JP2005156462A - Alpha-radioactivity measuring apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an α-radioactivity measuring instrument and an α-radioactivity measuring method capable of measuring a radioactive waste of a non-conductor, and capable of reducing an expense for an exhaust treatment facility. <P>SOLUTION: This α-radioactivity measuring apparatus for the radioactive waste of which the measuring object is the non-conductor such as polyvinyl chloride and polytetrafluoroethylene is provided with an ionization chamber 2 for storing the radioactive waste to be passed with a measuring gas therethrough, and having an application device 1 for applying an antistatic agent onto the radioactive waste, and an ionization device 3 for measuring an ionization current of the measuring gas exhausted from the ionization chamber 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an α (alpha) radioactivity measuring apparatus and an α radioactivity measuring method for radioactive waste of non-conductive materials such as vinyl chloride, Teflon (registered trademark), and rubber.

  With the operation of a nuclear fuel cycle facility such as a spent fuel reprocessing plant, TRU (a super uranium element; an artificial radioactive element whose mass is larger than uranium) containing α radionuclides is generated as high-level radioactive waste. For example, it has been studied that plutonium generated by reprocessing is finally solidified with a solidifying agent such as glass and sealed in a container for long-term storage.

  By the way, if all TRU waste generated from facilities handling radioactive materials such as reprocessing factories is handled in the same way, the disposal cost becomes enormous. For this reason, by measuring the radioactivity concentration of TRU wastes accurately, those having a low radioactivity level can be treated in a simple disposal form, and the overall disposal cost can be reduced. In this way, timely measurement and evaluation of α-activity of radioactive waste is an important task for radioactive waste and radioactivity management.

  Regarding the evaluation of α radioactivity of radioactive waste (glass solidified), which has been vitrified from high-level radioactive waste, etc., the radioactive waste is sampled before solidifying the radioactive waste, and α-ray spectrum measurement and chemical analysis are performed. Etc. have been implemented.

  However, this is a measurement of α radioactivity performed before the production of the vitrified body. After producing high-level radioactive waste into a vitrified body or when measuring the α radioactivity during storage, After cutting a part of the solidified body and pretreating it, the α radioactivity must be evaluated by so-called destructive analysis, which is measured by the above-mentioned α-ray spectrum measurement or chemical analysis method.

  When α radioactivity is measured after the production of high-level radioactive waste vitrified material, the radioactive waste solidified material will be subjected to a destructive analysis. It is necessary to break the containment of the radioactive material and extract the sample.

  Furthermore, solidified radioactive waste after sample extraction and samples used for analysis are generated as new radioactive waste, and complicated work including prevention of radioactive contamination is required for the treatment of these wastes. Is required.

  Since the method of measuring the radioactivity by destroying the measurement object in this way causes many problems, an α radioactivity measurement apparatus that can measure the radioactivity concentration of TRU waste in a non-destructive manner has been proposed. .

  As shown in FIG. 4, in the conventional α radioactivity measuring apparatus, an ionization chamber 102, an ionization chamber 103, a HEPA filter 105, and a blower 106 are arranged in this order between the upstream line 101 and the downstream line 107. TRU waste is placed in the ionization chamber 102. The ionization chamber 102 is filled with a measurement gas (ionized gas) containing a substance that is ionized by α rays through the line 101. The α rays react with the ionizable measuring gas filled in the ionization chamber 102 to generate ionized ions. As the measurement gas, for example, air, helium He, argon Ar gas alone or a mixture thereof is used. Since these gases have high ionization efficiency by α rays, it is possible to accurately measure α radioactivity.

  The measurement gas is sent to the ionization chamber 103 after being exposed to the radiation of the TRU waste in the ionization chamber 102. When high-speed charged particles pass through the measurement gas, excited molecules and ionized molecules are generated along the passage. Cations and free electrons generated by separating neutral molecules are called ion pairs. This ion pair is detected by the ionization chamber 103 as an ionization current. The electric signal detected by the electrode in the ionization chamber 103 is input to the ionization current measuring device 104. The ionization current measuring device 104 converts the input electric signal into a pulse signal, counts it, and outputs the counting result to the data processing computer. The data processing computer displays the counted number of pulses on the display device and calculates the α radioactivity based on the number of pulses. This calculation result is also displayed on the display device as necessary.

