JPH0312278B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a ventilation system for the operation floor of a nuclear reactor building.
In particular, the present invention relates to a duct system on the operating floor of a nuclear reactor building that is suitable for collecting pollutants generated from a swimming pool.

[Background of the invention]

FIG. 4 shows a ventilation system during periodic inspections (hereinafter referred to as periodic inspections) on the operating floor of a reactor building in a conventional boiling water nuclear power generation facility. In the conventional method, ventilation air is blown out from the outlet of the air supply duct 4 installed approximately 4 m above the floor of the operating floor, and a portion of the air is sent to the reactor well 1 and the dryer/separator equipment temporary storage pool (hereinafter referred to as the dryer/separator equipment temporary storage pool). Contaminated air 8 containing radioactive materials generated from the pool surface is sucked in through an embedded duct 7 in the wall of a spent fuel storage pool (hereinafter referred to as a fuel pool) 2 and a spent fuel storage pool (hereinafter referred to as a fuel pool) 3. The other airflow is taken in by the suction port of the exhaust duct 5 installed approximately 5m above the floor facing the air supply duct, and is guided to the main exhaust stack together with the airflow taken in by the embedded duct, and then released to the outside. It was becoming.

However, the opening of the buried duct is installed approximately 70 mm above the pool water surface, and water may flow into the duct due to the ripples of the pool water during an earthquake or when the pool is filled with water. A valve was installed to prevent water from flowing. In addition, since the duct is installed under the floor around the pool, there is a lot of interference with reinforcement, piping, etc., which requires a large amount of man-hours for construction. Regarding the effectiveness of collecting radioactive materials emitted from pools, there is no study of its quantitative effect, but it is approximately
A small duct opening was installed in the wall of the 12m pool, and its effectiveness is questionable.

Examples of patents related to preventing pool water from flowing into ducts include Japanese Patent Publication No. 53-131585 and Japanese Patent Publication No. 55-131585.
There are 24612 and 55-46141. In addition, examples of patents related to pollution diffusion prevention include Patents No. 51-48591 and No. 55-
No. 48698, No. 56-46496, and No. 58-33596, but none of them are designed to solve all of the above problems.

[Purpose of the invention]

The purpose of the present invention is to prevent the spread of contamination to the operating floor by using a duct system that exhausts air from the ceiling instead of a buried duct, and to improve the reduction of radiation exposure to workers on the operating floor of the reactor building. duct system.

[Summary of the invention]

The conventional duct system on the operating floor of the reactor building is difficult to install due to the embedded duct method.
In addition to problems with the installation of a function to prevent pool water from flowing into the ducts, there were also questions about its effectiveness in preventing the spread of radioactive materials to the operating floor.

In the present invention, instead of the conventional buried duct method,
Ventilation air is supplied from both walls perpendicular to the pool,
By exhausting air through a cross-shaped duct on the ceiling truss above the reactor well and spent fuel pool, the collection rate of pollutants generated from the pool is improved and the above problems are solved. be.

FIGS. 5 and 6 show the distribution of contaminated air in each section of FIG. 4 in the conventional ventilation system for the operating floor. This figure is a schematic diagram of the results of determining the temperature distribution and airflow state on the operating floor by simulation analysis using a certain plant as an example. The temperature of the pool water is higher than the temperature of the ventilation air (18 to 30 degrees Celsius) (40 to 30 degrees Celsius).
~50℃), as shown in the figure, an updraft occurs near the spent fuel pool, and air that may contain contaminants from the pool flows above the pool.
stay. The lower part of Figure 6 shows the area where there is a high possibility of contamination on the ceiling surface. When contaminants adhere to the ceiling surface and accumulate, they turn into dust and fall to the floor, exposing workers to radiation. There is a high possibility that

In order to solve the above problems, we applied for application No. 59-106625.
The specification states that ventilation air is blown out from air supply ducts installed on both walls parallel to the line connecting each pool,
A ventilation system is shown in which exhaust air is carried out through ducts installed on the ceiling truss directly above each pool in parallel with these ducts. However, since the present invention does not take into account the interference between equipment temporarily placed on the floor during regular inspections and the air supply duct, the above interference is inevitable when applied to BWR type nuclear power generation equipment with current specifications. Its adoption is difficult. Therefore, by blowing out ventilation air from the air supply ducts installed on both walls perpendicular to the line connecting each pool, a forced upward airflow is created above the pools, and the pollutants generated from the pools are absorbed into this airflow. He invented a duct system that exhausts air through ducts installed on the ceiling truss. This duct system has a duct configuration that takes into consideration airflow treatment during periodic inspections and normal reactor operation, and exhaust ducts are arranged in a cross shape on the ceiling truss above the reactor well and spent fuel pool. It's summery.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1, 2, and 3.

