JP5728309B2 - Radioactive gas leakage measuring device and radioactive gas leakage measuring method - Google Patents

Description

  The present invention relates to a radioactive gas leakage measuring device and a radioactive gas leakage measuring method.

Radioactive waste generated from nuclear power plants, nuclear fuel cycle facilities, etc. is stored in a metal waste container such as stainless steel, stored for a certain period of time for cooling, etc., and finally buried in the formation It is planned to be disposed of. If this waste container has defects such as minute holes or poor welding, radioactive dust (for example, ¹³⁷ Cs) or radioactive gas (for example, ¹⁰⁶ Ru, ⁸⁵ Kr, ¹³³ Xe, etc.) from the waste during storage ) May leak and be released into the atmosphere. Therefore, in the inspection (acceptance inspection) when the waste is received in the storage facility, the soundness of the waste is confirmed by evaluating the amount of radioactive dust leakage and the amount of radioactive gas leakage of the waste, and whether or not long-term storage is possible. I have confirmed.

  As a conventional technique for evaluating the leakage amount of radioactive gas, for example, as described in Japanese Patent Application Laid-Open No. 2004-170330 (Patent Document 1), a waste body is accommodated in a leakage inspection container and left for a certain period of time. Later, there is a technique for sampling the gas in the leak test container and measuring the concentration of the sampled gas. Sampling of the gas in the leak test container and measurement of the concentration of the sampled gas are performed by taking in outside air (for example, gas such as air).

  The technique described in Patent Document 1 is a technique for selecting a sampling gas using a special filter, reducing a background value, and improving a signal intensity ratio. That is, the technique described in Patent Document 1 is designed to reduce the background value so that the measured value does not fall below the lower limit value of the measurable range.

JP 2004-170330 A

  However, in the conventional radioactive gas leak amount measuring apparatus and the radioactive gas leak amount measuring method including the device and method described in Patent Document 1 described above, even if the background value is reduced, outside air such as air during sampling Therefore, the radioactive gas is diluted by the taken-in outside air. Therefore, when the concentration of the radioactive gas to be sampled is low, the radioactive gas can be diluted to the same extent as the background value.

  When the concentration of radioactive gas to be sampled is diluted to the same level as the background value, the measured value detected by the radioactive gas detector is below the lower limit of measurement detectable by the radioactive gas detector, Measurement may become impossible, and measurement at low concentrations is difficult.

  The present invention has been made to solve the above-described problems. In the prior art, the waste is diluted to the same level as the background value at the time of sampling and emits a radioactive gas having a concentration that can be determined to be impossible to measure. In contrast, an object of the present invention is to provide a radioactive gas leakage amount measuring apparatus and a radioactive gas leakage amount measuring method capable of measuring the concentration and leakage amount of radioactive gas leaking from the waste.

In order to solve the above-described problem, a radioactive gas leakage measuring apparatus according to an embodiment of the present invention is connected to an intake line that sucks outside air and a first on-off valve, and a measurement target object that releases radioactive gas. A leakage inspection container for storing gas, a radioactive gas sampling container connected to the leakage inspection container via a second on-off valve, and storing gas sampled from the leakage inspection container, and the radioactive gas sampling container and a third opening / closing while that will be connected through a valve, is connected to the fourth on-off valve attached to the downstream side, evacuated, a vacuum pump for discharging gas to the exhaust duct for exhausting the gas, closing the third on-off valve The fourth on-off valve is opened and operated before measurement, and the vacuum pump is stopped after the pressure in the container is made negative, and the fourth on-off valve is closed before the measurement. 3 open It can give upstream and the pressure difference from the valve, and a pressure regulating vessel for guiding the gas pressure difference the vacuum pump remains stopped the leak test container at the time of measurement by using the radioactive gas collection container, A flow path formed by connecting a fourth on-off valve attached between the pressure regulating container and the vacuum pump; a pressure in the flow path including the radioactive gas sampling container and the pressure regulating container; A pressure transmitter for measurement, a measurement signal processing unit for obtaining a measurement value by processing an output signal of a radioactive gas detector for detecting radiation from the gas filled in the radioactive gas sampling container, and the measurement signal processing And a data processing unit for calculating a leakage amount of radioactive gas leaking from the waste container of the measurement target object based on the measured value obtained by the unit.

In order to solve the above-described problem, a method for measuring a radioactive gas leakage amount according to an embodiment of the present invention is connected to an intake line that sucks in outside air and a first on-off valve, and a measurement target object that releases radioactive gas. A leakage inspection container for storing gas, a radioactive gas sampling container connected to the leakage inspection container via a second on-off valve, and storing gas sampled from the leakage inspection container, and the radioactive gas sampling container and a third opening / closing while that will be connected through a valve, is connected to the fourth on-off valve attached to the downstream side, evacuated, a vacuum pump for discharging gas to the exhaust duct for exhausting the gas, closing the third on-off valve The fourth on-off valve is opened and operated before measurement, and the vacuum pump is stopped after the pressure in the container is made negative, and the fourth on-off valve is closed before the measurement. 3 open It can give upstream and the pressure difference from the valve, and a pressure regulating vessel for guiding the gas pressure difference the vacuum pump remains stopped the leak test container at the time of measurement by using the radioactive gas collection container, A flow path formed by connecting a fourth on-off valve attached between the pressure regulating container and the vacuum pump, a pressure transmitter for measuring the pressure in the flow path, and the radioactive gas sampling container A measurement signal processing unit that obtains a measurement value by processing an output signal of a radioactive gas detector that detects radiation from a gas filled in the gas, and the measurement target based on the measurement value obtained by the measurement signal processing unit A data processing unit for calculating a leakage amount of radioactive gas leaking from a waste container for waste, on / off of the vacuum pump, the first on-off valve, the second on-off valve, the third on-off valve, and Opening and closing of the fourth on-off valve; Controls, a radioactive gas leak amount measuring method using a radioactive gas leak amount measuring apparatus comprising a controller for acquiring a pressure value measured from the pressure transmitter, said controller said first on-off valve The second on-off valve and the third on-off valve are closed, the fourth on-off valve is opened, the vacuum pump is turned on, and the pressure in the pressure regulating container is changed to a desired negative pressure. a step of maintaining the pressure of the pressure adjusting container as closes the fourth closing valve switching the vacuum pump to the desired negative pressure, wherein the controller, the second on-off valve and the third opening and closing Opening the valve to guide the gas in the leak test container to the radioactive gas sampling container; and the measurement signal processing unit detects radiation from the gas filled in the radioactive gas sampling container. Processing the signal output from the radioactive gas detector to obtain a measured value, and calculating the amount of radioactive gas leaked from the waste container based on the measured value obtained by the measurement signal processing unit. It is characterized by comprising.

  According to the present invention, in the prior art, a radioactive gas that is diluted to the same level as the background value at the time of sampling and emits a radioactive gas having a concentration that can be determined to be unmeasurable also leaks from the waste. Concentration and leakage can be measured.