  In addition, there are various types of radioactive waste, such as metal, synthetic resin, glass, wood, concrete, etc., and in order to measure α radioactivity accurately, α radioactivity measurement methods according to the material are proposed. There was a need to be done.

  Patent literature includes, for example, Japanese Patent No. 2703409, which measures γ-rays with a Ge detector.

Japanese Patent No. 2703409 (FIG. 1)

  In the radioactive waste measuring device using the ionizing current measurement method by α-ray, if the material of the object to be measured has been a non-conductive material such as synthetic resin, vinyl chloride, Teflon, rubber, etc. It was impossible. This is because the ionized ions ionized by α-rays were adsorbed by the measurement object due to the static electricity of the measurement object itself, and did not arrive at the ionization chamber of the ionization device on the downstream side, and the ionization current could not be measured. Is due to.

  Further, in the conventional α radioactivity measuring apparatus, since the measurement gas is a once-through method (once-through method) in which the measurement gas flows through the ionization chamber 102, the ionization chamber 103, and the filter 105, the amount of gas discharged out of the system is reduced. In many cases, the burden on the exhaust treatment facility was excessive.

  The present invention has been made to solve the above-described problems, and is capable of measuring radioactive waste of a non-conductive material, and reducing the cost of an exhaust treatment facility. The purpose is to provide.

In order to solve the above problems, the present invention proposes the following means: (1) In the radioactive waste α radioactivity measuring apparatus whose measurement object is a non-conductive material such as vinyl chloride or Teflon, the radioactive waste An ionization chamber having a coating device for applying an antistatic agent to the radioactive waste, and an ionization device for measuring an ionization current of the measurement gas discharged from the ionization chamber. Α radioactivity measuring device characterized by that.

  (2) In a radioactive waste α radioactivity measuring device whose measurement object is a non-conductive material such as vinyl chloride or Teflon, a coating device for applying an antistatic agent to the radioactive waste, and the radioactive waste are stored. And an ionization chamber for measuring the ionization current of the measurement gas discharged from the ionization chamber.

  In addition, the above-described coating device may be any device that applies an antistatic agent (antistatic agent) to the surface of the radioactive waste. If there is a hole in the radioactive waste, the antistatic agent is applied to the inner surface of the radioactive waste. Specific application means include spray coating using a spray nozzle, coating by placing radioactive waste in an ultrasonic spray atmosphere, coating by immersing radioactive waste in an antistatic agent tank, etc. Conceivable.

  In addition, the non-conductive material according to the present invention means, in other words, a material (material) that charges static electricity and is easily charged.

  (3) The α according to (1) or (2) above, wherein a circulation channel is provided for circulating at least a part of the measurement gas discharged from the ionization device to the ionization chamber. Radioactivity measuring device.

  (4) The α radioactivity measuring apparatus according to (2) above, wherein a dryer for adjusting the humidity of the flow measurement gas is provided in the circulation channel.

  (5) The α radioactivity measuring apparatus according to (1), wherein the ionization chamber includes a rotary table on which the radioactive waste is placed and rotated.

  (6) The α radioactivity measuring apparatus according to (2), wherein the coating apparatus includes a rotary table on which the radioactive waste is placed and rotated.

  (7) The α radioactivity measuring apparatus according to (1) or (2), further comprising a drying means for drying the antistatic agent applied to the radioactive waste. .

  In addition, the drying means may be any means for drying the antistatic agent solution applied to the radioactive waste and for removing moisture and moisture adhering to the radioactive waste, and drying before measurement. In this way, adverse effects on measurement accuracy due to moisture mixed in the measurement gas are prevented, and air drying and heater heating drying are conceivable.

  (8) An ionization current measuring instrument that converts the ionization current from the electrode into a cylindrical ionization chamber in which the measurement gas flows in the axial direction, an electrode extending in the axial direction of the ionization chamber, and an ionization current from the electrode The α radioactivity measuring apparatus according to the above (1) or (2), characterized by comprising:

  (9) In the α radioactivity measurement method of radioactive waste whose measurement object is a non-conductive material such as vinyl chloride or Teflon, the measurement gas is sprayed on the radioactive waste coated with the antistatic agent, and the measurement gas is ionized An α radioactivity measuring method, wherein the α radioactivity of the radioactive waste is measured by measuring an electric current.