FIG. 1 shows the duct configuration and ventilation system in the duct system for the operating floor of a nuclear reactor building according to the present invention. The upper figure shows a plan view of the operating floor, and the lower figure shows a cross-sectional view near the center of the pool. Also, the second
The figure and FIG. 3 schematically show the results obtained by simulation analysis of the wind flow direction and the distribution of potentially contaminated air in each cross section of FIG. 1.

According to FIG. 1, the duct system of the operating floor of a nuclear reactor building according to the present invention has the following configuration.
Air supply ducts 4a and 4b are installed at positions approximately 4 m above the floor on both opposing walls that are perpendicular to the line connecting each pool on the operating floor, and ventilation air is blown from 10 openings in each duct. put out. In addition, an exhaust duct 5 is installed on the ceiling truss 6 approximately 15 m above the floor surface, and contaminated air is sucked in through 19 downward openings. This exhaust duct 5 has a cross-shaped duct configuration above the reactor well 1 and the spent fuel pool 3, and both ducts are placed in a position to avoid interference with the truss beam and are connected above the pool. It's on. Then, on the wall on the spent fuel pool side,
A vertically downward duct 5d leads to the exhaust treatment equipment located on the lower floor of the operating floor. Therefore, the ventilation air blown out from the ducts installed approximately 4 meters above the floor on both walls in the direction perpendicular to the line connecting each pool collides near the pool water surface above the reactor well, causing forced An updraft is created, which is sucked into the opening of the exhaust duct installed on the ceiling truss approximately 15m above the pool, and after being filtered by the filter in the exhaust treatment equipment on the lower floor, it is released into the main exhaust stack. is released to the outside.

According to Figures 2 and 3, radioactive substances 8 were dispersed on the operating floor due to evaporation of pool water during regular inspections.
is exhausted upward by the above-mentioned forced upward airflow, and the area where contaminants adhere to the ceiling surface becomes as shown in the lower part of FIG. 3.

Further, during normal reactor operation, the dryer/separator pool 2 and the reactor well 1 are covered with a shielding cover, so that the spent fuel pool 3 is the only heating element that affects the airflow condition on the operating floor. As described above, since the water temperature of the pool is higher than the temperature of the blown air, the buoyancy due to the heat generated by the pool water has a large effect on the airflow on the operating floor, and an upward air current is generated above the spent fuel pool. For this reason, in order to prevent the spread of contaminants that may spread from the pool during normal reactor operation, the ducts are arranged in a cross-shape above the pool.

According to this embodiment, as shown in the lower diagram of FIG. 3 and the lower diagram of FIG. At the same time, it has the effect of reducing the amount of radiation exposure to workers when these substances accumulate on the ceiling surface and fall into the work area on the floor as dust. In addition, the following effects can be expected.

(1) Because the embedded ducts in conventional duct systems are thick, they account for most of the ductwork on the operating floor. In the present invention, since there is no embedded duct, the amount of ductwork on the entire operating floor is significantly reduced.

(2) Isolation valves, remote control switches, etc. associated with embedded ducts are no longer required, improving the efficiency of ventilation and air conditioning equipment.

(3) There is no need to adjust the interference with reinforcement, piping, etc. around the pool, greatly improving workability.

(4) In the current duct system, mode switching was performed to change the exhaust air volume of each pool-embedded duct depending on the work in the pool, but this will no longer be necessary with the new system, so the control system will be significantly simplified. becomes.

(5) Compared to the conventional buried duct system, maintenance and inspection efficiency is greatly improved.

〔Effect of the invention〕

According to the present invention, it is possible to improve the collection rate of pollutants generated from a pool on the operating floor of a nuclear reactor building, which has the effect of preventing the spread of contamination during operation and improving the reduction of radiation exposure to workers.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the operating floor of the duct system according to the present invention, and FIGS. 2 and 3 are A-A in FIG.
Cross-sectional views taken along lines A', B-B', C-C' and D-D', Figure 4 is an explanatory diagram of the operating floor using a conventional duct system, and Figures 5 and 6 are E- in the diagram
FIG. 3 is a cross-sectional view taken along line E', line FF', line GG', and line H-H'. 1... Reactor well, 2... Dryer/separator equipment temporary storage pool, 3... Spent fuel storage pool, 4
...Air supply duct, 5...Exhaust duct, 6...Ceiling truss, 7...Embedded duct, 8...Contaminated air (substance).

Claims (1)

[Claims] 1. In the ventilation air conditioning equipment on the operating floor of the reactor building, which consists of air supply ducts and exhaust ducts, the air supply ducts are installed on both opposing walls in a perpendicular direction on the line connecting each pool, and A duct system for the operation floor of a nuclear reactor building, characterized by a cross-shaped exhaust duct placed on the ceiling truss above the pool.