JP2644950B2 - Steam condensing tube for cooling system during reactor isolation - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam condensing pipe, and more particularly to a steam condensing pipe for a steam discharged from a cooling system turbine during isolation of an improved boiling water reactor.

[0002]

2. Description of the Related Art One of the systems for maintaining the operation and safety of a nuclear power plant is a cooling system at the time of reactor isolation. This lineage
When the reactor coolant is lost or when the reactor is isolated, it is installed to inject coolant into the reactor and remove decay heat of the core. This cooling system will be described with reference to the drawings.

FIG. 4 is an explanatory view of a cooling system at the time of nuclear reactor isolation in a boiling water nuclear power plant. During operation of the reactor isolation cooling system, the steam in the reactor pressure vessel 6 is supplied to the steam turbine 7 through the steam supply pipe 11 in FIG.

[0004] A reactor isolation cooling pump 8 directly connected to the steam turbine 7 is driven by the steam turbine 7.
Coolant injection pipe 13 from condensate storage tank 9 or pressure suppression chamber 10
The coolant is injected into the reactor pressure vessel 6 through the reactor, and a required water level in the reactor pressure vessel 6 is secured to cool the reactor core.

The exhaust steam discharged from the steam turbine 7 is
The water is sent into the suppression chamber 10 through the steam discharge pipe 12, and is condensed by the steam condensation pipe 1 submerged in the water in the suppression chamber 10.

That is, since the injection of the coolant into the reactor pressure vessel 6 requires urgency, the above-described method is employed. However, in this case, since the condensation of the steam discharged from the steam condenser tube 1 tends to be unstable, the steam condenser tube 1 is likely to vibrate. Fluctuation is likely to occur. Therefore, the check valve 14 frequently opens and closes, and there is a possibility that the valve may be damaged due to the repetitive stress generated thereby.

In order to solve these problems, conventionally, a plurality of steam discharge holes having an appropriate arrangement are provided on the wall of a steam condensing tube to stably condense turbine exhaust steam, thereby reducing the time of steam condensation. Vibration is prevented.

In Japanese Patent Application Laid-Open No. 50-29997, a conditional expression for performing stable steam condensation using the distance below the surface of the steam discharge port in the steam condenser tube, the hole diameter, the steam pressure in the tube, and the subcool temperature. Has been disclosed.

[0009]

In the improved boiling water reactor, when designing the cooling system at the time of reactor isolation, the design conditions of the conventional boiling water reactor will be changed. I have.

The main changes are to take into account various conditions such as an increase in the turbine exhaust steam flow rate, an increase in the depth of the steam condensing pipe in the suppression chamber, and an increase in the exhaust pressure of the steam condensing pipe due to an increase in the pressure in the suppression chamber. It is.

The change in the design conditions deteriorates the condensation characteristics of the turbine exhaust steam by the steam condensing tube, and there is a concern that steam condensation vibration may occur.

An object of the present invention is to provide a steam condensing tube capable of stably condensing steam to solve the above-mentioned problems.
It is an object of the present invention to provide steam for the steam discharged from the cooling system turbine at the time of reactor isolation in the improved boiling water reactor.

[0013]

The above object can be achieved as follows.

Turbine for pump drive of cooling system during isolation of reactor
The steam condensing pipe that discharges the steam discharged from the steam into the water in the pressure suppression chamber has a plurality of
It drilled several steam emission holes, the sum of Anadan area <br/> of the vapor discharge hole is from small Kushida <br/> be perpendicular to the axis the cross-sectional area of the steam condensing tubes.

[0015]

On the wall of the steam condensing tube submerged in the water,
A plurality of vapor discharge holes are drilled, the hole diameter of the vapor discharge holes is in the range of 5 to 20 mm, and the distance between the holes in the axial direction is 5 to 50 mm.
In the range of, and, the number of holes the steam release holes on the axis perpendicular same section, if the inner diameter of 5 inches or more, it to x ² / less than 5 with respect to the internal diameter x inches, are set, respectively.

In the wall of the steam condenser tube submerged in the water,
A plurality of vapor discharge holes are drilled, and
The number of steam discharge holes is set such that the inner diameter of the steam condenser tube is 5 inches.
For above, x ² / less than 5 with respect to the internal diameter x inches,
The sum of the cross-sectional areas of the vapor discharge holes is equal to the vapor condensation
It must be set smaller than the cross-sectional area of the pipe perpendicular to the axis .

[0018]

[0019]

In the wall of the steam condensing tube submerged in the water,
A plurality of vapor discharge holes are formed, and the diameter of the vapor discharge holes is gradually reduced from the inside to the outside.

