JPS5967497A - Reactor coolant clean-up device - 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 The present invention relates to a nuclear reactor coolant purification system, and more particularly to one equipped with a merging pipe section for merging treated and purified coolant with main coolant flowing into a nuclear reactor. .

The reactor coolant purification system continuously purifies a part of the coolant that is circulated and used as a heat medium to extract the heat generated in the nuclear reactor to the outside. The one shown in the system configuration diagram is known.

In Fig. 1, water is continuously supplied as a coolant to a boiling water reactor 1, and a recirculation pump 2 is used to forcefully circulate water in order to ensure sufficient convection of water within the JM sub-reactor l. is provided. A predetermined amount of water to be purified can be continuously drawn out from the suction side of the recirculation pump 2 by the purification system circulation pump 3. The water to be purified extracted by the purification system circulation pump 3 flows into the regenerative heat exchanger 4 as a heating medium. The water to be purified that flows out from the regenerative heat exchanger 4 flows into the non-regenerative heat exchanger 5 as a heating medium, and the water to be purified that flows out from this heat exchanger 5 flows into the demineralizer 6. has been done. Circulating cooling water flows into the cooling medium side of the non-regenerative heat exchanger 5 from the reactor auxiliary equipment cooling system 7, and this flow rate is controlled by the flow rate control valve 8.
It can be controlled by. The purified water purified by the filtration demineralizer 6 passes through the cooling medium side of the regenerative heat exchanger 4 and flows into the confluence piping section 9a. Feed water as a coolant flows into this confluence piping portion 9a from a water supply device (not shown), and the purified water is merged with this feed water and supplied to the nuclear reactor 1. Further, a temperature regulator 10 detects the temperature of the water to be purified flowing into the filtration demineralizer 6 and controls the flow rate control valve 8 so that the temperature matches a predetermined value.
is provided.

During normal operation of the conventional coolant purification device configured as described above, the water to be purified extracted by the purification system circulation pump 3 is cooled by the regenerative heat exchanger 4 from, for example, 285C to 110C, and further It is cooled by the non-regenerative heat exchanger 5 to, for example, 54c or less. The temperature of the water to be purified at the outlet of the non-regenerative heat exchanger 5 is determined by the processing temperature of the filtration demineralizer 6, and the temperature of the water to be purified at the outlet of the non-regenerative heat exchanger 5 is determined by the processing temperature of the filter demineralizer 6. By controlling the amount of cooling water flowing in, the temperature is controlled to a predetermined temperature. The thus cooled water to be purified is purified by the filtration demineralizer 6, heated by the regenerative heat exchanger 4, and then flows into the confluence piping section 9a. Here, the temperature of the purified water flowing into the confluence piping section 9a varies depending on the temperature determined by the filtration demineralizer 6 and the amount of heat exchanged in the regenerative heat exchanger 4. It is about 220C.

However, during normal operation, the water supply temperature is almost constant (for example, 1
96C), two fluids having different temperatures are allowed to flow into the confluence piping section 9a. For this reason, there is a fear that cracks or the like may occur in the piping of the confluence piping section 9a due to thermal fatigue due to the temperature difference between these fluids.

Therefore, conventionally, the confluence piping section 9a has a thermal sleep structure to absorb the thermal stress difference, or to quickly and uniformly mix two fluids having a temperature difference, thereby preventing thermal fatigue. Efforts have been made to prevent the occurrence of cracks and the like.

However, even with a thermal sleeve structure, there is a drawback that cracks due to thermal fatigue over time due to repeated temperature differences cannot be completely prevented.

In addition, the initial temperature of the feed water supplied from the water supply device, especially during startup operation of a nuclear reactor, is low (for example, 38 C), and normally the temperature of the feed water rises slowly. On the other hand, the temperature of the purified water rises rapidly, sometimes up to about 285C. Therefore, the temperature difference between the purified water and the supplied water in the confluence piping section 9a is extremely large, and it is difficult to absorb the thermal stress difference due to this temperature difference only by the thermal sleeve structure, which may cause cracks due to thermal fatigue. It has the disadvantage that it is not possible to prevent the occurrence of

An object of the present invention is to provide a nuclear reactor coolant purification device that prevents cracks from occurring in a confluence piping section due to thermal fatigue.

The present invention provides means for controlling the flow rate of the cooling medium in at least one of the regenerative heat exchanger and the non-regenerative heat exchanger so that the temperature of the purified water flowing into the confluence piping portion matches the temperature of the supply water. Second, it is intended to prevent the occurrence of cracks due to thermal fatigue caused by the temperature difference between the two fluids flowing into the confluence piping section.

Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 2 shows a system 44 diagram of the first embodiment to which the present invention is applied. In the figure, the same reference numerals as those in the conventional example shown in FIG. 1 have the same configuration and function.

As shown in FIG. 2, a purified water temperature detector 11 and a feed water temperature detector 12 are provided to detect the temperature of purified water and feed water flowing into the confluence piping section 9b. Temperature detection signals output from the purified water temperature detector 11 and the feed water temperature detector 12 are input to a temperature controller 13. This temperature regulator 13 is a replacement for the conventional example (111λ degree regulator 10 in FIG.
is man-powered.

The temperature regulator 13 calculates the difference between the input purified water temperature and the supplied water temperature, and outputs a flow rate control signal to control the opening degree of the flow rate control valve 8 based on this temperature difference signal. .

