JPS61118695A - Light water cooling 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 "Industrial Application Field" The present invention controls the output by controlling the concentration of boric acid water in the primary cooling system, and in particular directs the upward flow of cooling water from the core to the heat exchanger. This relates to a light water-cooled nuclear reactor designed to increase thermal efficiency by being forced into the reactor.

``Prior art'' A light water-cooled nuclear reactor whose output is controlled by the concentration of boric acid water is capable of reducing the amount of water in the vicinity of the reactor core and surrounding pool water in the event of an abnormal rise in internal temperature. This system takes advantage of the phenomenon of convection caused by differences in the specific gravity of fluids due to temperature differences, etc., and sends spray water, which is pool water, into the reactor core to bring the reactor to a state of natural shutdown. It is a proof type, and has attracted attention in recent years because of the need to fully consider the location conditions of nuclear power plants, such as proximity to cities.

An example of the conventional structure will be explained based on FIGS. 3 and 4. A pressure vessel 33 for storing pool water W made of boric acid water is constructed of a thick prestressed concrete wall, and a liner of the pressure vessel 33 is constructed of a thick prestressed concrete wall. 3
A reactor core 5 is provided in the reactor core 4, and the reactor core 5 is surrounded by a double-structured outer case 20 and a reactor core casing 19, and
Double cylindrical bodies 16 and 35 are connected to the upper part of the double casings 19 and 20, and the core casing 19 is connected to the annular flow path 23 between the double cylindrical bodies 16 and 35, and between the double casings 19 and 20. The annular flow path 21 is connected to the inner cylinder 16 via a communication pipe 22, and the upper part of the outer cylinder 35 is connected to the primary cooling water inlet 4 of the heat exchanger (steam generator) 3, and the upper part of the outer cylinder 35 is connected to the primary cooling water inlet 4 of the heat exchanger (steam generator) 3. The upper part is connected to the primary cooling water outlet 15 of the heat exchanger 3, respectively. Further, a pump 36 for forcedly circulating primary cooling water is provided at the lower part of the heat exchanger 3.

An upper plenum casing 8 for supporting the piping to the primary cooling water inlet 4 and outlet 15 in a penetrating state is provided above the double cylinders 16 and 35. The cover 37 is attached,
Furthermore, the structure has a shielding lid 38 disposed on the upper part of the pressure vessel 33 etc., and the inner cylinder 16 and the primary cooling water inlet 4.
An entrance angle header 39 having a communication path between the annular flow path 23 and the inside of the upper plenum casing 8 is provided between the outer cylinder 35 and the lower part of the upper plenum casing 8. The upper boundary 9 is designed to allow gradual passage of cooling water and pool water (acidic acid water) W outside the primary system.

When a nuclear reactor with such a structure is put into operation, the primary cooling water flows through the core 5, as shown by the solid arrow in FIG.
Core casing 19, annular flow path 23, primary cooling water inlet 4, heat exchanger 3, primary cooling water outlet 15, inner cylinder 16
, a circulating flow passes through the communication pipe 22, the annular flow path 21, and the reactor core 5, and at this time, a liquid level WLI is formed in the upper plenum casing 8, and a liquid level WL2 is formed in the cover 37. be done. On the other hand, when the operation is stopped, natural circulation occurs as shown by the broken line arrow in FIG. That is, the primary cooling water is in the core 5 and in the core casing 1.
9, the annular flow path 23, the upper boundary 9, the pool water W surrounding the outer cylinder 35, etc., the lower opening of the outer case 20, the core 5
At this time, the pool water W with a high concentration of hydrogenated acid water is sequentially supplied to the reactor core 5, thereby suppressing the nuclear fission reaction and leading to a natural shutdown.

"Problems to be Solved by the Invention" However, with the structure of the conventional example, the primary cooling water and the pool water W pass through the upper boundary 8 at a lower position close to the primary cooling water inlet 4. are in a communicating state, mutual interference is likely to occur between the primary cooling water and the pool water W due to the flow path resistance of the heat exchanger 3 etc., the temperature of the primary cooling water, etc. Possible problems include temperature fluctuations, fluctuations in reactor output due to intake of pool water W, etc.

The present invention aims to effectively solve these problems.

"Means for Solving the Problems" The present invention provides a riser pipe for raising primary cooling water in the upper part of the reactor core, connects the riser pipe to the primary cooling water inlet of the heat exchanger, and connects the riser pipe to the primary cooling water inlet of the heat exchanger. A pump is installed in the heat exchanger to send primary cooling water into the heat exchanger.