[0021]

[0022]

According to the present invention, the sum of the cross-sectional areas of the steam discharge holes is smaller than the cross-sectional area of the steam condensing pipe.
The flow velocity of the steam ejected from the steam discharge hole is increased, and stable steam condensation is enabled.

Further, the hole diameter of the steam discharge hole and the hole interval in the axial direction of the steam condenser tube are appropriately set, and the number of steam discharge holes on the same cross section perpendicular to the axis of the steam condenser tube is determined by the inner diameter of the steam condenser tube. Is set to an appropriate number, the critical steam flow rate at which unstable steam condensation occurs can be reduced.

In addition, the diameter of the steam discharge hole and the distance between the holes in the axial direction of the steam condenser tube are constant, and in any position in the axial direction, the inside of the vapor discharge hole is cut off on the same cross section perpendicular to the axis of the steam condenser tube. Since the sum of the areas is constant, the amount of steam discharged from the steam discharge holes can be evenly dispersed, and local concentrated condensation of steam can be prevented.

Further, since the diameter of the steam discharge hole is gradually reduced from the inside to the outside of the steam condenser tube, the pressure loss at the time of steam discharge is small, and the discharge flow rate can be increased. When the water in the pressure suppression chamber flows back into the pipe, the pressure loss is large and the backflow of water can be prevented.

Since the steam condensing tube of the present invention has these functions, the steam condensing tube of the present invention is applied to steam condensing of steam discharged from a turbine cooling system at the time of reactor isolation in an improved boiling water reactor. In this case, the vibration of the steam condenser tube due to the unstable condensation and the pressure fluctuation in the steam condenser tube can be prevented, and the reliability of the reactor safety system can be improved.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is an explanatory view of a steam condenser tube according to one embodiment of the present invention. In FIG. 1, the axial hole interval 4 and the circumferential hole interval 5 of the steam discharge holes 2 of the steam condenser tube 1 are made constant, and the steam discharge holes 2 are evenly arranged on the steam Local concentrated condensation was avoided, and stable vapor condensation was obtained. The same reference numerals are used for the steam condensing pipe 1 as the steam condensing pipe in FIG.

That is, in the present embodiment, the hole diameter 3, the axial hole interval 4, and the circumferential hole interval 5 were determined as follows. Table 1 shows the contents of the tests performed to determine these.

[0030]

[Table 1]

In Table 1, the hole diameter 3, the hole interval 4 in the axial direction, the number of holes on the same cross section perpendicular to the axis, and the total hole area ratio (the sum of the cross-sectional areas of the steam discharge holes and the cross-sectional area of the steam condensing tube) ), And numerical values of these four parameters were respectively selected from the test ranges shown in No. 1 of Table 1, and tests were performed for many combinations having different numerical values of the parameters.

In the test, a steam condenser tube 1 having a diameter of 5 inches was used, and the hole interval 5 in the circumferential direction was changed according to the number of holes on the same cross section perpendicular to the axis.

As a result of the test, the steam discharge hole 2 of the steam condenser tube 1
The values shown in No. 2 in Table 1 were obtained as a range in which no vibration was generated during the release of steam from the. That is, N in Table 1
It was found that stable condensation characteristics could be obtained within the range shown in O.2.

The test results were obtained with a steam condenser tube having a diameter of 5 inches. The effect of the diameter of the steam condenser tube on the condensation characteristics was examined, and the results shown in FIG. 2 were obtained.

FIG. 2 is a diagram showing the relationship between the diameter of a steam condenser tube according to another embodiment of the present invention and the critical flow velocity. Here, the critical flow velocity is a low-velocity critical vapor velocity at which unstable vapor condensation occurs, and a case where the circumferential hole interval is proportional to the diameter. From FIG. 2, it can be seen that as the diameter of the steam condensing tube increases, the steam condensation improves, and in the range where the vibration of No. 2 in Table 1 does not occur, the steam condensing tube can be applied even when the diameter of the steam condensing tube is large. I was able to clarify something.

The effect of the number of holes on the same cross section perpendicular to the axis on the condensation characteristics was investigated using a steam condenser tube having a diameter of 5 inches. As a result, if the diameter of the vapor condensation tube is x inch, hole number is be in the range of less than x ^2/5 at x ^2/25 or more, it was found that stable condensed characteristics can be obtained. When the diameter is 5 inches, the number of holes is 1 to 1 as shown in Table 1.
There are four ranges. That is, in the design of the steam condenser tube,
The number of holes on the axis perpendicular same section x less than ^2/5 (where, x ² /
25 or more).

