RU149132U1 - HYDRAULIC CAPACITY FOR A PASSIVE SYSTEM OF EMERGENCY EMPLOYMENT OF A NUCLEAR REACTOR - Google Patents

Abstract

1. Hydraulic reservoir for a passive system of emergency flooding of a nuclear reactor with an upper inlet pipe for a vapor-gas mixture and lower main and additional drain pipes for water, the lower outer ends of which are connected to each other, with a device installed inside the hydraulic reservoir housing for stepless flow profiling, made in the form of a vertical partitions along the entire height of the tank body with an opening for water passage, the flow area of which decreases from top to bottom, while the lower drain pipes are located on opposite sides of the partition. 2. The hydraulic reservoir according to claim 1, characterized in that a larger volume of the vessel body, divided by a partition, is connected to the upper inlet pipe for the steam-gas mixture and an additional lower drain pipe, and a smaller volume of the container body is connected to the main lower drain pipe. 3. The hydraulic reservoir according to claim 2, characterized in that a diaphragm is installed in the lower additional drain pipe between the body of the hydraulic reservoir and the junction of the lower outer ends of the drain pipes. 4. The water tank according to claim 1, characterized in that the opening for the passage of water in the partition is a vertical slot of variable profiled width. Hydraulic reservoir according to claim 3, characterized in that the partition can be made composite. 6. The reservoir according to claim 1, characterized in that the opening for the passage of water can be formed by the gaps between the body of the reservoir and the partition of variable width. Hydraulic reservoir according to claim 1, characterized in that the hole for the passage of water is a set of holes, the total area of which is

Description

The utility model relates to nuclear energy and can be used at nuclear power plants (NPPs) with pressurized water reactor plants as an optimized emergency bay system and reactor core cooling.

To ensure the filling of the active zone of water-cooled reactor installations (RU) in case of emergency leaks in the reactor plants, along with active pump systems for emergency cooling of the zone, passive hydraulic systems (TE) with a coolant reserve, for example, an aqueous solution of boric acid, are provided at nuclear power plants .

For long-term supply of coolant to the reactor zone with large leaks occurring with the imposition of loss of alternating current sources at nuclear power plants, hydraulic reservoir systems with a large supply of coolant having a relatively low working pressure of the medium are provided. The supply of coolant from them occurs due to the hydrostatic column. The inclusion of these hydraulic systems in the work is a passive way.

Such a system of hydraulic reservoirs is described in RF patent No. 2108630 “Power plant” (IPC G21C 15/18, published on 04/10/1998). According to the description, the pumped storage tank of this system communicates with the reactor through two pipes, namely, through the lower drain pipe intended for supply coolant into the reactor, and through the upper inlet pipe, which is connected by a pipe to the main circulation pipe of the reactor at the exit section of the steam generator.

On the pipelines connecting the hydraulic reservoir to the reactor, check valves are installed.

A non-return valve installed on the pipeline connecting the upper nozzle of the hydraulic reservoir with the reactor installation is a type of valve that cannot be opened. It opens when the pressure in the reactor installation decreases below the value set for the system. The hydraulic capacity is protected from repeated pressure by installing safety valves on the pipelines.

To change the flow rate of the coolant from the hydraulic tank as it is emptying, a collector is installed inside the hydraulic tank, profiling the flow, which is a perforated cylinder in height. This design of the collector creates difficulties in setting up or changing the flow characteristics of the hydraulic capacity.

Also known is the patent of the Russian Federation No. 22447434 (IPC G21C 15/18, published May 27, 2005) - a hydraulic reservoir for a passive system for emergency gulf of the reactor, having an upper inlet pipe for steam and lower drain pipes for a coolant of different heights, the lower outer ends of which are interconnected, and the smallest pipe is the lower drain pipe. The change in flow rate from the hydraulic capacity is as follows.

At the beginning of the hydraulic capacity operation, the coolant flows through all the pipes, and this ensures the maximum total flow rate. As the coolant level in the hydraulic tank decreases, the number of pipes through which the coolant flows out decreases stepwise, which creates a stepwise decreasing coolant flow from the hydraulic tank to the reactor.

The disadvantages of the device are: 1) the presence of time periods when the water flow provided by this system of CGUs is less than that required based on the current core power; 2) non-optimal use of the available water supply (including due to drip entrainment of the coolant into the leak at its excessive level in the reactor).

The technical result of the proposed device is to increase the efficiency of the hydraulic capacity by providing a change in the supply of cooling water to the reactor in accordance with the change in the current power of the active zone and thereby extend the operating time of the hydraulic capacity due to the optimal use of the water supply in it.

