JPS60146963A - Liquid metal sodium valve - Google Patents

Abstract

PURPOSE:To prevent breakdown of liquid metal sodium valve having metallic expansion joint by constructing the drive shaft with slide drive shaft and valve body drive shaft and jointing through a slip mechanism with the valve body. CONSTITUTION:When metal sodium is solidified in a valve box 2, a handle 5 is turned to push down a slid drive shaft 4b thus to lower a slip shaft opening indicator 12b. But since a metal expansion/shrinkage joint 13 can not displace, reaction will occur in the valve drive shaft 4a. Since the fastening force of slip joint 15 is set lower than said reaction, the slip drive shaft 4b can not be stopped but slip through the slip joint 15 to prevent transmission of displacement of valve body drive shaft 4a.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a valve having an expansion joint, and in particular to a metal expansion joint suitable for a valve having a metal expansion joint used in IJum equipment. This invention relates to a liquid metal sodium valve with a protection mechanism.

[Background of the invention]

In fast breeder reactors, liquid metallic sodium is used as the reactor's primary coolant. Metallic sodium is normally solid, but it has the property of turning into a liquid when heated above 980°C, and also has the property of igniting due to a chemical reaction when it comes into contact with moisture in the air. Since this liquid metal sodium is used as a primary coolant in a fast breeder reactor, in addition to the above characteristics, it becomes a radioactive corrosion product and becomes a source of radiation. For this reason,
Equipment containing liquid metal sodium must have a structure that takes the above characteristics into consideration, and the liquid metal sodium valve has the following characteristics.

FIG. 1 shows the structure of a liquid metal sodium valve according to the prior art. It is the valve box 2 that holds the liquid metal sodium 1, and the valve body 3 is in line contact with the valve box 2 in order to block the flow path of the liquid metal sodium 1. Since the drive shaft 4 moves up and down with the rotation of the nondle 5, the valve body 3 similarly moves up and down with the operation of the drive shaft 4. A bonnet 6 is fastened to the upper end of the valve body 2 by bolts 7 and nuts 8 and is welded to the valve body 2. A gland packing 9 is attached to the upper end of the bonnet 6 to close the gap with the drive shaft 4, and is held down by a packing presser 10. Further, a yoke 11 for supporting the handle 5 is attached to the bonnet 6. A detent 12 is attached to the drive shaft 4 below the nondle 5 to indicate the position of the valve body 3 and to prevent rotation of the drive shaft 4. Inside the valve box 2, there are a valve body 3 and a bonnet 6.
A metal expansion joint 13 is attached by welding between each. An electric heater 14 is wound around the outside of the small valve box 2.

This structure allows the liquid metal sodium 1 inside the valve body 2 to
It is completely isolated from the outside and all connections are welded, but a metal expansion joint 13 is provided between the valve body 3 and the bonnet 6 to absorb the amount of vertical displacement of the valve body 3. be. Normally, when the liquid metal sodium 1 is contained in the valve, the valve is preheated by the electric heater 14 to a temperature higher than the temperature at which the liquid metal sodium 1 is melted.
If the power to the electric heater 14 is turned off due to a malfunction of the valve, inadequate preheating equipment, or operational necessity, the metal (IJum 1) solidifies inside the valve. If the valve is operated incorrectly in this state, an excessive load will be applied to the metal expansion joint 13 because the metal expansion joint 13 inside the valve body 2 is made of a thin metal plate, and the metal expansion joint 13 will be damaged. There was a drawback. Due to the damage, when the electric heater 14 is energized, the liquid metal inside the valve box 2 melts.
Damaged part Lf); '57b''': yHy9 part 2 pieces 91・outside'1mK1.t.

I will do it. If moisture in the external atmosphere of the valve comes into contact with the leaked liquid metal sodium 1, it may cause a fire, and the liquid metal sodium 1 of the secondary coolant may
If so, there would be the disadvantage of radioactive contamination and internal exposure to workers. Additionally, repairing this damaged valve involves work under high radiation doses, which has the disadvantage of increasing external radiation exposure for workers.

[Purpose of the invention]

The purpose of the present invention is to prevent the metal expansion joint and valve body from being restrained by solidified metal sodium in the valve box, and to prevent the drive unit from applying an excessive load to the metal expansion joint even in the event of an erroneous operation. A liquid metal slurry that prevents damage to metal expansion joints, which are structurally weak in valves, by cutting off the force transmitted to the valve body.
- To provide an IJum valve.