The piping system figure of the radioactive gas leak amount measuring apparatus which concerns on the 1st Embodiment of this invention. Explanatory drawing which shows the structure of the measurement system of the radioactive gas leakage amount measuring apparatus which concerns on the 1st Embodiment of this invention. Explanatory drawing explaining the operation timing of the measurement signal processing apparatus in the radioactive gas leak amount measuring apparatus which concerns on the 1st Embodiment of this invention, each valve, and a vacuum pump. Explanatory drawing which shows the result of having simulated the mode that radioactive gas diffuses in the leak test container of the radioactive gas leak amount measuring apparatus which concerns on the 1st Embodiment of this invention. The concentration of the sampling gas measured by the radioactive gas leak amount measuring apparatus and the radioactive gas leak amount measuring method according to the embodiment of the present invention, the concentration of the sampling gas measured by the conventional method, and the detection limit concentration of the radioactive gas detector are shown. Illustration. Explanatory drawing explaining the operation timing of the measurement signal processing apparatus, each valve, and a vacuum pump in the radioactive gas leakage amount measuring apparatus which concerns on the 2nd Embodiment of this invention. The flowchart which showed the processing flow of the measurement result suitability determination procedure which the radioactive gas leakage amount measuring apparatus which concerns on the 3rd Embodiment of this invention performs. The piping system figure of the radioactive gas leakage amount measuring apparatus which concerns on the 4th Embodiment of this invention. Explanatory drawing explaining the operation timing of the measurement signal processing apparatus, each valve, gas supply apparatus, and a vacuum pump in the radioactive gas leak amount measuring apparatus which concerns on the 4th Embodiment of this invention. Explanatory drawing which shows the result of simulating a mode that radioactive gas diffuses within the leak test container of the radioactive gas leak amount measuring apparatus which concerns on the 4th Embodiment of this invention. The piping system figure of the radioactive gas leakage amount measuring apparatus in the 5th Embodiment of this invention.

  Hereinafter, a radioactive gas leakage measuring apparatus and a radioactive gas leakage measuring method according to embodiments of the present invention will be described with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a piping system diagram of a first radioactive gas leakage measurement device 10A which is an example of the radioactive gas leakage measurement device according to the first embodiment of the present invention. Note that the open / close states of the open / close valves V1, V2, V3, V4 shown in FIG. 1 indicate the open / close states at the time of measurement (measurement time T ₃ shown in FIG. 3 described later).

  The first radioactive gas leakage measuring device 10A is a flow path (sampling) for sampling the gas in the leakage inspection container 12 that accommodates the waste body 2 that is the measurement object in which the waste body 2b is filled with the radioactive waste 2a. 11A, a measurement system 41 for measuring the amount of radioactive gas present in the leak test container 12, and a controller 54 for controlling the pressure and open / close state of the sampling line.

  The piping system 11 </ b> A constitutes a flow path (sampling line) for discharging outside air (for example, gas such as air) guided from the intake line 13 to the exhaust duct 14. 11 A of piping systems are arrange | positioned from the upstream side, for example in order of the intake line 13, the intake filter 15, the leak test container 12, the radioactive gas collection container 16, the pressure regulation container 17, the vacuum pump 18, and the exhaust duct 14, and each component However, it is connected in a state where gas can flow in a tubular structure such as a pipe.

  Further, in the piping system 11A, between the intake filter 15 and the leak test container 12, between the leak test container 12 and the radioactive gas collection container 16, and between the radioactive gas collection container 16 and the pressure adjustment container 17, On-off valves V3, V2, V4, V1 for switching the flow path between the intake line 13 and the exhaust duct 14 so as to be openable and closable are attached between the pressure regulating container 17 and the vacuum pump 18, respectively.

  In the following description, an example in which the open / close state of the open / close valves V1, V2, V3, V4 is an electromagnetic valve that can be controlled by the controller 54 will be described. Further, the on-off valve V3 attached between the intake filter 15 and the leakage inspection container 12 is referred to as an air intake valve V3, and the on-off valve V2 attached between the leakage inspection container 12 and the radioactive gas collection container 16 is sampled. An on-off valve V4 called the valve V2 and attached between the radioactive gas collection container 16 and the pressure adjustment container 17 is called a pressure adjustment container inlet valve V4, and an on-off valve V1 attached between the pressure adjustment container 17 and the vacuum pump 18 Is referred to as a sampling source valve V1.

  Further, in the piping system 11A, a pressure transmitter 21 that measures the pressure of the flow path (sampling line) is attached to a position downstream of the pressure regulating container 17 and upstream of the sampling source valve V1.

  The intake filter 15 is a filter that removes floating substances such as dust contained in the outside air taken in from the intake line 13.

  The leak test container 12 is an openable / closable airtight container having a hollow inside. The waste body 2 is accommodated in a hollow region formed inside the leak test container 12. When the lid (not shown) is closed, the leakage inspection container 12 can shield the atmosphere inside the container (internal atmosphere) from the gas outside the container and seal it inside the container.

  The radioactive gas collection container 16 is a container for storing a gas (gas) sampled from the leakage inspection container 12. In the first radioactive gas leakage measuring apparatus 10 </ b> A, the radioactive gas detector 23 detects the radiation radiated from the gas (sampling gas) stored and filled in the radioactive gas sampling container 16.

  The radioactive gas detector 23 detects radiation such as a plastic scintillation detector, an inorganic scintillation detector such as a NaI (Tl) detector, a semiconductor detector such as a germanium (Ge) detector or a silicon (Si) detector. The detector is selected from the possible detectors according to the application. Here, a case where a plastic scintillation detector is employed as an example of the radioactive gas detector 23 will be described.

In the pressure adjusting container 17, the pressure in the container is adjusted to a negative pressure so that the gas inside the leak test container 12 is guided to the radioactive gas sampling container 16. The vacuum pump 18 evacuates the pressure adjustment container 17. The pressure in the pressure regulating container 17 reaches a pressure level that is a so-called high vacuum, such as 10 ⁻⁵ Pa.

  In the first radioactive gas leakage measuring apparatus 10A, an intake filter 15 is attached to the intake line 13 of the piping system 11A. However, floating substances that hinder measurement when measuring the amount of radioactive gas leakage. Is not necessarily mixed with outside air, the intake filter 15 is not necessarily attached to the intake line 13 of the piping system 11A.

  FIG. 2 is an explanatory diagram (block diagram) showing the configuration of the measurement system of the first radioactive gas leakage measurement apparatus 10A.

  The measurement system 41 is a measurement signal processing unit that obtains count data by performing signal processing such as amplification and noise removal on the detection signal acquired by the radioactive gas detector (denoted as “DET” in FIG. 2) 23. The measurement signal processing device 43, an equation for calculating the concentration distribution of the gas leaked in the leak test container 12 and the leakage amount of the radioactive gas using the count value data obtained as a result of the signal processing by the measurement signal processing device 43 and the measurement signal And a data processing computer 45 as a data processing unit that calculates the concentration distribution of the gas leaked in the leak test container 12 and the leak amount of the radioactive gas based on the count value data obtained as a result of the signal processing by the processing device 43. .

  The measurement signal processor 43 includes a preamplifier (indicated as “PRE” in FIG. 2) 46, a linear amplifier (indicated in FIG. 2 as “LIN”) 47, and a pulse height discriminator (in FIG. 2). 48) and a pulse analyzer (indicated as “MCA” in FIG. 2) 49. Reference numeral 50 denotes a power source (indicated as “HV” in FIG. 2) for supplying a high voltage to the preamplifier 46.

  When the measurement signal processor 43 receives a pulse signal from the radioactive gas detector 23, first, the preamplifier 46 amplifies the pulse signal received from the radioactive gas detector 23 and sends it to the linear amplifier 47. Subsequently, the linear amplifier 47 amplifies the signal received from the preamplifier 46 and sends it to the pulse height discriminator 48.

  When the pulse height discriminator 48 receives a signal (amplified pulse signal) from the linear amplifier 47, the pulse wave height discriminator 48 compares the set value and pulses only the necessary pulses among the pulses received from the linear amplifier 47. Send to analyzer 49. Subsequently, the pulse analyzer 49 counts the count rate for each energy in the pulse received from the pulse height discriminator 48 and sends the count value to the data processing computer 45 as a measured value.

  The data processing computer 45 gives the measurement signal processing device 43 (more specifically, the pulse analysis device 49) a request for starting measurement of the amount of radioactive gas leakage (measurement start request) and a request for termination (measurement end request). The data processing computer 45 receives a measurement value, which is a measurement result, from the measurement signal processing device 43 until the measurement signal processing device 43 gives a measurement start request to the measurement end request.