"Function" The upward flow of primary cooling water heated in the reactor core is guided to the riser pipe, and on the way up, pressure is applied by a pump and sent to the heat exchanger, and the upper part of the riser pipe is connected to the pool water. so that an upper border can be placed to
This is to suppress the occurrence of interference with pool water.

``Example'' As shown in Figures 1 and 2, the light water-cooled nuclear reactor in this example has a pressure vessel l made of steel and an upper part with a diameter narrower than that of the body. The primary cooling water inlet 4 of the heat exchanger (steam generator) 3 and the reactor core 5 are connected via the riser pipe 6 and the jet pump 7, and the riser An upper plenum casing 8 that is separate from the heat exchanger 3 and can be pulled upward is disposed above the opening of the tube 6, and the lower opening of the upper plenum casing 8 and the riser tube 6 is an upper boundary 9 to allow gradual passage of primary cooling water and pool water W, which is significantly different from the conventional examples shown in FIGS. 3 and 4. be.

To explain these details, the pressure vessel 1 includes:
The wall is, for example, several hundred mm thick and has a pressure-resistant integral structure, and as shown in Fig. 1, a pipe penetration part is provided only in the upper part. A hemispherical upper lid IO for closing the upper plenum is attached, and the upper lid 10 and the upper plenum casing 8
A cap 11 is interposed between the upper lid 10 and the upper lid 10, and the cap 11 is integrally attached to the inner surface of the upper lid 10 with bolts 12 etc.
In this structure, the liquid level WL2 is formed in the pressure gas chamber 13 inside the gas chamber.

A plurality of the heat exchangers 3 are arranged in the pressure vessel 1 at equal intervals around the riser pipe 6 as shown in FIG. The primary cooling water outlet 15 passes through the riser pipe 6 and is connected to the inner cylinder 16, and the secondary cooling water inlet 17 and outlet 18 that exchange heat with the primary cooling water are connected to the upper mirror of the pressure vessel l. It is a structure that penetrates through the

Further, a core casing 19 and an outer case 20 surrounding the core 5 are provided around the core 5, and an annular flow path 2 is formed therebetween. The structure is such that the core casing 19 is connected to the inner cylinder 16 via the annular flow path 23 between the riser pipe 6 and the inner cylinder 16 in a communicating state. Note that a lower plenum section 24 is located between the lower opening of the outer case 20 and the vicinity of the lower mirror section of the pressure vessel 1, and between the lower plenum section 24 and the core-encased Roblenum section 25, the primary system A lower boundary 26 is provided to allow gradual passage of outside pool water (boric acid water) W.

The jet pump 7 has a driving section 27 connected to the riser pipe 6.
A part of the primary cooling water filling the annular flow path 23 is sucked into the drive section 27, and the ring pipe 28 and The driving flow is ejected from the nozzle 29 to the diffuser 14, and the outlet flow of the diffuser 14 is forced into the primary cooling water inlet 4 of the heat exchanger 3. In the example in FIG. The nozzle 29 of the jet pump 7 and the diffuser 14 are connected to the drive unit 2.
Multiple units are installed per 1 unit of 0.

The upper plenum casing 8 is formed so that its outer diameter is smaller than the inner diameter of the equipment loading port 2, so that it can be pulled upward through the equipment loading port 2, and a liquid level W is formed at the top of the opening. [, 1 is the structure formed.

In the figure, reference numeral 30 is a pool water cooler, 31 is an air vent for the upper lid 10, and 32 is a device externally connected to the pressure gas chamber 13 formed by the cap 11, liquid level WLI, and liquid level WL2. This is a connection pipe for the pressure control system and steam relief system.

When a light water-cooled nuclear reactor with such a structure is put into operation, it becomes a circulation system similar to that of the conventional example in FIG. 3, as shown by the solid arrow in FIG. A distinctive difference occurs between the primary cooling water inlet 4 of the exchanger 3 and the primary cooling water inlet 4 of the exchanger 3. That is, a part of the primary cooling water heated in the core 5 is captured as it ascends through the annular flow path 23, passes through the drive section 27, and flows from the ring pipe 28 and the nozzle 29 into the diffuser 14 as a drive flow. By ejecting, the 8-th order cooling water in the vicinity is drawn in and becomes a jet flow from the diffuser 14, and this jet flow is forced into the primary cooling water inlet 4 of the heat exchanger 3.

