JPH0465699A - Small-sized nuclear reactor pressure vessel - Google Patents

Abstract

PURPOSE:To securely charge fuel in the nuclear reactor pressure vessel equipped with a communication part with a specific small opening in a short period of time by providing a return passage for fuel charging gas which communicates with the nuclear reactor pressure vessel. CONSTITUTION:A metal net 13 which communicates with the vessel is provided over nearly the entire surface of the internal wall of the nuclear reactor pressure vessel 2 from nearby a fuel insertion opening 8. This net 13 has meshes smaller than the grain size of the nuclear reactor fuel and discharges only the fuel charging gas except nuclear reactor fuel flowing in the nuclear reactor pressure vessel 2 and the return passage for the fuel gas to the fuel tank 1 is formed. The fuel insertion opening for charging the nuclear reactor fuel in the nuclear reactor pressure vessel is provided at only one place and the pressure vessel pressure resistance part itself is not machined as much as possible to charge the nuclear reactor fuel in the nuclear reactor pressure vessel in a short period of time.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a small nuclear reactor pressure vessel, and in particular to a small nuclear reactor pressure vessel that allows reactor fuel to be filled in a short time under zero gravity. Regarding pressure vessels.

(Prior art) The technology for filling reactor fuel into a reactor pressure vessel under zero gravity conditions in outer space has not been sufficiently established, and the technology for filling reactor fuel into a reactor pressure vessel under zero gravity conditions has not been sufficiently established. However, the filling time required a lot of time.

In addition, a large number of heat pipes are installed inside the reactor pressure vessel, and the heat generated through these heat pipes is taken out to the outside, but in this case, the temperature difference near the heat pipe exit is This caused a large amount of thermal stress, which shortened the life of the heat pipe material and, by extension, the small reactor pressure vessel.

By the way, there is a desire to have only one fuel insertion port for filling reactor fuel into the reactor pressure vessel, and since the inside of the reactor pressure vessel is exposed to high temperatures, the pressure vessel itself should be machined as much as possible. It is necessary not to do so.

(Problems to be Solved by the Invention) However, when attempting to meet the above requirements, there was a problem in that granular reactor fuel was deposited in the reactor pressure vessel in a short period of time.

Furthermore, the temperature difference between the outlet portions of the heat pipes provided in the reactor pressure vessel is large, and as a result, thermal stress there becomes considerably large.

The present invention has been made in consideration of the above-mentioned circumstances, and an object of the present invention is to provide a small-sized nuclear reactor pressure vessel that can reliably fill the reactor pressure vessel with reactor fuel in a short time.

Another object of the present invention is to provide a small nuclear reactor pressure vessel in which the thermal stress at the outlet of a heat pipe provided in the small nuclear reactor pressure vessel can be reduced. .

[Structure of the invention]

(Means for Solving the Problems) In order to solve the above problems, a small nuclear reactor pressure vessel according to the present invention includes a large number of heat pipes inside the reactor pressure vessel, and a part of the reactor pressure vessel has a fuel insertion port. A return passage for fuel filling gas is provided inside the pressure vessel and extends along the inner wall of the pressure vessel and opens toward the fuel insertion port, and this return passage communicates with the inside of the reactor pressure vessel to prevent reactor fuel particles. It is equipped with a communication section having an opening smaller than the diameter.

(Function) According to the present invention configured as described above, out of the reactor fuel and gas (fuel filling gas) flowing into the reactor pressure vessel from the fuel tank, only the gas is allowed to pass through the return passage.
The fuel can be discharged to the outside of the reactor pressure vessel from the fuel insertion port, thereby adjusting the gas pressure within the reactor pressure vessel and filling the reactor pressure vessel with reactor fuel in a short time.

Furthermore, when the return passage is formed of a wire mesh and a spacer, the temperature difference at the exit portion of the heat pipe can be reduced by connecting the return passage to the heat pipe.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

Figures 1 to 3 show that it functions even under zero gravity in outer space.
This figure shows a first embodiment of a small nuclear reactor pressure vessel according to the present invention. In FIG. 3, a fuel tank 1 and a reactor pressure vessel 2 are removably connected via a joint nut 3, and the inside of the fuel tank 1 contains powdered or granular reactor fuel. A genus of fuel cylinders 4 filled with high-pressure gas are housed.