  In addition, the application of the antistatic agent to the radioactive waste may be hand-painted with a brush or a spray can in addition to the above-described apparatus application. It may be wiped off and air dried.

  The invention relating to the α radioactivity measuring device according to claim 1 is a measurement device that stores the radioactive waste in an α radioactivity measuring device for radioactive waste whose measurement object is a non-conductive material such as vinyl chloride or Teflon. Since it comprises an ionization chamber having a coating device for applying an antistatic agent to the radioactive waste, and an ionization device for measuring the ionization current of the measurement gas discharged from the ionization chamber, the gas flows. Measurement can be performed with the static electricity of the waste itself removed, and the radioactive ion does not adsorb the ionized ions at the time of measurement, and the α radioactivity of the non-conductive material can be measured.

  The invention relating to the α radioactivity measuring device according to claim 2 is an α radioactivity measuring device for radioactive waste whose measurement object is a non-conductive material such as vinyl chloride or Teflon, wherein an antistatic agent is added to the radioactive waste. Since it comprises a coating device for coating, an ionization chamber in which the radioactive waste is stored and the measurement gas flows, and an ionization device for measuring the ionization current of the measurement gas discharged from the ionization chamber, the radioactive waste Measurements can be made with the static electricity removed, and the radioactive ions cannot be adsorbed by the ionized ions at the time of measurement.

  The invention according to claim 3 is characterized in that a circulation flow path for supplying at least a part of the measurement gas discharged from the ionization device to the ionization chamber is provided. 2. The α radioactivity measuring apparatus according to 2, wherein at least the total amount of the circulated gas is not discharged outside the facility system, so the total exhaust gas amount outside the system can be reduced, and the burden on the exhaust treatment system of the facility Decrease.

  The invention described in claim 4 is the α radioactivity measuring apparatus according to claim 3, characterized in that a dryer for adjusting the humidity of the measurement gas is provided in the circulation channel. It has been found that the measurement accuracy is affected, and it is possible to stabilize the measurement accuracy by performing humidity management with a dryer.

  The invention according to claim 5 is the α radioactivity measuring apparatus according to claim 1, wherein the ionization chamber includes a rotary table on which the radioactive waste is placed and rotated. While rotating the waste, it can be sprayed from the circumferential direction, and even when there are irregularities or holes on the surface of the radioactive waste, it is possible to uniformly apply to the entire surface. In particular, when the radioactive waste is a pipe or a valve, the inner surface is usually most contaminated, and it can be applied to the inner surface hole, thereby enabling high quality measurement. Further, by rotating the radioactive waste also at the time of measurement, the measurement gas is sprayed on the entire surface of the radioactive waste, and measurement with high accuracy becomes possible.

  The invention according to claim 6 is the α radioactivity measuring apparatus according to claim 2, wherein the coating apparatus includes a rotary table on which the radioactive waste is placed and rotated. While rotating the waste, it can be sprayed from the circumferential direction, and even when there are irregularities or holes on the surface of the radioactive waste, it is possible to uniformly apply to the entire surface. In particular, when the radioactive waste is a pipe or a valve, the inner surface is usually most contaminated, and it can be applied to the inner surface hole, thereby enabling high quality measurement.

  The invention described in claim 7 is characterized in that the α radioactivity measuring device according to claim 1 or 2 is provided with a drying means for drying the antistatic agent applied to the radioactive waste. This is an α radioactivity measuring device that can quickly dry the moisture adhering to radioactive waste and the applied antistatic agent solution before the measurement, thereby enabling efficient and accurate measurement.

  According to an eighth aspect of the present invention, the ionization device includes a cylindrical ionization chamber for flowing the measurement gas in the axial direction, an electrode extending in the axial direction of the ionization chamber, and an ionization current from the electrode as an electric signal. 3. The α radioactivity measuring apparatus according to claim 1 or 2, characterized by comprising an ionization current measuring device to be converted into an ionization function, wherein the entire cylindrical ionization chamber in which a measurement gas flows is ionized. It becomes a sensitive volume part, and the measurement gas can be continuously measured with high accuracy, and accurate α radioactivity can be measured.

