JAEA-Conf 2011-002 - 日本原子力研究開発機構

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JAEA-Conf 2011-002 (5.0-9.0MeV), a high energy beam transport line and a beam dump (9MeV-125mA CW) [4]. In the accelerator building, an accelerator vault is surrounded by the concrete wall with thickness of 1.5m. For the radiation controlled area (with no possibility of RI contamination), the effective dose rate has to be suppressed to less than 12.5 micro Sv/h with no neutron leakage. For Personal Protection System [PPS] in the prototype accelerator, a design study of the area monitoring system, comprising of Si semiconductors and ionization chambers for covering wide energy spectrum of gamma-rays and 3 He counters for neutrons, is now in progress. In this system, the upper limits of detectable photon and neutron energies are set to be 1.5MeV and 15MeV, respectively. In the previous works, the reduction of neutron and photon energies penetrating through shield of water and concrete layers were evaluated by using PHITS code, and it was found that the highest photon energy exceeded over 10MeV when the shield consists of water and concrete layers only [5]. In order to fulfill the requirement of the maximum photon energy, a model with iron layer is evaluated. 2. IFMIF/EVEDA Accelerator 2.1 Accelerator Building A schematic drawing of the prototype accelerator is shown in Fig.1. The IFMIF/EVEDA accelerator building in Rokkasho site has the total area of 2019.5m 2 , and the accelerator vault has the inside area of W: 8.0m x D: 41.5m x H: 7.0m. The vault is surrounded by concrete walls of 1.5m thickness. Additional local concrete shield of 0.5m thickness around the beam dump is also planned. 2.2 Beam Dump A beam dump is required stopping the deuteron beam with maximum power of 1.125 MW in the CW Figure 1: IFMIF/EVEDA accelerator building and area monitor layout
operation mode. A selection of the beam facing materials has to take into account the neutron production and the activation level as well as the thermal stresses. In the present design, a cone shaped copper with 0.005m thickness is used, and it is surrounded by water tank of a 0.75m-radius. 2.3 Area Monitoring System Area monitoring system consists of two types; gamma-ray monitors and neutron monitor. The specifications of these monitors are shown in Table 1, and the location is shown in Fig.1. As shown in Table 1, the detectable energy range of the neutron monitor is from 0.025eV to 15MeV and the directional characteristics is -60 to +240° for a vertical direction, and that of the gamma-ray monitor is from 80keV to 1.5MeV and ±90° for a horizontal direction, -60 to +240° for a vertical direction. As shown in Fig.1, the area monitors are installed the external side of accelerator vault. Table 1: The kinds of area monitor Monitor Specification Neutron monitor Gamma-ray monitor JAEA-Conf 2011-002 Type helium-3 counter Energy range 0.025eV to 15MeV Dose rate characteristic dose equivalent rate: 10 -2 to 10 4 Sv/h Directional characteristics vertical direction: -60 to +240° Type semiconductors type Energy range photon: 80keV to 1.5MeV Dose rate characteristic dose equivalent rate: 10 -1 to 10 4 Sv/h Directional characteristics horizontal direction: ±90°, vertical direction: -60 to + 90 Type ionization chamber type Energy range photon: 80keV to 1.5MeV Dose rate characteristic dose equivalent rate: 10 -1 to 10 5 Sv/h Directional characteristics horizontal direction: ±90°, vertical direction: -60 to +90 3. Analysis 3.1 Nuclear data Deuteron induced thick target neutron yield at 9MeV was measured in collaboration with Kyushu University because there was no experimental data for Cu(d,nx) reaction in the range of 5-9MeV[6]. The experimental data which is neutron generation in case of 1 C irradiated to cupper is used as a source term in neutron transportation, and the energy reduction of photon are evaluated by PHITS code. The JENDL 4.0 is used for nuclear cross-section library. 3.2 Model A point source which has the neutron angular distribution is used for this analysis as shown in Fig.2. The neutron point source is located in the center, and the total number of 1.35 x10 10 [n] by a 9MeV-1C deuteron beam, is emitted. The 0.005m thickness copper is set around the point source. As for concrete
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JAEA-Conf 2011-002 Proceedings of t
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JAEA-Conf 2011-002 31. Preliminary
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6.2 Measurement of neutron-induced
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JAEA-Conf 2011-002 Table 1 Comparis
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JAEA-Conf 2011-002 (T1/2=8,900,000
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JAEA-Conf 2011-002 Though words too
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JENDL-3.3 showed better applicabili
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ENDF. Thus this cross section store
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Acknowledgement JAEA-Conf 2011-002
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In the MALIBU program, isotope conc
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some minor actinides. For major act
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JAEA-Conf 2011-002 code MVP-BURN an
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JAEA-Conf 2011-002 [3] Measurements
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3.1 Experimental Set up JAEA-Conf 2
