JPS63149596A - Overhead type core spray sparger - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Objective of the invention] [Field of application of n soil collection] The present invention is an emergency core cooling system that cools the reactor core and prevents the reactor from running out of control in the event of a rupture accident in the reactor-subsystem piping. 7JI equipment is attached to the A--head type core spresparger.

(Prior art) Generally, during operation of a nuclear reactor, when an abnormal situation such as a rupture of secondary system piping occurs and an emergency shutdown of the reactor is to be carried out, cooling i.p.
Water is sprayed. The reactor core is cooled by cold JI water within 1 minute, the temperature of the fuel cladding tubes is suppressed below the specified value, and the leakage of radioactive materials is prevented.

Generally, the steam purge V1 is supported by a support fitting 5 protruding from the inner surface of the shroud head cover 4 in the upper space of the reactor core 3 formed in the center of the reactor pressure vessel 2, as shown in FIG. spray purge t7
A large number of spray nozzles 6 for dispersing and spouting cold 7Jl water are attached to the lower end of the nozzle 1. .

As shown in Fig. 6, the overhead type core press barge 1711, which has been conventionally adopted for the core 2JI,
A large number of branch pipes 1b are branched in the side direction of the sparge t/water pipe 1a formed in a semicircular arc shape to form a comb-shaped piping, and a large number of spray nozzles 6 are installed at predetermined intervals on the lower surface of the branch pipe 1b.
The Fi1 port is taken toward the core (=j j). Two comb-shaped spres spargers 1 are assembled and attached to a support fitting 5 on the inner surface of the shroud head cover 4 at the upper part of the reactor core.
It is supported and fixed through.

When an abnormality occurs in the reactor and an emergency shutdown is to be performed, cold fJJ water is fed into the reactor via the spray sparger 1 as shown in Fig. 7, and the fuel assembly 7 below from the spray nozzle 6 hs is fed. By distributing and injecting cold water to the reactor, the reactor core is sufficiently cooled and the safety of the reactor is maintained.

(Problems to be Solved by the Invention) In the conventional overhead type core spray purge 11 J3, the opening of the spray nozzle is provided directly in the direction of the reactor core, so a sufficient distance between the fuel assembly and the frontage of the spray nozzle cannot be secured. Therefore, the cooling water ejected from the reactor was sprayed onto the upper surface of the fuel assembly before it was sufficiently dispersed, making it impossible to uniformly cool the entire core.

Therefore, if the above-mentioned distance is set to be large, the shroud will also become attached to the person, and the reactor pressure vessel itself will need to be enlarged, which will reduce operational performance.

Conventional countermeasures have been to improve the shape of the spray nozzle so that the cooling water can be dispersed over a wide area, and to increase the capacity R of the cold IJI water pump to compensate for the uneven distribution of the cooling water. A new problem has arisen in that the shape of the device has become complicated, making it more likely to cause failure.

In addition, the overhead type core pressure purge 11 is the sixth
As shown in the figure, it has a complex shape, so
Thermal deformation during emergency cooling IJ1 is significant, and in order to avoid damage due to the thermal stress, the entire structure including the supporting metal fittings needs to be made into a flexible structure.

On the other hand, since the In2 port of the spray nozzle faces the direction of the reactor core, when cold water is spouted out at high speed, the spray sparger
Due to the reaction of the ejected fluid, the shroud receives a reaction force that pushes it up in the direction of the head cover. This reaction force acts as compressive stress on the support fitting. In order to cope with the protrusion caused by this reaction force, the supporting structure of the Sprespersite is required to have a certain degree of rigidity.

Therefore, it has been extremely difficult to create a support structure for the spray purge 11 that harmonizes the contradictory softness and rigidity of the structure.

The present invention was devised to solve the above problems, and has the ability to uniformly disperse and spray cooling water to the reactor core during emergency shutdown of a nuclear reactor, and has a simple structure.
The purpose is to provide an A-type reactor core press purge p which is easy to construct and install.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, an overhead type reactor core spresparger according to the present invention is arranged between a nuclear reactor core loaded with a fuel assembly and a C:L loudhead cover. In the core spresparger J3, the spouting holes of the spres barge are arranged so as to point toward the shroud head cover, while the cooling water spouted in one direction of the shroud head cover is reversed toward the core, and is directed to the upper part of the core. A dispersion plate dispersing over a wide area is installed opposite the 1-2 nozzle holes, and the dispersion plate is formed in a shape of 111 expanded in the direction of the f center.

