JPH0222588A - Radioactive material sampling device - Google Patents

Abstract

PURPOSE:To prevent the quantity of radioactivity from exceeding a permissible quantity and to performing safe nuclide analysis radiation measurement for a sampled radioactive material by closing a supply valve when the integrated quantity of radioactivity exceeds the permissible quantity. CONSTITUTION:A 1st computing element 21 calculates the radioactive concentration of the radioactive material collected by a filter 5 from the component ratio and the radioactive concentration of rare gas. Then a 2nd computing element 23 also calculates the quantity of radioactivity of the collected radioactive material from a sampling quantity per unit time and its radioactive concentration. Further, a 3rd computing element 24 uses collection efficiency to calculate the real quantity of radioactivity. Then an integrating computing element 26 integrates the actual quantity of radioactivity per unit time and when the integrated quantity of radioactivity exceeds the permissible quantity, a comparing computing element 27 sends a closure command to the supply valve 4 to close the valve automatically. Therefore, the quantity of radioactivity of the radioactive material such as dust and iodine collected by the filter 5 never exceeds the permissible quantity.

Description

[Detailed description of the invention] [Object of the invention] (Industrial application field) The present invention relates to a radioactive substance sampling device for sampling radioactive substances such as dust and iodine contained in sampling gas collected from a nuclear reactor etc. .

(Prior art) For example, when performing nuclide analysis of radioactive substances such as dust and iodine contained in sampling gas collected from a nuclear reactor, a radioactive substance sampling device shown in Fig. 5 is generally used to analyze the collected radioactive substances. The filter collects radioactive substances such as dust and iodine contained in the sampled gas.

That is, a pipe 3 through which a sampling gas containing radioactive substances such as dust, iodine, and rare gas flows is provided between a sampling gas sampling port 1 and a return port 2 installed in a nuclear reactor (not shown) or the like. has been done. And sampling port 1
The sampling gas sampled into the pipe 3 is guided to a supply valve 4 formed by an electromagnetic valve, and then passed through a filter 5 consisting of a particle filter 5a for collecting dust and an iodine filter 5b for collecting iodine. By passing through the sampling gas, radioactive substances such as dust and iodine contained in the sampling gas are removed. The sampling gas from which dust and iodine have been removed is manually supplied to a rare gas radioactivity concentration measuring device 8 via a flow rate control valve 6 and a flow meter 7, and the rare gas radioactivity concentration measuring device 8 emits rare gas. The activity concentration is measured. The sampling gas that has passed through the rare gas radioactivity concentration measuring device 8 is returned to the return port 2 via a pump 9.

As shown in the figure, the rare gas radioactivity concentration measuring device 8 includes a gas sampler 8a inserted into the pipe 3, a radiation detector 8b that detects the radiation intensity of the rare gas sampled by the gas sampler 8a, and a radiation detector 8b. Release! n, J tIAFA output 3
and a radioactivity concentration calculator 8c that calculates the radioactivity concentration of the rare gas from the radioactivity intensity output from the radioactivity intensity calculator 8b.

Further, a purge valve 10 for injecting purge gas into the pipe 3 is provided between the supply valve 4 and the filter 5 in the pipe 3. The solenoid valve 4 and the purge valve 10 are switched by an operation switch 11. That is,
The supply valve 4 and the purge valve 10 are not opened at the same time, and are switched between open and closed states by operating the operation switch 11.

Further, the pump 9 is also started and stopped by the operation switch 12. Note that the open time T of the supply valve 4 is determined by the timer 13.

In such a radioactive material sampling device, when the operation mode is set to collection mode, the operation switch 11.
12 operates to open the supply valve 4 and close the purge valve 10. Then, the timer 13 starts counting a predetermined opening time T. During the opening time T, dust and iodine are collected by the particle filter 5a and the iodine filter 5b of the filter 5. At the same time, the rare gas radioactivity concentration measuring device 8 measures the radioactivity concentration of the rare gas. Then, when the opening time T has elapsed, the operation switch 11 is operated to close the supply valve 4 and open the purge valve 10. Then, purge gas is injected into the pipe 3, and the sampling scum containing radioactive substances remaining in the pipe 3 is returned to the reactor through the return port 2 by the pump 9. After all the sampling gas is discharged from the pipe 3, the particle filter 5a and iodine filter 5b of the filter 5 are replaced.

