JPH06174870A - Light-water cooled reactor - Google Patents

Abstract

(57) [Summary] [Purpose] In relation to a light water cooling type reactor, when the flowability of boric acid water is increased and the coolant is lost and the primary cooling water pump is stopped,
To promptly and surely bring the reactor to a stopped state to ensure safety and to secure an internal space of the reactor containment vessel to improve maintainability of the reactor and the like. [Structure] A poison tank arranged on the inner wall of the upper lid of the reactor containment vessel, a liquid supply system pipe connected between the reactor pressure vessel and the poison tank, and a reactor installed on the liquid supply system pipe. And a liquid supply control means for opening the pipeline when the internal pressure of the pressure vessel drops.

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 accommodating a poison tank together with a reactor pressure vessel in a reactor containment vessel.

[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
5 is a riser pipe, 16 poison tanks, 17 is a cooling water inlet, 18 is a hydraulically 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 flow differently (circulate) as described below, depending on the difference during operation and when the pump is stopped.

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.

In the reactor shown in FIG. 2 as described above, the inside and outside of the poison tank 16 are surrounded by the primary cooling water at a high temperature, and when the output of the reactor changes, the boric acid water P The amount of liquid changes due to expansion and contraction, and therefore, the boundary between the primary cooling water and the boric acid water P easily changes at the portion of the poison distributor 19 and the controllability of the reactor output tends to be impaired.

Next, FIG. 3 shows another structural example (plan example) of the light water cooling type reactor. In the plan example, the reactor pressure vessel 1 is placed in the pool water W of the reactor containment vessel 21 in a state of being immersed in water, and the poison tank 22 is also placed in the pool water W. And the reactor pressure vessel 1
And the poison tank 22 are connected by a pressure equalizing pipe 23a and a liquid supply pipe 23b which constitute the liquid supply system pipe 23. With this structure, the poison tank 22 is housed in the pool water W in a low temperature state, and is thermally isolated from the reactor pressure vessel 1, and the primary cooling water and the boric acid water P are contained.
It is possible to bring the reactor into a natural shutdown state by supplying the boric acid water P using the drop and the specific gravity difference, and to increase the capacity of the boric acid water P to a large capacity. .

[0009]

However, in the reactor of the example in FIG. 3, the poison tank 22 is arranged around the reactor pressure vessel 1 and the head is limited, so that the supply of the boric acid water P is performed. Is slowed down, and there is a limit in securing the submerged state of the core 2 when the primary cooling water is lost, and in promptly inducing the reactor to shut down.

The present invention effectively solves the above-mentioned problems, and enhances the flowability of boric acid water to promptly and surely bring the reactor to a stopped state when the coolant is lost and the primary cooling water pump is stopped. To secure safety and to secure the internal space of the reactor containment vessel to improve the maintainability of the reactor.

[0011]

[Means for Solving the Problems] In a light water cooling type reactor in which a reactor pressure vessel is placed in a submerged state in pool water of a reactor containment vessel, a poison tank is provided on an inner wall of an upper lid of the reactor containment vessel. , A liquid supply system pipe arranged in a connected state between the reactor pressure vessel and a poison tank, and a pipe line opened when the internal pressure of the reactor pressure vessel decreases, which is arranged in an intervening state in the liquid supply system pipe A configuration including a liquid supply control means is adopted.

[0012]

When the primary cooling water pump is stopped or the reactor cooling water level is lowered, the liquid supply control means is activated to establish communication between the inside of the reactor pressure vessel and the inside of the poison tank, and a large head of both Based on the difference, the boric acid water in the poison tank flows down into the reactor pressure vessel, and the increase of the boric acid concentration leads to the natural shutdown of the reactor. By removing the upper lid, the upper opening of the reactor containment vessel is opened in the poison tank portion, and the maintainability of the reactor is improved.

[0013]

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), 24 is an upper lid, 25 is a poison tank, and 26 is a heat insulating material.

The upper lid 24 is detachably attached to the upper opening of the reactor containment vessel 21.

The poison tank 25 is integrally arranged on the inner wall of the upper lid 24, and is set so as to have a pressure resistance equivalent to that of the reactor pressure vessel 1, and stores a high concentration boric acid water P.