  The data processing computer 45 controls the open / close states of the on-off valves V1, V2, V3, and V4 and the operating state (ON / OFF) of the vacuum pump 18 and also records the pressure (measured value) measured by the pressure transmitter 21 as data. A data acquisition request is given to the controller 54 to be transmitted to the processing computer 45, and the measurement value of the pressure transmitter 21 acquired by the controller 54 is received.

  Further, the data processing computer 45 has information on mathematical formulas and coefficients for calculating the concentration of gas in the leak test container 12 and the leak amount. More specifically, the data processing computer 45 calculates the concentration of the gas in the leak test container 12 given by the concentration conversion coefficient information and the measurement value acquired as the measurement result from the concentration conversion coefficient × measurement signal processing device 43. It has formula information, volume information of the piping system 11A, and formula information for calculating the amount of gas leakage in the leak test container 12 given by the volume of the pipe system 11A × the concentration of gas in the leak test container 12.

  The data processing computer 45 uses the mathematical formula and coefficient information for calculating the concentration of gas in the leak test container 12 and the amount of leak, and the measurement value acquired as a measurement result from the measurement signal processing device 43 to store in the leak test container 12. Calculate the gas concentration and leakage amount. The calculation result of the gas concentration and the leakage amount in the leak test container 12 is sent to the display 55 and displayed on the display 55.

  Subsequently, a radioactive gas leakage amount measuring method (hereinafter referred to as “first radioactive gas leakage amount measuring method”) according to the first embodiment of the present invention will be described.

  In the first radioactive gas leakage measurement method, for example, the first radioactive gas leakage measurement device 10A is used to sample the gas in the leakage inspection container 12 that houses the waste body 2, and to obtain the concentration of the sampled gas. This is a method of measuring the amount of gas leaking into the leak test container 12 based on the above.

  FIG. 3 is an explanatory diagram (timing chart) for explaining the operation timing of the measurement signal processing device 43, the valves V1, V2, V3, V4, and the vacuum pump 18 in the first radioactive gas leakage measurement device 10A. .

In the timing chart shown in FIG. 3, the horizontal axis represents elapsed time, and the vertical axis represents states such as ON (on) and OFF (off), OPEN (open), and CLOSE (closed). T ₁ , T ₂ , T ₃ , T ₄ , T _V , and T _S are a standing time, a measurement preparation time, a measurement time, a post-processing time, a vacuuming time, and a sweep time (purge time), respectively.

In the first radioactive gas leakage measurement method, first, the waste body 2 is stored in the leakage inspection container 12, and then the sampling source valve V1, the sampling valve V2, the air intake valve V3, and the pressure regulating container inlet valve V4 are provided. Closed. Then, for example, the gas is allowed to diffuse uniformly into the leak test container 12 by being left for a certain time such as the time T ₁ .

Thereafter, as preparation for measurement, first, the sampling source valve V1 is opened, and at the same time, the vacuum pump 18 is started to evacuate the pressure regulating container 17. At this time, since the leakage inspection container 12 is isolated by the pressure regulating container inlet valve V4, there is no pressure drop and the atmospheric pressure state remains. The pressure value due to evacuation of the pressure regulating container 17 is confirmed by the pressure transmitter 21. When the degree of vacuum is reached as necessary, the sampling valve V1 is closed and the vacuum pump 18 is stopped to vacuum the pressure regulating container 17. It is in a sealed state (evacuation time T _V ). Subsequently, the on-off valves V2 and V4 are opened in the order of the sampling valve V2 and the pressure regulating container inlet valve V4 (measurement preparation time T ₂ ).

  As a result of opening the on-off valves V2 and V4 that have been closed, the pressure regulating container 17 and the leakage inspection container 12 are connected. Since there is a large pressure difference between the pressure adjustment container 17 in the vacuum state and the leakage inspection container 12 in the atmospheric pressure state, leakage can be achieved in a shorter time than in the prior art by opening the sampling valve V2 and the pressure adjustment container inlet valve V4. The gas in the cuvette 12 is diffused in the entire flow path located downstream of the closed air intake valve V3 and upstream of the closed sampling source valve V1 in the piping system 11A. To do.

Thereafter, the radiation diffused from the leak test container 12 and emitted from the sampling gas filled in the radioactive gas collection container 16 is detected as a pulse signal by the radioactive gas detector 23, and the detected pulse signal is measured by the measurement system 41. The processing device 43 receives (measurement time T ₃ ). The signal received by the measurement signal processing device 43 is subjected to signal processing by the measurement signal processing device 43, and the concentration and amount of leakage of the gas in the leakage test container 12 are calculated by the data processing computer 45. The calculation result of the data processing computer 45 is displayed on the display 55.

Here, in the subsequent time when opening the sampling valve V2 and a pressure regulating vessel inlet valve V4 in the measurement preparation time T ₂ and the measurement time T _3, of the piping system 11A, from Iriben V3 air intake is closed The pressure in the flow path located downstream and upstream of the closed sampling source valve V1 is reduced from the atmospheric pressure to a negative pressure.

After the measurement has been completed (elapsed measurement time T _3), it performs post-processing for removing the radioactive gas from the piping system 11A (post-treatment time T _4). More specifically, the vacuum pump 18 is started with all the open / close valves V1, V2, V3, and V4 opened, and the air taken in from the intake line 13 is caused to flow through the entire piping system 11A to generate radioactive gas. Scavenging (sweep time T ₄ ). When air is flowed through the entire piping system 11A to scavenge the radioactive gas, the post-processing is terminated.

Then, time required for the radioactive gas leak test vessel 12 of the first radioactive gas leak rate measuring device 10A is diffused, i.e., whether will be described to set how the standing time T _1.

The diffusion of the radioactive gas in the leak test container 12 in the horizontal direction means that the radioactive gas diffuses in air different from the radioactive gas. During the leaving time T ₁ during which radioactive gas diffuses in the leak test container 12, it is assumed that the gas concentration has a gradient in the horizontal direction in the leak test container 12. In addition, this gas concentration gradient is assumed to change over time.

  For the evaluation of the gas gradient in the leak test container 12, the concentration can be calculated by the diffusion equation given by the following equation (1).

Further, since the gas concentration distribution in the entire piping system 11A follows the Maxwell-Boltzmann distribution by self-diffusion, the horizontal distance in the leak test container 12 is expressed by the following equation (2). The distribution function depends on x and diffusion time (leaving time) t. Therefore, the size of the leak test container 12, pressure, temperature, etc., diffusion atoms, the diffusion time based on the conditions of the diffusing medium, i.e., determining the standing time T _1.

  FIG. 4 is an explanatory diagram (graph) showing a result of simulating a state in which the radioactive gas diffuses in the leakage inspection container 12 of the first radioactive gas leakage measuring device 10A.

  In the graph shown in FIG. 4, the horizontal axis indicates the horizontal direction (substantially the radial direction of the cylindrical container) from the waste body 2 serving as a radioactive gas source stored in the leak test container 12, and the vertical axis indicates the leak test container 12. The radioactive gas distribution function [%] normalized with the total amount of radioactive gas present in the inside as 100% is shown.

The simulation results shown in FIG. 4 show that the conditions for the leak test container 12 are as follows: a diameter of 3 m, an internal pressure of atmospheric pressure, an internal temperature of 27 ° C., a diffusion atom of ⁸⁵ Kr, and a diffusion medium of N ₂ . , The radioactive gas with respect to the horizontal distance (horizontal distance in the leak test container) from the waste body 2 stored in the leak test container 12 when the diffusion time (leaving time T ₁ ) is 0.1 seconds and 1000 seconds The distribution function is shown.

