JP2519774B2 - Radioactive exhaust gas treatment equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a radioactive exhaust gas treatment device for treating exhaust gas extracted from a main condenser through a turbine in a nuclear power plant.

(Prior Art) In a nuclear power plant, steam generated in a reactor pressure vessel is sent to a turbine through a main steam pipe, and steam after performing work is condensed in a main condenser. The emission of radioactivity is reduced by adopting an activated carbon exhaust gas system in order to reduce the emission of radioactivity of the exhaust gas extracted by this main condenser.

As shown in FIG. 3, a conventional radioactive exhaust gas treatment device for treating exhaust gas from a turbine in a nuclear power plant is a main condenser 1, an air extractor 5, a first pipe 6, an exhaust gas preheater 7, an exhaust gas reheater. A first system to which a coupler 8, an exhaust gas condenser 9, an activated carbon exhaust gas treatment system 10, a vacuum pump 11, a second pipe 12 and an exhaust stack 4 are connected, a main condenser 1, and a condenser vacuum pump. 2, a third pipe 3 and a second system to which the exhaust pipe 4 is connected.

At the time of starting the nuclear power plant, the air in the main condenser 1 is extracted by the condenser vacuum pump 2 to a vacuum of about 650 mmHg and discharged from the exhaust pipe 4 through the third pipe 3.

During normal operation, the air extractor 5 using the reactor steam as the working steam source is operated to extract the exhaust gas from the main condenser 1 and maintain the degree of vacuum.

The extracted exhaust gas is heated through the first pipe 6 in the exhaust gas preheater 7 to about 150 ° C., and then the exhaust gas recombiner 8 converts hydrogen and oxygen in the exhaust gas into H ₂ O by a chemical reaction to form an exhaust gas condenser. Cooling and draining is carried out at 9, and only the remaining gas content is attenuated in radioactivity by the activated carbon exhaust gas treatment system 10. Then, the exhaust gas vacuum pump 11 discharges the gas from the exhaust stack 4 into the atmosphere through the pipe 12.

Also, from the turbine ground steam exhauster to the fourth pipe 20
Are connected to the third pipe 3.

Further, the downstream side of the exhaust gas condenser 9 and the condenser vacuum pump 2
A bypass pipe 21 is connected to the upstream side of the.

FIG. 4 shows an arrangement example of the turbine building 13, the reactor building 14, the piping trench 15 and the exhaust stack 4 in the nuclear power plant.

That is, in the turbine building 13, a main condenser 1, an air extractor 5, a first pipe 6, an exhaust gas preheater 7, an exhaust gas recombiner 8, an exhaust gas condenser 9, an activated carbon exhaust gas treatment system 10, and an exhaust gas. A vacuum pump 11 etc. is installed. The second pipe 12, the condenser vacuum pump 2, and the third pipe 3 are connected from the turbine building 13 through the reactor building 14 and the outdoor piping trench 15 to the exhaust pipe 4.

 A plan view of the outdoor piping trench 15 is shown in FIG.

Inside the trench 15, the third pipe 3 on the condenser vacuum pump 2 side, the second pipe 12 on the exhaust gas vacuum pump 11 side, and the emergency gas treatment system pipe 16 are arranged, and an inspection space 17 is provided inside. Has become. The space of the trench 15 is about vertical
There are 3100 and about 4100 horizontal.

(Problems to be Solved by the Invention) However, in the conventional radioactive exhaust gas treatment device, the second pipe 12 connecting the exhaust gas vacuum pump 11 and the exhaust pipe 4, and the second pipe connecting the condenser vacuum pump 2 and the exhaust pipe 4 are connected. There is a pipe 3 of 3, especially the outlet pipe of the exhaust gas vacuum pump 11, that is, the second pipe.
There is a drawback that the surface dose rate by the pipe 12 is large and the amount of radiation exposure of the worker is large. In addition, the longer the pipes 12 and 3, the more welded portions there are, which lowers workability and further increases the space of the outdoor pipe trench 15. The present invention has been made to eliminate the above drawbacks, and is a radioactive exhaust gas treatment device capable of reducing the surface radiation line of the outlet pipe on the exhaust gas vacuum pump side, that is, the second pipe, and making the space of the outdoor pipe trench compact. To provide.

[Structure of Invention]

(Means for Solving the Problems) The present invention relates to an air extractor for extracting exhaust gas from a main condenser by driving steam, and an exhaust gas preheater, an exhaust gas recombiner, and an exhaust gas condensate that are sequentially connected to this air extractor. In a turbine exhaust gas treatment apparatus comprising a reactor, an activated carbon exhaust gas treatment system, an exhaust gas vacuum pump, and a condenser vacuum pump provided in parallel with the air extractor, the exhaust gas vacuum pump outlet pipe and the condenser vacuum pump outlet pipe It is characterized in that it is configured to join.

