrum near the first
wall of the simulated model was calculated. The vessels
filled with borated water at the ends of the neutron
irradiation zone absorb the outflowing neutrons and
sufficiently reduce the neutron flux to outer space. The
neutron fluxes that are emitted into the stellarator
vacuum chamber at both sides of the neutron source
have also been calculated.
ACKNOWLEDGEMENT
This work is supported in part by a grant from
Swedish Institute.
REFERENCES
1. V.E. Moiseenko, K. Noack, O. Ågren // J Fusion
Energ (25). 2010, p. 65.
2. OECD NEA, 2007. http://www.oecd-
nea.org/science/reports/2007/pdf/chapter2.pdf
3. D.V. Fix et al. LLNL report UCRL-PROC-202920
2004.
4. K. Noack et al. // AIP Conf. Proc. 2012, v. 1442,
p. 186-198
5. V.E. Moiseenko, O. Ågren. AIP Conf. Proc. 2012,
v. 1442, p. 199-207.
6. P. Vladimirov, A. Möslang // Journal of Nucl
Materials. 2004, v. 329-333, p. 233-237.
7. http://bibliothek.fzk.de/zb/berichte/FZKA6218.pdf
8. E.A. Azizov et al. // PAST. Ser. «Fusion». 2009, v. 3,
p. 3-9.
Article received 20.09.12
НЕЙТРОННАЯ МОДЕЛЬ ТЕРМОЯДЕРНОГО ИСТОЧНИКА НЕЙТРОНОВ
С.В. Черницкий, В.Е. Моисеенко, О. Агрен, К. Ноак, А. Абдуллаев
С помощью программы MCNPX разработана концепция термоядерного источника нейтронов на основе
открытой ловушки. Представлены спектры нейтронов вблизи первой стенки, а также результаты расчетов
радиальной утечки нейтронных потоков за пределы моделируемой системы.
НЕЙТРОННА МОДЕЛЬ ТЕРМОЯДЕРНОГО ДЖЕРЕЛА НЕЙТРОНІВ
С.В. Черницький, В.Є. Моісеєнко, О. Агрен, К. Ноак, А. Абдуллаєв
За допомогою програми MCNPX розроблена концепція термоядерного джерела нейтронів на основі
відкритої пастки. Представлені спектри нейтронів поблизу першої стінки, а також результати розрахунків
радіального витоку нейтронних потоків за межі модельованої системи.
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