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References JAEA-Conf 2011-002 [1] N
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JAEA-Conf 2011-002 was large. The a
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JAEA-Conf 2011-002 4. Results and D
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Acknowledgments Present study inclu
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Fig. 1 A conceptural picture of the
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4. Theoretical studies Theoretical
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JAEA-Conf 2011-002 Fig.9 Comparison
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Ion source JAEA-Conf 2011-002 LE
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JAEA-Conf 2011-002 3. Readiness
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JAEA-Conf 2011-002
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JAEA-Conf 2011-002 Figure 1. An exa
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JAEA-Conf 2011-002 Figure 6. Compar
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JAEA-Conf 2011-002 calculation of d
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JAEA-Conf 2011-002 equilibrium emis
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JAEA-Conf 2011-002 Cowley et al. [1
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4. Conclusions We have compared nuc
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of MeV region with highest cosmic-r
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JAEA-Conf 2011-002 events can be id
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JAEA-Conf 2011-002 models and its p
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JAEA-Conf 2011-002
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JAEA-Conf 2011-002
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JAEA-Conf 2011-002 xx
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JAEA-Conf 2011-002 1. The recent ac
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JAEA-Conf 2011-002 4. Conceptual de
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The Institute's staff of about 280
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3. Nuclear Theory Laboratory JAEA-C
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JAEA-Conf 2011-002 References [1] P
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JAEA-Conf 2011-002 reaction 6 Li +
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Using the approximated distribution
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momentum of the constituents of P.
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dσ/dΩ (mb/sr) c.m. scattering ang
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JAEA-Conf 2011-002 [2] N. Austern,
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moderating fast neutrons emitted fr
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JAEA-Conf 2011-002 3. Results and d
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JAEA-Conf 2011-002 the detection de
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Fig.1. Experimental arrangement for
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in this work was confirmed. (2) 153
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Neutron Capture Cross Section of 15
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ENDF resonance parameters are based
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sample changer. The measured flux s
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REFERENCES JAEA-Conf 2011-002 [1] W
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JAEA-Conf 2011-002 Fig. 4: The rela
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Fig. 10: The PHITS2 calculation geo
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for such a low energy region should
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MCNPX calculation was performed bas
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JAEA-Conf 2011-002 We measured dou
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1mm-thick carbon target 22mm in dia
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JAEA-Conf 2011-002 Figure 2 shows e
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The double-differential (n,xp) and
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JAEA-Conf 2011-002 forward angles.
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Fig.3. Two-dimensional plot of PI v
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JAEA-Conf 2011-002 Fig. 7. Deuteron
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JAEA-Conf 2011-002 The new detector
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4. Off line data analysis Double di
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eports of data of carbon-ion incide
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Count [-] 4 10 3 10 2 10 10 1 Charg
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Acknowledgement We are grateful to
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Beam Line BM1 Copper Target BM2 5×
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φ = φbm · ρtof · ρmulti (2) E
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References [1] K. Ishibashi, H. Tak
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JAEA-Conf 2011-002 hint at the orig
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Page 192 and 193: analysis of integral experiments [6
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