As shown in FIG. 4, when the diffusion time (leaving time T ₁ ) is 0.1 second, the radioactive gas distribution function varies depending on the horizontal distance in the leak test container 12. That is, the gas is unevenly distributed in the horizontal direction in the leak test container 12 and is not sufficiently diffused. On the other hand, when the diffusion time (leaving time T ₁ ) is 1000 seconds, the radioactive gas distribution function is almost the same even if the horizontal distance in the leak test container 12 changes. That is, it can be said that the gas is evenly distributed in the horizontal direction in the leak test container 12 and is sufficiently diffused.

  On the other hand, the distribution of radioactive gas in the vertical direction in the leak test container 12 is higher in density than air in which the radio gas nuclide is a diffusion medium, so that the concentration in the lower part in the leak test container 12 is increased by the action of gravity. . Therefore, by installing a flow path serving as a sampling line such as a pipe below the leak test container 12, radioactive gas accumulated at a higher concentration can be preferentially sampled and evaluated. As a result, since the concentration in the leak test container 12 can be calculated on the safer side, the leak detection performance is improved.

  Subsequently, the concentration of the sampling gas measured by the radioactive gas leakage measuring apparatus and the radioactive gas leakage measuring method (hereinafter simply referred to as “the present method”) according to the embodiment of the present invention, and the conventional radioactive gas leakage. The concentration of the sampling gas measured by the quantity measuring device and the radioactive gas leakage measuring method (hereinafter simply referred to as “conventional method”) will be described in comparison.

  FIG. 5 is an explanatory diagram (graph) showing the concentration of the sampling gas measured by this method, the concentration of the sampling gas measured by the conventional method, and the detection limit concentration of the radioactive gas detector 23.

Here, in evaluating the concentration of the sampling gas measured by this method, the concentration of the sampling gas measured by the conventional method, and the detection limit concentration of the radioactive gas detector 23, the estimated waste amount of waste is set to 4.0 × 10. ² Bq / line / h, the sampling flow rate of the conventional method is 50 liters per minute (L / min), the concentration conversion factor of the radioactive gas detector 23 is 3.0 × 10 ⁻³ Bq / cm ³ / s ⁻¹ , The time is evaluated as 1 hour for both the present method and the conventional method, and the measurement time is evaluated as 1 hour for both the present method and the conventional method.

In the graph shown in FIG. 5, the horizontal axis indicates the background count rate (BG count rate), and the vertical axis indicates the concentration of the radioactive gas. Lines L ₀ , L ₁ and L ₂ are respectively measured by a line indicating the detection limit concentration of the radioactive gas detector 23, a line indicating the concentration of the sampling gas measured by this method, and a conventional method. It is a line which shows the density | concentration of sampling gas.

  The detection limit concentration calculation formula, the conventional concentration calculation formula, and the present concentration calculation formula are given by Formula (3), Formula (4), and Formula (5), respectively.

As shown in FIG. 5, the line L1 indicating the concentration of the sampling gas to be measured by this method, in the entire range of BG count rate is shown, the detection limit concentration curve L ₀ is calculated from the background value Is also big. This result is due to the fact that the concentration of the sampling gas is maintained without being diluted in this method. Therefore, in this method, since the concentration of the sampling gas is not diluted, it is possible to avoid a situation in which measurement becomes impossible due to the same detection limit calculated from the background value.

On the other hand, the line L ₂ indicating the concentration of the sampling gas measured by the conventional method is larger than the detection limit concentration curve L ₀ calculated from the background value within the range where the BG count rate is 0 or more and 8 s ⁻¹ or less. However, when the BG count rate exceeds 8 s ⁻¹ , it is smaller than the detection limit concentration curve L ₀ calculated from the background value. That is, in the conventional method, when the concentration of the sampling gas is diluted and a certain BG count rate is reached, there are cases where the measurement is less than the lower limit of measurement detectable by the radioactive gas detector, that is, measurement is impossible.

  As described above, the radioactive gas leakage amount measuring apparatus and the radioactive gas leakage amount measuring method according to the embodiment of the present invention cannot be measured by the conventional radioactive gas leakage amount measuring apparatus and the radioactive gas leakage amount measuring method. Even under the environment, it will not be impossible to measure.

  According to the first radioactive gas leakage measuring apparatus 10A and the first radioactive gas leakage measuring method, when measuring the concentration and leakage of the sampling gas, the flow path through which the sampling gas diffuses, that is, the air intake valve Since the flow path located downstream of V3 and upstream of the closed sampling source valve V1 is completely separated from the other flow paths, inflow of outside air can be prevented.

  Therefore, in the first radioactive gas leakage measurement apparatus 10A and the first radioactive gas leakage measurement method, the radioactive gas concentration is not diluted even if the amount of radioactive gas leaking from the waste body 2 is very small. Since it is held, the radioactive gas can be sampled by the radioactive gas detector 23 while the radioactive gas concentration is maintained, and the leakage amount of the radioactive gas can be measured.

  Further, according to the first radioactive gas leakage measuring apparatus 10A and the first radioactive gas leakage measuring method, when measuring the concentration and leakage of the sampling gas, the flow path through which the sampling gas diffuses, that is, the air intake Since the pressure in the flow path located downstream of the inlet valve V3 and upstream of the closed sampling source valve V1 is a negative pressure, it is possible to prevent the outflow of the radioactive gas when the power is lost. Therefore, safety can be improved as compared with the conventional case.

  Furthermore, according to the first radioactive gas leakage measurement device 10A and the first radioactive gas leakage measurement method, an apparatus for controlling and measuring the flow rate is not required as compared with the prior art. Therefore, the number of parts can be reduced and the installation space can be reduced.

  In the above-described first radioactive gas leakage measuring apparatus 10A, the on-off valves V1, V2, V3, and V4 have been described as examples of electromagnetic valves. However, when the on-off control is not performed by the controller 54, the on-off valves V1, V2, V3, and V4 can also be comprised with a manual valve.

[Second Embodiment]
The radioactive gas leakage amount measuring apparatus according to the second embodiment of the present invention differs from the radioactive gas leakage amount measuring apparatus according to the first embodiment of the present invention in a substantial apparatus configuration (hardware configuration). Don't be. That is, in the piping system diagram of the first radioactive gas leakage measuring device 10A shown in FIG. 1 and the configuration diagram of the measurement system 41 of the first radioactive gas leakage measuring device 10A shown in FIG. In other words, FIG. 1 and FIG. 2 after replacement are respectively a piping system diagram of a second radioactive gas leakage measuring device 10B which is an example of the radioactive gas leakage measuring device according to the second embodiment of the present invention. And it becomes a block diagram of the measurement system 41.

  On the other hand, the radioactive gas leakage measuring device and the radioactive gas leakage measuring method (hereinafter referred to as “second radioactive gas leakage measuring method”) according to the second embodiment of the present invention are described. Compared to the radioactive gas leakage measuring apparatus and the radioactive gas leakage measuring method according to the first embodiment, the operation timing of the sampling valve V2, the pressure regulating container inlet valve V4 and the vacuum pump 18, that is, the control sequence of the controller 54. Is different. Therefore, in the description of the present embodiment, the description will focus on a control sequence of the controller 54 that is different from the first embodiment described above.

  FIG. 6 is an explanatory diagram (timing chart) for explaining operation timings of the measurement signal processing device 43, the valves V1, V2, V3, V4 and the vacuum pump 18 in the second radioactive gas leakage measuring device 10B.

As shown in FIG. 6, in the second radioactive gas leak rate measuring device 10B, in that the preparation time T ₀ before standing in front of the standing time T ₁ is set, the first radioactive gas leak rate measuring device 10A This is different from the control sequence in FIG. Here, the pre-leaving preparation time T ₀ is a preparation time for bringing the inside of the leakage inspection container 12 into a negative pressure state prior to the leaving time T ₁ in which the waste body 2 is left in the leakage inspection container 12.

