JPS6195278A - Stop device for nuclear 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 [Technical Field of the Invention] The present invention relates to a nuclear reactor shutdown system, and is mainly suitable for use in future large-scale fast augmented reactors for its safety profile, and is This invention relates to an innovative nuclear reactor shutdown system whose operating principle is completely different from that of the control rod drive mechanism of 2015.

[Technical background of the invention and its problems]

In fast breeder reactors in Japan, both experimental reactors in operation and prototype reactors under design, reactor start-up, shutdown, and operation control are carried out by injecting MIII rods into and out of the reactor core.
Jll! This is done by the organization. However, the restraint is inserted into the lower guide pipe installed in the reactor core,
The pulling and insertion operations are performed by mechanically coupling the drive mechanism and latch mechanism installed on the shielding plug. A long extension shaft is connected to a ball nut screwed into the ball screw, and a control rod connected to the extension shaft is driven by a latch mechanism at the end of the extension shaft F. In particular, when scramming a nuclear reactor, either release the connection with the latch alt at the lower end of the extension shaft, separate the control rod from the extension shaft, and drop it alone, or demagnetize the electromagnet installed in the drive section on the shielding plug. The extension shaft is separated from the drive shaft and dropped together with the control rod. By using both methods together in the DEMO reactor, common cause failures during reactor scram are avoided and the reliability of the reactor shutdown system is improved.

However, if larger reactors are to be put into practical use as commercial reactors in the future, it will be necessary to improve layer reliability compared to conventional ones, and from this perspective, the conventional 1tiJJ allll reactor has already been used overseas. A reactor shutdown device with a completely different driving mechanism has been proposed.

As shown in FIG. 3, an example of the electromagnetic stop device transmits the rotation of a drive motor 23 mounted on a drive section on the upper lid shielding plug 22 of a reactor vessel 21 to a ball screw 24, and This is converted into the vertical movement of the nut 25, and the extension shaft 26, which is provided with an electromagnet 27 at the lower end, is moved up and down. ) 28, and pulls out and inserts it. At the time of scram, the current to the electromagnet 27 is cut off to demagnetize it.
The control rod 28 is separated from the extension shaft 26 and dropped. Also,
By forming the iron core material of the electromagnet 27 with a special all-island material whose magnetic properties rapidly drop (to a single point) when the temperature of the coolant rises abnormally, Then, the holding force of the electromagnet 27 is made to decrease rapidly,
Therefore, it is assumed that scramming can be performed without external operations.

However, such devices have structural limitations.
・It is difficult to make the size of the electromagnet 27 large enough with enough margin, and if foreign matter adheres to the suction surface, the holding force may change significantly. There are some issues that need to be addressed.

In addition, the electromagnetic pump type stopper has a completely different operating principle from such an electromagnetic stopper, as shown in Figure 4.
The core 2 inside the reactor I unit 21 penetrates the shielding plug 22.
An electromagnetic pump 31 is inserted into the outer periphery of the reactor 9, and the discharge side of the electromagnetic pump 31 is connected to the lower end of the guide tube 30 via a connecting pipe 32. During reactor operation, the electromagnetic pump 31
The control rods 28 are constantly pulled out and held by the fluid pressure generated by the control rods 1 to push them out of the reactor core, and during scram, the electromagnetic pumps 31
By stopping, reversing, or reversing the control rod 28,
There are things that fall. Incidentally, the reference numeral 35 in the figure is a holder for the electromagnetic pump 31, and the core upper mechanisms 1 and 36 are suspended from the shielding plug 2.

However, in this device, the support plate 34 is
It is necessary to install a connecting pipe 32 at the bottom of the reactor, and the integrity of this pipe 32 is almost impossible to inspect. Even if a special Curie single point material is used as the core material, there are problems such as the response being considered to be extremely slow due to position.

