JAEA-Conf 2011-002 - 日本原子力研究開発機構
JAEA-Conf 2011-002 - 日本原子力研究開発機構
JAEA-Conf 2011-002 - 日本原子力研究開発機構
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operation mode. A selection of the beam facing materials has to take into account the neutron production<br />
and the activation level as well as the thermal stresses. In the present design, a cone shaped copper with<br />
0.005m thickness is used, and it is surrounded by water tank of a 0.75m-radius.<br />
2.3 Area Monitoring System<br />
Area monitoring system consists of two types; gamma-ray monitors and neutron monitor. The<br />
specifications of these monitors are shown in Table 1, and the location is shown in Fig.1. As shown in Table<br />
1, the detectable energy range of the neutron monitor is from 0.025eV to 15MeV and the directional<br />
characteristics is -60 to +240° for a vertical direction, and that of the gamma-ray monitor is from 80keV to<br />
1.5MeV and ±90° for a horizontal direction, -60 to +240° for a vertical direction. As shown in Fig.1, the<br />
area monitors are installed the external side of accelerator vault.<br />
Table 1: The kinds of area monitor<br />
Monitor Specification<br />
Neutron<br />
monitor<br />
Gamma-ray<br />
monitor<br />
<strong>JAEA</strong>-<strong>Conf</strong> <strong>2011</strong>-<strong>002</strong><br />
Type helium-3 counter<br />
Energy range 0.025eV to 15MeV<br />
Dose rate characteristic dose equivalent rate: 10 -2 to 10 4 Sv/h<br />
Directional characteristics vertical direction: -60 to +240°<br />
Type semiconductors type<br />
Energy range photon: 80keV to 1.5MeV<br />
Dose rate characteristic dose equivalent rate: 10 -1 to 10 4 Sv/h<br />
Directional characteristics horizontal direction: ±90°, vertical direction: -60 to + 90<br />
Type ionization chamber type<br />
Energy range photon: 80keV to 1.5MeV<br />
Dose rate characteristic dose equivalent rate: 10 -1 to 10 5 Sv/h<br />
Directional characteristics horizontal direction: ±90°, vertical direction: -60 to +90<br />
3. Analysis<br />
3.1 Nuclear data<br />
Deuteron induced thick target neutron yield at 9MeV was measured in collaboration with Kyushu<br />
University because there was no experimental data for Cu(d,nx) reaction in the range of 5-9MeV[6]. The<br />
experimental data which is neutron generation in case of 1 C irradiated to cupper is used as a source term<br />
in neutron transportation, and the energy reduction of photon are evaluated by PHITS code. The JENDL<br />
4.0 is used for nuclear cross-section library.<br />
3.2 Model<br />
A point source which has the neutron angular distribution is used for this analysis as shown in Fig.2.<br />
The neutron point source is located in the center, and the total number of 1.35 x10 10 [n] by a 9MeV-1C<br />
deuteron beam, is emitted. The 0.005m thickness copper is set around the point source. As for concrete