JPS5855882A - Bwr type 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 boiling water nuclear reactor equipped with a control rod drive mechanism above the core.

A conventional boiling water nuclear reactor is generally configured as shown in FIG. That is, a is a reactor pressure vessel, and a reactor core is installed inside this pressure vessel 1. In addition, a control rod drive mechanism C is provided below the core.
Additionally, a steam separator d and a steam dryer are provided above the reactor core. The steam generated in the reactor core passes through the steam separator d and the steam dryer [phase] to remove moisture, and drives an external heat equipment g such as a power generation turbine via the main steam pipe f. The condensate that has passed through the condenser is sent back into the reactor pressure vessel 1 through the water supply ponder 1 and the water supply tank m.

In addition, inside the reactor pressure vessel a, there is a zoe for coolant recirculation,
A toponzo j is provided and the coolant is circulated by a recirculation pump k.

In the conventional nuclear reactor configured as described above, the control rod drive mechanism C is provided below the reactor core, and the control rods are raised and lowered by water pressure using a hydraulic control rod drive unit, etc. Water pressure control such as withdrawal control is relatively troublesome, and the structure is complicated.

In addition, control rods are subject to gravity in the direction in which they fall due to their own weight, that is, in the direction that promotes nuclear reactions in the reactor core, so strict safety measures are required to prevent accidental withdrawal of control rods. For example, in the past, a speed limiter was attached to the control rod itself to prevent it from falling, or a locking device was provided to the control rod drive mechanism, resulting in a complicated structure. In addition, since the control rod drive mechanism C is located at the bottom of the reactor where the degree of radiation contamination is relatively high, the degree of radiation contamination of the control rod drive mechanism C is high, and therefore it is difficult to maintain and replace the control rod drive mechanism e. There was a problem that workers were exposed to a large amount of radiation. Moreover, conventionally, Ji8. The engine is driven by a recirculation pump, which has a dedicated recirculation system independent of the coolant water supply system, which makes the reactor equipment even more complex and allows the reactor to be made smaller. This has become an obstacle in configuring the system.

In addition, in conventional nuclear reactors, the steam separator d and the steam dryer are not isolated from the boiling water surface, so the dry steam that has passed through the steam separator d and the steam dryer is exposed to the boiling water surface. It was easy for the wet steam generated in the process to get mixed in, which was a problem in obtaining high-quality steam.

The present invention has been made based on the above circumstances, and its purpose is to simplify the structure of a nuclear reactor, to be particularly advantageous in obtaining a medium-sized or smaller nuclear reactor with medium or small output, and to provide high quality. An object of the present invention is to provide a boiling water nuclear reactor that can obtain steam and reduce the degree of contamination of a control rod drive mechanism.

That is, the outline of the present invention is constructed as shown in FIG. In the figure, 1 is the core 2, which will be explained below with reference to Figure 2.
The control rod guide tube 3 is installed vertically above the reactor core 2. A control rod drive mechanism 4 is provided above these control rod guide tubes 3, and the control rods 5 are raised and lowered from above the reactor core 2 through the guide tubes 3. Further, a partition cylinder 6 is provided between the upper inner peripheral wall of the reactor pressure vessel 1 and the control rod guide tube 3, and a space between the partition cylinder 6 and the reactor pressure vessel wall 7 is provided. A steam separator 8 is installed in the reactor core 2 to allow steam generated in the reactor core 2 to be introduced. Also,
A steam dryer 9 is provided above the steam separator 8, and the dried steam is passed through a main steam nozzle 10 to a main steam pipe 11.
It is supposed to be sent to

12 is an external heat device such as a power generation turbine, 13 is a condenser, and a water supply pipe 14 is connected to the condenser 13. A water supply pump 15 is provided in the middle of this water supply pipe J4.

Further, a side-pressure coolant inflow chamber 20 is formed on the lower surface of the core 2 so that coolant can be fed from the bottom of the core 2. Furthermore, a jet ring 21 is installed inside the reactor pressure vessel 1 . This jet Inf21 has a suction port 2Ja communicated with the discharge side of the water supply pump 15, and an injection port 21b communicated with the coolant inflow chamber 20. The force of water jetted out from the water supply pump 15 (K) sucks in the coolant around the suction port 21a and injects it into the coolant inflow chamber 204fC. In addition, the water supply pipe 14 is connected to - on the downstream side of the water supply 4 pump J5.
For example, the pipe is branched into two, with one pipe connected to the intake port 21mlC of the jet topong 21, and the other pipe connected to the water supply pipe 22.