In general, it can be assumed that the component ratios of the radioactive concentrations of dust, iodine, and rare gases contained in sampling gas collected from a nuclear reactor are constant. That is, even if the radioactivity concentration of the entire sampling gas changes, the component ratio of radioactivity concentration among each radioactive substance does not change. Therefore, when the radioactivity concentration Cn of the rare gas is measured by the rare gas radioactivity concentration measuring device 8, the radioactivity concentrations of the remaining dust and iodine are calculated. For example, if the radioactivity concentration component ratio of the dust to the rare gas is Bd, the radioactivity concentration Cd of the dust alone becomes Cd mcn -Bd.

Further, for example, let Qa be the allowable amount of radioactivity contained in the dust collected by the particle filter 5a of the filter 5, let η be the collection efficiency of the filter 5, and let the pipe 3, the opening time T is (1
).

T-Qa / (Cd-F ・77)=Qa / (
Cn −Bd −F ・77) −(1) Therefore,
By opening the supply valve 4 for the opening time T obtained by equation (1), the amount of radioactivity contained in the dust collected by the particle filter 5a of the filter 5 is prevented from exceeding the limit radioactivity mQa. , the safety of workers handling the filter 5 is ensured.

However, even in the radioactive substance sampling device configured as described above, there are still problems as described below that must be solved.

That is, the open time T was calculated manually using equation (1) based on the measurement result Cn in the rare gas radioactivity concentration measuring device 8. On the other hand, the collection work using the dust or iodine filter 5 is often performed several times in succession. Therefore, in many cases, the open time T is simply set using the measurement result Cn obtained by the rare gas radioactivity concentration measuring device 8 before performing a series of collection operations.

Therefore, after setting the -0-opening time T, if the radioactivity concentration Cn of the rare gas contained in the sampling gas increases, the radioactivity concentration of dust and iodine will increase correspondingly to the increase in the radioactivity concentration Cn. Cd.

C1 will also increase. As a result, if the opening time T is constant, there is a concern that the amount of radioactivity contained in the dust and iodine collected by the particle filter 5a and iodine filter 5b of the filter 5 will exceed the above-mentioned allowable radioactivity port Qa. .

As a result, when carrying out nuclide analysis of dust and iodine using the radiation needle M1, it was necessary to take measures to increase the amount of radiation exposure to workers and to reduce the counting efficiency of the nuclide H7 radiometer M1 device.

(Problem to be Solved by the Invention) In this way, in the conventional radioactive material sampling device, since the opening time T of the supply valve is set in advance, the dust collected on the filter 5 and There is a concern that the amount of radioactivity of radioactive substances such as iodine may be constant, for example, exceed the permissible amount of radioactivity, or the amount of radioactivity of collected radioactive materials may be extremely low, causing problems in nuclide analysis and radiation measurement. Ru.

The present invention continuously calculates the amount of radioactivity of the collected radioactive material collected by the filter every unit time, and closes the supply valve when the integrated amount of radioactivity reaches the allowable amount of radioactivity. An object of the present invention is to provide a radioactive substance sampling device that can prevent the amount of radioactivity from exceeding the permissible amount of radioactivity, and can more safely perform nuclide analysis and radiation measurement on the sampled radioactive substances.