In standing before preparation time T _0, first, the sampling main valve V1 is opened when the vacuum pump 18 is operated simultaneously with (ON), the inside pressure adjustable container 17 in a state of vacuum (so-called high vacuum). Once passed evacuation time T _V is the inside pressure adjustable container 17 reaches the desired pressure (vacuum), the vacuum pump 18 is stopped (OFF) at the same time when the sampling source valve V1 is closed.

  Subsequently, the sampling valve V2 is opened, and then the pressure regulating container inlet valve V4 is opened (OPEN). By opening the sampling valve V2 and the pressure regulating container inlet valve V4, the flow path located downstream of the closed air intake valve V3 and upstream of the closed sampling source valve V1 is atmospheric pressure. The pressure drops to a negative pressure state. That is, the pressure in the leak test container 12 becomes a negative pressure.

  Here, opening the sample collection valve V2 before the pressure regulating container inlet valve V4 avoids the pressure in the radioactive gas collection container 16 from becoming a large negative pressure and damages the radioactive gas detector 23. This is to make the inside of the leakage inspection container 12 into a negative pressure state while preventing the above.

  When the sample collection valve V2 and the pressure adjustment tank inlet valve V4 are opened and a time enough to bring the inside of the leak test container 12 into a negative pressure state has elapsed, the sample collection valve V2 and the pressure adjustment container inlet valve V4 are closed (CLOSE).

Of the control sequence executed in the second radioactive gas leak rate measuring device 10B, the control sequence of standing before preparation time T ₀ after, similar to the control sequence executed in the first radioactive gas leak rate measuring device 10A It is.

  According to the second radioactive gas leakage measuring device 10B and the second radioactive gas leakage measuring method, in addition to the effects exhibited by the first radioactive gas leakage measuring device 10A and the first radioactive gas leakage measuring method. Since the waste body 2 can be left with the negative pressure inside the leak test container 12, the first radioactive gas leak amount measuring apparatus 10A and the first device for leaving the waste body 2 under the atmospheric pressure within the leak test container 12 and the first The amount of radioactive gas leakage from the waste body 2 can be increased as compared with the method 1 for measuring the amount of radioactive gas leakage.

  Therefore, in the second radioactive gas leak amount measuring apparatus 10B and the second radioactive gas leak amount measuring method, the first radioactivity capable of obtaining a concentration value sufficiently large with respect to the detection limit calculated from the background value. Since a larger concentration value can be obtained than the gas leakage amount measuring apparatus 10A and the first radioactive gas leakage amount measuring method, the certainty of measurement of the radioactive gas leakage amount can be further improved.

  In the description of the present embodiment, an example of a radioactive gas leakage amount measuring device in which the control sequence of the controller 54 is changed with respect to the radioactive gas leakage amount measuring device according to the first embodiment of the present invention has been described. In a radioactive gas leakage measuring device according to another embodiment to be described later, a radioactive gas leakage measuring device with a changed control sequence may be configured.

[Third Embodiment]
The radioactive gas leakage amount measuring apparatus according to the third embodiment of the present invention differs from the radioactive gas leakage amount measuring apparatus according to the first embodiment of the present invention in a substantial device configuration (hardware configuration). Don't be. That is, in the piping system diagram of the first radioactive gas leakage measuring device 10A shown in FIG. 1 and the configuration diagram of the measurement system 41 of the first radioactive gas leakage measuring device 10A shown in FIG. In other words, FIG. 1 and FIG. 2 after the replacement are piping system diagrams of a third radioactive gas leakage measuring device 10C which is an example of the radioactive gas leakage measuring device according to the third embodiment of the present invention. And it becomes a block diagram of the measurement system 41.

  On the other hand, the radioactive gas leakage amount measuring apparatus according to the third embodiment of the present invention is normal (abnormal or abnormal) with respect to the radioactive gas leakage amount measuring apparatus according to the first embodiment of the present invention. ) Is added (hereinafter referred to as “measurement result suitability determination function”). In other words, the radioactive gas leakage measuring device and the radioactive gas leakage measuring device (hereinafter referred to as “third radioactive gas leakage measuring method”) according to the third embodiment of the present invention are described. With respect to the radioactive gas leakage measuring apparatus and the first radioactive gas leakage measuring method according to the first embodiment, the data processing computer 45 determines whether the measurement result is normal or abnormal (hereinafter, “measurement result suitability”). This is different in that it is referred to as “determination procedure”. Therefore, in the description of the present embodiment, the measurement result suitability determination procedure different from that in the first embodiment described above will be mainly described.

  FIG. 7 is a flowchart (flow chart) showing a processing flow of a measurement result suitability determination procedure executed by the third radioactive gas leakage measuring device 10C.

  The measurement result suitability determination procedure includes processing steps of Step S1 to Step S13. In the third radioactive gas leakage measuring apparatus 10C, the data processing computer 45 holds the processing contents of the processing steps of step S1 to step S13 and the information of the processing flow, and the processing contents of steps S1 to S13 that are held. Based on the processing flow information, the processing steps of the measurement result suitability determination procedure (step S1 to step S13) are executed.

  In the measurement result suitability determination procedure, first, the data processing computer 45 gives a measurement start request to the measurement signal processing device 43, starts the first measurement (step S1), and measures the first measurement data measured. Is received from the measurement signal processing device 43 (step S2).

  Subsequently, the data processing computer 45 determines whether or not there is an abnormality in the first measurement data received in step S2 (step S3). The determination as to whether or not the measurement data is normal is normal if it matches a preset standard for determining normality, and is determined to be abnormal if it does not match. For example, it is determined that there is an abnormality when the data is missing within the set time or when the received measurement value is in a range that cannot be received.

  If the data processing computer 45 determines that there is no abnormality in the first measurement data in step S3 (YES in step S3), the process proceeds to step S4, where the data processing computer 45 starts from the measurement signal processing device 43. The concentration calculated based on the received measurement value is compared with a preset detection limit concentration (step S4).

  In step S4, if the data processing computer 45 determines that the concentration to be calculated is higher than the detection limit concentration (YES in step S4), the second measurement is performed in the same manner as in the first measurement. Is started (step S5), measurement data is received from the measurement signal processing device 43 (step S6), and it is determined whether there is an abnormality in the received second measurement data (step S7).

  In step S7, when the data processing computer 45 determines that there is no abnormality in the second measurement data (YES in step S7), the process proceeds to step S8, and the data processing computer 45 receives the first data received in step S2. It is compared whether the first measurement value is larger than the second measurement value received in step S6 (step S8).

  If the data processing computer 45 determines that the first measurement value is larger than the second measurement value (YES in step S8), the data processing computer 45 discards the leakage in the leak test container 12. It is determined that radioactive gas is leaking from the body 2 (leak is present) (step S9), and the measurement result suitability determination procedure is terminated (END).

  On the other hand, when the data processing computer 45 determines in step S3 that the first measurement data is abnormal (NO in step S3), the process proceeds to step S10, and the data processing computer 45 executes the remeasurement. The presence or absence is confirmed (step S10). When the data processing computer 45 determines that remeasurement has been performed (YES in step S10), the data processing computer 45 issues a warning that the measurement data is abnormal (step S11) and performs measurement. The result suitability determination procedure is terminated (END).

  The warning here may be of any type as long as it can inform the user that there was an abnormality in data reception. For example, it may be visual such as displaying a warning on the display 55, or may be auditory such as emitting a warning sound from a speaker (not shown). Moreover, these combinations may be sufficient.

  On the other hand, when the data processing computer 45 determines in step S4 that the concentration calculated based on the measurement value received from the measurement signal processing device 43 is lower than the preset detection limit concentration (NO in step S4). ), The process proceeds to step S12, and the data processing computer 45 determines whether or not there is a significant instruction variation in the measurement data (step S12).

