JPH0235276B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a tritium breeder blanket for a nuclear fusion reactor, and relates to a tritium breeder blanket with improved nuclear and thermal performance.

A nuclear fusion reactor, for example, a tokamak type, in which a current is passed through a toroidal magnetic field created by a toroidal magnetic field coil and a plasma created along the circumference, and the plasma is confined by the force of the poloidal magnetic field generated by this current. In a fusion reactor, as shown in Fig. 1, an inner blanket 2, an outer blanket 2', an inner shield 3, an outer shield 3', a toroidal magnetic field coil 4, a poloidal magnetic field coil 5, etc. are arranged around a donut-shaped plasma 1. has been done.

Blanket 2, 2' is one of the important core components, and produces tritium (tritium), which is the fuel for the fusion reactor, by causing a nuclear reaction between neutrons generated by the fusion reaction and a breeder material such as lithium oxide. It has the function of producing neutrons, the function of converting the nuclear energy of the neutrons into thermal energy that can be used for power generation, etc. within the blanket, and the function of shielding radiation together with the shielding body.

The conventional tritium breeding blanket has a diameter of 1 mm in a box-shaped blanket container 11 as shown in Fig. 2.
It is filled with small spheres of lithium oxide 12 of about 100 mL, and has a cooling pipe 13 buried therein for removing the heat generated by the nuclear reaction with neutrons. Furthermore, in order to increase the tritium production rate, as shown in Figure 3, a neutron multiplier material 14 such as lead or beryllium is placed at the front of the blanket, and the (n, 2n) reaction between neutrons and the multiplier material 14 is utilized. The aim was to increase the number of neutrons incident on the lithium oxide 12 region.

However, the tritium production rate is relatively small, and the effective thermal conductivity of the area filled with lithium oxide 12 globules is relatively small, making thermal design difficult.Furthermore, the heat generation rate within the blanket increases in the direction of the blanket thickness. It has the disadvantage that thermal design is difficult because it changes exponentially and also changes in a complicated manner in the poloidal direction depending on the fusion power distribution in the plasma and the shape of the blanket.

In view of the above technical problems, the present invention aims to provide a blanket for a nuclear fusion reactor with improved nuclear and thermal performance.

That is, the present invention dramatically improves tritium breeding performance by mixing a tritium breeding material made of lithium oxide etc. formed into small spheres with a diameter of about 1 mm and a neutron multiplication material made of beryllium etc. according to the position in the thickness direction of the blanket. This is related to a blanket for a nuclear fusion reactor that can improve the radiation heat generation rate by changing the mixing ratio as well as improving the radiation heat generation rate. The mixing ratio of the neutron multiplier is increased, thereby increasing the heat generation rate at the rear of the blanket, reducing the change in heat generation rate in the thickness direction, and further dividing the blanket into appropriate regions in the poloidal direction, increasing the heat generation rate at the rear of the blanket. This makes it possible to change the mixing ratio of neutron multiplier materials depending on the number of incident neutrons and piping density. This is intended to improve core and thermal performance by reducing changes in heat generation rate in the thickness direction and in the poloidal direction inside the blanket.

Hereinafter, one embodiment of the tritium breeder blanket for a fusion reactor according to the present invention will be described in detail.

The tritium breeder blanket is located inside the shields 3, 3' in the portion surrounding the plasma 1 of the reactor core in FIG. In FIG. 4, which shows the structure of the tritium breeding blankets 2 and 2', a filling material 20, which is a mixture of small spheres of tritium breeding material and neutron multiplier material, is housed inside a box-shaped blanket container 11. Cooling pipes 13 for taking out thermal energy inside are installed so as to correspond to the heat generation distribution. Blanket 2,
The interior of 2' is a separation wall 21 that connects 22a and 2 from the core side.
It is divided into four regions 2b, 22c, and 22d, and the mixing ratios of the tritium breeder material and neutron multiplier material filled therein are a%, b%, and 22d, respectively.
c% and d%. Figure 5 shows the details of the cooling pipe 13, where 13 is a cooling pipe with an outer diameter of about 10 mm, 13a is a spacer that maintains a gap of about 2 mm with the cooling pipe 13, and a tritium breeder material ( A neutron multiplier material 14 and a neutron multiplier material 12 (such as lithium oxide) are mixed at an appropriate mixing ratio and arranged.

Next, the operation of this embodiment configured as described above will be explained.

The tritium breeding blankets 2, 2' contain a tritium breeding material 12 such as lithium oxide,
This breeder material 12 reacts with neutrons generated in a nuclear fusion reaction and passing through the inner wall of the blanket container 11 to generate tritium. The energy of the neutrons becomes thermal energy inside the blankets 2, 2', exchanges heat with a coolant such as He _, and is transported to the outside of the reactor via the cooling pipe 13.

On the other hand, since the filler 20 contains the tritium breeder material 12 and the neutron multiplier material 14 mixed in an appropriate ratio, the tritium production rate due to neutron multiplication during operation increases. The inside of the blankets 2, 2' is divided into four parts by a separation wall 21 from the core, and filled so that the mixing ratio of the tritium breeder material 12 and the neutron multiplier material 14 is a, b, c, and d%, respectively. Therefore, by appropriately adjusting the mixing ratio, a tritium production rate corresponding to the mixing ratio can be obtained. The respective mixing ratios are a<b<c<b
By adjusting so that As a result, the blankets 2, 2' are free from thermal stress and have a long service life.

As detailed above, according to the tritium breeding blanket of the present invention, the inside of the blanket is divided into several regions in the thickness direction, and the mixing ratio of the tritium breeding material and the neutron multiplier material in each region is adjusted. Therefore, a tritium production rate corresponding to the mixing ratio of each region can be obtained. Moreover, by increasing the mixing ratio of the neutron multiplier material as the distance from the reactor core increases, it is possible to obtain an average heat generation rate in the thickness direction, further improving nuclear and thermal performance. It has a positive effect.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view schematically showing a tokamak-type fusion reactor, Figs. 2 and 3 are cross-sectional views showing a conventional tritium breeder blanket, and Fig. 4 shows an embodiment of the tritium breeder blanket of the present invention. The sectional view, FIG. 5, is an enlarged detailed view of section A in FIG. 4. DESCRIPTION OF SYMBOLS 11... Box-shaped blanket container, 12... Tritium breeder material, 13... Cooling piping, 14... Neutron multiplier material, 20... Filling material, 21... Separation wall, 2
2a, 22b, 22c, 22d... divided areas.

Claims (1)

[Claims] 1 A spherical tritium breeder and a neutron multiplier are mixed and stored in a box-shaped blanket container, the container is divided into several regions in the thickness direction and the poloidal direction, and neutron multipliers are added to each region. A tritium breeder blanket for a fusion reactor, characterized in that the mixing ratio of doubler material and breeder material is adjusted and stored to average the heat generation rate in the thickness direction and poloidal direction.