JP2005127718A - Tritium decontamination apparatus and method - Google Patents

Abstract

【Task】
An object of the present invention is to provide a tritium decontamination apparatus and method for decontaminating a treatment material composed of a metal and a nonmetal contaminated with tritium in a safe and short time.
[Solution]
The present invention relates to a tritium decontamination apparatus for decontaminating a tritium-contaminated treatment material in a gas atmosphere and collecting the tritium, a heating container that can contain the treatment material and enclose and seal the gas, and a high-frequency induction of the treatment material. A high-frequency induction heating unit for heating, a microwave heating unit for microwave-heating the processing material, a tritium recovery unit for circulating the gas in the heating container and recovering tritium released from the processing material into the heating container, and a high-frequency induction The tritium decontamination apparatus includes a control unit that controls switching between a heating unit and a microwave heating unit and a heating temperature.
[Selection] Figure 1

Description

  The present invention relates to a novel tritium decontamination apparatus and method for decontaminating a treatment material contaminated with tritium.

  In the piping of heavy water nuclear facilities, the piping of nuclear fusion devices, etc., the metal constituting them is contaminated with tritium. As a method for decontaminating tritium on a metal surface, as shown in Patent Document 1, a method of circulating a gas containing water vapor through a metal pipe and removing tritium by isotope exchange is shown in Patent Document 2. Thus, there is a method of decontamination in a decontamination gas atmosphere.

  As a method for decontaminating tritium present inside a metal, Non-Patent Document 1 reports a method in which the treatment material is heated to about 650 ° C. while hydrogen gas, helium gas, etc. are circulated, and tritium is desorbed. Yes.

  Many tritium recovery systems are known in addition to Patent Document 3, and are also known in actual tritium handling facilities.

Japanese Patent Laid-Open No. 11-281792 JP 2002-162498 A Japanese Patent Laid-Open No. 11-248882 IEEE Journal 0-7803-2969-4 / 95 (1995)

  In the prior art, it is known that the temperature of the processing material is raised to about 650 ° C. as a method for desorbing tritium inside the metal, but the heating method and apparatus configuration are not shown. As a heating method, an electric furnace is generally used. However, in this heating method, heating and heat removal take time, so that the work time becomes enormous. In addition, the device configuration does not take into consideration the risk of leakage of tritium, which is a radioactive material, or exposure.

  An object of the present invention is to provide a tritium decontamination apparatus and method for decontaminating a treatment material composed of a metal and a nonmetal contaminated with tritium in a safe and short time.

  The present invention relates to an apparatus for decontaminating a processing material contaminated with tritium, a heating container that contains the processing material and encloses and seals a gas, a high-frequency induction heating unit that heats the processing material by high-frequency induction heating, and a processing material. Switching and heating between a microwave heating unit that performs microwave heating, a tritium recovery unit that circulates gas in the heating vessel and collects tritium released from the processing material into the heating vessel, an induction heating unit, and a microwave heating unit A tritium decontamination apparatus having a controller for controlling temperature.

The tritium decontamination of the present invention uses high frequency and microwave, which is a direct heating method of the processing material, in order to shorten the working time. The shortening of the work time depends on shortening of the temperature raising time by high-speed high-temperature heating and shortening of the heat removal time by direct heating.
Furthermore, in order to eliminate as much as possible troubles such as sealing performance and pipe connection work, a heating container, a tritium recovery system, and a control system are packaged.

  Tritium is also present in the form of water in the concrete used as biological shielding materials in nuclear facilities. Water is one of the main components in concrete, and most of it evaporates and desorbs when heated. Therefore, it is possible to desorb tritium by heating concrete.

  As a heating method for the treatment material, the high-frequency induction heating device is effective for metal, and the method of heating by irradiating microwave is effective for concrete having moisture. Both high-frequency and microwave heating methods can be directly heated and heated at a high temperature and high temperature, and the temperature can be easily controlled. Further, since the heating object itself generates heat, there is little thermal influence on the surroundings.