419, the opening degree of the flow rate control valve 8 can be increased depending on the temperature difference between the two fluids flowing into the confluence piping section 9b, for example, when the temperature of the purified water is high. By increasing the flow rate of the cooling water, which is the cooling medium of the non-regenerative heat exchanger 5, and in the opposite case, decreasing the flow rate of the cooling water, control is performed to match the temperature of the purified water with the temperature of the feed water. be exposed.

Therefore, according to this embodiment, since the temperature of purified water is controlled to match the temperature of the water supply by following the change in the temperature of the water supply, the temperature difference between the two fluids flowing into the confluence piping section 9b is It is possible to prevent the occurrence of cracks due to thermal fatigue caused by this, which has the effect of improving the reliability and operation rate of the entire nuclear reactor plant.

FIG. 3 shows system 4, 'J' of the second embodiment to which the present invention is applied.
A composition diagram is shown. In the same figure, the same reference numerals as in the embodiment shown in FIG. 2 have the same functions.

As shown in FIG. 3, a flow rate valve 14 is provided at the outlet of the cooling medium of the regenerative heat exchanger 4, and the downstream side of this flow rate control valve 14 and the regenerative heat exchanger The cooling medium inlet 4 is the bypass flow control valve 15.
Connected via bypass. Purified water.

The outputs of the temperature detector 11 and the feed water temperature detector 12 are input to a subtraction adder 16, respectively. The output of this subtraction adder 16 is input to a temperature A stopper 17. The output of the temperature regulator 17 is a signal for controlling the opening degree of the flow control valve, and is input to the flow control valve 14 and the bypass flow control valve 15 via an electro-pneumatic signal converter 18, respectively. Note that the temperature regulator 17 adjusts one flow rate f1 according to the input temperature difference signal.
The opening degree of the 71J control valve is controlled to be a pilot flame, and the opening degree of the other valve is decreased.

Since it is configured in this way, the flow rate of high-temperature purified water heated by the regenerative heat exchanger 4 and the flow rate of the high-temperature purified water heated by the regenerative heat exchanger 4 and the filtration demineralizer 6 which bypasses this are determined according to the temperature difference between the purified water temperature and the feed water temperature. The ratio of the flow rate of the low-temperature water flowing in from the flow rate is controlled in a complementary manner, thereby matching the temperatures of the two fluids flowing into the confluence piping section 9C.For example, At startup, the flow control valve 14
is fully opened, the bypass flow control valve 15 is fully opened, and r
The low-temperature purified water flowing out from the A demineralizer 6 is shrunk and made to flow into the confluence piping section 9C. At this time, reactor 1
Although the water to be purified (for example, temperature 285C) extracted from the The temperature of the water to be purified flowing into the vessel 6 can be cooled to a predetermined temperature.

After the start-up starts, the feed water temperature is gradually increased as steady operation is achieved. When this supply water temperature becomes equal to or higher than the purified water temperature, the temperature regulator 17 outputs a control signal that increases the opening degree of the flow rate control valve 14 and reduces the opening degree of the bypass flow rate control valve 15 according to the temperature difference. . In this way, by controlling the opening degrees of the flow rate control valve 14 and the flow rate control valve 15 in a complementary manner according to the 1+'M degree difference between the purified water and the supplied water, purified water can be controlled. It is controlled so that the temperature of the water matches the temperature of the water supply.

Therefore, according to this embodiment, in addition to the effects of the first embodiment, it is possible to significantly reduce the temperature difference between the two fluids in the confluence piping section at startup, and to further reduce the occurrence of cracks due to thermal fatigue. It is possible to prevent such problems.

It should be noted that the present invention is not limited to the first or second embodiment described above; for example, by combining them, the heat balance and temperature controllability of the entire coolant purification device can be achieved as desired. Needless to say, it is also possible to make it as appropriate.

As described above, according to the present invention, it is possible to prevent the occurrence of cracks or the like due to thermal fatigue in the merging piping section where purified water and supplied water are joined.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of a conventional example, FIG. 2 is a system configuration diagram of a first embodiment of the present invention, and FIG. 3 is a system configuration diagram of a second embodiment of the present invention. 1... Nuclear reactor, 3... Purification system circulation bonder, 4...
Regenerative heat exchanger, 5... Non-regenerative heat exchanger, 6... Filtration demineralizer, 7... Reactor auxiliary equipment cooling system a, 8... Flow rate control valve, 9... Merging pipe Part 10... Temperature controller,
11... Purified water temperature detector, 12... Feed water temperature detector,
13... Temperature controller, 14... Flow device iI+1 valve,
15... Bypass flow rate control valve, 16... Area calculator,
17...Temperature regulator, 18...Electro-pneumatic 1st port Z port

Claims (1)

[Claims] 1. A regenerative heat exchanger that uses as a heating medium the coolant to be purified that is continuously extracted from the reactor into which coolant supplied from the coolant supply device is flowing, and temperature reduction by the regenerative heat exchanger. a non-regenerative heat exchanger that uses the purified coolant as a heating medium and any fluid as a cooling medium; a purification device that purifies the coolant that has been cooled by the non-regenerative heat exchanger;
A merging piping section that combines the purified coolant flowing out from the purification device with the coolant of the regenerative heat exchanger and joins the purified coolant heated by the heat exchanger with the coolant flowing into the nuclear reactor. In the reactor coolant purification system, the flow rate of the coolant in at least one of the heat exchangers is adjusted so that the temperature of the coolant flowing into the merging pipe section and the purified coolant match. 1. A nuclear reactor coolant purification system comprising means for controlling.