[Structure 1 of the invention (Means for solving the problem) In order to solve the above problem, the present invention uses a plurality of radioactive substances such as dust, iodine, and rare gas whose radioactivity concentration component ratio is known in advance. In the pipe line for the sampling gas containing the gas, there is a supply valve for gas supply, a filter for collecting collected radioactive substances such as dust and iodine to be sampled among multiple radioactive substances, and a filter for collecting collected radioactive substances such as dust and iodine to be sampled among multiple radioactive substances. Radioactive substance sampling involves a rare gas radioactivity concentration measurement device that detects the radioactivity concentration of the rare gas, and controls the opening time of the supply valve according to the radioactivity concentration measured by the rare gas radioactivity concentration measurement device. In the device, there is a component setting device that sets the radioactivity concentration component ratio of the sampling gas, and the radioactivity of the collected radioactive material is calculated from the component ratio set by this component setting device and the measurement value of the rare gas radioactivity concentration all determination device. a first computing unit that calculates the concentration; a sampling amount detection means that detects the sampling amount per unit time of the sampling gas flowing into the piping; a second computing unit that calculates the amount of radioactivity of the collected radioactive material contained in the sampling amount from the radioactivity concentration calculated by the computing unit; a collection efficiency setting device that sets the collection efficiency in the filter; A third computing unit that calculates the actual amount of radioactivity of the collected radioactive material from the collection efficiency of the collection efficiency setting device and the radioactivity amount of the second computing unit, and a third computing unit that calculates the actual amount of radioactivity of the collected radioactive material from the collection efficiency of the collection efficiency setting device and the amount of radioactivity of the second computing unit; an integration calculator that integrates the actual amount of radioactivity that is input; an allowable radiation setting device that sets the allowable amount of radioactivity of collected radioactive materials; and a supply valve that and a comparator that sends a closing command to.

(Function) According to the radioactive substance sampling device configured in this way, the radioactivity concentration of the collected radioactive substances collected by the filter is calculated from the component ratio and the radioactivity concentration of the rare gas in the first computing unit. , the amount of radioactivity of the collected radioactive substance is calculated by the second computing unit based on the sampling amount per unit time and the radioactivity concentration.

Furthermore, the actual amount of radioactivity is calculated using the collection efficiency in a third arithmetic unit. Then, the actual amount of radioactivity per unit time is integrated by the integration calculator, and when the integrated radioactivity exceeds the allowable amount of radioactivity, the supply valve is automatically closed.

Therefore, the amount of radioactivity of the dust and iodine radioactive substances collected by the filter does not exceed the permissible amount of radioactivity.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a radioactive substance sampling device according to an embodiment. Components that are the same as those in FIG. 5 are marked with the same numerals, and explanations of overlapping portions will be omitted.

In this embodiment, the radioactivity concentration Cn of the rare gas output from the rare gas radioactivity concentration measuring device 8 is calculated by the first computing unit 2.
1 is manually powered. The component setting device 22 also includes a component ratio Bd of the dust collected by the particle filter 5a to the radioactivity concentration Cn of the rare gas, and a component ratio Bd of the dust collected by the particle filter 5a to the radioactivity concentration Cn of the rare gas of iodine collected by the iodine filter 5b. A ratio Bl is set, and its component ratios Bd and Bi are input to the first arithmetic unit 21. The first calculator 21 converts the radioactivity concentration Cn of the rare gas into the radioactivity concentration Cd (-Cn-Bd) of the dust.
and iodine radioactivity concentration CI (-Cn-BI).

Each radioactivity concentration Cd, Ci calculated by the first calculator 21
is then input to the second arithmetic unit 23.

This second computing unit 23 includes a flowmeter 7 inserted in the piping 3.
The sampling gas flow ff1F per unit time when the supply valve 4 is opened is input from . Therefore, the second computing unit 23 calculates the radioactivity WPd, Pi per unit time contained in each collected radioactive substance of dust and iodine by multiplying by the sampling flow mF. The calculated radioactivity WPd, Pi is sent to the third computing unit 24. This third arithmetic unit 23 includes the filter 5.
Each collection efficiency ηd, η for each collected radioactive substance in
Each collection efficiency η from the collection efficiency setting device 25 where l is set
d and ηl are input. Then, the third arithmetic unit 23 multiplies each radioactivity ff1Pd, Pi by the collection efficiency η, thereby calculating the actual radioactivity amount Rd (
-ηd-Pd) and R1 (-η1-Pl).

