JPH0259699A - Operating method for nuclear reactor apparatus cooling equipment - Google Patents

Abstract

PURPOSE:To suppress water temperature of a well pool to a low level in the beginning of a periodical inspection by feeding sea water from a sea water pump of the other train to heat exchangers of nuclear reactor apparatus cooling systems of two trains, when a sea water pump of one train stops. CONSTITUTION:When for instance, a nuclear reactor apparatus cooling sea water pump 15a is stopped for the purpose of an inspection, sea water which is brought to intake by a sea water pump 15b of the other train is fed to a nuclear reactor apparatus cooling heat exchanger 11b, and also, fed to a nuclear reactor apparatus cooling heat exchanger 11a of the other train through a sea water supply tie line 17. Pool water which is brought to intake through a surge tank 6 from a fuel pool 2 is cooled by fuel pool cooling and purifying heat exchangers 8a, 8b. Filtered water which is brought to intake from a nuclear reactor pressure vessel 3 is cooled by residual heat eliminating heat exchangers 5a, 5b. Cooling water which is warmed up by the heat exchangers 5a, 5b, 8a and 8b is cooled by the nuclear reactor apparatus cooling heat exchangers 11a, 11b. In such a way, even in the course of inspecting the sea water pump of one train, water of a well pool 1 can be cooled by two sets of residual heat eliminating heat exchangers 5a, 5b.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a method of operating a nuclear reactor equipment cooling facility that cools a nuclear reactor and reactor equipment, and is particularly applicable to operations around a reactor well pool. This invention relates to an operating method for nuclear reactor equipment cooling equipment that achieves both improved performance and shortened periodic inspection (hereinafter referred to as periodic inspection) period.

(Prior Art) Generally, in nuclear power plants, periodic inspections and fuel replacement are performed approximately once a year. During fuel exchange, the reactor well and equipment temporary pool are filled with water.

In addition, the fuel pool gate is opened to move fuel underwater, and the reactor and reactor well pool.

The equipment temporary storage pool and fuel pool are one large pool.

The reactor contains core fuel, and the fuel pool contains spent fuel, each of which generates decay heat, so they are continuously cooled by a residual heat removal system and a fuel pool cooling and purification system. In modern plants, cooling water is supplied to both systems from the reactor equipment cooling system.

During periodic inspections, maintenance and inspection of each equipment will be carried out, but immediately after the reactor is shut down, two trains will be operated due to the large amount of decay heat.

The conventional operating method will be explained below with reference to FIG.

In FIG. 3, numeral 1 is the reactor well pool.

2 indicates a fuel pool. Reactor water taken from the reactor pressure vessel 3 is cooled through the residual heat removal pump 4 (4a4b) and the residual heat removal heat exchanger 5 (5a, 5b>), and then returned to the reactor pressure vessel 3.

On the other hand, fuel pool water is taken from the surge tank 6, and from the fuel pool cooling purification pump 7 (7a, 7b).
Fuel pool cooling purification heat exchanger 8 (8a.

After being cooled in 8b) and purified in filtration and demineralization equipment 9 (9a, 9b), the fuel pool 2 or reactor well pool 1
has been returned to.

Residual heat removal heat exchanger 5 (5a, 5b') and fuel pool cooling purification heat exchanger 8 (8a, 8b) exchange heat with reactor water and fuel pool water, and the heated cooling water is transferred to each heat exchanger. After flowing out of reactor equipment cooling pump 1
0. Reactor equipment cooling heat exchanger 11 (11a).

11b) and cooled again through each heat exchanger 5°8.
sent to. The cooling water is a regular load 12 (12a).

12b).

The reactor equipment cooling heat exchanger 11 (lla, 11b) uses the aforementioned cooling water and the reactor equipment cooling seawater pump 15 (15
a.

Heat exchange takes place with the seawater sent from 15b),
The warmed seawater is released into the ocean.