In addition, when the reactor is in operation, there is a liquid level WL1 in the upper plenum casing 8 and a cap 1 in the upper plenum casing 8.
1, a liquid level WL2 is formed in the liquid level WLI, and the liquid level WLI is determined by the difference in specific gravity based on the water temperature.
It will be located slightly above L2. At this time,
The upper boundary 9 is located at a higher position than the primary cooling water suction port of the jet pump 7, and the primary cooling water rising up the riser pipe 6 is captured on the way and sent to the primary cooling water inlet 4. Therefore, the phenomenon in which the primary cooling water and the pool water W move via the upper boundary 9 is suppressed.

On the other hand, even when a light water-cooled nuclear reactor is shut down,
As shown by the broken line arrow in FIG. 1, the circulation system is similar to the conventional example shown in FIG. 3, but there is a distinctive difference in that an annular flow is generated via the heat exchanger 3. That is, a portion of the primary cooling water flows from the diffuser 14 of the jet pump 7 through the primary cooling water inlet 4, the heat exchanger 3, and the primary cooling water outlet 15, to the inner cylinder 16, the communication pipe 22, and the annular flow path 21. , flows into the core-entering loplenum section 25, pool water W1 lower plenum section 24, lower boundary 26, core-entering loplenum section 25
, will merge with the circulation flow passing through the reactor core 6. At this time, pool water W with a high concentration of boric acid water is sequentially supplied to the reactor core 6 and mixed with the initial pure water, suppressing the nuclear fission reaction and leading to a spontaneous shutdown, but the heat exchanger 3 Due to the existence of the circulation flow passing through the pressure vessel 1, cooling is performed by effectively utilizing the inside of the pressure vessel 1, and the nuclear decay heat of the radioactive material can be quickly removed.

As mentioned above, in the case of the light water cooled nuclear reactor of the present invention, it is a so-called fool-proof type, but the primary cooling system and the secondary cooling system of the heat exchanger 3 each have pipes that break. Due to such an abnormal accident, the primary and secondary cooling systems may be connected, and the primary cooling water may be sucked out and discharged due to a siphon phenomenon. When considering such an unexpected situation, it is desirable to install a siphon breaker to suppress the siphon phenomenon, but since the jet pump 7 has a diffuser 14 of a type of siphon breaker structure, the siphon breaker is It is only necessary to install it above the jet pump 7.

"Effects of the Invention" As explained above, according to the present invention, the following excellent effects can be achieved.

■A riser pipe is provided at the top of the reactor core to raise the primary cooling water by 1", and the riser pipe and the primary cooling water inlet of the heat exchanger are connected, and the primary cooling water is introduced into the heat exchanger through the connection. Because a pump is installed to feed the primary cooling water, the primary cooling water heated in the core is captured by the pump during the first ascent and sent to the heat exchanger. By smoothing the circulation of cooling water, improvements in thermal efficiency can be expected.

■ By using a jet pump as the pump, it is possible to reduce uneven pushing of primary cooling water and to generate circulation flow through the heat exchanger when the reactor is shut down, improving the cooling effect. .

■By installing the pump in front of the primary cooling water inlet,
Circulating flow can be simplified.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view showing an embodiment of the light water-cooled nuclear reactor of the present invention, Fig. 2 is a view taken along the line ll-Tl in Fig. 1, and Fig. 3 is a conventional example of a light water-cooled nuclear reactor. FIG. 4 is a longitudinal sectional view taken along the ]'V-IV line in FIG. 3. I...Pressure vessel, 2...Equipment entrance,
3...Heat exchanger, 4...Primary cooling water inlet, 5...Reactor core, 6...Riser tube, 7...
... Jet pump, 8 ... Casing for upper plenum, 9 ... Upper boundary, 14 ...
- Diffuser, 16... Inner cylinder, 23...
... Annular flow path, 27 ... Drive section, W ...
・Pool water. Figure 4

Claims (1)

[Claims] In a light water-cooled nuclear reactor in which the core and its primary cooling system heat exchanger are buried in boric acid water and the output is controlled by the concentration of the boric acid water, a riser pipe is provided above the core to raise the primary cooling water. A light water-cooled nuclear reactor, characterized in that a pipe and a primary cooling water inlet of the heat exchanger are connected, and a pump for feeding primary cooling water into the heat exchanger is disposed at the connecting portion.