According to the nuclear reactor of the present invention configured as described above, all the control rod drive systems are provided above the reactor core 1, and the control rods 5 are inserted and withdrawn from above the reactor core 2, so that even if control Even if an accident occurs in which the control rod 5 falls due to a malfunction in the rod drive mechanism 4, the control rod 5 will fall in a direction that suppresses the nuclear reaction, which is very advantageous in terms of safety measures. That is, compared to the conventional case where the control rods are inserted from the bottom of the reactor core, the control rod drive mechanism 4 with a relatively simple structure can be adopted, the drive control is easy, and the control rods 5 are equipped with speed limiters. There is no need for this, and safety can be ensured sufficiently.

Moreover, since the control rod guide tube 3, control rod drive mechanism 4, etc. are installed in the upper part of the reactor where the degree of radiation contamination is relatively low,
For example, the radiation exposure of workers can be reduced when performing maintenance, inspection, and replacement work on the control rod drive mechanism 4. Therefore, safety is high and workability is improved.

Moreover, according to the above configuration, since the jet pump 21 is directly driven by the coolant sent out from the water supply pump 15, a dedicated recirculation system using a recirculation pump as in the past is not required, and the structure is simplified. . Therefore, in combination with the fact that all the control rod drive systems are installed above the reactor core 2 as described above, this is very advantageous in configuring the reactor in a compact size. The effect on obtaining a furnace is great.

Moreover, according to the present invention, the partition cylinder 6 and the reactor pressure vessel J
A steam separator I and a steam dryer 9 are installed in the space between the steam separator 8 and the steam dryer 9. The steam dryer 9 can be isolated from moist steam. Therefore, since it is possible to prevent wet steam from being mixed into the dry steam that has passed through the steam separator 8 and the steam dryer 9, high-quality steam can be obtained more efficiently than in the conventional system shown in FIG. It is something that can be done.

Next, an embodiment embodying the present invention will be described with reference to FIGS. 3 to 13. In addition, the same reference numerals are given to the parts common to those in the WJ2 diagram, and the description thereof will be omitted.

In FIG. 3, reference numeral 1 indicates the lid of the reactor pressure vessel 1, and this lid 11 is fixed to the pressure vessel main body 1b by a bolt 30.

In addition, a cylindrical shroud S1 that constitutes the outside of the reactor core 2 is installed inside the pressure vessel 1, and an upper lattice plate 31 is provided above the JL shroud 3, and the reactor core A support plate 33 is provided. A fuel support fitting 34 is installed on this core support plate JJ, and is configured to hold four fuel assemblies 35 between it and the upper grid plate 32. These fuel assemblies 15
A large number of fuel rods are housed in a rectangular cylindrical chamber called Channelmex, and the structure is the same as that of a conventional boiling water reactor fuel assembly. As shown in FIG. 5, a control rod 5 is inserted through the center.

Further, a rectifier plate 38 is provided below the core support plate J3. This rectifying plate 18 has a large number of rectifying holes S9...
By forming these straightening holes 1g, the coolant in the coolant inlet chamber 2o can flow into the straightener 40.Therefore, the coolant in the coolant inlet chamber 2o can be sent to the coolant inlet chamber 2o. The injected coolant can be evenly distributed and rectified to enter the orifice tixK5M of each fuel support fitting 34.

Further, above the upper lattice plate 31, a partition plate 41 having a large number of communication holes is provided, and furthermore, this partition plate 41
A door 42 is provided on the upper side of the shroud. This shroud head 42 has a concave shape with the center being the lowest. Therefore, the steam/water mixture rising through the partition plate txt can be smoothly guided to the lower end opening of the stand pipe 43 of the steam/water separator 8.

Further, as shown in FIGS. 6 and 7, the control rod 5 is a grade 45 with a cross-shaped cross section, which houses a large number of I-ZON-46 filled with melon carbide. be.