Figure 3: Notice number 16 is a seawater supply tie line stop valve, 17 is a seawater supply tie line stop valve, 18 is a return tie line stop valve, 1
9 is a return tie line, 20 is a seawater tie line, 20 is a seawater tie line stop valve, 21 is a seawater tie line, 22 is a core fuel, and 23 is a spent fuel.

As is clear from FIG. 3, the seawater supply tie line stop valve 16. The return tie line stop valve 18 and the seawater tie line stop valve 20 are closed, and the routes by which heat is carried from the reactor pressure vessel 3 to the sea are independently divided into the first series (A) and the second series (B).
), but because each piece of equipment needs to be inspected and maintained during a regular period, it is not possible to operate two sets of equipment at all times.

In particular, the reactor equipment cooling seawater pump 15 (15a, 15
Regarding '), it is necessary to perform maintenance and inspection of the water intake turret, etc. that guides seawater to the pump suction port, so at least one series will be unusable. On the other hand, the reactor equipment cooling system remains connected to the cooling water supply even during periodic inspections, and the necessary regular load is 12.
Therefore, it is not possible to completely stop both trains.

Therefore, a seawater tie line 20 is installed between two systems in the reactor equipment cooling water system, and the following operations are performed during periodic inspections.

This will be explained with reference to FIG. In FIG. 4, the same parts as in FIG. 3 are designated by the same reference numerals, and the explanation of the overlapping parts will be omitted and only the main points will be described.

The following describes the case where the reactor equipment cooling water system A is stopped, but when the reactor equipment cooling water system B is stopped, the A/B status is simply reversed, and there is no difference in the overall function.

For example, only one residual heat removal system (B side) is operated.

Water intake from the reactor pressure vessel 3, residual heat removal pump 4b,
The cooled reactor water is returned to the pressure vessel 3 through the residual heat removal heat exchanger 5b.

Two lines of the fuel pool cooling and purification system are operated in the same way as in the two-line operation described above.

The reactor equipment cooling water system A stops the reactor equipment cooling pump 10a, and the residual heat removal heat exchanger outlet valve 14a closes. The reactor equipment cooling seawater system A stops the seawater pump 15a.

As described above, the cooling water pump 10a of the reactor equipment cooling system A
, the reactor equipment cooling heat exchanger 11a and the seawater pump 15a of the reactor equipment cooling seawater system A can be maintained and inspected.

On the other hand, reactor equipment cooling water system B, reactor equipment cooling seawater system B
is in operation, and heat is removed in the residual heat removal heat exchanger 5b, the fuel pool cooling purification heat exchanger 3b, and the regular load 12b. At the same time, a seawater tie line stop valve 20 on a seawater tie line 21 branched from the downstream side of the reactor equipment cooling heat exchanger 11b and a return tie line stop valve 18 on a return tie line 19 connected to the upstream side of the reactor equipment cooling pump 10b. Open it to supply cooling water to the reactor equipment cooling water system A as well. That is, the cooling water cooled by the reactor equipment cooling heat exchanger 11b is diverted to the seawater tie line 21, sent to the fuel pool cooling purification heat exchanger 3a, the regular load 12a, and then merged and returned to the tie line 19. It is returned to the reactor equipment cooling pump 10b through the reactor equipment cooling pump 10b and sent again to the reactor equipment cooling heat exchanger 11b.

In this case, as described above, the residual heat removal heat exchanger outlet valve 14
Since point a is closed, no water is passed through the residual heat removal heat exchanger 5a. The reason why water does not flow is that the amount of water required to flow through the exchanger 5a accounts for about 50% of the amount of cooling water in one series as a whole when the tie lines 19.21 are not used. That is, in order to allow water to also flow through the residual heat removal heat exchanger 5a during the aforementioned tie line operation, the capacity of the cooling pump 10 should be increased to approximately 5.
This is because it is necessary to increase the amount by 0%, which is not economically advisable.