The piping 5 from each fuel cylinder 4 joins in front of a fuel intermittent valve 6 that controls fuel injection.
A fuel insertion pipe 9 is connected to the tip of the fuel injection pipe 9, which allows the reactor fuel injection lower to be inserted into the teleskok into the fuel insertion port 8 of the reactor pressure vessel 2. A shutter 10a that opens and closes with the internal pressure of gas from the fuel cylinder 4 is provided at the tip.

Further, near the lower end of the fuel tank 1, the fuel insertion pipe 9 is provided.
A gear 11 that expands and contracts the reactor pressure vessel 2 and a pressure regulating valve 12 that adjusts the internal pressure of the reactor pressure vessel 2 and discharges excess gas are arranged.

Inside the reactor pressure vessel 2, a shutter 10b is disposed at the lower end of the fuel insertion port 8, and is opened and closed by the internal pressure of the gas from the fuel cylinder 4, similar to the shutter 10b at the tip of the fuel insertion tube 9. ing.

Furthermore, a wire mesh 13 is stretched over almost the entire inner wall of the reactor pressure vessel 2 from the vicinity of the fuel insertion port 8 .

This wire mesh 13 is formed into a mesh shape smaller than the particle size of the reactor fuel, and is used to remove only the fuel and gas (fuel filling gas) that have flowed into the reactor pressure vessel 2, leaving behind only the fuel. It is designed to discharge.

Furthermore, a hatch 14 is provided inside the fuel insertion port 8 to close the fuel insertion port 8 after the fuel insertion tube 9 is pulled out, and as shown in FIG. After the fuel tank 1 is removed from the reactor pressure vessel 2, the fuel insertion port 8 of the reactor pressure vessel 2 is plugged.
Furthermore, a cap 15 is provided for doubly improving sealing performance by pressing the hatch 14.

By the way, as shown in FIGS. 1 and 2, the reactor pressure vessel 2 is surrounded by a reflector 18, while the reactor pressure vessel 2
A plurality of heat pipes 17 are provided inside the reflector 18 and extend vertically in FIG. 1 by passing through the inside of the reflector 18. Each heat pipe 17 is connected to the wire mesh 13, and between the wire mesh 13 and the inner wall of the pressure vessel 2, the heat pipe 17 has a substantially semicircular cross section and extends from the bottom surface of the pressure vessel along the inner wall surface.
A spacer 16 that opens toward the fuel insertion port 8 is arranged.

As for the wire mesh 13, the mesh is smaller than the particle size of the reactor fuel, that is, since the particle size of the nuclear reactor fuel is, for example, about IW, the size is such that particles with a particle size of about 1 mm cannot pass through. are used. Spacer 16
A through hole 16a having a diameter of 1 to 5 steps is also bored in the peripheral wall of the holder.

As a result, the wire mesh 13 and the spacer 16 create a space between the reactor pressure vessel 2 and the inner wall of the reactor pressure vessel 2.
A fuel filling gas (gas) having a communication part that communicates with the inside of the reactor fuel and has an opening smaller than the particle size of the reactor fuel, that is, a communication part constituted by the overlapping part of the mesh of the wire mesh 13 and the through hole 16a of the spacer 16. A return passage 20 is formed.

By forming the return passage 2o with the communication portion smaller in size than the particle size of the reactor fuel in this way, the fuel and gas (fuel filling gas) flowing from the fuel tank 1 into the reactor pressure vessel 2 are prevented. Among them, only the gas passes through the return passage 10 and is discharged from the fuel insertion port 8 to the outside of the reactor pressure vessel 2, thereby reducing the gas pressure inside the reactor pressure vessel 2 and converting the reactor fuel into fuel. The reactor pressure vessel 2 can be filled from the tank 1 in a short time.

Next, a case will be described in which the above embodiment is used in zero gravity and zero atmospheric pressure space to fill the reactor pressure vessel 2 with fuel.

First, attach the fuel tank 1 to the reactor pressure vessel 2 using the joint nut 3.
Then, the fuel insertion tube 9 is inserted using the gear 11 until the tip of the tube comes into close contact with the lower end of the fuel reservoir 8.

Then, by opening the fuel intermittent valve 6, the fuel cylinder 4 is opened.
Reactor fuel and gas are spewed out from the reactor. Then, shutter 1
0a and 10b are opened by the pressure of the gas at this time, and reactor fuel and gas flow into the reactor pressure vessel 2.