47 is a tube cooling hole. And the above grade 4
Attach end fittings 411.49 to both the upper and lower ends of j, and attach upper guide rows 250... and lower sf guide rollers 51... to the outer cylinder ends of these end fittings 48.49. be. Therefore, it is possible to move up and down smoothly inside the control rod guide tube 3, and also to move up and down smoothly between the channels and the boxes of each fuel assembly 350. Further, a dome 52 is provided on the control rod for lifting the upper end hardware 4gK.

On the other hand, the fuel support fitting 34 is constructed as shown in FIGS. 8 and 9. In other words, there are fuel support holes 5 in four locations.
5... are formed, and a substantially cross-shaped control rod support hole 56 is formed in the center, and this control rod support hole 56
A loose impingement element 57 is provided at the center position. This loose collider 57 is always urged upward by the repulsive force of a spring 59 housed in a spring housing chamber 58, and its head protrudes. In addition, reactor water is allowed to enter the spring housing chamber 58.Furthermore, the fuel support holes 55...
Coolant flow holes 60 . . . K formed in the vertical direction communicate with each other, and orifices 61 .

62 is a positioning pin fitting recess, and the recess 62 is used for positioning the positioning pin (
(not shown) is K-fitted.

Since the fuel support metal odor 34 is configured as described above,
Even if the control rod 5 is quickly fully inserted during an emergency stop such as a scram and falls to a position where the end metal fitting 49 collides with the fuel support fitting 34, the end metal fitting 49 hits the loose collider 51, so the falling impact is can be absorbed. In other words, the repulsive force of the spring 59 and the pressure caused by the water accumulated in the spring storage chamber 58,
7. It can absorb the impact of a fall.

Moreover, the orifice 6 of the fuel support fitting 34 opens directly below the fuel support hole 55, and the coolant flowing into the orifice 61 can be raised straight up and guided to the fuel support hole 55, as described above. Coupled with the fact that the coolant is rectified by the baffle plate 18 and pressure is applied so that it can be evenly distributed, the coolant is transferred to the fuel assembly 35 in a stable and even flow.
1C can be introduced. In other words, compared to the conventional method in which an orifice is provided on the side of the fuel support fitting and the coolant is injected from the side through this orifice, the flow of coolant is more stable, so the fuel can be distributed evenly and It enables efficient cooling and improves the functionality and life of the fuel.

On the other hand, the jet balance 21, which has the function of feeding the coolant into the coolant inflow chamber 20, is a multi-stage jet type with a second suction port 11et provided downstream of the suction port 21a. It is a trap that allows coolant to be sucked in and recirculated.

Since the jet pump 21 is driven by the feed water I ring 16, the recirculation I ring is used like a conventional boiling water reactor. There is no need for a dedicated recirculation system, which is very advantageous in terms of equipment savings.

Next, the control rod drive system will be explained. Control rod guide tube 3
A tubular housing 65 is connected to the upper end of the housing.

These housing 65 and control rod guide tube 3 are inserted into a space formed inside fIK of partition cylinder C. The housing 65 is directly welded to the pressure vessel lid JaK.

Then, in the housing C5, as shown in FIG. 10, and 1!2. A mouth with a chi mechanism 6G at the tip.

A drawer is inserted through the drawer so that it can be raised and lowered freely. Above.

The opening mechanism 66 has a tip attached to the mouth and the tip of the drawer.
IFg7m, a slide member 68 that is attached to the tip opening and the do σ1& so that it can be raised and lowered, and a slide member 68 that is pivoted to the slide member 68 so as to be swingable about pin 6#.
Tsuchi 7o, etc., this way, Chi 10's tip locking W
The structure is such that 670 m can be connected to the control rod by the Doro IK. For example, the slide member 61 is inserted into the tip opening.

When it is raised relative to the drawer 1a, the tip l and the first protrusion 11 of the dore 47m are moved, and the support of the cheerer 0 is the seat 72K.
lr contact, whereby the tip locking portion 20a engages with the control rod 11K, and the control rod 5 and rod 67 are connected. Further, when the slide member 68 is lowered relative to the tip opening and the drawer m pressure, the second pushing protrusion 7B comes into contact with the receiver seat 74, thereby securing the tip end locking portion 70m. The rod 52 is rotated in the direction in which it is uncoupled, and the rod 52 can be separated from the control rod.