[Purpose of the invention]

Therefore, the present invention was devised in order to solve the problems that existed in the past, as described above, and has a completely different operating principle from the conventional ones, and has a self-sustaining function when the coolant temperature is abnormal. The purpose of this invention is to provide a nuclear reactor shutdown system that can improve control responsiveness, facilitate maintenance and inspection, and diversify reactor shutdown systems.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention utilizes the fluid pressure of an electromagnetic pump, but the electromagnetic pump itself is placed on the guide tube of the reactor core, and the control rods are pulled out by the suction action of the electromagnetic pump itself. , I changed it to 2 for insertion. In other words, the atomic power plant consists of a control rod that is inserted into a guide tube installed in the core of a nuclear reactor, and a drive mechanism that is inserted through a shielding plug and controls the control rod's protrusion and retraction from the guide tube. Furnace shutdown,
In the equipment, an electromagnetic pump is installed at the lower end of the drive mechanism to suck the coolant in the guide tube. During reactor operation, the control rod is held in the fully retracted position by sucking the coolant from the electromagnetic pump, and during a scram, the electromagnetic pump The purpose is to allow the control rods to fall into the reactor core when the pumps are stopped or reversed.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

Reference numeral 1 shown in FIG. 1 is an atom, a reactor vessel,
The upper opening of the reactor vessel 1 is shielded by a shielding plug 2, and the shielding plug 2 is provided with a driver #f47 that is inserted into the reactor vessel 1 through the shielding plug 2. Although not shown, the am drive mechanism 7 includes a portion in which an upper guide tube and an electromagnetic pump 8, which will be described later, are integrated, and a ball screw, nut, and drive motor that connect the portion. This drive mechanism 7 is a drive mechanism arranged on the shielding plug 2! i
11 section 3, and the entire drive unit 1iie7 is raised and lowered by the drive of the drive section 3. The drive unit 3 transmits the rotation of the drive motor 4 to the ball screw 5,
It is designed to convert the vertical movement of the ball nut 6 screwed into this ball screw 5, and this ball nut 6
A drive mechanism 7 is connected to the drive mechanism 7.

At the lower end of the drive mechanism 7, there is a helical induction (
HIP) type electromagnetic pump 8 is provided, and when the drive mechanism 7 is lowered with a predetermined stroke by the drive operation of the drive unit 3, the electromagnetic pump 8 at the lower end of the drive mechanism 7 is inserted into the lower guide pipe 11. It is like that. FIG. 2 is an enlarged sectional view showing the state in which the electromagnetic pump 8 is inserted into the drive mechanism 7. An annular iron core 13 is inserted into the upper guide tube 12, and a solid iron core 14 is inserted into the annular iron core 13. A spiral duct 15 is attached to the outer surface of the solid iron core 1-4. A coil 16 is attached to the annular core 13.
is buried. Note that 17 and 18 indicate the core support □, respectively.

During reactor operation, the electromagnetic pump 8 is activated to suck the coolant in the lower guide pipe 11. Furthermore, during scram, the electromagnetic pump 8 is stopped and reversed to allow the r-υJtlll rod 9 to fall into the reactor core 10. That is, the fluid pressure of the electromagnetic pump 8 placed above the reactor core 10, especially its suction action, is used to handle the control rod 9, and the suction W is released, and the Ruru 8 and Koto r Sapphire 9 are dropped. It's a thing. □ The iron core material i of the electromagnetic bong 18 is, for example, 550°C to 65°C.
Select a material that has a magnetism of 8 (lower) at 0°C, such as Nt:i-(:, o alloys, etc.). Select a material that can be rolled. The lower guide tube can be made of a material such as electromagnetic soft iron that has strong magnetism.In addition, by making it from a special material whose magnetism suddenly decreases at the appropriate temperature where the coolant becomes abnormally high, the lower guide tube can be 11 The cold fJI material that has flowed out of the surrounding fuel can flow directly to the external cause of the electromagnetic pump 8, so if the temperature at the exit of the reactor core 10 becomes abnormally high, the magnetic force of the iron core material of the electromagnetic pump 8 will cause the control rods 9 to It can automatically avoid falling without external operation, further improving safety.