  The invention relating to the α radioactivity measurement method according to claim 9 is the α radioactivity measurement method for radioactive waste whose measurement object is a non-conductive material such as vinyl chloride or Teflon, wherein the radioactive waste is coated with an antistatic agent. A measurement gas is sprayed on an object, and the ionization current of the measurement gas is measured to measure the α radioactivity of the radioactive waste, which can be measured with the static electricity of the radioactive waste removed. The ionized ions at the time of measurement are not adsorbed on the radioactive waste, and the α radioactivity of the nonconductive material can be measured.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
An embodiment of the α radioactivity measuring apparatus will be described with reference to FIGS.
In FIG. 1, 1 is a coating device for applying an antistatic agent T press-fitted into a cylinder 5a to a radioactive waste H (the illustrated example shows a radioactive waste pipe). The antistatic agent T is spray-applied from the upper side, the side, and the lower side of the radioactive waste H. Reference numeral 2 denotes an ionization chamber that accommodates the radioactive waste H and in which the measurement gas flows and includes the above-described five spray nozzle groups. The ionization chamber 2 is provided with a rotary table 2a for placing and rotating the radioactive waste H. A large number of holes 2c are provided on the entire surface of the rotary table 2a. The spray liquid is allowed to pass through. Reference numeral 2b denotes a rotation mechanism, 5c denotes an excess coating agent drain tank, and 5d denotes a valve. In FIG. 1, the radioactive waste H is placed in a state of being slightly lifted from the surface of the turntable 2 a by a cradle (not shown).

  Reference numeral 3 denotes an ionization device that measures the ionization current of the measurement gas discharged from the ionization chamber 2, and includes a cylindrical ionization chamber 3a that flows the measurement gas in the axial direction and an electrode 3b that extends in the axial direction of the ionization chamber 3a. And an ionization current measuring device 3c that converts the ionization current from the electrode 3b into an electrical signal. Reference numeral 6 denotes a drying means, which includes a drying blower 6a and a heater 6b. The above-mentioned antistatic agent T (antistatic agent) is liquid from the viewpoint of easy application, and may be a general-purpose one that is commercially available.

  In the α radioactivity measuring apparatus, when the radioactive waste coated with the antistatic agent T is dried, the valves A and B are closed and the valves C and D are opened to dry. Next, when measuring the α radioactivity of the dried radioactive waste H, the valves A and B are opened and the valves C and D are closed as shown in FIG. The valve B is a gate type so as not to disturb the gas flow path.

  FIG. 2 shows an overall system diagram of the α radioactivity measuring apparatus, and the α radioactivity measuring apparatus in this case is not charged with radioactive waste H without providing the coating apparatus 1 in the ionization chamber 2 as shown in FIG. This is an example in which the coating apparatus 1 for applying the agent T is provided separately and independently. The ionization chamber 2 in which the radioactive waste H is stored and the measurement gas flows, and the ionization current of the measurement gas discharged from the ionization chamber 2 The ionizing device 3 for measuring the amount of radiation, the rotary table 4 for horizontally rotating the radioactive waste H, the spray nozzle 5 for the antistatic agent T, the heater 6 as a drying means, and the dryer 7. In addition, the ionization device 3 converts the ionization current from the electrode 3b into a cylindrical signal, a cylindrical ionization chamber 3a that flows the measurement gas in the axial direction, an electrode 3b that extends in the axial direction at the center of the ionization chamber 3a. It is comprised with the ionization current measuring device 3c.

  This α radioactivity measuring device includes a loop-shaped gas circulation flow path L1, a flow path L2 for sending dry air from the dryer 7 to the coating apparatus 1, a return flow path L4, a bypass flow path L5, and three A measurement gas circuit including the dispersion channels L6, L7, and L8 of the system is provided. The gas circulation channel L1 is provided with an ionization chamber 2, a HEPA filter 8, a flow meter F2, a blower 9, a valve V5, a dew point meter (humidity meter) D1, a valve V7, and a flow meter F3 in this order. The measurement gas is circulated and supplied to the ionization chamber 2 through the gas circulation flow path L1 by discharge. 1 also has the same system (such as the gas circulation channel L1) as in FIG.