The opening and the drawer are driven up and down by the control rod drive mechanism 4, and the control rod 5 can be moved up and down together with the opening and the drawer. As the control rod drive mechanism 4, for example, a well-known structure such as a magnetic, Kujak type two-stage, vertical, or three-stage electromagnet can be adopted, and during scram drive, a free fall method is used by demagnetizing the electromagnet.

On the other hand, as shown in FIG. 12, the steam/water separator 8 adopts, for example, a vertical axial flow centrifugal type. That is,
43 is a stand/dive, 75 is a stationary wing, and the air-water mixture that has risen through the stand-dia "4J"
5, a swirling flow is created, and water is separated to the outside and steam to the inside by centrifugal separation.0 The separated water is returned to the water outside the partition cylinder 6.

The steam/water separator 8 has a partition cylinder 6 as shown in FIG.
A plurality of steam separators 8 are installed on the outside of the partition cylinder 6 in the local direction, and are separated from the boiling water surface 16 inside the partition cylinder 6 by the partition cylinder 6.
It is possible to prevent the steam from being mixed with @, and to send high quality steam to the steam dryer 9. Moreover, since the steam/water mixture can be evenly distributed to each standpipe 43 by the partition plate 4, each steam/water separator 8 can function efficiently.

Further, the steam dryer 9 is configured as shown in FIG. 13 as an example. That is, a large number of parallel wave plates 80...
· are arranged horizontally, and these corrugated plates 80...
A drain gutter 81 is attached to the bottom of the corrugated plate 80.
Each time the steam passing between ... changes direction, the corrugated plate 8
The water droplets that collided with 0... are collected in drain gutter 8 and separated from the steam.

This steam dryer 9 has a partition cylinder 6 as shown in FIG.
A plurality of them are installed along the circumferential direction outside @, and are housed between the partition cylinder 6 and the f-id plate 81. That is, since it is isolated from the wet steam in the partition cylinder 6, it is possible to prevent the wet steam from being mixed into the dry steam that has passed through the steam dryer 9, and it is possible to efficiently obtain high-quality steam.

Next, the operation of the nuclear reactor according to the above embodiment will be explained. The coolant sent out by the water supply pump 15 is sent to the water supply pump 15.
When the coolant is injected into the reactor pressure vessel 1 through the dagger 22 and replenishes the coolant, the coolant is sent to the inlet 21mK of the topong 21 to drive the topimp 21 and coolant is released from the outside of the shroud 31. The coolant is sucked into the coolant inflow chamber 2.
Send it within 0. Further, the amount of water in the reactor is adjusted according to the amount of water spouted from the water supply valve 4-jar 22. The coolant flowing into the coolant inflow chamber 20 passes through the JI flow plate 38, flows into the orifice 61 of the fuel support fitting 34, ascends through the coolant flow hole 60 while the flow rate is adjusted, and flows into the fuel assembly. The coolant enters the Channel MEX through a coolant inflow nozzle provided at the lower end of the body 35 and rises while receiving nuclear reaction heat. Then, it becomes a two-phase flow of air and water, flows out from the upper outlet of the fuel assembly 35, passes through the partition plate 4, goes to the shroud, is guided to the outer circumferential side along the lower surface of the door 42, and enters the lower end opening of the stand pipe 43. Inflow.

Then, the wet steam separated from water by the steam separator JK enters the steam dryer 9, where the moisture is removed and it becomes dry steam.
It flows out from the main steam nozzle 1o. Then, external heat equipment 12 such as a power generation turbine is driven through the main steam pipe 11 shown in FIG. It will be done. The above is the steam circulation loop.

On the other hand, the output of the core 2 is controlled by adjusting the nuclear reactivity by moving the control rods 5 up and down using the control rod drive mechanism 4. During an emergency shutdown such as a scram, the control rods 5 are dropped by their own weight and quickly fully inserted into the reactor core 2. In this case, as described above, the lower end of the control rod collides with the gentle collider 57 of the fuel support fitting 34, and the impact of the fall is absorbed.