To achieve the indicated result, a hydraulic capacity is proposed for a passive system of an emergency bay of a nuclear reactor with an upper inlet pipe for a steam-gas mixture and lower main and additional drain pipes for water, the lower external ends of which are interconnected, with a device for stepless flow profiling installed inside the hydraulic tank, made in the form of a vertical partition along the entire height of the container body with an opening for the passage of water, the passage area of which decreases aetsya from top to bottom, and the bottom drain connections are located on opposite sides of the partition.

Besides:

- a larger volume of the tank body, divided by a partition, is connected to the upper inlet pipe for the gas mixture and an additional lower drain pipe, and a smaller volume of the tank body is connected to the main lower drain pipe,

- in the lower additional drain pipe between the housing of the hydraulic reservoir and the junction of the lower outer ends of the drain pipes, a diaphragm is installed,

- the hole for the passage of water in the partition is a vertical slot of variable profiled width,

- the partition can be made composite,

- the hole for the passage of water can be formed due to the gaps between the casing and the bulkhead of variable width,

- the hole for the passage of water is a lot of holes, the total area of which decreases along the height of the partition from top to bottom,

- holes can be of arbitrary shape.

In FIG. 1 shows the costs of cooling water - required based on their current level of residual energy release of the active zone and corresponding to the design characteristic of the CGU according to the patent of the Russian Federation No. 22447434.

In FIG. 2 - is a schematic diagram of the proposed device, where:

1 - inlet pipe for gas-vapor mixture;

2 - housing hydraulic capacity;

3 - a partition;

4 - a hole in the partition, made in the form of a gap;

5 - additional lower drain pipe;

6 - the main lower drain pipe;

7 - single hole (diaphragm);

8 - pipeline to the reactor (core);

9 - hole system.

In FIG. 3 and 4 show the location of the partition 3 in the casing 2.

In FIG. 5 shows an embodiment of an opening in the partition 3 in the form of a slit 4.

In FIG. 6 and 7 show embodiments of the holes in the partition 3 in the form of a system of holes 9 of various shapes.

In FIG. Figure 8 shows the dependence of the required and profiled expenses of the proposed CGU on time.

In FIG. 9 gives a comparison of the results of calculations of the costs of the CGU according to patent No. 22447434 (design and calculated values) and the proposed CGU.

The device operates as follows.

The hydraulic reservoir is a sealed housing 2, in the upper part of which there is an inlet pipe for the gas-vapor mixture 1, inside the housing 2 there is a vertical partition 3, dividing the housing into two parts - a larger and a smaller volume. In the partition 3 there is generally a hole with a decreasing passage area from top to bottom, the dimensions of which are calculated. This may be a longitudinal slot 4, providing hydraulic connection between a large volume containing a working supply of water, and a smaller one, playing an auxiliary role of a collector of a jet (jets) of water coming from the main volume. From a smaller volume, water flows through the lower main drain pipe 6 with a profiled water flow.

In order to ensure that, with a decrease in the water level in the hydraulic tank to its bottom, the flow rate does not decrease smoothly to zero, but is maintained at a certain, albeit decreasing value, an additional lower drain pipe 5 with a single hole (diaphragm) 7 located below the hydraulic tank bottom is necessary above the insertion mark of the connecting pipe 8 into the reactor vessel, providing a final flow rate G _{od. open} (Fig. 8) at the end of the hydraulic operation (end of the period of "stabilization" of the residual energy of the core and the corresponding flow rate).

Both drain pipelines - the main 6 and auxiliary 5 - are connected to the pipeline 8, which connects the hydraulic reservoir to the reactor vessel.

In this case, the stepless profiling of the water flow from the hydraulic unit is achieved by continuity (continuity) along the height of the passage section of the longitudinal slit (or equivalent system of holes) 4 and by changing its width along the height of the hydraulic capacity. Due to this, there are no sharp changes in the flow rate in the profile of the water flow rate of the CGU versus time (characteristic), and it smoothly monitors the change in the power of the reactor core. A hole for the passage of water can be formed due to gaps between the casing 2 and the partition of variable width.

The current value of the flow rate of the hydraulic unit is determined by the change in the width of the slit over the entire height of the hydraulic capacity in relation to the current water level in it, since the flow rate of the fluid flowing out of the vessel, ceteris paribus, is a function of the leveling head and the area of the passage section of the expiration device.

The use of the idea of the width of the vertical slit monotonically decreasing in height of the hydraulic capacity (the area of the passage sections of the system of holes) is possible due to the monotonously decreasing with time (exponentially) value of the residual energy release of the core.

During the operation of the CGU, the water levels in its larger and smaller volumes differ, since after the beginning of the water discharge, the smaller volume is sufficiently quickly emptied, the level in it decreases to a balance between the flow of water into it from the larger volume and the flow rate into the pipeline connected to the reactor (pos. 8).