  In addition, it is necessary to consider the equipment configuration by eliminating the troubles such as sealing performance and piping connection work as much as possible in consideration of leakage of radioactive tritium and reduction of exposure risk.

  The tritium recovery part in the present invention has a catalyst tower for converting the released tritium into a water form, a tritium water adsorption tower for adsorbing tritium in the form of water, and an upstream of the catalyst tower. And a tritium monitor in the gas for detecting and monitoring the tritium concentration on the side, and a surface tritium monitor for detecting and monitoring the tritium concentration released from the processing material in the vicinity of the surface of the processing material.

  Furthermore, it has a circulation means for circulating the gas between the heating container and the recovery step, and the control unit for controlling based on the tritium concentration detected on the upstream side of the catalyst tower. .

  The present invention also provides a tritium decontamination method in which a treatment material contaminated with tritium is decontaminated in a gas atmosphere and collects the tritium, and the treatment material is housed in a heating container that can enclose and seal the gas. A step of supplying the gas into the heating vessel, a heating step of heating the processing material by high frequency induction heating or microwave heating, and contacting tritium released from the processing material into the heating vessel with the catalyst The tritium decontamination method comprising a tritium recovery step of adsorbing and removing the tritium water.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to decontaminate the processing material which consists of nonmetals, such as a metal contaminated with tritium, concrete, in a short time.

FIG. 1 is a configuration diagram of a tritium decontamination apparatus of the present invention. The apparatus of the present invention accommodates various treatment materials 1 such as metal and concrete, and also includes a heating container 2 capable of enclosing and sealing a gas such as hydrogen and helium, a gas introduction valve 4 and a gas cylinder 5. Consists of a supply unit, a high-frequency heating unit composed of a high-frequency power source 6, a high-frequency current transformer 7, a feeder 8 and a high-frequency coil 9, a power source for microwaves 12, a transformer 13, a magnetron 14, an antenna 15 and a waveguide 16. A microwave heating unit, a tritium recovery unit including a blower 22, a catalyst tower 23, and a tritium water adsorption tower 24, and a control unit 28 that performs switching of the heating unit and temperature control.
In addition, a non-contact thermometer 10 for monitoring the temperature, a filter 18 for preventing contamination of the waveguide 16, a tritium monitor 25 in the gas for monitoring tritium in the gas phase, and tritium on the surface of the processing material 1 It has a surface tritium monitor 26 to be monitored, a valve 20 for closing the tritium recovery system, and a valve 21 for opening.

  In the operation procedure, first, the treatment material 1 containing tritium is put in the crucible 3 in the heating container 2. The gas introduction valve 4 is opened, hydrogen gas is introduced from the gas cylinder 5 into the heating container 2, and the gas introduction valve 4 is closed.

  When the processing material 1 is a metal such as austenitic stainless steel used for piping, the current from the high-frequency power source 6 is transformed by the high-frequency current transformer 7 and then flows through the feeder 8 to the high-frequency coil 9 to be treated in the crucible 3. Induction heating 1 The heating temperature is about 650 ° C. The temperature of the processing material 1 is measured by the non-contact type thermometer 10, the result is fed back to the high frequency output monitoring unit 11, and the output and frequency are adjusted so as to keep the temperature of the processing material 1 at a set value.

  When the treatment material 1 is concrete, heating by microwaves is performed. Electricity is supplied from the microwave power source 12 to the magnetron 14 through the transformer 13, and microwaves are oscillated by the magnetron 14, introduced into the inside of the heating container 2 via the antenna 15 and the waveguide 16, and applied to the processing material 1. Irradiate. The frequency of the microwave is about 2450 MHz that is generally used for heating water, and water contained in the treatment material 1 is heated. The magnetron is constantly cooled by a cooling fan 17 to prevent overheating. In order to prevent contamination in the waveguide 16, a non-conductive filter 18 made of glass fiber is installed at the outlet of the waveguide 16. The heating temperature is 100 ° C. or higher. The temperature of the processing material 1 is measured by the non-contact type thermometer 10, the result is fed back to the microwave output monitoring unit 19, and the output is adjusted so as to keep the temperature of the processing material 1 at a set value.