  In the coating device 1, there is provided a rotary table 4 on which the radioactive waste H is placed and rotated horizontally, and the antistatic agent T in the antistatic liquid tank 5a is sprayed on the spray nozzle while rotating the radioactive waste H. By spraying from No. 5, even if the radioactive waste is a TRU waste having a complicated shape such as a curved pipe or a valve, the antistatic spray solution can be blown and applied to the inner hole. Further, in the coating apparatus 1, there are provided a heater 6 as a heating means for drying the radioactive waste H coated with the antistatic agent T, and circulation paths L2 and L4 for dry air heated by the dryer 7. Yes. V3 is an outside air introduction valve. Note that the radioactive waste H that is relatively easily deformable by heat (flammable) is not heated by the heater 6 but dried by blowing and drying from the dryer 7.

  In the ionization chamber 2, the radioactive waste H is placed and a rotating mesh plate 2a that rotates horizontally is provided. By blowing the measurement gas while rotating the radioactive waste H, complicated pipes, valves, etc. Even in the case of TRU waste with a shape, measurement gas can be blown into its internal hole and measurement can be performed with high accuracy.

  The measurement gas only needs to be a gas made of air or helium (He) or argon (Ar) gas, which has the property of ionizing when it reacts with α-rays. In this embodiment, air is used for environmental considerations. In addition, the entire amount of air (measurement gas) discharged from the ionization chamber 2 is supplied to the ionization chamber 3 to improve the measurement accuracy (however, in the following description, it will be described as measurement gas).

  The measurement gas is introduced into the gas circulation passage L1 from the valve V6 connected to the gas supply source, circulated through the gas circulation passage L1 for a predetermined period, and then collected from the gas circulation passage L9 through the building duct of the factory. It is discharged to a processing device (not shown). When the measurement gas is circulated in the gas circulation flow path L1, both the valve V6 of the flow path L1 and the valve V4 of the flow path L9 are closed.

Radioactive contaminants in the measurement gas are removed by the HEPA filter 8.
The ionization device 3 includes a tubular ionization chamber body 3a that allows a measurement gas to pass in the axial direction, an electrode 3b that extends in the axial direction in the ionization chamber body 3a, and an ionization current measuring device 3c. An electric field is applied from 3b to the radial direction of the body 3a. The ionized measurement gas from the ionization chamber 2 enters the ionization chamber body 3a and passes through the axial direction of the body 3a. When the measurement gas passes through the body 3a, the ionization current generated by the ionization action is collected on the electrode 3b, and the electric signal is input to the ionization current measuring device 3c. In the ionization current measuring device 3c, the input electric signal is converted into a pulse signal and counted, and the counting result is output to a data processing computer (not shown). Further, the data processing computer displays the counted number of pulses on the screen of a display device (not shown) and calculates the α radioactivity based on the number of pulses. This calculation result is also displayed on the screen of the display device as necessary.

  Three systems of distributed flow paths L6, L7, and L8 branched from the gas circulation flow path L1 communicate with the upper surface portion, the side surface portion, and the lower surface portion of the ionization chamber 2, respectively, toward the object to be measured H in the ionization chamber 2. Measurement gas is sprayed from above, from the side and from below. The first dispersion flow path L6 further branches into three via the valve V11 and the flow meter F5. Each branch passage communicates with an upper surface portion, a side surface portion, and a lower surface portion of the ionization chamber 2 through valves. Similarly to the first dispersion flow path L6, the second and third dispersion flow paths L7, L8 also pass through the valves V11, V12 and the flow meters F6, F7, and further branch into three, via the valves. The ionization chamber 2 communicates with the upper surface portion, side surface portion, and lower surface portion. In short, the measurement gas is blown from the entire periphery of the object to be measured (radioactive waste) H in the ionization chamber 2.

  The second bypass flow path L5 branches from the gas circulation flow path L1 on the downstream side of the blower 9, flows through the inside of the dryer 7, and then returns to the gas circulation flow path L1 on the upstream side of the dew point meter D1. Have joined. The dryer 7 is filled with an adsorbent, and a regenerative heater is provided so as to penetrate the center of the filled adsorbent. The adsorbent absorbed by the regenerative heater is periodically heated and regenerated. A zeolite compound is used as the adsorbent in this example.