[Summary of the invention]

The liquid metal sodium valve of the present invention comprises a valve body, a reciprocating drive shaft that drives the valve body, and a metal expansion joint that connects to the valve body and wraps around the drive shaft from the outside.
The IJum valve is characterized in that the drive shaft is connected to a sliding drive shaft and a valve body drive shaft via a sliding mechanism.

(The metal inside the valve box) When IJum is molten, its physical properties are similar to water, so if you turn the handle and close the valve body while it is molten, there will be a vertical displacement on the drive shaft. A reaction force B is generated, which is made up of the force A and the spring constant of the metal expansion joint that is indirectly connected to the drive shaft. When the valve is displaced in the closing direction, the force relationship at this time is A>B as shown in FIG.

When the valve body contacts the valve body, a reaction force C of the valve body is generated. At this time, the force relationship becomes A≦C as shown in FIG. 3, and the displacement of the valve body stops.

If IJum is solidified, metal IJum will be present in the valleys of metal expansion joints and valve discs.
A large restraining force is generated. The power relationship at this time is the fourth
As shown in the figure, A<D, and the valve body is not displaced. However, if a larger displacement force A' is applied, an excessive displacement is applied to the metal expansion joint, which exceeds the tensile strength of the material and causes it to break. From the relationship of forces when this metallic sodium is solidified, the displacement force A
As a means to cut off the transmitted force when ' exceeds A, independent drive shafts are provided on the handle side and the valve body side, and the drive shafts are connected with a joint.

This joint can transmit force without slipping on the drive shaft under force A.
When the force exceeds , it slides on the drive shaft and prevents displacement from being transmitted to the metal expansion joint.

[Embodiments of the invention]

The details of the present invention will be explained below with reference to embodiments shown in the drawings.

FIG. 5 shows an embodiment of the present invention, and the same reference numerals as in FIG. 1 indicate components having the same functions.

A valve body drive shaft 4a is attached to the bonnet 6 side, and a slide drive shaft 4b is attached to the handle 5 side. The valve body drive shaft 4a and the sliding drive shaft 4b are connected by a slide joint 15. The slide joint 15 is tightened by a tightening ring 16.

A valve opening degree indicator 12a, which also serves as a stopper for shaft rotation 9 for driving the valve element, is attached to the valve element drive shaft 4a so as to sandwich the yoke 1'1a. A slide shaft opening degree indicator 12b, which also serves as a rotation stopper for the slide drive shaft 4b, is attached to the slide drive shaft 4b so as to sandwich the yoke lla.

FIG. 6 is a detailed diagram showing the structure of the slide joint 15. The joint consists of two sliding joints 15a and 15b, each of which has a tapered pipe thread 17 cut on its outer surface. A slip joint 15a is provided on the valve body drive shaft 4a.

A groove 18 is cut into which the sliding joint 15b fits, and the sliding joints 15a and 15b come into contact with the sliding drive shaft 4b. The sliding joints 15a and 15b are clean! 7JIt! A gap is provided to ensure the stroke of the first moving shaft 4b. A tightening ring 16 threaded on the inside is attached to the outside of the slide joints 15a, 15b.

FIG. 7 is a cross section of the sliding joint 15 taken along line E-E.

The tightening ring 16 is attached with two small screws 19° and 19b so that it can be fixed in any position.2 To close the valve body 3, turn the handle 5, and the handle 5 acts as a female screw. The force is also transmitted to the valve body drive shaft 4a connected to the slide joint 15, and the valve body 3 is pressed against the valve body 2. When the metallic sodium is solidified, turning the handle 5 pushes the sliding shaft drive shaft 4b downward, and the corresponding sliding shaft opening degree display 12b also moves downward.However, the metallic expansion joint 13 is displaced. As a result, a reaction force is generated on the valve body drive shaft 4a.At this time, since the slide joint 15 is set to a force that cannot be tightened below this reaction force, the slide joint 15 cannot be held down. The sliding drive shaft 4b slides at the sliding joint 15, and only the sliding drive shaft 4b is displaced, and the displacement is not transmitted to the valve body drive shaft 4a. Slide shaft opening display 12b and valve body opening display 12
This can be determined by reading the indicated value of a.

According to one embodiment of the present invention, if the metal inside the valve is liquid, the valve body can be opened and closed easily, and when it is solid, the valve body and metal expansion joint can be fixed. Since the displacement force is not transmitted to the valve body using the fixing force, it is effective in preventing damage to metal expansion joints with a weak number of structural beads. Furthermore, this solidification phenomenon can be confirmed by reading the difference in opening degree display between the drive unit side and the valve body side.

