JPH06174871A - Light-water cooled reactor - Google Patents

Abstract

PURPOSE:To enhance thermal efficiency and to maintain safety by isolating a reactor pressure vessel from pool water by means of a watertight container having a plurality of independent hollow portions partitioned from one another. CONSTITUTION:A watertight container surrounds and seals a reactor pressure vessel 2 and has independent, partitioned hollow portions 24a-c to accommodate heat insulating material 25. Pressurized gas supply means 26A-26C connected to the individual hollow portions supply pressurized gas to the hollow portions, the head pressure of the pressurized gas being set higher than that of pool water W. The heat insulating material 25 prevents transfer of heat from the vessel 1 to the pool water W to enhance the heat exchange efficiency of a steam generator 3. When a pressurized atmosphere is created in each of the hollow portions by operation of the means 26A-26C, water is not allowed to flow into the hollow portions because of the pressure higher than that of the pool water W, and the strength of the wall of the container 24 is increased by settings that take into account the difference in water head between the pool water W and each hollow portion, so as to prevent deformation of the heat insulating material 25 due to compression. Should water leak from through piping, etc., and enter the hollow portions 4a-c, because the hollow portions are partitioned from one another the area immersed in the water is restricted to one hollow portion to avoid thermal impact from being exerted to the whole part of the vessel 1 so as to maintain the safety of the reactor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light water cooling type nuclear reactor, and more particularly to a technique for placing a reactor pressure vessel in pool water in a submerged state.

[0002]

2. Description of the Related Art FIG. 2 is a Japanese Unexamined Patent Publication No. 3-252593 (fuel assembly exchange device), Japanese Unexamined Patent Publication No. 3-252594 (fuel assembly exchange device), and Japanese Unexamined Patent Publication No. 3-25259.
5 shows an example of a light water cooled nuclear reactor described in Japanese Patent Publication No. 5 (fuel assembly exchange device).

In FIG. 2, reference numeral 1 is a reactor pressure vessel,
2 is a core, 3 is a steam generator, 6 is a primary cooling water pump, 1
Reference numeral 5 is a riser pipe, 16 is a poison tank, 17 is a cooling water inlet, 18 is a water pressure operated valve, 19 is a poison distributor, 20 is a core support plate, and P is boric acid water (pool water in the reactor).

In the nuclear reactor having such a structure, the primary cooling water and the boric acid water P flow differently (circulate) as described below depending on the difference between the operation and the stop of the pump.

During operation, the primary cooling water passes through the core 2, the riser pipe 15, the primary cooling water pump 6, the steam generator 3, and the cooling water inlet 17, as shown by the solid arrow in FIG. However, the boric acid water P is isolated by the hydraulically operated valve 18 and the poison distributor 19 to prevent the phenomenon of insertion and the phenomenon of mixing.
Therefore, the steady operation state is maintained without changing the boric acid water concentration in the primary cooling water.

When the primary cooling water pump 6 is stopped, the steam generator 3 is not fed, and when the discharge pressure drop of the primary cooling water pump 6 is detected, the hydraulically operated valve 18 opens the pipeline. In addition, since the primary cooling water continuously heated in the core 2 rises, the raised primary cooling water is sent out to the inside of the poison tank 16 as shown by a dashed arrow in FIG. The boric acid water P flows into the core 2 via the poison distributor 19 and the concentration of boric acid in the core 2 increases, whereby the fission reaction is suppressed and the suspension is led to a natural stop.

[0007]

However, in the reactor having such a structure, the inside and outside of the poison tank 16 are surrounded by the primary cooling water at a high temperature, and the output of the reactor is When it changes, the amount of boric acid water P changes due to expansion and contraction.
In the section 9 there is still a problem to be solved that the boundary between the primary cooling water and the boric acid water P is likely to fluctuate and the controllability of the reactor power is likely to be impaired.

The present invention effectively solves the above problems, and aims to improve the shielding and controllability of a nuclear reactor, improve the thermal efficiency, and ensure the safety.

[0009]

[Means for Solving the Problems] In a light water cooling type reactor in which the reactor pressure vessel is submerged in the pool water of the reactor containment vessel, it is arranged around the reactor pressure vessel and divided into upper and lower sections. A configuration is provided that includes a watertight container having a plurality of hollow portions, a heat insulating material housed in each hollow portion, and a pressurized gas supply unit connected to each hollow portion and having a pressurized atmosphere inside.