  The dew point meter (humidity meter) D1 detects moisture in the measurement gas flowing through the gas circulation flow path L1, sends a detection signal to a control panel (not shown), and the valve V5 and the signal from the control panel V9 is automatically controlled to open and close. When the measured value of the humidity exceeds the reference value, the valve V5 is closed and the valve V9 is opened, and the hygroscopic gas is introduced into the dryer 7. The measurement gas (hygroscopic gas) is continuously sent to the dryer 7 until the actual measurement value of the measurement gas humidity of the circulation flow path L1 measured by the dew point meter D1 falls below the set reference value. The flow meter F <b> 2 is provided between the HEPA filter 8 and the blower 9 and measures the gas flow rate passing through the chamber 2. The flow path L9 branches from the gas circulation flow path L1 on the downstream side of the blower 9, and communicates with a collective exhaust treatment device (not shown) in the factory. When the valve V4 is opened, the gas in the gas circulation flow path L1 is discharged to the collective exhaust treatment device through the flow path L9.

  Next, the case where the α radioactivity radiated from the radioactive waste of the nonconductive material is measured using the above apparatus will be described. First, radioactive waste H, which is a measurement object, is stored in the coating apparatus 1, and the antistatic agent T is sprayed from the spray nozzles 5 in the upward and circumferential directions while the radioactive waste H is rotated horizontally by the rotary table 4. The antistatic agent H is applied to the outer surface of the radioactive waste H and the inner surface of the hole. Even if the radioactive waste H is tubular, the antistatic agent T is sprayed and applied from the nozzle 5 in the upper direction and the circumferential direction while rotating the radioactive waste H horizontally. T is applied. The rotation speed of the turntable 4 is about a half rotation per minute and sprays for about 3 to 5 minutes. Next, the valve V2 of the flow path L2 is opened, and the heated and dried air from the dryer 7 is circulated and supplied into the coating apparatus 1 and heated by the heater 6, so that the antistatic agent T applied to the radioactive waste H is heated. Dry.

  Next, the radioactive waste H on which the coating and drying of the antistatic agent T has been completed is taken out from the coating apparatus 1, and is opened on the rotating mesh plate 2 a in the ionization chamber 2 from the opening / closing window (the chamber front surface is opened / closed). Placed on. When the open / close window is closed, the inside of the ionization chamber 2 is kept airtight. In the ionization chamber 2, the radioactive waste H is exposed to the measurement gas flow while rotating, and ionized ions proportional to the α dose are generated. The measurement gas accompanied by the ionized ions enters the ionization chamber 3 a of the downstream ionization device 3. be introduced. An electrode 3b is provided inside the ionization chamber 3a, and an electric signal collected on the electrode 3b is input to the ionization current measuring device 3c. In the ionization current measuring device 3c, the input electric signal is converted into a pulse signal and counted, and the counting result is output to a data processing computer (not shown). Further, the data processing computer displays the counted number of pulses on the screen of a display device (not shown) and calculates the α radioactivity based on the number of pulses. This calculation result is also displayed on the screen of the display device as necessary.

  FIG. 3 shows the measurement result of α radiation of radioactive waste by the above-described embodiment apparatus (method). In the table, the material (vinyl chloride, vinyl, Teflon) and shape (piping, flange) of each sample (S1 to S12) , Hose, valve), ionization current value (unit A), α radioactivity value (unit Bq), ND value (limit measurement value, unit Bq), and sample state. The upper part of the sample state column shows the case of untreated (no application of the antistatic agent), and the lower part shows the case where the antistatic agent is applied. As a result of the measurement, the ionization current without the antistatic agent showed a negative (or extremely small) value, while those with the antistatic agent applied measured the ionization current, and each sample (radioactive waste) was properly measured. It was confirmed that the α radioactivity value of) was measurable. In this measurement, the product name Seiden X SX-235 manufactured by Sanhayato Co., Ltd. was used as the antistatic agent, and the coating procedure was spray coating on the entire surface of the sample, and measurement was performed after drying for 30 minutes or more. It is.

  Since the coating apparatus 1 of the present embodiment includes the rotary table 4 on which the radioactive waste H is placed and rotated, and the spray nozzle 5 of the antistatic agent T directed toward the rotary table 4, the radioactive waste H Even if it is a curved pipe or a valve, the antistatic agent T can be applied to the inner surface hole. In addition, since the coating apparatus 1 according to the present embodiment includes drying means (the heater 6, the dryer 7, and the circulation channels L2 and L4), the radioactive waste H coated with the antistatic agent T is quickly dried. It can be done.