Also, by changing the way the slip joint is tightened, the transmitted force can be adjusted freely. The slip joint is equipped with a pipe taper thread, which has the effect of making it easier to adjust the tightening force. Also, insert a small screw into the tightening ring.
This has the effect of preventing arbitrary changes in the tightening force of the sliding joint.

FIG. 8 shows another example of application of the present invention. Normally, liquid metal sodium valves are operated from the valve body, but in nuclear power plants such as fast breeder reactors, the atmosphere at the installation site is replaced with nitrogen gas, an inert gas, in case of a leakage accident of liquid metal sodium. Therefore, it must be operated remotely. The internal structure of the liquid metal sodium valve is similar to that shown in FIG.

What is different in appearance is the universal joint 20a instead of the handle 5.
is attached to the drive shaft 4, an extended drive shaft 21a is connected to one end of the universal joint 20a, and a universal joint 20b is connected to one end of the extended drive shaft 21a.

An extended drive shaft 21b is connected to the universal joint 20b. The extended drive shaft 21b passes through a sleeve 23 embedded in the concrete 22 of the floor or wall that it penetrates, and is connected to the sliding drive shaft 4b within the drive unit stand 24 by a sliding joint 15 and a tightening ring 16. There is. The sliding drive shaft 4b passes through the drive unit stand 24, and the nondle 5 is attached to the top thereof. Sliding drive shaft 4b and extension drive shaft 21
b, a slide shaft opening degree display 12 is provided in the drive unit stand 24.
b and a valve body opening degree display 12a are attached.

At the upper part of the sleeve 23, the mounting is tightened by a gland packing 26 provided on the stand 25 in order to isolate the atmosphere from the room in which it is installed. Sleeve 23
The penetrating portion of the concrete 22 is filled with a filler material 27 for shielding.

This embodiment also has the effect of protecting the metal expansion joint of the remotely operated valve, which cannot be accessed during operation. Furthermore, although the drive section requires some work to install at a different location, the sliding joint is divided into two parts, so it can be easily installed.

〔Effect of the invention〕

According to the present invention, focusing on the fact that the sticking force between the valve body and the metal expansion joint that occurs when metallic sodium is stuck inside the valve exceeds the driving force caused by normal valve operation, the drive shaft is
By setting the pressure force of the divided joint parts within a range that does not exceed this fixing force, it is possible to generate slippage in the joint parts. As a result, the driving force is not transmitted to the metal expansion joint, which is structurally weak, so that damage to the metal expansion joint can be prevented. Furthermore, it is possible to determine whether or not sticking has occurred based on the difference in the opening degree display provided in the two stages. Furthermore, since the pressure of the sliding joint can be freely adjusted, valves that use solidified metallic sodium have the effect of making the valve completely inoperable by opening the joint.

to

[Brief explanation of the drawing]

4. / Fig. 1 is a sectional view showing the structure of a conventional liquid metal sodium valve, Figs. Sectional view shown, No. 6
7 is a sectional view taken along the line EE in FIG. 6, and FIG. 8 is a sectional view of the structure showing an example of application of the present invention. 4a... Valve body drive shaft, 4b... Sliding drive shaft, 11a
...Yoke, 12a...Valve opening degree display, 12b...
・Sliding shaft opening display, 15, 15a, 15b-... Slip 9 joint, 16... Clamping ring, 17... Pipe tee (screw,
18... Groove, 19a, 19b... Machine screw, 21b.
・Extended drive shaft. Agent Patent Attorney Akio Takahashi No. 10 Bemine 20 Kaya 40 Kaya 50

Claims (1)

[Claims] 1. A liquid metal sodium valve comprising a valve body, a reciprocating drive shaft that drives the valve body, and a metal expansion joint that connects to the valve body and wraps around the drive shaft from the outside; A liquid metal sodium valve characterized in that the shaft consists of a sliding drive shaft and a valve body driving shaft, which are connected via a sliding mechanism. 2. In claim 1, the sliding joint is a sliding joint divided into a plurality of parts and having a tapered pipe thread on the outside;
A liquid metal sodium valve consisting of a clamping ring with a tapered pipe thread on the inside. 3. A liquid metal valve consisting of a drive shaft and a valve body that are raised and lowered by the driving force, and a metal expansion joint that connects to the valve body and wraps around the drive shaft from the outside. consists of a slide drive shaft and a valve body drive shaft, which are connected via a sliding mechanism, and is characterized in that the slide drive shaft and the valve body drive shaft are provided with valve opening degree indications before and after the slide mechanism. liquid metal sodium valve.