Incidentally, depending on the type of plant, a seawater supply tie line may also be provided between the reactor equipment cooling seawater systems.

In FIG. 4, there is a seawater supply inlet 17 that branches from the seawater pump 15a outlet and connects to the seawater pump 15b outlet. The seawater supply tie line 17 is provided with a seawater supply tie line stop valve 16, and the stop valve 16 is normally closed because it is not used.

For some reason, this seawater supply tie line 17 is connected to the seawater tie line 21 of the cooling water system. It is installed as a backup in case the return tie line 19 is unavailable, but since such a situation is considered to be rare, some plants have it installed and others do not.

(Problems to be Solved by the Invention) Recently, in order to improve the operating rate of plants, shortening the regular period has become an important design issue. on the other hand,
Seawater pumps are used for long periods of time for maintenance and inspection work, but as mentioned above, at least one of the two series requires continuous operation, so the maintenance and inspection work period for the two series of seawater pumps is very long. ing. Therefore, in order to shorten periodic inspections, it is necessary to begin maintenance of seawater pumps as early as possible after the nuclear reactor is shut down. However, in the cooling method described above, if the seawater pump is stopped early, the cooling capacity of the entire reactor equipment cooling system decreases, and the peak water temperature of the reactor well pool 1 increases.

This state will be explained with reference to FIG. Figure 5 shows the pool water temperature according to the conventional operation method, with temperature on the vertical axis,
The horizontal axis shows the number of regular inspection days.

As mentioned above, when the seawater pump is stopped, the cooling water pump on the stop train side is stopped and water flow to the residual heat removal heat exchanger is also stopped, so the reactor water is transferred to the residual heat removal heat exchanger 1.
As a result, the reactor well pool water temperature increases.

Thereafter, the pool water temperature decreases as the decay heat of the fuel attenuates, so the water temperature peaks at a certain point.

Since the peak temperature increases as the decay heat increases, the sooner the seawater pump is stopped, the higher the peak temperature will become.

During regular inspections, work such as fuel exchange is carried out around the reactor well pool 1 and above the water surface, and an increase in water temperature has a negative impact on work efficiency. In order to lower the water temperature, it would be possible to increase the capacity of the heat exchanger, but this is not economical.

The present invention was developed with these points in mind, and it is possible to keep the peak water temperature of the reactor well pool low even during the shortened periodic inspection process without increasing the capacity of heat exchangers, etc. An object of the present invention is to provide a method of operating a nuclear reactor equipment cooling facility that can improve performance.

[Structure of the Invention] (Means for Solving the Problems) The present invention takes a part of the reactor water in the reactor pressure vessel from the lower part, cools it with a heat exchanger for removing residual heat, and then returns it to the reactor pressure vessel. It has two lines of residual heat removal systems that return the residual heat removal system to the residual heat removal heat exchanger, and after cooling the heated cooling water by cooling the residual heat removal heat exchanger with the reactor equipment cooling heat exchanger, the residual heat removal system returns to the residual heat removal heat exchanger. The reactor equipment cooling seawater system has two lines, which take seawater from the reactor equipment cooling seawater pump and send it to the reactor equipment cooling heat exchanger for cooling.
A nuclear reactor having a reactor equipment cooling system, the outlet side of the first reactor equipment cooling seawater pump of the reactor equipment cooling system and the outlet side of the second reactor equipment cooling seawater pump of the reactor equipment cooling system are connected by a seawater supply tie line. In step 6 of the operating method for equipment cooling equipment, the reactor equipment cooling seawater pump of the first series is stopped, and the seawater taken from the reactor equipment cooling seawater pump of the second series is transferred to the reactor equipment cooling seawater pump of the second series. It is characterized in that the seawater is sent to the reactor equipment cooling heat exchanger of the first series through the reactor equipment cooling heat exchanger and the seawater supply tie line for cooling.