  In step S12, when the data processing computer 45 determines that there is no significant indication variation in the measurement data (in the case of YES in step S12), radioactive gas leaks from the waste body 2 in the leak test container 12. If so, it is determined that the radioactive gas is not leaking (no leakage) because it is below the detection limit (step S13), and the measurement result suitability determination procedure is terminated (END).

  In step S7, when the data processing computer 45 determines that the second measurement data is abnormal (in the case of NO in step S7), the first measurement value is the second measurement value. If it is determined that it is smaller (NO in step S8), the process proceeds to step S10, and the processing steps after step S10 are executed.

  According to the third radioactive gas leakage measuring device 10C and the third radioactive gas leakage measuring method, the same effects as those of the first radioactive gas leakage measuring device 10A and the first radioactive gas leakage measuring method are obtained. In addition, since the measurement result suitability determination procedure is further executed with respect to the first radioactive gas leakage amount measuring apparatus 10A and the first radioactive gas leakage amount measuring method, from the waste body 2 in the leakage inspection container 12 It is possible to more reliably detect the presence or absence of leakage of the leaking radioactive gas and the abnormality of the measurement data. That is, since the reliability of the measurement data can be confirmed at the time of measurement, the reliability of the measurement result can be improved.

  In the description of the present embodiment, the example of the radioactive gas leak amount measuring apparatus in which the measurement result suitability determining function is added to the radioactive gas leak amount measuring apparatus according to the first embodiment of the present invention has been described. The apparatus to which the determination function is added is not necessarily limited to the radioactive gas leak amount measuring apparatus according to the first embodiment of the present invention. That is, it is possible to configure a radioactive gas leakage amount measuring apparatus in which the determination of whether or not the measurement result is appropriate is added to the radioactive gas leakage amount measuring apparatus according to another embodiment of the present invention.

[Fourth Embodiment]
FIG. 8 is a piping system diagram of a fourth radioactive gas leakage measuring device 10D which is an example of the radioactive gas leakage measuring device according to the fourth embodiment of the present invention. Note that the open / close states of the valves V1, V2, V3, and V4 shown in FIG. 8 indicate the open / close states at the time of measurement (the measurement time T ₃ shown in FIG. 3 described above).

  The fourth radioactive gas leakage measuring device 10D is different from the first radioactive gas leakage measuring device 10A in that a piping system 11B is provided instead of the piping system 11A. Therefore, in the description of the present embodiment, the description will focus on differences from the above-described first embodiment, and the same components are denoted by the same reference numerals and description thereof is omitted.

  The fourth radioactive gas leakage measuring device 10D is a pipe that constitutes a flow path (sampling line) for sampling the gas in the leakage inspection container 12 that houses the waste body 2 in which the waste body 2b is filled with the radioactive waste 2a. A system 11B, a measurement system 41, and a controller 54 are provided.

  In the piping system 11B, a bypass switching three-way valve V11 and a diffusion medium supply source switching three-way valve V31 are attached to the piping system 11A, respectively, instead of the sampling source valve V1 and the air intake valve V3.

  The diffusion medium supply source switching three-way valve V31 has an upstream side (intake line 13 side) end connected to the intake filter 15 and a downstream side (exhaust duct 14 side) end connected to the leak test container 12. A third end portion is further provided for the air intake valve V3. At the third end of the diffusion medium supply source switching three-way valve V31, the gas as the diffusion medium stored in the gas supply device 25 is leaked via the diffusion medium supply source switching three-way valve V31 via the pressure regulating valve V5. A gas supply line 26 for supplying the cuvette 12 is connected.

The gas as a diffusion medium stored in the gas supply device 25 is preferably a high-purity non-radioactive gas having a density greatly different from that of air such as hydrogen H ₂ .

  The bypass switching three-way valve V11 has an upstream end (intake line 13 side) end connected to the pressure regulating container 17 and a downstream end (exhaust duct 14 side) end connected to the vacuum pump 18. A third end portion is further provided for the sampling source valve V1. A bypass line 27 serving as a flow path for bypassing the vacuum pump 18 is connected to the third end of the bypass switching three-way valve V11.

  In the fourth radioactive gas leakage measuring device 10D including the piping system 11B configured as described above, the open / close state of the diffusion medium supply source switching three-way valve V31 is switched as necessary, so that the leakage inspection container 12 can be opened. The type of gas as the diffusion medium to be supplied can be switched.

  Subsequently, a radioactive gas leakage measurement method (hereinafter referred to as “fourth radioactive gas leakage measurement method”) according to a fourth embodiment of the present invention will be described.

  The fourth method for measuring the amount of radioactive gas leakage is, for example, using the fourth radioactive gas leakage amount measuring device 10D to sample the gas in the leakage inspection container 12 containing the waste body 2, and to obtain the concentration of the sampled gas. This is a method of measuring the amount of gas leaking into the leak test container 12 based on the above.

  The fourth radioactive gas leakage amount measuring method is different from the first radioactive gas leakage amount measuring method in that it further includes a diffusion medium filling step for filling the flow path of the piping system 11B with the diffusion medium. Therefore, in the description of the fourth radioactive gas leakage amount measuring method, the diffusion medium filling step will be mainly described.

  FIG. 9 is an explanatory diagram for explaining the operation timing of the measurement signal processing device 43, the valves V11, V2, V4, V31, V5, the gas supply device, and the vacuum pump 18 in the fourth radioactive gas leakage measurement device 10D. Timing chart).

In the timing chart shown in FIG. 9, the horizontal axis is the elapsed time, and the vertical axis is, for example, ON (on) and OFF (off), OPEN (open) and CLOSE (closed), PUMP (vacuum pump 18 side) and BYPASS. The state of (bypass line 27 side) is shown. T ₁ , T ₂ , T ₃ , T ₄ , T ₅ , T _V , and T _S are the standing time, measurement preparation time, measurement time, post-processing time, diffusion medium filling time, evacuation time, and sweep, respectively. Time (purge time).

As shown in FIG. 9, the fourth radiating gas leak rate measuring device 10D, in that the diffusing medium fill time T ₅ before the standing time T ₁ is set, the first radioactive gas leak rate measuring device 10A This is different from the control sequence in FIG. Here, the diffusing medium fill time T _5, prior to the standing time T ₁ to leave the waste 2 at the leakage test vessel 12, the time to fill the diffusing medium in the flow path of the piping system 11B, i.e., diffusing medium The time at which the charging step is performed.

  In the diffusion medium filling step, the diffusion medium supply source switching three-way valve V31 opens the gas supply line 26 connected to the gas supply device 25 and connects the flow path, while closing the flow path connected to the intake filter 15. (BOMBE). The bypass switching three-way valve V11 opens the bypass line 27 side and connects the bypass line 27, while closing the flow path connected to the vacuum pump 18 (BYPASS). Further, the pressure regulating valve V5 is opened (OPEN), and the gas as the diffusion medium accumulated inside is sent out from the gas supply device 25 to the gas supply line 26 (ON).

Diffusing medium filling step, for example, diffusing medium conducted fill time predetermined time ₅ such T, gas supply line 26, diffusing medium supply source switching three-way valve V31, leak test container 12, the sampling valve V2, radioactive gas collection containers 16 The inside of the pressure regulating container inlet valve V4, the pressure regulating container 17, the bypass switching three-way valve V11 and the bypass line 27 is filled with a diffusion medium such as hydrogen H ₂ gas.