[0010]

The pool water around the reactor pressure vessel reduces radiation leakage to the outside of the containment vessel, and the heat transfer from the reactor pressure vessel to the pool water is hindered by the heat insulating material. By making the hollow part of the watertight container a pressurized atmosphere, the pressure difference with the reactor pressure container was reduced and the ingress of pool water etc. was suppressed, and the primary cooling water and pool water invaded the hollow part. In some cases, the water immersion area is limited to the area of one hollow portion.

[0011]

FIG. 1 shows an embodiment of a light water cooling type nuclear reactor according to the present invention. In FIG. 1, reference numeral 18 is a liquid supply control means (for example, a water pressure operated valve), 21 is a reactor containment vessel, 22 is a poison tank, 23 is a liquid supply system pipe, and 23a.
Is a pressure equalizing pipe, 23b is a liquid supply pipe, 24 is a watertight container,
Reference numeral 24a is an upper hollow portion, 24b is a central hollow portion, 24c is a lower hollow portion, 25 is a heat insulating material, 26A is a pressure device (upper pressure device), 26B is a pressure device (central pressure device), Two
6C is a lower pressurizing device (pressurizing device), and W is pool water.

In the pool water W of the reactor containment vessel 21, the reactor pressure vessel 1 and the poison tank 22 are placed in a submerged state.

The poison tank 22 is arranged at an upper position while being supported by the inner wall of the reactor containment vessel 21, is set to have a pressure resistance comparable to that of the reactor pressure vessel 1, and has a high pressure. The boric acid water P having a concentration is stored.

The liquid supply system piping 23 is used for the reactor pressure vessel 1.
And the poison tank 22 are arranged with the liquid supply control means 18 interposed so as to connect them. The upper position of the reactor pressure vessel 1 and the poison tank 22
Is connected by a pressure equalizing pipe 23a with the liquid supply control means 18 interposed, and a liquid supply pipe is provided between the lower position of the reactor pressure vessel 1 and the lower position of the poison tank 22. It is connected by 23b.

The watertight container 24 is arranged around the reactor pressure vessel 1 so as to surround and close the reactor pressure vessel 1 and is divided into a plurality of vertically separated hollow portions (in FIG. 1, an upper hollow portion 24a, a central portion). It has a hollow portion 24b and a lower hollow portion 24c).

The heat insulating material 25 includes hollow portions 24a, 24
b and 24c, heat transfer from the reactor pressure vessel 1 to the pool water W is suppressed.

Each of the pressurized gas supply means 26A, 26B,
26C is individually connected to each of the hollow portions 24a, 24b, 24c, and a pressurized gas such as pressurized air set to be slightly higher than the head pressure of the pool water W is supplied to each of the hollow portions 24a, 24b, 2c.
4c, and the hollow portions 24a, 24b, 24c are set to a pressurized atmosphere at least higher than the head pressure of the pool water W to prevent the heat insulating material 25 from being compressed and deformed.

In the light water cooling type reactor having such a structure, when the primary cooling water pump 6 is operated during the operation of the nuclear reactor, the primary cooling water heated in the core 2 to a high temperature state is generated. , The riser tube 1 as shown by the solid arrow in FIG.
5, primary cooling water pump 6, steam generator 3, cooling water inlet 1
A circulation flow returns to the core 2 via 7 and at this time, steam is generated and primary cooling water is cooled by heat exchange in the steam generator 3.

The discharge pressure of the primary cooling water pump 6 is transmitted to the liquid supply control means 18 via the pressure equalization pipe 23a, so that the liquid supply control means 18 shuts off the pipe of the pressure equalization pipe 23a. Continue to hold the state. In this case, since the lower position of the reactor pressure vessel 1 and the lower position of the poison tank 22 are connected, the pressure of the primary cooling water rises and the boric acid water P in the liquid supply pipe 23b becomes Equilibrate at a slightly elevated position. Therefore, the boric acid water P in the poison tank 22 is not injected into the reactor pressure vessel 1, and the reactor pressure vessel 1
The operation is performed based on the amounts of primary cooling water and boric acid water stored in the inside of the.

When the pool water W intervenes around the reactor pressure vessel 1, the pool water W absorbs radiation, reducing the amount of radiation leaked to the outside.
By disposing the heat insulating material 25 around the reactor pressure vessel 1, the heat transfer from the reactor pressure vessel 1 to the pool water W is hindered by the heat insulating material 25, and the heat exchange efficiency of the steam generator 3 is improved. It will rise.

On the other hand, each pressurized gas supply means 26A, 26
When B and 26C are activated and the hollow portions 24a, 24b and 24c of the watertight container 24 are in a pressurized atmosphere, water invades based on the fact that the pressure is higher than the pool water W. Without doing so, the strength of the container wall of the watertight container 24 can be increased by setting in consideration of the difference with the head pressure of the pool water W.