(Function) From the reactor equipment cooling seawater pump 15a (t5b) of one series to the reactor equipment cooling heat exchanger 11a (llb) of the same series and the seawater supply tie line 17 to the reactor equipment cooling heat exchanger of other series. At the same time, two lines of reactor equipment cooling systems and two lines of residual heat removal systems are operated. This makes it possible to keep the reactor well pool water temperature low at the beginning of periodic inspections.

That is, since the water in the reactor well pool is cooled by the two residual heat removal heat exchangers even during maintenance and inspection of one row of seawater pumps, the water temperature can be kept low. Thereafter, the timing of switching to single-unit operation can be delayed from after the nuclear reactor has stopped, so the peak temperature at the time of switching can be kept low.

(Example) An example of the method of operating a nuclear reactor equipment cooling facility according to the present invention will be described with reference to FIGS. 1 and 2.

Note that the same parts in FIG. 1 as in FIG. 3 are given the same reference numerals.

In FIG. 1, reactor pressure vessel 3. There is no barrier between the reactor well pool 1 and the fuel pool 2, and they form one pool.

A residual heat removal pump 4 (
4a, 4b), residual heat removal heat exchanger 5 (5a.

A residual heat removal system pool is formed which returns to the reactor pressure reactor via 5b).

A surge tank 6 is installed adjacent to the fuel pool 2. From the surge tank 6 are a fuel pool cooling purification pump 7 (7a, 7b), a fuel pool cooling purification heat exchanger 8 (8a, 8b), and a filtration chlorination device 9 (9a, 9b).
) to the fuel pool 2. Contacting reactor well pool 1.

Two residual heat removal systems are provided, and two residual heat removal heat exchangers 5 (5a, 5b) are installed. The fuel pool cooling purification system also has two units of each device, and two fuel pool cooling purification heat exchangers 8 (8a, 8b) are also installed. The two heat exchangers 5.8 are divided into A and B series, which are also piped to the reactor equipment cooling system in two series.

From the reactor equipment cooling pumps 10 (10a, 10b) to the reactor equipment cooling heat exchangers 11 (lla, 11b)
through each heat exchanger 5, 8 and regular load 12 (12
a, 12b'), and the downstream side is also connected to the reactor cooling pump 10 after merging in parallel.

The cooling water side piping of the residual heat removal heat exchanger 5 is provided with residual heat removal heat exchanger artificial valves 13 (13a, 13b) and residual heat removal heat exchanger outlet valves 14 (14a, 14b). Reactor equipment cooling seawater pump 15 (15a, 1
5b) is the reactor equipment cooling heat exchanger 11 (lla, 1
1b), the seawater discharge piping is connected to the outlet.

In the present invention, after the reactor equipment cooling seawater pump 15a is stopped for maintenance inspection, it is operated several times until maintenance inspection of equipment from the same system is started.

Reactor water taken from the lower part of the reactor pressure vessel 3 is pressurized by the residual heat removal pump 4, cooled by the residual heat removal heat exchanger 5, and returned to the reactor pressure vessel 3.

In addition, the pool water taken from the fuel pool 2 via the surge tank 6 is supplied to the fuel pool cooling purification pump 7 (7a, 7
After being pressurized in b), the fuel pool cooling purification heat exchanger 8
(8a, 8b), and is cooled by the filtration and desalination equipment 9 (9
a, 9b) and returned to the reactor well pool 1 or fuel pool 2.

The cooled water heated by exchanging heat with the residual heat removal heat exchanger 5 (5a, 5b) and the fuel pool cooling purification heat exchanger 8 (8a, 8b) joins the cooled water warmed by the regular load 12, Reactor equipment cooling pump 10 (10a.

10t)), cooled by the reactor equipment cooling heat exchanger 11, and then transferred again to the residual heat removal heat exchanger 5. The fuel is sent to the regular load 12 through the fuel pool cooling purification heat exchanger 8 (8a, 8b).