Further, since the total hole area ratio was set to 1 or less, the discharge flow rate of the vapor was increased, and the vapor condensation could be stabilized.

That is, from the above, it is assumed that the water depth in the pressure suppression chamber increases, a high pressure is applied to the steam discharge holes of the steam condenser tube, the steam density in the steam condenser tube increases, and the steam discharge flow rate tends to decrease. Even below, it was possible to secure a sufficient vapor discharge flow rate.

FIG. 3 is an explanatory view of a hole of a steam condenser tube according to another embodiment of the present invention. In this embodiment, as shown in FIG. 3, the diameter 3 of the steam discharge hole 2 is tapered so as to gradually decrease from the inside to the outside of the steam condenser tube 1.

By making the hole of the steam condensing pipe 1 into the shape shown in FIG. 3, the pressure loss of the steam discharge hole 2 is small at the time of steam discharge, so that the discharge flow rate is increased. (See FIG. 4) When the water in the steam flows backward to the steam condenser tube 1, the pressure loss of the steam discharge hole 2 increases due to the orifice effect, so that it is possible to prevent water from entering the steam condenser tube 1. Was.

[0041]

According to the present invention, it is possible to provide a steam condensing pipe for turbine exhaust steam capable of performing stable steam condensation. For example, exhaust steam of a cooling system turbine at the time of reactor isolation can be provided in water in a pressure suppression room. At the time of discharge, the use of the steam condenser tube according to the present invention makes it possible to prevent the vibration of the steam condenser tube due to unstable condensation and the pressure fluctuation in the steam condenser tube, thereby improving the reliability of the reactor safety system. Can be.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a steam condenser tube according to one embodiment of the present invention.

FIG. 2 is a relationship diagram between a diameter of a steam condensing tube and a critical flow velocity according to another embodiment of the present invention.

FIG. 3 is an explanatory view of a hole of a steam condenser tube according to another embodiment of the present invention.

FIG. 4 is an explanatory diagram of a cooling system at the time of reactor isolation of the improved boiling water reactor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Steam condensing pipe, 2 ... Steam discharge hole, 3 ... Pore diameter, 4 ... Axial hole interval, 5 ... Circumferential hole interval, 6 ... Reactor pressure vessel, 7 ... Steam turbine, 8 ... At the time of reactor isolation Cooling system pump, 9: condensate storage tank, 10: pressure suppression chamber, 11: steam supply pipe, 12: steam discharge pipe, 13 ... coolant injection pipe, 14 ...
Check valve.

Claims (4)

(57) [Claims] 1. A pump driving pump for a cooling system at the time of reactor isolation
In a steam condenser tube for discharging steam discharged from a bottle into water in a pressure suppression chamber , a plurality of steams are formed on a wall of the steam condenser tube that is submerged in the water.
Drilled the release holes, the sum of Anadan area of the vapor discharge hole before
Serial vapor condensation pipe reactor core isolation vapor condensation tube of the cooling system, characterized in that the shaft are from small comb perpendicular cross-sectional area of the. 2. A pump driving pump for a cooling system at the time of reactor isolation.
In a steam condenser tube for discharging steam discharged from a bottle into water in a pressure suppression chamber , a plurality of steams are formed on a wall of the steam condenser tube that is submerged in the water.
A discharge hole is formed, and the diameter of the vapor discharge hole is 5 to 20 mm.
In the range of 5 to 50 mm.
And the number of the vapor discharge holes on the same cross section perpendicular to the axis,
If the inside diameter of the steam condenser tube is 5 inches or more, the inside diameter x inches
To x ^2/5 fewer than range for, respectively set tare
A steam condensing pipe for a cooling system at the time of isolation of a nuclear reactor . 3. A pump driving pump for a cooling system at the time of reactor isolation.
In a steam condenser tube for discharging steam discharged from a bottle into water in a pressure suppression chamber , a plurality of steams are formed on a wall of the steam condenser tube that is submerged in the water.
A discharge hole is drilled, and the vapor discharge hole
When the number of holes is 5 inches or more,
To x ² / less than 5 with respect to the internal diameter x inch, and the steam
The sum of the cross-sectional areas of the gas discharge holes is perpendicular to the axis of the steam condenser tube.
Reactor space characterized by being set smaller than the area
Steam condenser tube for cooling system when separated. 4. A turbine for driving a pump of a cooling system during isolation of a nuclear reactor.
A plurality of steams on a wall of the steam condensing tube submerged in the water.
A discharge hole is formed, and the diameter of the vapor discharge hole is changed from inside to outside.
Characterized by a gradual reduction as one heads toward
Steam condensing tube for cooling system when the reactor is isolated .