Note that the mechanism for absorbing the falling impact of the control rod is not limited to the above-mentioned gentle collider 57, but may also include, for example, a dash ram provided at the lower end of the control rod, and a dash ram fitted to this dash ram on the core support plate side. A shock absorbing mechanism with a dash and /t may be adopted.

The present invention is constructed as described above, and the upper part of the inside of the reactor pressure vessel is partitioned by a partition cylinder, and the control rod drive system is all installed above the reactor core using the inner space of this partition cylinder. Therefore, drive control is easier and safer than the conventional method in which control rods are inserted from the bottom of the reactor.
Also, the structure is simplified. Furthermore, since these control rod drive systems are installed in the upper part of the reactor where the degree of radiation contamination is relatively low, it is possible to reduce the amount of radiation exposure associated with maintenance, inspection, replacement work, etc. of the control rod drive systems.

In addition, since a steam water separator and a steam dryer are provided outside the partition cylinder so as to confine the wet steam inside the partition cylinder, the dry steam that has passed through the steam separator and the steam dryer is Contamination with CFL steam can be prevented and high quality steam can be obtained.

Since the jet pump for recirculating the coolant is directly driven by the water supply inlet connected to the water supply pipe, there is no need for a dedicated recirculation system using four recirculation knobs as in the past. This will have a major effect on providing highly efficient small and medium-sized nuclear reactors, such as the ability to make equipment easier.

[Brief explanation of drawings]

FIG. 1 is a schematic longitudinal sectional view showing a conventional nuclear reactor. FIG. 2 is a schematic vertical sectional view of a nuclear reactor showing the configuration of the present invention. 3 to 13 show one embodiment of the present invention, FIG. 3 is a vertical cross-sectional view of the nuclear reactor, and FIG. 4 is -111' in FIG. 3.
FIG. 5 is a cross-sectional view of the upper grid plate portion, FIG. 6 is a side view partially showing the control rod in cross section, FIG. 7 is a bottom view of the control rod, and FIG. 8 is a cross-sectional view along the line. Plan view of fuel support fitting, No. 9
The figure is a vertical sectional view taken along the line IX-EK in Figure 8, and Figure 1θ is the 2nd view of the control rod drive mechanism. FIG. 12 is a longitudinal cross-sectional view of the steam separator, and FIG. 13 is a partial perspective view of the steam dryer. DESCRIPTION OF SYMBOLS 1... Reactor pressure vessel, 2... Reactor core, 3... Control rod guide tube, 4... Control rod drive mechanism, 5... Control rod,
6... Partition cylinder, 7... Reactor pressure vessel wall, 8...
・Steam water separator, 9... Steam dryer, 14... Water supply piping, 15... Water supply pump, 20... Coolant inflow chamber,
2100. Jet pump, 21a... Suction port, 21
b...Injection port. Applicant's representative Patent attorney Takehiko Suzue Figure 10 Figure 13

Claims (2)

[Claims] (1) A reactor pressure vessel with a built-in reactor core, a control rod guide tube 3° installed vertically above the core, and a control rod drive mechanism that raises and lowers the control rods from above the core through this control rod guide tube. and a partition cylinder provided between the inner circumferential wall of the upper part of the reactor pressure vessel and the control rod guide tube, and a partition cylinder accommodated between the partition cylinder and the reactor pressure vessel wall to introduce steam generated in the reactor core. a steam dryer installed above the steam separator, a water supply pipe that supplies coolant from outside the reactor into the reactor pressure vessel, and a water supply pump connected to this water supply pipe. and a coolant inflow chamber formed on the lower surface side of the reactor core, and a jet which accommodates the internal pressure of the reactor pressure vessel and has an inlet communicating with the discharge side of the feedwater pump and an injection port communicating with the coolant inflow chamber. A boiling water nuclear reactor characterized by comprising: (2) The above-mentioned water supply pipe is branched into two directions, one pipe is connected to the inlet of the above-mentioned jet and toponde, and the other pipe is connected to the water supply sparger in the reactor pressure vessel. A boiling water nuclear reactor as described in scope item (1).