The actual radioactivity amounts Rd and R1 outputted from the third calculator 24 each time this unit time elapses are sequentially integrated by the next integrating calculator 26. And the cumulative radioactivity mQd up to now,
Qi is sent to the next comparison calculator 27. The comparison calculator 27 receives the allowable radioactivity m Q a from the allowable radioactivity setter 28 that sets the allowable radioactivity amount Qa of the collected radioactive substances collected in the filter 5 . Then, when the integrated radioactivity ff1Qd, Qi of either one exceeds the allowable radioactivity taQa, the comparator 27 sends a close command to the supply valve 4, closes the supply valve 4, and opens the purge valve 1°. A command is sent to open the purge valve 10.

Also, the alarm 'a29 is sounded.

Furthermore, the timer 13 is reset to the initial value, the integration operation is stopped for the integration calculator 26, and the integrated radioactivity m
Qd and Ql are held in a hold state.

The sampling gas in piping 3 is returned to valve 2 using purge gas.
When the filter 5 is returned to the reactor, the particle filter 5a and the iodine filter b of the filter 5 are taken out. Then, a new particle filter 5a and a new iodine filter 5b are attached to the filter 5. Then, the operation switch 11 is operated to close the purge valve 10 and open the supply valve 4. At the same time, the value of the integration calculator 26 is reset. Then, the next cycle of radioactive material collection begins.

With the radioactive material sampling device configured in this way, after operating the operation switch 11 to open the supply valve 4 and start supplying the sampling gas, the filter 5 within that unit time is The amount of radioactivity of the collected dust and iodine radioactive materials is calculated,
It is integrated every time a unit of time passes, and the integrated radioactivity amounts Qd and Qi contained in the collected radioactive substances collected by the filter at that point in time are calculated. When the cumulative amounts of radioactivity Qd and Ql exceed the allowable amount of radioactivity Qa, the supply valve 4 is automatically closed and the alarm 29 sounds.

Therefore, the radioactivity RQd, Ql contained in the radioactive substance collected by the filter 5 does not exceed the allowable radioactivity Qa. Therefore, when performing nuclide analysis radiation measurement of dust or iodine, it is possible to prevent the radiation exposure of workers from increasing beyond the permissible amount.

Furthermore, there is no need to take measures to reduce the counting efficiency of the nuclide analysis radiation measurement device.

Further, since the amounts of radioactivity Qd and Ql contained in the dust and iodine collected by the filter 5 are approximately constant, the amount of radioactivity does not become extremely small, and the nuclide analysis radiation measurement can be carried out efficiently.

FIG. 2 shows a radioactive material sampling device according to another embodiment of the present invention, and the same parts as in FIG. 1 are given the same reference numerals.

In this embodiment, a sampling flow rate setting device 30 for setting the flow rate of the sampling gas flowing through the pipe 3 is provided as a sampling amount detection means per unit time.
The sampling flow rate setter 30 supplies the sampling EAF per unit time to the second computing unit 23. Even with such a configuration, it is possible to obtain substantially the same effect as the embodiment shown in FIG. 1 described above.

FIG. 3 is a block diagram showing a radioactive substance sampling device according to yet another embodiment of the present invention. The same parts as in FIG. 1 are given the same reference numerals.

In this embodiment, an instruction recorder 31゜32.33.3 displays and records the calculation results obtained by each calculation unit.
There are 4. That is, the radioactivity concentrations Cd and CI of dust and iodine obtained by the first calculator 21 are displayed and recorded by the instruction recorder 31, and the amount of radioactivity per unit time obtained by the second calculator 23 is displayed and recorded. Pd, Pl instruction recorder 3
Display and record in 2. Furthermore, the actual radioactivity mRd, R1 per unit time obtained by the third calculator 24 is displayed and recorded by the instruction recorder 33, and the integrated radioactivity ff1Qd, Qi obtained by the final integration calculator 26 is calculated. Instruction recorder 34
to display and record.