(Embodiment) An embodiment of the radioactive exhaust gas treatment apparatus according to the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, the same parts as those in FIGS. 3 and 5 are designated by the same reference numerals. In the figure, reference numeral 1 is a main condenser, and the non-condensable gas in the main condenser 1 is extracted by an air extractor 5,
It flows through the first pipe 6 and sequentially flows to the exhaust gas preheater 7, the exhaust gas recombiner 8 and the exhaust gas condenser 9, and is further radioactively attenuated by the activated carbon exhaust gas treatment system 10, and the exhaust gas vacuum pump 11 negatively pressures the system. While being discharged, it is discharged from the exhaust stack 4 to the atmosphere. Here, a condenser vacuum pump 2 is provided in parallel with the air extractor 5, and is connected to an exhaust pipe 4 via a third pipe 3. Furthermore, the fourth pipe from the grand steam exhauster
20 is also connected to the third pipe 3.

The outlet pipe 22 on the discharge side of the exhaust gas vacuum pump 11 is a third pipe 3 connected to the outlet side of the condenser vacuum pump 2.
It is connected to the. The exhaust gas treated by the activated carbon exhaust gas treatment system 10 is discharged from the exhaust stack 4 to the atmosphere by the exhaust gas vacuum pump 11 through the outlet pipe 22 and the third pipe 3.

In this embodiment, the condenser vacuum pump 2, the third pipe, the exhaust gas vacuum pump 11, and the outlet pipe 22 are the turbine building.
The third pipe 3 connected inside 13 and joined with the outlet pipe 22 is connected to the exhaust pipe 4 from the turbine building 13 through the reactor building 14 and the outdoor piping trench 15. As shown in FIG. 2, the outdoor piping trench 15 can be made compact with the space of the outdoor piping trench 15 of about 3100 and about 4100 by reducing the second piping 12 of the activated carbon exhaust gas system. Therefore, the construction cost can be reduced and the radiation concentration in the outdoor piping trench 15 can be reduced from the conventional surface area dose rate of 1.5 millirem / h to 0.5 millirel / h.

〔The invention's effect〕

According to the present invention, the surface dose rate of the outdoor pipe of the conventional exhaust gas treatment system was 1.5 mRem / h, whereas in the present invention, the outlet pipe of the exhaust gas vacuum pump is from the outlet of the condenser vacuum pump to the exhaust stack. 0.5mRe by merging with the third pipe of
It is possible to reduce to m / h, which brings about the effect of reducing radiation exposure.

As a result, even if a patrol of the pipes is performed during operation, the exposure will be greatly reduced (1/3 of the conventional level).

Further, there is no need to change the design pressure, piping dimensions, operation of the system, etc., so there is no influence on other systems.

Further, in terms of cost, it is possible to reduce the number of outdoor piping trenches, reduce the number of outdoor distribution pipes for exhaust gas treatment systems, and reduce the support that accompanies this.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a radioactive exhaust gas treatment apparatus according to the present invention, FIG. 2 is a plan view showing an outdoor pipe trench in FIG. 1, and FIG. 3 is a system showing a conventional radioactive exhaust gas treatment apparatus. FIG. 4 is a conceptual diagram showing an example of arrangement of a nuclear power plant, and FIG. 5 is a plan view showing an outdoor pipe trench in FIG. 1 ... Main condenser, 2 ... Condenser vacuum pump, 3 ... Third piping, 4 ... Exhaust pipe, 5 ... Air extractor, 6 ... First piping, 7 ... Exhaust gas Preheater, 8 ... Exhaust gas recombiner, 9 ... Exhaust gas condenser, 10 ... Activated carbon exhaust gas treatment system, 11 ... Exhaust gas vacuum pump, 12 ... Second piping, 13 ... Turbine building, 14 ... … Reactor building, 15 …… Arrangement trench, 16 …… Piping, 17 …… Inspection space, 20 …… Fourth piping, 21 …… Bypass piping, 22 …… Outlet piping.

Claims (1)

(57) [Claims] 1. A condenser vacuum pump for discharging air from a main condenser, an air extractor for extracting exhaust gas from the condenser, and an activated carbon exhaust gas treatment system sequentially provided on the downstream side of the air extractor. A radioactive exhaust gas treatment device comprising an exhaust gas vacuum pump and an exhaust stack, characterized in that an outlet pipe of the exhaust gas vacuum pump is connected to a pipe connecting the condenser vacuum pump and the exhaust stack. apparatus.