JPS59231390A - Condensing device - Google Patents

Abstract

PURPOSE:To supply the condensate into a water supply channel after deairing a radioactive gas dissolved in the condensate by a method wherein the inside of the second hot well for supplying the condensate to the water supply channel is made negative pressure wth a gas removing device, and the cleaned condensate supplied from the first hot well is atomized and sprayed. CONSTITUTION:The first hot well 22 and the second hot well 30 in a condenser 20 is made negative pressure with an air extractor 44 of the condenser, and kept at approximate vacuum condition of -720mm. Hg with gauge pressure. A radioactive substance contained in a condensate 50 condensed in the first hot well 22 is removed with a condenser filter 26 and a condensing-desulting device 28, then atomized into an empty space part 62 for spraying in the second hot well from an atomizer 64. When the condensate is atomized into the second hot well 30, the radioactive gas such as a xenon, a krypton and the like dissolved in the condensate is deaerated.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a condenser device suitable for use in a boiling water nuclear power plant, and in particular to a so-called side stream condenser device having a first hot well and a second hot well. Concerning a type condenser device.

[Background of the invention]

In recent years, condenser equipment has made the condensate demineralizer flow rate and the feed water flow rate independent in order to prevent fluctuations in the feed water flow rate due to condensate demineralizer blockages, etc., and to facilitate control of the feed water flow rate. The side stream type is becoming popular.

FIG. 1 schematically shows a condensate water supply system of an IWi# water type nuclear power plant having a Cytos IJ-type condenser device. In FIG. 1, steam generated in the nuclear reactor IO is guided to a high pressure turbine 14 through a main steam pipe 12t and drives the high pressure turbine 14. The steam that drove the high pressure turbine 14 is turned into dry steam by the steam separator 16, which drives the low pressure turbine 18.
When the water enters the water, it condenses in the first hot well 22 and becomes condensate. The condensate in the first hot well 22 is sucked into the condensate circulation port 24, and is passed through the condensate filter 26 and the condensate demineralizer 2.
8 to be purified and guided to the second hot well 30 of the condenser 20. The condensate that has entered the second hot well 30 is sent by the high-pressure condensate pump 32 to the water supply system consisting of the feed water heaters 34 and 36 and the feed water pump 38, heated to a certain temperature, and then supplied to the reactor 10. Ru.

The condenser 20 includes a first hot well 2 as shown in FIG.
2 and the second hot well 30 are partitioned by a partition wall 40, and an opening 4 is provided in the upper part of the partition wall 40 to communicate the two.
2 is formed. The first hot well 22 is provided with a pipe 46 communicating with a condenser air extractor 44, and a condensate purification pipe 48 is connected to the bottom thereof. This condensate purification pipe 48 is connected to the second hot well 3 via the aforementioned condensate circulation pump 24, condensate filter 26, and condensate demineralizer 28.
0, condensed water 5 condensed in the first hot well 22
0, the second hot well 30 is removed from the nozzle 52.
It is designed to be injected internally. Further, the second hot well 30 is provided with a condensate supply pipe 54 that communicates with the high-pressure condensate pump 32.

The operation of the side stream type condenser device constructed as described above is as follows. Low-pressure turbine 18f: The driven steam enters the condenser 20 and condenses to become condensate 50, which accumulates in the first hot well 22.

The condensate 50 is then sucked into the condensate circulation pump 24 via the condensate purification pipe 48, and is passed through the condensate filter 26 and the condensate demineralizer 2.
Sent to 8th. The condensate filter 26 and the condensate demineralizer 28 purify condensate, which is a secondary coolant, and reduce the radioactivity concentration in the condensate so that the decontamination coefficient for radioactive substances with respect to iodine is 100. The condensate thus purified is injected into the second hot well 30 through the nozzle 52'f.

The condensate entering the second hot well 30 is connected to the condensate supply distribution a5.
4 into the water supply system, a portion overflows into the first hotwell 22 through the opening 42 and is refluxed into the first hotwell 22.

Note that the inside of the first hot well 22 is made negative pressure by a condenser air extractor 44 via a pipe 46, so that oxygen gas and hydrogen gas decomposed in the reactor 10 can be extracted.

However, in the conventional condenser device having the above structure, the radiation dose around water supply system equipment such as the high pressure condensate pump 32 and the feed water heater 34 shown in FIG. 1 is relatively high. That is, among the radioactive substances captured in the condensate filter 26 and the condensate demineralizer 28, radioactive gases such as radioactive xenon produced by the decay of radioactive iodine and radioactive krypton produced by the decay of radioactive bromine. is condensate demineralizer 2
8, it dissolves in the condensate in a supersaturated state, and the second
Transported to Hotwell 30. For this reason, the condensate sent to the water supply system has radioactive gas dissolved in it, and this radioactive gas increases the radiation dose around water supply system equipment such as the high-pressure condensate pump 32 and the feed water heater 34. It was necessary to shield it with a concrete wall.

[Purpose of the invention]

The present invention has been made to eliminate the drawbacks of the prior art, and has an overall object to provide a condenser system capable of reducing 1 lf of gold emitted in condensate sent to a water supply system.

[Summary of the invention]

In the present invention, the inside of the second hotwell that supplies all of the condensate to the water supply system is made negative pressure using the exhaust device Kk, and the purified condensate from the first hotwell is sprayed into the second hotwell. After degassing the radioactive gas dissolved in the water, condensate is supplied to the water supply system.

[Embodiments of the invention]

A preferred embodiment of the condenser device according to the present invention will be described in detail with reference to the accompanying drawings. Note that the same reference numerals are given to the parts corresponding to the parts explained in the prior art, and the explanation thereof will be omitted.