Thus, as water is drained from the hydraulic reservoir, there is a decrease in the water level in it and, accordingly, the leveling pressure (elevation difference) of the water column between large and smaller volumes. The flow area of the hydraulic connection between them also decreases. In general, according to a complex mathematical law, due to a decrease in the water level and a decrease in the area of the orifice of the slit occupied by the water flowing through it, there is a decrease in time of water flow from the hydraulic unit. To ensure that the flow rate of water from the CU corresponds to the residual energy release in the reactor core (a.z.), the function of changing the slit width f (h) in height according to the system of equations given below was estimated using computer programs:

where (Fig. 2):

the desired calculated function f (h) (m) is the width of the gap at a height h (m) from the bottom of the hydraulic reservoir, so dF (h) = f (h) dh (m ² ) is the increase in the area of the gap at a height h, or ΔF ( h) (m ² ) is the area of the holes at a height h in the case of a system of holes;

od. open - an index relating to the parameters of a single hole 7, which determines the flow rate in the final stage ("stabilization") of the hydraulic capacity;

syst. open - index related to the parameters of the system of holes (slots);

total - index related to the parameters of the entire system;

G (kg / s) - fluid flow rate;

µ is the dimensionless discharge coefficient of the hole;

ρ (kg / m ³ ) is the fluid density in the hydraulic capacity;

g (m / s ² ) is the acceleration of gravity;

t (s) - current time;

N (t) (m) - the height of the liquid level in the hydraulic capacity;

N _{od. open} (m) - elevation of a single hole;

F _{od. open} (m ² ) is the area of the passage section of a single hole;

H _days (m) - elevation of the bottom of the hydraulic reservoir;

h (m) is the integration variable over the liquid level in the hydraulic capacity;

K _stock - dimensionless stock coefficient;

G _required (kg / s) - the required flow rate from one hydraulic capacity, determined by the residual energy release a.z. (Fig. 8).

F _tank (m ² ) - cross-sectional area (relative to the longitudinal - high-altitude - axis) of the hydraulic capacity section;

G ₁ (kg / s), C ₂ (1 / s) are the coefficients in the function that determines the value of the residual energy release a.z. (depend on the initial power of the a.s., the isotopic composition of the fuel, the burnup depth, etc.) (Fig. 8);

M _w. (kg) is the mass of fluid in the hydraulic capacity;

N _top. (m) - elevation of the top of the hydraulic capacity;

T (s) - the full planned time of fluid outflow from the hydraulic reservoir, or the operating time of the hydraulic reservoir.

After finding a preliminary estimate of the function f (h), it must be clarified by mathematical modeling of the entire CG system using specialized computer programs for calculating thermohydraulic processes.

The calculations (see Fig. 9) for the characteristics of the AES-2006 project with a VVER-1000 and GE reactor show that this device for continuously changing the flow rate of cooling water will make it possible to rationally use the available GE water supply and extend its work in cooling the reactor core to 130,000 s, whereas the design time of the CU is 86400 s.

Claims (8)

1. Hydraulic reservoir for the passive system of the emergency bay of a nuclear reactor with an upper inlet pipe for the gas mixture and lower main and additional drain pipes for water, the lower outer ends of which are interconnected, with a device for stepless profiling of the flowmeter installed inside the hydraulic reservoir, made in the form of a vertical partitions along the entire height of the container body with an opening for the passage of water, the area of the passage section of which decreases from top to bottom, while the lower drain pat CRAs are located on opposite sides of the partition. 2. The hydraulic reservoir according to claim 1, characterized in that a larger volume of the container body, separated by a partition, is connected to the upper inlet pipe for the gas-vapor mixture and an additional lower drain pipe, and a smaller volume of the container body is connected to the main lower drain pipe. 3. The hydraulic reservoir according to claim 2, characterized in that a diaphragm is installed in the lower additional drain pipe between the hydraulic reservoir housing and the junction of the lower external ends of the drain pipes. 4. The hydraulic reservoir according to claim 1, characterized in that the hole for the passage of water in the partition is a vertical gap of variable profiled width. 5. The hydraulic reservoir according to claim 3, characterized in that the partition can be made integral. 6. The hydraulic reservoir according to claim 1, characterized in that the hole for the passage of water can be formed due to gaps between the hydraulic reservoir housing and the partition of variable width. 7. The hydraulic reservoir according to claim 1, characterized in that the hole for the passage of water is a plurality of holes, the total area of which decreases along the height of the partition from top to bottom. 8. The hydraulic reservoir according to claim 6, characterized in that the holes can be of arbitrary shape.

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