When the fuel intermittent valve 6 is closed when the reactor fuel and gas are filled to a certain extent, the gas inside the reactor pressure vessel 2 will mainly flow from the bottom of the reactor pressure vessel 2 to the return formed by the wire mesh 13 and the spacer 16. Passage 20. That is, it passes through the mesh of the wire mesh 13 and the through hole 16a of the spacer 16, passes through the space defined by the spacer 16 and the inner wall of the reactor pressure vessel 2, passes through the outside of the fuel insertion pipe 9, and becomes fully open. Pressure regulating valve 12
is discharged to the outside.

Then, at the point where the gas in the reactor pressure vessel 2 was released,
The fuel intermittent valve 6 is opened again, and the opening and closing of the fuel intermittent valve 6 is repeated until all the contents of the fuel cylinder 4 have been spouted out.

At this time, the reactor fuel is in a weightless state, so it is freely flying around inside the reactor pressure vessel 2, and even if the fuel filling rate becomes high, the mesh of the wire mesh 13 and the through-holes of the spacer 16
6a will not become clogged, and filling of reactor fuel and discharge of gas can be performed smoothly. Furthermore, when the fuel intermittent valve 6 is closed, the double shutters 10a and 10b arranged at the tip of the fuel insertion tube 9 and the lower end of the fuel insertion port 8 are closed, so that the reactor fuel flows into the fuel insertion tube 9 or the fuel insertion port 8. This can prevent the flow from flowing backwards.

When the last gas inflow from the fuel cylinder 4 occurs, the pressure of the gas in the reactor pressure vessel 2 is adjusted via the pressure regulating valve 12 to the level required for operating the reactor, and the fuel insertion pipe 9 is moved into gear. 11, the hatch 14 is closed, and the reactor pressure vessel 2 is hermetically sealed.

Furthermore, loosen the joint nut 3 and connect the fuel tank 1 to the pressure vessel 2.
After removing it, the cap 14 is closed, thereby doubly sealing the fuel insertion port 8 and completing the reactor fuel filling operation.

Here, the wire mesh 13 is made of a material with high thermal conductivity and is connected to the heat pipe 17 as described above, so that heat is conducted to the heat pipe 17 through the wire mesh 13, thereby reducing the temperature difference in this area. Can be made smaller.

Note that, as shown in FIG. 5, the particle size of the reactor fuel is smaller than the particle size of the reactor fuel, for example, on the order of one day, on the peripheral wall of the spacer 16' without providing the wire mesh 13. A through hole 16' with a diameter of, for example, about 0°5-2, is large enough that particles of about 1111I11 cannot pass through.
It is also possible to form a return passage 20' between this spacer 16' and the inner wall of the reactor pressure vessel 2 for a return flow passage of the fuel filling gas (gas) by drilling a hole in the spacer 16'.

It is also possible to use perforated tubes instead of the spacers 16, 16'.

〔Effect of the invention〕

Since the present invention has the above-mentioned configuration, the fuel insertion port for filling reactor fuel into the reactor pressure vessel is set at one place, and the pressure vessel pressure-resistant part itself is not processed as much as possible while meeting the requirements. Reactor fuel can be filled into the reactor pressure vessel in a short time.

Moreover, if the return passage is formed of a wire mesh and a spacer, and this wire mesh is made of a material with good thermal conductivity, by connecting this return passage to the heat pipe, the pipe at the outlet of the heat pipe can be This has the effect of being able to reduce the temperature difference between the area and the area where it is not present.

[Brief Description of the Drawings] Figures 1 to 3 show an embodiment of a small nuclear reactor pressure vessel according to the present invention. Figure 3 is a cross-sectional view along the line ■-■ in the figure, Figure 3 is an overall vertical cross-sectional view showing an outline of the state in which the fuel tank is connected to the reactor pressure vessel, Figure 4 is a front view showing the cap, Figure 5 is the main body. FIG. 2 is a diagram corresponding to FIG. 2 showing another embodiment of the invention. 1... Fuel tank, 2... Pressure vessel, 4... Fuel cylinder, 8... Fuel insertion port, 9 River fuel insertion pipe, 12.
...Pressure regulating valve, 13...wire mesh, 16.16'...
Spacer, 16a, 16' a... Through hole, 17...
・Heat pipe, 20.20'...Return passage.

Claims (1)

[Claims] Return fuel filling gas that extends along the inner wall of the pressure vessel and opens toward the fuel insertion port into a reactor pressure vessel that is provided with a large number of heat pipes and partially equipped with a fuel insertion port. A small nuclear reactor pressure vessel characterized in that a passage is provided, the return passage communicating with the inside of the reactor pressure vessel, and comprising a communication portion having an opening smaller than the grain size of the reactor fuel.