FIG. 3 is an explanatory diagram of an embodiment of the condenser device according to the present invention. In FIG. 3, the second hotwell 30 of the condenser 20 is formed from a partition wall 5G and a partition plate 58.

The partition wall 5G is installed in the first hot well 2 to a higher position than before.
condensate 50 in the second hot well 30;
has a free surface 60. A sprayer 64 for spraying condensate is attached to the space 62 of the second hot well 30. Further, a branch pipe 66 branched from the partition a46 is connected to the upper part of the partition wall 56, and an opening 68 is connected to the lower end, that is, the bottom of the hot well 30.
is formed. The partition plate 58 described above is located outside the partition wall 56 (on the first hot well 22 side), and its upper end is connected to the first hot well 22 side.
It is located at a higher position than the free surface of the condensate 50 in the real well 22, and forms a water discharge lower 0 between it and the partition wall 56.

The operation of the embodiment configured as described above is as follows.

In FIG. 3, the first hot well 22 and the second hot well 30 of the condenser 20 are depressurized by the condenser air extractor 44 and maintained at a vacuum of about -720 tars Hg in gauge pressure. The condensate 50 condensed in the first hot well 22 has radioactive substances removed by the condensate filter 26 and the condensate demineralizer 28 as described above, and is sprayed from the sprayer 64 into the space 62 of the second hot well 30. be done. When condensate is sprayed into the second hot well 30, radioactive gases such as xenon and krypton dissolved in the condensate are degassed according to the following principle.

(1) The concentration of a gas that can be dissolved in water is directly proportional to the partial pressure ratio of that gas present at the surface of the water.

(2) The concentration of dissolved gases in water decreases as the temperature of the water increases, and when the pressure is further reduced below the saturated vapor pressure, that is, when the temperature of the water reaches the saturated temperature or higher, gases cannot be dissolved in the water.

Therefore, when the condensate containing the radioactive gas in a supersaturated state is sprayed from the sprayer 64 into the second hot well 30, the condensate is atomized and the coating area increases rapidly. As a result,
The radioactive rare gas component dissolved in the condensate is quickly diffused and degassed to a saturation concentration corresponding to the degree of vacuum in the second real well 30 (approximately -720 mmHg).

In particular, nuclides such as radioactive xenon yafligton produced in the condensate filter 26 and condensate demineralizer 28 have low solubility in water because they are chemically inert, and are almost completely desorbed through the above process. It bothers me. The radioactive gas vaporized by the degassing is sucked into the condenser air extractor 44, sent to a gaseous waste treatment system (not shown), and treated. Therefore, the radioactivity concentration due to the radioactive gas in the condensate is reduced to a negligible level compared to the radioactivity of other fission products contained in the condensate. For example, in an iiiooMwe class nuclear power plant, the condensate 50 condensed in the first hotwell typically contains approximately 1.4 x 10-"p
Radioactive fission products of about Cs/cc are included, and these radioactive fission products are removed by the condensate filter 26 and the condensate desalter 28 and reduced to about 1/100. However, when the iodine and bromine captured in the condensate filter 26 and the condensate demineralizer 28 decay, radioactive rare gases such as xenon and krypton are generated, and the condensate flowing into the conventional second hot well 30 is is about 5
．． It contains 8X10-"μCi/cc of radioactive noble gas, and if you read the radioactive fission products, it will be about 6.0X10-"
The radioactivity concentration was approximately 2 μCi/cc. However, by spraying condensate into the second hot well 30 as described above, the radioactive rare gas gold can be reduced to almost zero, and the radioactivity concentration in the condensate sent to the first water supply system as water supply is approximately 1. 4X10-3μCi/CC, compared to the conventional 115
It becomes possible to reduce it to 0. As a result, the thickness of concrete walls required for radiation shielding is now 930 mm
It can be made as thin as CIn, and in particular it is possible to eliminate shielding walls around the high pressure condensate pump chamber.

In addition, when installing a normal deaerator for the purpose of reducing radiation in the water supply system in a conventional condenser system, a deaeration tank with a solubility equivalent to the feed water flow rate for 3 to 5 minutes is required. However, according to this embodiment, radioactivity can be reduced without compromising the characteristics of the sidestream condenser and without installing all new large equipment. can be achieved. Therefore, the total radiation exposure of workers in nuclear power plants can be significantly reduced.

The condensate from which the radioactive gas has been degassed is sent to the water supply system via the condensate water supply pipe 54, and a portion of the condensate flows in a U-shape and circulates from the water discharge lower 0 into the first hot well 22.

In addition, in the embodiment described above, the case where the water discharge lower 0 is formed by the partition wall 56 and the partition plate 58 has been explained.
One end of the tube may be formed by a pipe connected below the free surface 60 of the second hotwell, or an orifice-like opening may be formed in the partition wall 60 below the free surface 60.

〔Effect of the invention〕

As explained above, according to the present invention, the second
By spraying condensate into the hot well, the radiation dose in the condensate can be significantly reduced.

[Brief explanation of drawings]

Figure 1 is a schematic system diagram of a condensate water supply system for a boiling water reactor, Figure 2 is an explanatory diagram of a conventional cytosm type condenser system,
FIG. 3 is an explanatory diagram of an embodiment of the condenser device according to the present invention, and FIG. 4 is a schematic perspective view of the second hot well of the embodiment. 20... Condenser, 22... First hot well, 30
...Second Hot Quell, 44...Condenser and air extractor, 64...Sprayer Agent: Patent Attorney Tatsuyuki Unuma Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] L. A condenser device comprising a first hotwell for condensing steam and a second hotwell into which the condensate in the first hotwell is purified and flows, an exhaust device for discharging gas in the second hotwell; , and a sprayer for spraying the condensate in the second hot well.