  The diffusion medium filling step includes the gas supply line 26, the diffusion medium supply source switching three-way valve V31, the leakage inspection container 12, the sample collection valve V2, the radioactive gas collection container 16, the pressure adjustment container inlet valve V4, the pressure adjustment container 17, and the bypass switching. After filling the inside of the three-way valve V11 and the bypass line 27 with the diffusion medium, the diffusion medium supply source switching three-way valve V21, the bypass switching three-way valve V31 and the pressure regulating valve V5 are closed (CLOSE), and the gas from the gas supply device 25 is closed. It ends by stopping (OFF) the supply. In the fourth radioactive gas leakage measurement method, the processing steps after the diffusion medium filling step are the same as in the fourth radioactive gas leakage measurement method.

In the fourth radiating gas leak amount measuring method, before the standing time T _1, for performing the diffusing medium filling step, radioactive gas, such as ^{85 Kr} will be spread through the much lighter diffusing medium than itself. That is, the horizontal diffusion coefficient in the leak test container 12 is greater than that of air as a diffusion medium applied in the first radioactive gas leakage measurement method, and diffusion is promoted.

FIG. 10 is an explanatory diagram (graph) showing the result of simulating the state in which radioactive gas diffuses in the leakage inspection container 12 of the fourth radioactive gas leakage measuring device 10D. Note that the simulation conditions shown in FIG. 10 are the same as the simulation conditions shown in FIG. 4 except that the diffusion medium is hydrogen H ₂ .

According to the simulation result shown in FIG. 10, in the case of the first radioactive gas leakage measurement method in which the diffusion medium is nitrogen N ₂ , 1000 seconds until the concentration of the radioactive gas in the leakage inspection container 12 becomes substantially uniform. (FIG. 4). On the other hand, in the case of the fourth radioactive gas leakage measurement method using hydrogen H ₂ as an example of a non-radioactive gas as a diffusion medium, it takes 500 seconds until the concentration of the radioactive gas in the leakage inspection container 12 becomes substantially uniform. It takes (FIG. 10). That is, when hydrogen H ₂ is used as the diffusion medium, the concentration of the radioactive gas in the leak test container 12 is uniform in half the time when nitrogen N ₂ is used as the diffusion medium.

  According to the fourth radioactive gas leakage measuring device 10D and the fourth radioactive gas leakage measuring method, the same effects as those of the first radioactive gas leakage measuring device 10A and the first radioactive gas leakage measuring method are obtained. It can be obtained in a shorter time.

[Fifth Embodiment]
FIG. 11 is a piping system diagram of a fifth radioactive gas leakage measuring device 10E which is an example of the radioactive gas leakage measuring device according to the fifth embodiment of the present invention. Note that the open / close states of the valves V1, V2, V3, V4 shown in FIG. 11 indicate the open / close states at the time of measurement (the measurement time T ₃ shown in FIG. 3 described above).

  The fifth radioactive gas leakage measuring device 10E is different from the first radioactive gas leakage measuring device 10A in that a piping system 11C is provided instead of the piping system 11A. Therefore, in the description of the present embodiment, the description will focus on differences from the above-described first embodiment, and the same components are denoted by the same reference numerals and description thereof is omitted.

  The fifth radioactive gas leakage measuring device 10E is a pipe that constitutes a flow path (sampling line) for sampling the gas in the leakage inspection container 12 containing the waste body 2 filled with the radioactive waste 2a in the waste container 2b. A system 11C, a measurement system 41, and a controller 54 are provided.

  11C of piping systems are further provided with the gas circulation line 31 which is a flow path which circulates the gas in the leak test container 12 with respect to 11A of piping systems. In the gas circulation line 31, a circulation pump 33 and a cooling device 34 that dissipates (heats removes) the heat of the gas in the leak test container 12 are installed. Here, the circulation pump 33 is a pump that circulates the gas in the leak test container 12 through the gas circulation line 31. The cooling device 34 is a device that cools the gas by dissipating (removing heat) the heat of the gas since the gas in the leak test container 12 is overheated and increases in temperature when passing through the circulation pump 33 that rotates at high speed.

  The gas in the leak test container 12 is sequentially guided from the leak test container 12 to the circulation pump 32 and the cooling device 34 by the circulating pump 33 that is operated, and is returned to the leak test container 12 from the cooling device 34 again.

  That is, when the circulation pump 33 is operated in the fifth radioactive gas leakage measurement apparatus 10E, the gas in the leakage inspection container 12 circulates in the gas circulation line 31 while the circulation pump 33 is operating.

  Subsequently, a radioactive gas leakage measurement method (hereinafter referred to as “fifth radioactive gas leakage measurement method”) according to a fifth embodiment of the present invention will be described.

  In the fifth radioactive gas leakage measurement method, for example, the fifth radioactive gas leakage measurement device 10E is used to sample the gas in the leakage inspection container 12 containing the waste body 2, and to obtain the concentration of the sampled gas. This is a method of measuring the amount of gas leaking into the leak test container 12 based on the above.

  The fifth radioactive gas leakage amount measuring method is different from the first radioactive gas leakage amount measuring method by circulating the gas in the leakage inspection container 12 through the gas circulation line 31 before the measurement. However, there is no substantial difference with respect to the other points.

  According to the fifth radioactive gas leakage measuring device 10E and the fifth radioactive gas leakage measuring method, the same effects as those of the first radioactive gas leakage measuring device 10A and the first radioactive gas leakage measuring method are obtained. In addition, since the gas in the leak test container 12 can be circulated through the gas circulation line 31 provided in the fifth radioactive gas leak amount measuring apparatus 10E, the gas concentration in the leak test container 12 is made uniform. Can be.

  Therefore, according to the fifth radioactive gas leakage measuring device 10E and the fifth radioactive gas leakage measuring method, the radioactive gas leakage can be more accurately performed than the other radioactive gas leakage measuring devices and the radioactive gas leakage measuring methods. Concentration and leakage can be measured.

  As described above, according to the radioactive gas leakage measuring apparatus and the radioactive gas leakage measuring method according to the embodiment of the present invention, when measuring the concentration and leakage of the sampling gas, the flow path through which the sampling gas diffuses, that is, the air intake Since the flow path located downstream of the inlet valve V3 and upstream of the closed sampling source valve V1 is completely separated from the other flow paths, the inflow of outside air can be prevented. .

  Therefore, in the radioactive gas leakage measuring apparatus and the radioactive gas leakage measuring method according to the embodiment of the present invention, the radioactive gas concentration is not diluted even if the amount of radioactive gas leaking from the waste body 2 is very small. Since it is held, the radioactive gas can be sampled by the radioactive gas detector 23 while the radioactive gas concentration is maintained, and the leakage amount of the radioactive gas can be measured.

  Further, according to the radioactive gas leakage amount measuring apparatus and the radioactive gas leakage amount measuring method according to the embodiment of the present invention, when measuring the concentration and leakage amount of the sampling gas, the flow path through which the sampling gas diffuses, that is, the air intake. Since the pressure in the flow path located downstream of the inlet valve V3 and upstream of the closed sampling source valve V1 is a negative pressure, it is possible to prevent the outflow of the radioactive gas when the power is lost. Therefore, safety can be improved as compared with the conventional case.

  Furthermore, according to the radioactive gas leakage amount measuring apparatus and the radioactive gas leakage amount measuring method according to the embodiment of the present invention, the number of components is reduced because a device for controlling and measuring the flow rate is not required as compared with the prior art. At the same time, the installation space can be reduced.

In the radioactive gas leakage measuring apparatus and the radioactive gas leakage measuring method according to the embodiment of the present invention, the pre-leaving preparation time T ₀ is set prior to the leaving time T ₁ in which the waste body 2 is left in the leak test container 12. In this case, the amount of radioactive gas leaked from the waste body 2 can be increased. Moreover, when the measurement result suitability determination procedure is executed, the reliability of the measurement result can be improved.