  Note that the surface on which the radioactive waste H is seated on the rotary table 4 may not be sufficiently coated with the antistatic agent T. In this case, the radioactive waste H is lifted by a receiving material. Alternatively, the rotary table 4 may be formed in a wire mesh shape or a multi-hole plate shape so that the spray liquid flows from the lower surface side.

  Of course, the above-described embodiment can measure a measurement object that is relatively difficult to be charged with static electricity, and in that case, it is not necessary to apply an antistatic agent. Instead of the antistatic agent T, the measurement object may be cleaned by spraying cleaning water from the spray nozzle 5 described above.

  In this embodiment, the entire measurement gas from the ionization chamber is flowed to the ionization chamber to improve the measurement accuracy. However, most of the measurement gas is flowed to the circulation flow path, and a part of the measurement gas (a very small amount) is measured. ) To the ionization chamber through the bypass channel, the ionization chamber can be reduced in size and weight.

  In addition, in the present embodiment, since the measurement gas that circulates is humidity-controlled by a dryer, measurement accuracy is improved and detection sensitivity is stabilized.

  Further, in the present embodiment, since the measurement gas is introduced into the ionization chamber from a plurality of directions through a plurality of dispersion channels, every corner of each part (upper surface / rear surface / lower surface) of the complex shape TRU waste. The measurement gas is sprayed evenly to the end, and it becomes possible to measure a complicated shape TRU waste such as a valve, which has conventionally been difficult to measure accurately, with high accuracy.

  Moreover, since the thing of this embodiment has the gas circulation flow path which circulates measurement gas, since only the total amount of the circulated gas is not discharged | emitted out of a facility system, it is the total exhaust gas outside a system. The amount can be reduced and the burden on the exhaust treatment system of the facility is reduced.

The lineblock diagram showing the alpha radioactivity measuring device concerning a 1st embodiment of the present invention. The lineblock diagram showing the alpha radioactivity measuring device system concerning a 2nd embodiment of the present invention. The measurement figure which shows the measurement result based on this invention method. The schematic system diagram which shows the conventional apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Application | coating apparatus 2 Ionization chamber 2a, 4 Rotary table 3 Ionization apparatus 5 Spray nozzle 6 Heater 7 Dryer L1 Circulation flow path

Claims (9)

In the radioactive waste α radioactivity measurement device whose measurement object is a non-conductive material such as vinyl chloride or Teflon, the measurement gas flows through the radioactive waste and the antistatic agent is applied to the radioactive waste. An α radioactivity measuring apparatus comprising: an ionization chamber having a coating device for performing ionization; and an ionization device for measuring an ionization current of a measurement gas discharged from the ionization chamber. In a radioactive waste α radioactivity measurement device whose measurement object is a non-conductive material such as vinyl chloride or Teflon, a coating gas for applying an antistatic agent to the radioactive waste, and a measurement gas containing the radioactive waste An α radioactivity measurement apparatus comprising: an ionization chamber through which a gas flows; and an ionization apparatus that measures an ionization current of a measurement gas discharged from the ionization chamber. The α radioactivity measuring apparatus according to claim 1 or 2, further comprising a circulation flow path for circulating and supplying at least part of the measurement gas discharged from the ionization apparatus to the ionization chamber. . The α radioactivity measuring apparatus according to claim 3, wherein a dryer for adjusting the humidity of the flow measurement gas is provided in the circulation channel. 2. The α radioactivity measuring apparatus according to claim 1, further comprising a rotary table on which the radioactive waste is placed and rotated in the ionization chamber. The α radioactivity measuring apparatus according to claim 2, further comprising a rotary table on which the radioactive waste is placed and rotated in the coating apparatus. The α radioactivity measuring apparatus according to claim 1, further comprising a drying means for drying the antistatic agent applied to the radioactive waste. The ionization device comprises a cylindrical ionization chamber for flowing a measurement gas in the axial direction, an electrode extending in the axial direction of the ionization chamber, and an ionization current measuring device for converting the ionization current from the electrode into an electrical signal. The α radioactivity measuring apparatus according to claim 1, wherein the α radioactivity measuring apparatus is provided. In the α radioactivity measurement method for radioactive waste whose measurement object is a non-conductive material such as vinyl chloride or Teflon, measure the ionization current of the measurement gas by blowing the measurement gas onto the radioactive waste coated with antistatic agent. Thus, the α radioactivity measurement method, wherein the α radioactivity of the radioactive waste is measured.

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