(Function) According to the configuration described in -1-, if an accident requiring an emergency shutdown occurs during reactor operation, the reactor core 7JI water supplied by the pump from the condensate storage tank etc. will pass through the press barge i/. It is then fed into the reactor. The supplied cooling water is jetted upward from the holes installed in the Suffles barge 11 at high speed. Reverse the direction of the flow.

Since the distribution plate is formed in a shape that expands in the direction of the core, the cooling water 1 is spread on the inner surface of the distribution plate, which is expanded, and is dispersed on both sides, so that the water is dispersed over a wide area in the second part of the reactor core. Therefore, compared to the conventional structure, the dispersion rate of cooling water is higher and the spraying range is significantly expanded, achieving a uniform cooling effect over the entire surface of the reactor core.
11.

Further, since the spouting hole of the spresparger opens downward, a reaction force is generated in the downward direction due to the reaction of the cold rJ] water jetted out at high speed. That is, since tensile stress acts on the supporting metal fittings, the rigidity of the SPRESS PURGE T, including the supporting metal fittings, is increased, and the support groove design of the SPRESS PURGE T is simplified.

(Example) Next, an example of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a sectional view showing a first embodiment of the present invention.

The spray sparger 1 is a fuel sparger loaded in the core of a nuclear reactor.
It is arranged in the space between the first assembly 7 and the seat loud head cover 4, and is fixed on the inner surface of the seat loud head cover 4 via the branch 8.

Cooling water ejection holes 9 are bored in the upper surface of the spray sheet 1 . Note that the ejection holes 9 may be formed by consecutively arranging fine holes at predetermined intervals, but may also be formed by a vortex in the shape of a slit.

Further, a dispersion plate 10 is provided on one side of the ejection hole 9,
This dispersion plate 10 is formed into an umbrella shape that expands in the direction of the reactor core.

When the reactor's emergency core cooling system is activated, cold IJ1 water supplied from the service water storage tank, etc. is sent to the reactor pressure vessel 2, and is further distributed from the wood pipe 1a of the steam purge PL to the branch pipe 1b. , branch pipe ibf/), and is ejected at high speed from the ejection hole 9 provided in the L part toward the shroud head cover.

The jetted cooling water collides with the dispersion plate 10 to be dispersed, and the direction of the flow is reversed, so that the cooling water is dispersed over a wide area in the reactor core.

Here, the spreader claws of the distribution plate 10 are adjusted so that the cooling water is appropriately distributed in the direction of the core, so that the cooling water is uniformly distributed over the entire area of the fuel assembly. Therefore, compared to the conventional spray nozzle structure, the spray area of cold 7JI water per spray nozzle is greatly increased, so the 6111 action in the core becomes uniform, and local overheating of the fuel assembly 7 is prevented. By doing so, the risk of the attack turning into a one-off attack is avoided.

Honji flI again! If the configuration of l@ is J:, cold 7J] water is spouted at high speed from the spout hole 9 of the spray purge I71 to the shroud head cover 4 side, so the spray purge 1
? A reaction force acts on fuel assembly 1 in the direction of fuel assembly 7 .

Since tensile stress will be applied to the bundle and branch 8, the rigidity of the support structure will be increased compared to the conventional structure.
The safety against thermal changes is further improved, and the support structure) Δ installation 1 is simplified.

Furthermore, since the cooling water is uniformly distributed over a wide area through the spray nozzle 6, effective core cooling can be achieved with a small amount of cold 7JI water. Therefore, the number of spray nozzles installed can be reduced, and the volume of the single cooling water pump can be reduced in size.

In addition, a spout hole 9 is provided in the spresparger 1 facing the soil,
The dispersion performance of the cooling water can be improved simply by installing the dispersion plate 10, which is a small component, in opposition to the ejection holes 9. Therefore, there is no need to secure a large space between the steam purge 1?1 and the fuel assembly 7, and it is easy to use.
Furthermore, since it is an existing facility, it can be easily modified.

Next, a second embodiment of the present invention will be explained with reference to FIG. In this embodiment, a cooling water jet hole 9 is provided on the upper surface of the branch pipe of the pressure barge p1, and a small hole 11 is bored on the lower surface of the pipe 6. By spouting a portion of the cold 741 water from this small hole 11, it is possible to directly spray the Ig coolant to the upper end of the core located directly below the steam purge 1-1.

If the structure of this embodiment is J, then the Sbress purge 111 and the combustion
Even if J5 is installed in a nuclear reactor with a narrow space between it and the east merger 7, cooling water is distributed directly below the spray seat 1, and the cold 7J1'Jr end of the entire reactor can be reduced by 1.

