JPS60157072A - Tritium permeation preventive structure of core structure material of fusion reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a tritium permeation prevention structure using liquid metal in core tube construction materials such as the first wall and diverter/limiter of a nuclear fusion reactor.

A nuclear fusion reactor, for example, a tokamak-type fusion reactor, in which a current is passed through the plasma created along the circumference, and the force of the poloidal magnetic field generated by this current confines the plasma in a torus shape to cause a fusion reaction. 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 doughnut-shaped plasma 1. There is. In addition, a neutral particle injection heating device (not shown) serves to raise the temperature of the plasma 1 by injecting electrically neutral particles with high energy into the plasma and giving the energy to the plasma 1; The exhaust device 7 exhausts impurities such as ions and atoms 9 molecules other than the discharge gas mixed into the plasma 1 out of the system, and the shape of the magnetic field lines around the plasma is devised.
A diverter or the like is installed to guide the escaped plasma to the exhaust device 7 so that it does not directly impinge on the wall of the inner blanket 2.

A tokamak-type fusion reactor is roughly configured as described above, and the inner and outer planchers (2 and 2') react with neutrons generated by a fusion reaction with the lithium compound in the container to perform nuclear fusion. Tritium, the fuel for the furnace (
It has the ability to produce tritium (tritium) and the energy of its neutrons, making it an important piece of equipment in tokamak-type fusion reactors. This inner and outer blanket 2,2
The surfaces of core structural materials surrounding the plasma 1, such as the first wall forming the wall surface on the plasma side of ' and the diverter/limiter 6, contain fast neutrons and charged/neutron tritium particles leaking from the plasma.

Severe particle loads such as deuterium particles and helium particles,
Subject to heat load. In particular, charged/neutral tritium particles have high permeability in high-temperature structural materials, are radionuclides, and are commonly used as coolants for structural materials such as H2O and D20.
It is difficult to separate and remove it from the coolant because it is an isotope of

Conventionally, as shown in FIG. 2, core structural members such as the first wall pass a coolant 9 such as H2O or D20 through the rear surface of the wall 8 on the plasma side, and the 14M8 radiated from the core plasma is heated.
A coolant flow path 10 is provided to maintain the material temperature of the plasma-side wall 8 below an allowable temperature under the high heat flux of the high-speed neutron flux of V and the charged/neutral tritium flux.

However, in this method, although the temperature of the core structural material falls below the allowable value, on the other hand, some of the charged/neutral tritium particles incident on the surface of the core structural material directly diffuse and leak into the coolant 9 side. The tritium concentration in 9 increased with operation, creating a safety problem.

The present invention has been made to solve such problems.
It is an object of the present invention to provide a structure for preventing tritium permeation of a core structural material of a nuclear fusion reactor, which can prevent a rise in the temperature of the structural material and reduce the amount of tritium permeated and leaked into a cooling system.

The tritium permeation prevention structure of the present invention provides a narrow fixed space between the plasma surface of the core structural material and the coolant flow path, fills the space with a liquid metal such as Na or Pb, and uses the liquid metal layer to Captures charged/neutral tritium particles before they diffuse into the coolant for cooling core structural materials, diffuses them into the plenum, and transfers them to the plasma side through a permeable diaphragm made of a thin Pd film, etc. It is designed to reduce the amount of tritium that permeates and leaks into the structural material cooling system by re-releasing it.

An embodiment of the present invention will be described in detail below. In FIG. 3, 8 is the plasma side wall of the core ffW material such as the first wall or diverter/limiter, and a liquid metal layer 11 consisting of a narrow space is formed between it and the coolant channel 10 on the back side. The liquid metal 11 is provided with liquid gold R such as N, Pb, etc.
12 has been filled. A plenum part 13 is installed above liquid gold M≦JPfl, and a permeable diaphragm 4 is provided on the plasma side of the plenum part 13. Also cooling HJ flow path 10
A coolant 9 such as ) 120 or D20 is flowed into the structure to cool the structural material.

Next, the operation of this embodiment of the above arrangement will be explained. Charged/neutral tritium particles that enter from the surface of the plasma-side wall 8' of the reactor core 474 chestnut repeatedly collide with the atoms of the gold scraps that make up the structural material and fly until they lose all of their energy. . The tritium that has reached this flight distance is diffused to the liquid metal layer 11 side where the concentration is lower due to the difference in tritium concentration between the part where the flight distance has been reached and the liquid metal layer 11, and is captured there. Since the liquid metal has a low tritium solubility and a large tritium diffusion coefficient, the tritium captured in the liquid metal layer 11 diffuses into the plenum section 13 provided above the liquid metal layer 11. The tritium that has migrated to the plenum section 13 is re-emitted to the plasma side, which has a high visibility, through a permeable diaphragm 14 made of a Pd thin film or the like having a large permeability coefficient.

As detailed above, according to the tritium permeation prevention structure of the present invention, the core 4:l'? By taking advantage of the large diffusion coefficient of tritium that enters the building material, it is possible to prevent the tritium from diffusing and leaking directly into the coolant, thereby suppressing the increase in tritium concentration in the coolant during furnace operation. In addition, the high thermal conductivity of liquid metal can be used to prevent poor heat removal performance from the structure, resulting in a core structural material that is superior in terms of functionality and safety.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the outline of a tokamak-type fusion reactor, Figure 2
The figure is a schematic cross-sectional view of a conventional core structural material, and FIG. 3 is a schematic cross-sectional view of one embodiment of the tritium permeation prevention structure of the core structure +4 of the present invention. 8...Plasma of reactor core '41.7 material (11th wall 9
...Cooling month 10...Coolant channel 11...Liquid metal layer 12...Liquid total bending J3...Pre-nano part 1
4...For permeable diaphragms Applicant: Kawasaki Heavy Industries Co., Ltd. Patent attorney: Yuji Taka (T"ゝ・) Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] A narrow fixed space is provided between the plasma surface of the core structural material and the coolant channel, a liquid metal layer filled with liquid metal is provided in the space, and a plenum is provided above the liquid metal layer, and the core of the plenum is provided with a liquid metal layer filled with liquid metal. A tritium permeation prevention structure for a nuclear fusion reactor core structure, characterized in that a permeable diaphragm is installed on the side surface to reduce the amount of tritium permeated and leaked into the structural material cooling system.