Further, as described above, the drive mechanism 7 is supported in a vertically movable manner via the drive unit 3 consisting of the drive motor 4, the ball screw 5, and the ball nut 6, and the electromagnetic pump 8 is removably fitted into the upper end opening of the guide tube 11. It is designed to match. In this way,
When the drive vj mechanism 7eK is pulled up with a predetermined stroke and the electromagnetic pump 8 and the guide tube 11 are disengaged, the drive fIl1
By separating the mechanism 7 from the core 10 and rotating the rotary plug in the same manner as before, fuel exchange can be performed.

Immediately 6. Drive-t"-"'D+mte deceleration 11 e *
L ril: -Transmit the screw to the screw, and move the nut that is screwed into the -F downward direction. The upper guide tube 12 connected to the nut moves up and down, and engages with and disengages from the lower guide tube 11 in the core 10.

When the one-position valve 8 is activated with the mated state tapped, the coolant (Na) in the lower guide tube 11 is sucked and controlled by the fluid pressure.
When the electromagnetic pump 8 whose rod 9 rises is stopped from the outside, fluid pressure disappears and the control rod 9 falls under its own weight.

If a magnetic material whose magnetism significantly decreases in the range of 550°C to 650°C is used in the iron core, in the unlikely event that something happens inside the core 10.
4, the electromagnetic force decreases and the suction force of the coolant decreases, so the control rod 9 falls naturally.

When the nuclear reactor is stopped and fuel is replaced, the drive motor is reversed, the upper guide tube 12, that is, the electromagnetic pump 8 is pulled up, and the connection with the lower guide tube 11 is released.

1 [Effects of the Invention] As described above, the present invention provides an electromagnetic pump at the lower end of the drive mechanism that sucks the coolant in the guide tube, and utilizes the fluid pressure of the electromagnetic pump disposed above the reactor core. Since the a11 control rod is pulled out and dropped, there is no need for conventional piping inside the reactor, making maintenance and inspection extremely easy.

Furthermore, it is possible to use a reactor shutdown system whose operating principle is completely different from that of the conventional control rod drive Is structure, resulting in extremely excellent effects such as further improving the reliability of the nuclear reactor.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a vertical sectional view showing an enlarged main part of FIG. 1, and FIG. 3 is a sectional view of a conventional M magnet type stopping device. FIG. 4 is a sectional view of a conventional electromagnetic pump type stop device. DESCRIPTION OF SYMBOLS 1... Reactor vessel, 2... Shielding plug, 3... Drive part, 4... Drive motor, 5... Ball screw, 6...
... Ball nut, 7... Drive mechanism, 8... Electromagnetic pump, 9... Control rod, 10... Reactor core, 11... Guide tube, 21... Reactor vessel, 22...・Shielding plug,
23... Drive motor, '24... Ball screw, 25
...Ball neck t-, 26...Extension shaft, 27...
Electromagnet, 28...control rod, 29...core, 30...
・Guide pipe, °31...electromagnetic pump, 32...connecting pipe. Figure 3 Figure 4

Claims (1)

[Claims] 1. A control rod that is inserted into a guide tube installed in the core of a nuclear reactor, and a control rod that is inserted through a shielding plug to control the emergence and retraction of the control rod from the guide tube. In a nuclear reactor shutdown system consisting of a drive mechanism, an electromagnetic pump is installed at the lower end of the drive mechanism to suck the coolant in the guide tube, and during reactor operation, the control rod is held in the withdrawn position by sucking the coolant from the electromagnetic pump. A nuclear reactor shutdown device characterized in that, during a reactor scram, all control rods are dropped into the reactor core by stopping or reversing the electromagnetic pump. 2. The nuclear reactor shutdown device according to claim 1, wherein the core material of the electromagnetic pump is made of a Curie point material. 3. The drive mechanism is supported so as to be able to move up and down via a drive unit consisting of a drive motor, a ball screw, and a ball nut, and the electromagnetic pump is removably fitted to the upper end opening of the guide tube. Nuclear reactor shutdown device as described in paragraph 2 or paragraph 2.