JPS6337920B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid storage device for storing radioactive liquid in nuclear power facilities such as nuclear power plants.

Lining tanks that store low-level radioactive liquids generated in nuclear power plants have a sealed structure, so it is necessary to eliminate internal pressure changes that occur due to the rise and fall of the liquid level. For this reason, air intake and exhaust equipment is provided that communicates with the gas phase at the top of the tank to maintain a constant pressure inside the tank. This intake/exhaust equipment has a natural opening in the ventilation air conditioning chamber inside the building where radioactive gas is exhausted, so that even if radioactive gas is generated in the tank, contaminated gas will not be released into the atmosphere. As the gas inside the tank frequently moves in and out of this ventilation/air conditioning chamber, the radioactivity level inside the chamber increases and is thought to become a source of radiation exposure.

This invention was made based on the above circumstances, and its purpose is to suppress the entry and exit of contaminated gas into the ventilation air conditioning chamber as much as possible, thereby reducing the radiation dose, and even if the pressure inside the chamber suddenly decreases. An object of the present invention is to provide a liquid storage device for nuclear equipment that can protect a lining tank.

The present invention will be explained below based on an illustrated embodiment. In the figure, 1 indicates a lining tank installed in the building of the nuclear reactor equipment. This lining tank 1 has a sealed structure with a lining coating 3 lined with stainless steel plates or the like on the inner surface of a surrounding concrete wall 2, and is capable of storing a liquid A with a low radioactivity level inside. 4 is an inlet pipe for this stored liquid A, and 5 is an outlet pipe. During operation of the nuclear reactor, the stored liquid flows in and out through these inlet and outlet pipes 4 and 5, thereby causing the liquid level to fluctuate.

Further, the upper wall 1a of the lining tank 1 is provided with a breather valve 7 (also referred to as a breathing valve) which communicates with the gas phase portion B of the stored liquid A via a breather communication pipe 6. This breather valve 7 is set to an operating pressure value such that it does not operate within the pressure fluctuation range due to normal liquid level fluctuations that occur during reactor operation, and opens when this tolerance range is exceeded to perform a breathing action. has been done.

Further, a vacuum relief valve 9 is provided on the upper wall 1a of the lining tank via a vacuum relief communication pipe 8 having a larger diameter than the breather communication pipe 6. This vacuum relief valve 9 is used when the internal pressure of the lining tank 1 suddenly drops due to some reason, for example, a large amount of stored liquid flows out at once due to a break in the outlet pipe 5, and the liquid level suddenly drops. The valve opens when the negative pressure is generated when the pressure drops to . Therefore, the operating pressure of this vacuum relief valve 9 is set lower than the operating pressure of the breather valve 7, and the fluid passage area of the vacuum relief valve 9 is larger than that of the breather valve 7. It is now possible to rapidly eliminate excessive negative pressure that occurs within the tank.

The breather valve 7 and the vacuum relief valve 9 are provided within the ventilation air conditioning chamber 10. This ventilation air conditioning chamber 10 is used for general ventilation inside the reactor building, and is connected to a radioactive gas treatment device to perform exhaust gas treatment so as not to release contaminated air directly into the atmosphere. There is.

In the liquid storage device configured as described above, when the stored liquid is introduced from the inlet pipe 4 during normal operation of the reactor, the liquid level in the lining tank 1 rises, and the pressure in the gas phase part B increases. do. Conversely, when the stored liquid is discharged from the outlet pipe 5, the liquid level drops and the internal pressure becomes low. However, within the range of steady pressure fluctuations that occur during normal operation of the nuclear reactor, the blazer valve 7 and the vacuum relief valve 9 do not operate, and the contaminated gas in the tank does not enter or exit the ventilation air conditioning chamber 10. Therefore, radioactive gas generated from the stored liquid is not released into the ventilation and air conditioning chamber 10 and becomes a source of contamination, and radiation exposure can be reduced.

Then, the liquid level fluctuation exceeds the fluctuation range during normal operation,
When the internal pressure of the lining tank 1 exceeds the permissible range, the breather valve 7 opens and performs a breathing action. That is, when the pressure inside the tank becomes high, gas is released into the ventilation air conditioning chamber 10 through the breather valve 7, and conversely, when the pressure inside the tank becomes low, the gas is released through the breather valve 7 into the ventilation air conditioning chamber 10. Air within the chamber 10 is drawn into the tank. Therefore, damage to the lining tank 1 can be prevented even if abnormal pressure fluctuations occur.

On the other hand, in the unlikely event that the stored liquid suddenly decreases due to a rupture in the attached piping, etc., the pressure in the tank will drop rapidly and the vacuum relief valve 9 will open, rapidly reducing the pressure in the tank. to recover. Therefore, damage to the lining tank due to negative pressure, such as peeling of the lining coating 3, and deformation of the lining tank 1 due to excessive load on the concrete wall can be prevented, and the lining tank can be protected. Incidentally, at this time, the breather valve 7 is also operated at the same time to help eliminate the negative pressure.

This invention has been described above, and is equipped with a breather valve that operates at a pressure greater than the range of pressure fluctuations that occurs during normal operation, and a vacuum relief valve that operates when the pressure in the tank suddenly drops. Therefore, within the range of liquid level fluctuations that occur during normal reactor operation, the blazer valve and vacuum relief valve do not operate and the tank can be kept airtight. Therefore, radioactive gases generated from the stored liquid will no longer be released into the ventilation and air conditioning chamber and cause contamination.
Exposure can be reduced compared to the conventional case where the suction/exhaust equipment was simply opened naturally into the ventilation/air conditioning chamber. In addition, when the normal pressure fluctuation range is exceeded, the blazer valve operates to protect the lining tank, and in the unlikely event that the internal pressure suddenly drops due to a rupture in the connecting pipe, the vacuum relief valve works to release negative pressure. It has great effects, such as being able to eliminate all problems at once and preventing deformation of the lining tank and peeling of the lining coating.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view of a liquid storage device showing an embodiment of the present invention. 1... Lining tank, 2... Concrete wall,
3... Lining coating, 7... Breather valve, 9...
Vacuum relief valve, 10...Chamber for ventilation and air conditioning.

Claims (1)

[Claims] 1. A closed lining tank in which the inner surface of the concrete wall is lined, a breather valve that communicates with the lining tank and operates when pressure exceeds a predetermined pressure fluctuation range in the tank, and a breather valve that operates at a lower operating pressure than the breather valve. 1. A liquid storage device for nuclear power equipment, comprising: a vacuum relief valve that operates to eliminate negative pressure generated in a tank; and a ventilation and air conditioning chamber that accommodates the blazer valve and the vacuum relief valve.