Each hollow portion 24a, 2 of the watertight container 24
Examining the case where water enters the 4 b and 24 c due to leakage from pipes penetrating these parts, the hollow parts 24 a, 24 b and 24
Since c is partitioned and independent, it is possible to prevent the water immersion area from staying within the defined one hollow portion and causing a thermal shock to the entire outer surface of the reactor pressure vessel 1.

When the primary cooling water pump 6 is stopped due to a cause such as a power failure or a failure during the operation of the reactor, the reactor is passively brought into a natural stop state as described below. Be guided.

When the primary cooling water pump 6 is stopped, the decrease or disappearance of the pump discharge pressure is transmitted to the liquid supply control means 18 via the pressure equalizing pipe 23a, and the liquid supply control means 1 is supplied.
By the operation of 8, the pipe line by the pressure equalizing pipe 23a is guided to the open state.

In addition to the communication between the lower position of the reactor pressure vessel 1 and the lower position of the poison tank 22, the upper position of the reactor pressure vessel 1 and the upper position of the poison tank 22 are connected to each other. The vapor in the vapor phase portion of the pressure vessel 1 is sent to the poison tank 22 to form the vapor phase portion in the poison tank 22 so that the pressure is equalized, and the head of the poison tank 22 and the reactor pressure vessel 1 is headed. Based on the difference, the boric acid water P is injected into the reactor pressure vessel 1 as shown by the dashed arrow in FIG. Boric acid water P
Is sent to the core 2, the reactor is brought into a spontaneous shutdown state by cooling the core 2 and suppressing the nuclear reaction.

During the operation of the reactor, when a phenomenon occurs in which the reactor water drops due to some failure of the primary cooling system (when the coolant is lost), the level of the primary cooling water is changed to the primary cooling water pump. When it is lowered to a position below the pump suction port of 6, the discharge pressure is lowered due to the primary cooling water pump 6 sucking in the gas component, and the liquid supply control means 18 is provided as in the case where the primary cooling water pump 6 is stopped. Opens the line of the pressure equalizing pipe 23a, the boric acid water P in the poison tank 22 is sent to the core 2, and the submerged state of the core 2 is maintained and the reactor is stopped.

[0027]

EFFECTS OF THE INVENTION According to the light water cooling type reactor of the present invention, the shielding property of the reactor based on the fact that the reactor pressure vessel is submerged in the pool water of the reactor containment vessel, and the poison tank. In addition to improving the controllability of the reactor power based on the installation of the inside of the reactor containment vessel, the following effects are exhibited. (1) Since the area around the reactor pressure vessel is surrounded by the watertight vessel having a plurality of independent hollow portions and is isolated from the pool water, the heat transfer from the reactor pressure vessel to the pool water is suppressed and the reactor is suppressed. The thermal efficiency of can be improved. (2) By holding each hollow part in a pressurized atmosphere, the shape of the heat insulating material is maintained to ensure heat insulation, and the pressure difference with the pool water is reduced to increase the strength of the watertight container. Can be improved. (3) When water enters the watertight container, the water immersion area is limited to one of the hollow parts to prevent thermal shock from reaching the entire reactor pressure container, The safety of the nuclear reactor can be secured.

[Brief description of drawings]

FIG. 1 is a front sectional view showing an embodiment of a light water cooling-type nuclear reactor according to the present invention.

FIG. 2 is a front sectional view showing a conventional example of a light water cooling type nuclear reactor.

[Explanation of symbols]

 1 Reactor Pressure Vessel 2 Core 3 Steam Generator 6 Primary Cooling Water Pump 15 Riser Pipe 17 Cooling Water Inlet 18 Liquid Supply Control Means (Water Pressure Operated Valve) 21 Reactor Containment Vessel 22 Poison Tank 23 Liquid Supply System Pipe 23a Pressure Equalizing Pipe 23b Liquid supply pipe 24 Watertight container 24a Upper hollow part 24b Central hollow part 24c Lower hollow part 25 Heat insulating material 26A Pressurized gas supply means (upper pressurizing device) 26B Pressurized gas supply means (central part pressurizing device) 26C Pressurized gas supply means (pressurizing device for lower part) P Boric acid water (pool water in furnace) W pool water

Claims (1)

[Claims] 1. A light water cooling type reactor in which the reactor pressure vessel is placed in the pool water of the reactor containment vessel in a submerged state. A light water-cooled atom comprising: a watertight container having a hollow portion; a heat insulating material housed in each hollow portion; and a pressurized gas supply means connected to each hollow portion and having a pressurized atmosphere inside thereof. Furnace.