Next, a 31st/11!1 example of the present invention will be described with reference to FIGS. 3 and 4.

Honji 111! In example i, J3 is configured such that the distribution plate 10 expands in the core direction due to the dynamic pressure of the cold 7JI water jetted from the jet hole 9. That is, the dispersion plate 10 has a hinge structure in which, for example, two dispersion plate elements 10a and 10b are pivotally connected via a support shaft 12.

When cooling water is introduced into the Sbress barge 171 in an emergency, the distribution plate 10 expands in the direction of the core due to the dynamic pressure of the cold L1 water jetted out from the jet holes 9 at high speed, and the distribution plate 10 spreads the cold W water in a predetermined direction according to the gap angle. It is guided in the same direction and turned around, dispersing cooling water over the top of the core.

On the other hand, during normal operation of the reactor, the distribution plate 10 is maintained in a state of 11+1t: at the top of the press barge t11, as illustrated in FIG. Blue flow resistance can be reduced.

By the way, during normal operation of a nuclear reactor, as shown in FIG. It reaches a water separator 15 where it is separated into steam and water. The separated steam is supplied to the turbine through the main steam pipe, while water is circulated within the reactor by a circulation pump 16 disposed around the lower part of the reactor core 3.

Therefore, the steam purge 1 disposed above the reactor core 3?
1 causes an increase in the flow resistance of the generated steam.

In particular, when a complicated and large spray nozzle 6 is adopted, there is a risk that the pressure due to the large flow fJ+resistance will be lost, reducing the original 15J capacity of the nuclear reactor.

However, according to the distribution plate 10 having the hinge structure of this embodiment, since it is open during normal operation, the smooth flow of steam is not impaired by N1, and the reactor's performance is maintained well. be done.

[Efficacy of invention Song Dynasty]

According to the overhead type core spurge p according to the present invention, the cold 51 water is guided and reversed by the dispersion plate provided opposite the ejection hole, and is uniformly dispersed over a wide area, so that the cold 51 water is uniformly dispersed over a wide area. Uniform cooling is possible over the entire surface.

In addition, since the jetting holes are located downward at I;'d l:] L/, the reaction of the cooling water jetting out at high speed generates a downward reaction force against the Sbress barge i. Therefore, since tensile stress acts on the support fittings of the spres sparge V, the rigidity of the spres sparger as a whole is increased, and the support structure S1 of the spres sparge is simplified.

[Brief explanation of the drawing]

Figure 1 shows the first embodiment of the present invention! 1 is a partial sectional view, FIG. 2 is a partial sectional view showing the second embodiment, and FIG. 3 is a partial sectional view showing the second embodiment.
A partial sectional view showing the third embodiment, FIG.
Fig. 5 is a sectional view showing the structure inside a conventional reactor pressure reactor;
FIG. 6 is a perspective view showing the structure of a conventional pressurized sheet, and FIG. 7 is a top view of the Vl-Vl arrow shown in FIG. 6. 1...Spray purge jy, 1a...Spar 911
Main pipe, 1b...Sbarge V branch pipe, 2...Atomic or pressure vessel, 3...Reactor core, 4...Shroud head cover, 5...Support fitting, 6...Spray nozzle, 7...・
Fuel assembly, 8... Strut, 9... Nozzle hole, 10...
・Dispersion plate, 10a, 1ob... Dispersion plate element, 11...
・Small hole, 12... Support shaft, 13... Steam flow, 14...
- Hole, 15...Steam water separator, 16...Circulation pump. Applicant's agent Hisashi Hatano Figure 1 Figure 2 Figure 4

Claims (1)

[Claims] 1. In a core spresparger disposed between a nuclear reactor core loaded with fuel assemblies and a shroud head cover, cooling water jet holes of the spresparger are directed toward the shroud head cover. At the same time, a dispersion plate is provided facing the above-mentioned ejection hole to reverse the cooling water ejected toward the shroud head cover toward the core and disperse it over a wide area in the upper part of the core, and the above-mentioned dispersion plate has a shape that expands in the direction opposite to the core. An overhead type reactor core spatter sparger characterized by being formed. 2. The overhead type core spresparger according to claim 1, wherein the spresparger has small holes drilled in the lower surface of the spresparger branch pipe for spouting cooling water toward the core. 3. The overhead type core spatter sparger according to claim 1 or 2, wherein the distribution plate has a hinge structure that expands in the core direction.