The seawater pressurized by the reactor equipment cooling seawater pump 15b is sent to the reactor equipment cooling heat exchanger 11b, and at the same time is also sent to the reactor equipment cooling heat exchanger 11a of another system through the seawater supply tie line 17, where heat exchange is performed. After being heated, it is released into the ocean.

However, since the period required for maintenance of seawater pumps is longer than that of other equipment, other equipment can be operated for several days after one part of the seawater system is stopped. Even if there is a delay in disclosing the maintenance and inspection of the seawater pump, it will not become critical. During this time, the seawater system is in tie-line operation.

If the cooling water system is operated in two lines, time can be acquired until one line of the seawater system is completely shut down, so that the effect of reducing the peak temperature commensurate with the attenuation of decay heat can be obtained. In other words, if the seawater pumps are stopped earlier to shorten periodic inspections, if the reactor equipment cooling pump and the reactor equipment cooling seawater system of one train are stopped at the same time as in the conventional example, the reactor well pool water at the time of shutdown will be reduced. Although the peak temperature is high as shown in FIG. 5, according to this embodiment, the peak temperature can be kept low as shown in FIG.

[Effects of the Invention] According to the present invention, even if the seawater pump is stopped earlier in order to shorten periodic inspections, the peak temperature of the reactor well pool water at the time of shutdown can be kept low without increasing the equipment capacity. . Additionally, workability around the reactor well pool can be improved and periodic inspections can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a system diagram for explaining an embodiment of the method of operating a nuclear reactor equipment cooling equipment according to the present invention, FIG. 2 is a characteristic diagram showing pool water temperature according to the method of operating the present invention, and FIGS. 4 is a system diagram for explaining the conventional operating method, and FIG. 5 is a characteristic diagram showing the pool water temperature according to the conventional operating method. 1... Reactor well pool 2... Fuel pool 3... Reactor pressure vessel 4... Residual heat removal pump 5... Residual heat removal heat exchanger 6... Surge tank 7... Fuel pool cooling purification pump 8... Fuel pool cooling purification heat exchanger 9... Filtration desalination device 10... Reactor equipment cooling pump 11... Reactor equipment cooling heat exchanger 12... Regular load 13... Residual heat removal heat exchanger population valve 14... Residual heat removal heat exchanger outlet valve 15... Reactor equipment cooling seawater pump 16... Seawater supply tie line stop valve 17... Seawater supply Tie line 18... Return tie line stop valve 19... Return tie line 20... Seawater tie line stop valve 21... Seawater tie line 22... Core fuel 23... Spent fuel (8733) Agent Patent Attorney Yoshiaki Inomata (Baka
1 person) 1st/1st death month (A) 2nd grade series (B) 3rd figure Yudo ￥4 figure

Claims (1)

[Claims] It has two residual heat removal systems that take in part of the reactor water in the reactor pressure vessel from its lower part, cool it with a heat exchanger for residual heat removal, and return it to the reactor pressure vessel again. It has two lines of reactor equipment cooling systems, in which the cooling water heated by cooling the heat exchanger is cooled by the reactor equipment cooling heat exchanger and then sent again to the residual heat removal heat exchanger. It has two series of reactor equipment cooling seawater systems that take seawater from a cooling seawater pump and send it to the reactor equipment cooling heat exchanger for cooling, and the reactor equipment cooling seawater in the first series of the reactor equipment cooling system. In the method of operating a reactor equipment cooling facility in which the outlet side of the pump and the outlet side of the reactor equipment cooling seawater pump of the second series are connected by a seawater supply tie line, the reactor equipment cooling seawater of the first series is connected to the outlet side of the reactor equipment cooling seawater pump of the second series. The pump is stopped, and the seawater taken from the seawater pump for cooling the reactor equipment of the second train is passed through the reactor equipment cooling heat exchanger of the second train and the seawater supply tie line to cool the reactor equipment of the first train. A method of operating a nuclear reactor equipment cooling equipment characterized by cooling equipment sent to a heat exchanger.