The liquid supply control means 1 is provided between the upper position of the reactor pressure vessel 1 and the upper position of the poison tank 25.
8 is connected by a pressure equalizing pipe 23a, and the lower position of the reactor pressure vessel 1 and the poison tank 25 are connected.
Is connected to the lower position by a liquid supply pipe 23b. Reference numeral 23c is a pressure guiding pipe, which is arranged between the reactor pressure vessel 1 and the liquid supply control means 18, and is provided with a pressure equalizing pipe 23.
It constitutes a part of a.

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 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 guiding pipe 23c, so that the liquid supply control means 18 shuts off the conduit of the pressure equalizing pipe 23a. Keep holding the state.

During operation of the nuclear reactor, the lower position of the reactor pressure vessel 1 and the lower position of the poison tank 25 are connected, so that the pressure of the primary cooling water rises and the supply pipe The boric acid water P in 23b is equilibrated at a position slightly pushed up. Therefore, the boric acid water P in the poison tank 25 is not injected into the reactor pressure vessel 1, and the operation is performed based on the amounts of primary cooling water and boric acid water stored in 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 nuclear reactor, the nuclear reactor is passively led to a naturally stopped state as described below. .

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 through the pressure guiding pipe 23c, and the liquid supply control means 18 operates to equalize the pressure distribution pipe 23a. The conduit is guided to the open state. In addition to communication between the lower position of the reactor pressure vessel 1 and the lower position of the poison tank 25, the reactor pressure vessel 1
Is connected to the upper position of the poison tank 25, the vapor of the vapor phase portion of the reactor pressure vessel 1 is sent to the poison tank 25 and the vapor phase portion is formed in the poison tank 25. Based on the head difference between the poison tank 25 and the reactor pressure vessel 1, boric acid water P is injected into the reactor pressure vessel 1 as indicated by the broken arrow in FIG. It 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 a reactor operation, 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 25 is sent to the reactor core 2, and the flooded state of the reactor core 2 is maintained and the reactor is shut down.

On the other hand, the portion of the poison tank 25 can be removed from the reactor containment vessel 21 together with the portion of the upper lid 24, and in comparison with the example of FIG.
By removing 5 and its supporting structure from the inside of the reactor containment vessel 21, a space between the periphery of the reactor pressure vessel 1 and the upper opening of the reactor containment vessel 21 is opened.
Therefore, various maintainability inside the reactor containment vessel 21 is improved.

[0024]

The light water cooled nuclear reactor according to the present invention has the following effects. (1) A poison tank arranged on the inner wall of the upper lid of the reactor containment vessel, a liquid supply system pipe connected between the reactor pressure vessel and the poison tank, and a reactor arranged on the liquid supply system pipe. By adopting a configuration provided with a liquid supply control means for opening the pipeline when the internal pressure of the pressure vessel decreases, the flowability at the time of supplying boric acid water is enhanced as compared with the prior art, and at the time of loss of coolant and primary When the cooling water pump is stopped, the reactor can be promptly and surely brought to a stopped state to ensure safety. (2) By removing the poison tank from around the reactor pressure vessel, the internal space of the reactor containment vessel is secured even when the reactor pressure vessel is immersed in water to maintain the reactor. Can be improved. (3) By arranging the poison tank integrally with the upper lid of the reactor pressure vessel, it is possible to improve the degree of freedom in setting the head difference for supplying boric acid water.

[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.

FIG. 3 is a front sectional view showing an example of a plan of a light water cooling type 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 23 Liquid Supply System Pipe 23a Pressure Equalizing Pipe 23b Liquid Supply Piping 23c Pressure guiding pipe 24 Upper lid 25 Poison tank 26 Insulation material P Boric acid water (in-reactor pool water) W Pool water

Claims (1)

[Claims] 1. A light water cooling type nuclear reactor in which a reactor pressure vessel is placed in a pooled water of a reactor containment vessel in a submerged state, and a poison tank arranged on an inner wall of an upper lid of the reactor containment vessel, A liquid supply system pipe arranged in a connected state between the reactor pressure vessel and a poison tank, and a liquid supply system which is arranged in an intervening state in the liquid supply system pipe and opens the pipeline when the internal pressure of the reactor pressure vessel decreases. A light water cooled nuclear reactor comprising: a control means.