RU2150757C1 - Nuclear reactor cooling device - Google Patents

Abstract

FIELD: nuclear reactors such as pressure-tube uranium-graphite ones. SUBSTANCE: device has cooling-water inlet pipelines, water outlet pipes connected to emergency pressurized-water storage tanks and makeup water system for storage tanks. Water outlet tubes accommodate throttling valves. Valve gates have through holes to discharge return water flow into reactor for short-time cooling of the latter in case of burst of cooling water inlet pipeline. Some portion of tanks is filled with compressed gas whose pressure is maintained by compressors. So, apart from its main function, that is, heat transfer from reactor, device also ensures its fast and reliable cooling in case of burst in coolant supply pipelines. EFFECT: enlarged functional capabilities of device. 3 dwg

Description

 The invention relates to nuclear energy and can be used for emergency cooldown of nuclear reactors in case of rupture of pipelines leading the liquid cooler into the reactor.

 A device for emergency cooling of the reactor [1] is known, including a pipeline for supplying cooling water to a vessel and through a choke to a steam generator that removes heat from the reactor. The pressure in the steam generator and the vessel is balanced. In this case, the water supply from the vessel can be regulated by a throttle. If the flow rate in the feed water supply pipe decreases, the water from the vessel through the throttle must enter the steam generator. The disadvantage of this device is that when the supply pipe ruptures, water from the vessel and the steam generator will flow into the gap, reducing the water level in the steam generator. In addition, in the event of a maximum accident with a rupture of the pipeline of the first coolant circulation circuit, the latter will leak into the gap, thereby removing heat from the reactor will become impossible.

 A reactor emergency cooling device [2], taken as a prototype, including a coolant supply pipe from the top into the reactor core, a hot coolant drain pipe located above the reactor core, and an emergency water storage tank associated with the place of coolant supply to the reactor core is also known and with a pipeline for the removal of hot coolant using shut-off valves with actuators and a pump.

 In case of an accident with a significant rupture of the pipeline for supplying coolant to the reactor, a valve closure signal is sent to the valve drive connecting the tank to the emergency water supply and the coolant supply point to the core, and a signal is sent to the valve drive connecting the tank to the hot coolant drain pipe opening. A pump is turned on, which must supply water from the tank through the hot coolant drain pipe to the core in the direction opposite to the normal coolant current. The disadvantage of this device is that it takes time to determine the place of the gap and turn on the valve and pump drives. During this time, the core can remain without a coolant and warm up to such a temperature that subsequent injection of water from the tank will lead to thermal stresses that can destroy the components of the core, the release of radioactive fission products, which will aggravate the consequences of the accident. In addition, a failure or a delay in the operation of any of the executive bodies of the device will render the device inoperative. So, a delay in turning on the pump or opening the valve for supplying water from the tank to the core can cause the coolant in the core to evaporate and the pressure of the generated vapor increasing due to residual heat will prevent the water from being supplied from the tank to the core, which will lead to further overheating of the heat elements.

 The objective of the invention is to increase the speed and reliability of emergency emergency cooling of the reactor when the piping for cooling water to the reactor is broken.

 The problem is solved in that in the cooling device of a nuclear reactor, including pipelines for supplying cooling water to the reactor, pipes for discharging water from the reactor with attached containers for storing emergency stock of water under pressure, a system for replenishing containers with water, installed in the pipes for draining water from the reactor throttling valves, in the gates of which openings are made to ensure the flow of reverse water flow in the reactor with the possibility of short-term cooling when the pipelines break under chi cooling water into the reactor, wherein the portion of the volume containers takes compressed gas whose pressure is maintained compressors.

 The dimensions of the through holes in the gates of the throttling valves are selected depending on the design and physicotechnical features of a particular nuclear reactor. They are determined by calculation, checked and refined during bench and field tests.

 So, for example, on uranium-graphite nuclear reactors with vertical technological channels loaded with cylindrical fuel elements cooled by water, the calculations take into account the maximum power level of the reactor, which determines the temperature of its core, overall dimensions of the core, the total mass of graphite masonry, material , the number and inner diameter of the technological pipes of the working channels loaded with a given number of fuel rods, the outer diameter of the latter, the size of the working hydraulic pressure in the channels and pressure of compressed gas in tanks with an emergency supply of water.

 The essence of the proposed design of the reactor cooling device is shown in FIG. 1 is a general cooling scheme, in FIG. 2 and 3 - throttle valve design.

 The pipeline (1) delivers cooling water to the reactor (2), from which water enters the water discharge pipes (3), hydraulically connected to tanks (4) containing an emergency supply of water (5). A part of the tank volume is occupied by compressed gas (6), the pressure of which is supported by compressors (7). The loss of water in the tanks can be compensated through the feed water lines (8) by pumps (9).

 Throttle valves (10), the positions of which are shown in FIG. 2 - for the normal state of the cooling device and figure 3 - for the emergency state. The valve consists of a housing (11) and a shutter (12) with an axial bore (13).

 Water pipes are connected by a common collector (14), from which water is supplied through a valve (15) to a heat exchanger (16).

 The reactor cooling device operates as follows. In the normal operating mode, water is supplied to the reactor at a predetermined power level, removes the heat generated in its core, and is cooled in the heat exchanger (16). At the same time, the pressure on the check valves (10) maintains their valves in the open state (Fig. 2), thereby ensuring a relatively high throughput of the valves. In the event of an emergency rupture of the water supply pipelines, the pressure at the inlet to the reactor decreases sharply to values close to atmospheric pressure, and the reactor is drowned out by the emergency protection absorbing rods, and the direction of the hydraulic force acting on the valve gates is reversed, and the gates are closed (Fig. 3 ) However, this causes a reverse flow of water through the holes (13) in the gates (12), due to the presence of excess pressure in the emergency tanks.

 Since the change in the direction of the water pressure during an emergency rupture of the pipelines for its supply to the reactor occurs at a high propagation speed, emergency cooling is switched on in almost no more than one second, and passively, i.e. unlike the prototype, regardless of the operator’s actions to turn on the equipment for emergency cooling and the inertia of the operation of this equipment. Thus, the speed of inclusion of the emergency cooling system and the reliability of this inclusion is significantly increased. The volume of water (5) and gas pressure (6) in the tanks for storing emergency stocks are sufficient for passive cooling of an emergency shutdown reactor for several minutes. During this time, emergency recharge of the tank (4) is switched on by pumps (9) and the reactor core continues to cool similarly to the prototype.

Sources of information
1. US patent 4239596, cl. G 21 C 15/18, 16.12.80.

 2. Application UK 2114802, CL G 21 C 15/18, 08.24.83.

Claims (1)

 A cooling device for a nuclear reactor, including pipelines for supplying cooling water to the reactor, pipes for discharging water from the reactor with attached containers for storing an emergency supply of water under pressure, a system for recharging containers with water, characterized in that throttling valves are installed in the pipes for discharging water from the reactor, in the gates of which openings are made to ensure the flow of reverse water flow in the reactor with the possibility of short-term cooling upon rupture of the cooling water supply pipelines pressure into the reactor, while part of the tank volume is occupied by compressed gas, the pressure of which is maintained by compressors.

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