JPH0534495A - Containment vessel vent device - Google Patents

Abstract

PURPOSE:To reduce size and weight of a device by reducing relative humidity of steam including radioactive solid particle and gaseous FP so as to increase absorption efficiency, and by providing a filter for which an absorber is used, so as to remove a radioactive material. CONSTITUTION:Steam including solid particle and gaseous FP is sent to a solid particle scavenging filter 1. Several layers of a filter unit for which stainless steel fiber is molded into rectangular shape form the filter 1. Silica gel is filled in the outer periphery of a wire gauze cylinder made of stainless steel, which is sealed in a cylindrical container so as to form a dryer 2, and relative humidity at the exit of the dryer 2 can be reduced by letting the steam run through the inside of the wired gauze. Iodine absorber such as silver alumina is filled in a gas scavenging filter 3, and removing efficiency of radioactive material can be improved, while the size and weight of a device can be reduced.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nuclear reactor, and more particularly, to removing radioactive substances from water vapor containing radioactive solid particles and gaseous FP discharged from a reactor pressure vessel to reduce the amount released to the environment. Regarding the device to minimize.

2. Description of the Related Art The prior art is based on a containment vessel with a filter vent device (ROSchlueter and RP Schumitz, "Filte
red Vented Containment ”, Fourth Workshop on Contai
nment Integrity, June 15, 1988.), in order to prevent damage to the containment vessel due to an increase in pressure inside the containment vessel at the time of an accident, gaseous FP is dissolved in pool water from the released radioactive material to remove solid particles. After removing with a filter
It was a system to release to the environment.

The above-mentioned prior art is a decompression vent system via a filter vent system to prevent damage to the containment vessel due to an increase in the pressure inside the containment vessel in the event of an accident, by removing radioactive substances to protect the environment. It is a system that suppresses the release of radioactivity. Conventional systems require pooled water to remove radioactive gaseous FP.
The size of the pool is larger than that of the filter that collects radioactive solid particles, which hinders the reduction in size and weight of the entire containment vessel vent device. An object of the present invention is to provide a small and lightweight containment vessel vent device.

The above-mentioned object is to adsorb and collect radioactive gaseous FP from a water vapor containing radioactive solid particles and gaseous FP discharged from a reactor pressure vessel by a filter filled with an adsorbent. And then vented.

When the containment vessel vent device is activated, radioactive solid particles and gaseous FP are contained in water vapor and discharged from the reactor pressure vessel. When solid particles pass through a filter composed of glass and metal fibers, inertia, gravity settling,
Adsorbs to the fiber surface by the force of diffusion. The molecules of the gaseous FP are carried by the inertial force of the gas into the inside of the innumerable pores vacant on the surface of the adsorbent, and collide with the surface of the adsorbent to be adsorbed. At this time, the adsorption operation is performed after the relative humidity is reduced by heating or the like, so that the adsorption of water molecules on the surface of the adsorbent is suppressed and the adsorption efficiency is prevented from lowering.

EXAMPLES Examples of the present invention will be described below. FIG. 1 is a simulation of a containment vessel venting device, and is composed of a solid particle collecting filter 1, a dryer 2 and a gas collecting filter 3. This time, CsI particles were used as the solid particles and I ₂ was used as the gaseous FP. The water vapor containing CsI particles and I ₂ is sent to the solid particle collection filter 1 through a pipe. The filter 1 is formed by stacking a plurality of filter units each having a rectangular shape made of stainless steel fiber of 4 μm. When aerated in the thickness direction of the filter, CsI with a particle size of about 0.3 μm
The particles are trapped in the filter fibers. Filter thickness 20
The collection efficiency is about 99.cm at a filter surface speed of 30 m / s.
9%. The dryer 2 is a stainless steel wire mesh cylinder filled with silica gel and sealed in a cylindrical container. By passing water vapor inside the wire mesh, the relative humidity at the dryer outlet can be reduced. The gas collection filter 3 is filled with an iodine adsorbent such as silver alumina having a particle diameter of 1 to 2 mm, and the particles have pores with a diameter of about 600 Å. A silver alumina adsorbent with a silver loading of 10 wt% is used for humidity 90
%, The removal efficiency is about 95%, and if the effective length of the dryer is increased and the relative humidity is reduced below 90%,
A removal efficiency close to 100% is obtained. FIG. 2 shows an example in which the heater 4 is used instead of the drier to reduce the relative humidity and to perform the adsorption. The conditions other than the heater 4 are the same as those in FIG.
The water vapor containing the gas molecule I ₂ is cooled while passing through the solid particle collecting filter 1 and becomes supersaturated. The heater 4 heats the filter 3 up to a temperature of about 250 ° C., the relative humidity of water vapor decreases, the adsorption efficiency of the adsorbent increases, and almost all the amount of I ₂ can be adsorbed. As described above, the present embodiment can reduce the size and weight of the containment vessel vent device.

According to the present invention, the radioactive material released from the reactor pressure vessel can be removed by the containment vessel vent device provided with the filter for collecting the gaseous FP, so that the size and weight of the apparatus can be reduced. , The freedom of design increases.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram of a second embodiment of the present invention.

[Explanation of symbols]

1 ... Solid particle collection filter, 2 ... Dryer, 3 ... Gas collection filter, 4 ... Heater.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masao Endo             1168 Moriyama-cho, Hitachi-shi, Ibaraki Japan             Tate Seisakusho Energy Research Institute (72) Inventor Hisato Tagawa             1168 Moriyama-cho, Hitachi-shi, Ibaraki Japan             Tate Seisakusho Energy Research Institute

Claims (3)

[Claims] 1. A containment vessel vent device for removing and releasing the radioactive solid particles and the gaseous FP from water vapor containing the radioactive solid particles and the gaseous FP released from the containment vessel, wherein the gaseous FP is removed. A containment vessel venting device, characterized in that radioactive substances are removed by providing a filter. 2. The containment vessel vent device according to claim 1, wherein an adsorbent is used as a filter material to adsorb the gaseous FP. 3. The containment vessel vent device according to claim 1, wherein the relative humidity of water vapor containing the gaseous FP is reduced to improve adsorption efficiency.