Furthermore, in the radioactive gas leakage measuring apparatus and the radioactive gas leakage measuring method according to the embodiment of the present invention, as a diffusion medium, for example, a high-purity non-radioactive gas having a greatly different density from air such as hydrogen H ₂ is measured. When the piping system 11B, which is a flow path for performing the above, is filled, the speed at which the radioactive gas diffuses in the horizontal direction in the leak test container 12 can be increased as compared with the case where the diffusion medium is air.

  Furthermore, in the radioactive gas leak amount measuring apparatus and the radioactive gas leak amount measuring method according to the embodiment of the present invention, when the gas in the leak test container 12 is circulated through the gas circulation line 31, Since the gas concentration can be made uniform, the concentration and leakage amount of the radioactive gas can be measured more accurately.

  It should be noted that the present invention is not limited to the above-described embodiment as it is, and can be implemented in various forms other than the above-described examples in the implementation stage, and various modifications can be made without departing from the spirit of the invention. Can be omitted, replaced, or changed. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

2 Waste 2a Radioactive waste 2b Waste container 10A, 10B, 10C, 10D, 10E Radioactive gas leakage measuring device 11A, 11B, 11C Piping system 12 Leakage inspection container 13 Intake line 14 Exhaust duct 15 Intake filter 16 Radioactive gas sampling Vessel 17 Pressure adjusting vessel 18 Vacuum pump 21 Pressure transmitter 23 Radioactive gas detector (DET)
25 Gas supply device 26 Gas supply line 27 Bypass line 31 Gas circulation line 33 Circulation pump 34 Cooling device 41 Measurement system 43 Measurement signal processing device (measurement signal processing unit)
45 Data processing computer (data processing unit)
46 Preamplifier (PRE)
47 Linear Amplifier (LIN)
48 Pulse height discriminator (DIS)
49 Pulse analyzer (MCA)
50 High voltage power supply (HV)
54 Controller 55 Display V1 Sampling source valve V11 Bypass switching three-way valve V2 Sampling valve V3 Air intake valve V31 Diffusion medium supply source switching three-way valve V4 Pressure regulating container inlet valve V5 Pressure regulating valve

Claims (9)

A leak test container that is connected to an intake line that sucks in outside air through a first on-off valve and that contains an object to be measured that emits a radioactive gas, and is connected to the leak test container and a second on-off valve. while the radioactive gas collection container to accumulate the gas sampled from the leak test container, Ru is connected via said radioactive gas sampling vessel and the third on-off valve, is connected to the fourth on-off valve attached to the downstream side, A vacuum pump that evacuates and exhausts gas to an exhaust duct that exhausts gas is operated before measurement with the third on-off valve closed and the fourth on-off valve open, and the pressure in the container is reduced. By stopping the vacuum pump after closing the negative pressure and closing the fourth on-off valve, a pressure difference can be given to the upstream side from the third on-off valve before the measurement. The vacuum during measurement Connect a pressure adjustable container for guiding the gas in the leak test container while stopping the pump to the radioactive gas collection container, and a fourth on-off valve mounted between said vacuum pump and said pressure adjustable container A flow path formed;
A pressure transmitter for measuring a pressure in a flow path including the radioactive gas collection container and the pressure regulating container;
A measurement signal processing unit that obtains a measurement value by processing an output signal of a radioactive gas detector that detects radiation from a gas filled in the radioactive gas sampling container;
And a data processing unit for calculating a leakage amount of radioactive gas leaking from the waste container of the measurement target object based on a measurement value obtained by the measurement signal processing unit, apparatus. Controlling on / off of the vacuum pump and opening / closing of the first on-off valve, the second on-off valve, the third on-off valve, and the fourth on-off valve, and measured from the pressure transmitter The radioactive gas leak amount measuring device according to claim 1, further comprising a controller that acquires a pressure value. The controller is configured to perform control to maintain the pressure in the pressure regulating container at a desired negative pressure before measuring the amount of radioactive gas leaking from the waste container. The radioactive gas leak amount measuring apparatus according to claim 1 or 2. The controller is configured to reduce the pressure in the flow path from the leakage inspection container to the pressure regulating container to a negative pressure from the atmospheric pressure before measuring the amount of radioactive gas leaking from the waste container. The radioactive gas leak amount measuring apparatus according to claim 1, wherein the apparatus is configured to perform the following. The radioactive gas leakage according to any one of claims 1 to 4, further comprising a gas supply line for supplying the non-radioactive gas into the flow path from a gas supply device in which the non-radioactive gas is accumulated. Quantity measuring device. The circulation line in which the circulation pump which circulates the gas in the said leakage inspection container, and the cooling device which radiates the heat of the gas in the said leakage inspection container is further provided. The radioactive gas leak amount measuring apparatus according to any one of the preceding claims. A leak test container that is connected to an intake line that sucks in outside air through a first on-off valve and that contains an object to be measured that emits a radioactive gas, and is connected to the leak test container and a second on-off valve. while the radioactive gas collection container to accumulate the gas sampled from the leak test container, Ru is connected via said radioactive gas sampling vessel and the third on-off valve, is connected to the fourth on-off valve attached to the downstream side, A vacuum pump that evacuates and exhausts gas to an exhaust duct that exhausts gas is operated before measurement with the third on-off valve closed and the fourth on-off valve open, and the pressure in the container is reduced. By stopping the vacuum pump after closing the negative pressure and closing the fourth on-off valve, a pressure difference can be given to the upstream side from the third on-off valve before the measurement. The vacuum during measurement Connect a pressure adjustable container for guiding the gas in the leak test container while stopping the pump to the radioactive gas collection container, and a fourth on-off valve mounted between said vacuum pump and said pressure adjustable container Signal processing is performed on the output signal of the formed flow path, the pressure transmitter for measuring the pressure in the flow path, and the radioactive gas detector for detecting the radiation from the gas filled in the radioactive gas sampling container. A measurement signal processing unit for obtaining a measurement value, a data processing unit for calculating a leakage amount of radioactive gas leaking from a waste container of the measurement object based on the measurement value obtained by the measurement signal processing unit, and the vacuum pump And the opening / closing of the first on-off valve, the second on-off valve, the third on-off valve, and the fourth on-off valve, and the pressure value measured from the pressure transmitter To get the controller A radioactive gas leak amount measuring method using a radioactive gas leak amount measuring apparatus for Bei,
The controller opens the fourth on-off valve with the first on-off valve, the second on-off valve, and the third on-off valve closed , turns on the vacuum pump, and enters the inside of the pressure regulating container. after the pressure was desired negative pressure, maintaining a pressure of the pressure adjusting container is closed the fourth on-off valve as switching the vacuum pump to the desired negative pressure,
The controller opens the second on-off valve and the third on-off valve to guide the gas in the leak test container to the radioactive gas collection container;
The measurement signal processing unit performs signal processing on an output signal of a radioactive gas detector that detects radiation from the gas filled in the radioactive gas sampling container, and obtains a measurement value;
And a step of calculating a leakage amount of radioactive gas leaking from the waste container based on a measurement value obtained by the measurement signal processing unit. Before the controller measures the amount of radioactive gas leaking from the waste container, the pressure in the flow path from the leak test container to the pressure regulating container is reduced from atmospheric pressure to a negative pressure. The method for measuring a radioactive gas leakage amount according to claim 7, further comprising: The data processing unit executes a measurement result suitability determination procedure for determining whether or not the measurement result of the radioactive gas leakage amount is normal based on the processing contents of the measurement result suitability determination procedure and the information of the processing flow, In the measurement result suitability determination procedure, the data processing unit
Receiving the first measurement data and the second measurement data;
A step of determining whether or not the measurement data has been successfully received;
Comparing the received measurement value as the first measurement data with the measurement value as the second measurement data is higher than the detection limit concentration of the radioactive gas detector;
And determining the received magnitude of the first round of the measurement value and the second time measurement is a measurement data which is measurement data,
The radioactive gas leakage amount measuring method according to claim 7 or 8, characterized by comprising:

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