By displaying and recording the calculation results at each stage in this manner, the status of the radioactive substance sampling device can be grasped more accurately.

Figure 4 shows the radioactive material sampling device 3 shown in Figure 1.
5 is a diagram illustrating a state in which several units of 5 are arranged in parallel.

Main pipes 3a and 3b are respectively connected to the sampling port 1a and return port 2a attached to the reactor, and the pipes 3 of each radioactive material sampling device 35 are connected to each of these main pipes 3a and 3b. By connecting a plurality of radioactive substance sampling devices 35 in parallel to the main pipes 3a and 3b in this way, each filter 5 can collect several types of radioactive substances with different integrated radioactivity from the same sampling gas. becomes possible.

[Effects of the Invention] As explained above, according to the radioactive substance sampling device of the present invention, the amount of radioactivity of the collected radioactive materials collected by the filter is continuously calculated every unit time, and the amount of accumulated radioactivity that is not accumulated is calculated. The supply valve is closed when the amount of radioactivity reaches the allowable amount. Therefore, the actual amount of radioactivity contained in the radioactive material collected by the filter can be prevented from exceeding the allowable amount of radioactivity, and nuclide analysis radiation measurement can be performed more safely on the sampled radioactive material.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a radioactive material sampling device according to one embodiment of the present invention, FIGS. 2 and 3 are block diagrams showing a radioactive material sampling device according to another embodiment of the present invention, and FIG. 5 is a diagram showing a system using several traps of the embodiment device, and FIG. 5 is a block diagram showing a conventional radioactive material sampling device. 3... Piping, 4... Supply valve, 5... Filter, 7
...Flowmeter, 8...Rare gas radioactivity concentration measuring device, 9
Pump, 10 Purge valve, 21 First computing unit, 22 Component setter, 23 Second computing unit, 24 Third computing unit, 25... Completion efficiency setting device, 26... Integration calculator, 27... Comparison calculator, 2
8... Allowable radioactivity setting device, 29... Alarm device, 30.
...Sampling flow rate setting device, 31.32, 33.34
...Instruction recorder.

Claims (1)

[Scope of Claims] A supply valve for gas supply, a gas supply valve, and a plurality of radioactive materials are installed in a piping line for a sampling gas containing a plurality of radioactive substances such as dust, iodine, and rare gases whose radioactive concentration component ratios are known in advance. A filter that collects collected radioactive substances such as dust and iodine to be sampled among substances, and a rare gas radioactive concentration measuring device that detects the radioactive concentration of rare gas after the collected radioactive substances have been collected. In a radioactive substance sampling device that controls the opening time of the supply valve according to the radioactivity concentration measured by the rare gas radioactivity concentration measuring device, the radioactivity concentration component ratio of the sampling gas is set. a first computing unit that calculates the radioactivity concentration of the collected radioactive substance from the component ratio set by the component setter and the measured value of the rare gas radioactivity concentration measuring device; sampling amount detection means for detecting the sampling amount per unit time of the sampling gas flowing into the piping path;
a second computing unit that calculates the amount of radioactivity of the collected radioactive substance contained in the sampling amount from the sampling amount detected by the sampling amount detection means and the radioactivity concentration calculated by the first computing unit; a collection efficiency setting device for setting the collection efficiency in the filter; and a collection efficiency setting device for calculating the actual amount of radioactivity of the collected radioactive substance from the collection efficiency of the collection efficiency setting device and the amount of radioactivity of the second computing unit. 3, an integration calculator that integrates the actual amount of radioactivity output from the third calculator every unit time, and an allowable radioactivity setting device that sets the allowable amount of radioactivity of the collected radioactive material. and a comparison calculator that sends a closing command to the supply valve when the integrated amount of radioactivity of the integration calculator exceeds the allowable amount of radioactivity.