  When the temperature of the processing material 1 rises, tritium inside the processing material 1 is desorbed and released to the gas phase part in the heating container 2. Since the heating container 2 is hermetically sealed, the influence of tritium on the surroundings can be suppressed. Next, the tritium recovery system inlet valve 20 and the tritium recovery system outlet valve 21 are opened, and the gas in the heating container 2 containing tritium is circulated to the tritium recovery system by the blower 22 to recover the tritium. In the tritium recovery system, gases containing various forms of tritium are oxidized in a catalyst tower 23 made of platinum-supported alumina, etc. to convert tritium into water, and then nonmagnetic stainless steel filled with molecular sieves of inorganic adsorbents. Adsorbed and removed by the steel tritium water adsorption tower 24.

The tritium concentration in the heating container 2 is monitored by measuring radiation with a tritium monitor 25 in the gas. Further, radiation near the treatment material 1 is measured by the surface tritium monitor 26, and the tritium remaining in the treatment material 1 is monitored. The sensor portion of the surface tritium monitor 26 is housed in a cylinder and inserted into the heating container 2 via a bellows seal 27. The cylinder tip is stored near the wall of the heating container 2 to avoid high frequency, microwaves, and radiant heat from the processing material 1 when the processing material 1 is heated, and moves to the processing material 1 as indicated by arrow 29 when measuring radiation. Let
When the radiation dose values in the gas tritium monitor 25 and the surface tritium monitor 26 become negligible, heating is stopped, and the treatment material 1 is removed and cooled. Continue gas circulation until cooling is complete.

  The temperature of the non-contact type thermometer 10, the radiation dose of the gas tritium monitor 25 and the surface tritium monitor 26, and the output values of the high frequency output monitoring unit 11 and the microwave output monitoring unit 19 are collected on the control panel 28 and displayed. The control panel 28 performs operations such as switching between high frequency and microwave, temperature control, heating device ON / OFF, gas introduction, blower start / stop, and the like.

It is a block diagram of the tritium decontamination apparatus of this invention.

Explanation of symbols

1 ... Processing material, 2 ... Heating vessel, 3 ... Crucible, 4 ... Gas introduction valve, 5 ... Gas cylinder, 6 ... High frequency power supply, 7 ... High frequency current transformer, 8 ... Feeder, 9 ... High frequency coil, 10 ... Non-contact type Thermometer, 11 ... high frequency output monitoring unit, 12 ... microwave power supply, 13 ... transformer, 14 ... magnetron, 15 ... antenna, 16 ... waveguide, 17 ... cooling fan, 18 ... filter, 19 ... microwave output monitoring Unit: 20 ... Tritium recovery system inlet valve, 21 ... Tritium recovery system outlet valve, 22 ... Blower, 23 ... Catalyst tower, 24 ... Tritium water adsorption tower, 25 ... Tritium monitor in gas, 26 ... Surface tritium monitor, 27 ... Bellows Seal, 28 ... Control panel, 29 ... Arrow.

Claims (2)

  In a tritium decontamination apparatus for decontaminating a treatment material contaminated with tritium in a gas atmosphere and recovering the tritium, a heating container that can contain the treatment material and enclose and seal the gas, and supply the gas to the heating container Gas supply unit, high-frequency heating unit for high-frequency induction heating the processing material, microwave heating unit for microwave-heating the processing material, and tritium for recovering tritium released from the processing material into the heating container A tritium decontamination apparatus comprising: a recovery unit; and a control unit that switches between the high-frequency heating unit and the microwave heating unit and controls a heating temperature. In a tritium decontamination method for decontaminating a treatment material contaminated with tritium in a gas atmosphere and recovering the tritium, a step of storing the treatment material in a heating vessel capable of enclosing and sealing the gas, and the heating vessel Supplying the gas therein, heating the treatment material by high-frequency induction heating or microwave heating, and bringing the tritium released from the treatment material into the heating vessel into contact with the catalyst to form water. And a tritium recovery step of adsorbing and removing the tritium water.

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