JPS6020200A - Monitor device for deposited layer of radioactive gas - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Technical Field of the Invention 1] The present invention relates to a device for monitoring the thickness of a deposited layer of radioactive gas, which detects the thickness of a deposited layer of radioactive gas formed on a member for fixing radioactive gas. Regarding.

[Technical Background of the Invention] Figure 1 shows a radioactive gas immobilization device for immobilizing a radioactive gas such as Kr-85. and a center electrode 2 made of metal such as copper or nickel, and this center electrode 2 coaxially. A discharge wire consisting of a circumferential electrode 3 is formed.

In the figure, the reference numeral 2a indicates a cooling pipe for cooling the center electrode 2, and the reference numeral 3a4 indicates a decompression pipe for reducing the pressure inside the discharge chamber.

In such a radioactive gas immobilization device, as shown in FIG. 2, the center electrode 2 is at ground potential and the circumferential electrode 3 is at -4kV.
R-85 is ionized (kr-85 is held at a high voltage of about
The -85 ions 4 are accelerated by the electric field, and are implanted inside the circumferential electrode 3 and fixed therein.

However, when immobilizing radioactive gas using such a method, the rate at which Kr-85 ions 4 are implanted into the circumferential electrode 3 and immobilized after a certain period of time, and the Kr-
Kr − immobilized on the circumferential electrode 3 by 85 ions 4
The rate at which Kr 85 is ejected reaches equilibrium and Kr -85
immobilization reaches its limit.

Therefore, at this time, as shown in FIG.
A voltage of about 4 kV is applied, and the circumferential electrode 3 is grounded. As a result, the Kr-85 ions 4 hit the center electrode 2 and the metal atoms 6 of the center electrode 2 are sputtered and deposited on the inner periphery of the circumferential electrode 3, and the Kr-85 gas is blown into the circumferential electrode 3. 5 is fixed. When the metal layer is deposited to a certain thickness, the state shown in FIG. 2 is restored, and Kr-85 ions 4 are again implanted into the inner surface of the circumferential electrode 3.

That is, in the radioactive gas immobilization device configured as described above, the above operation is repeated to sequentially grow the deposited layer 7 into which Kr-85 gas has entered, and the Kr-85 gas is immobilized.

"Problems with the Background Art" However, when radioactive gas is immobilized by such a conventional method, there is a problem that there is no suitable means for accurately measuring the thickness of the deposited layer 7 of Kr-85. .

That is, the state of Kr-85 immobilized on the circumferential electrode 3 is unknown, and there is a problem that the safety and reliability of immobilization cannot be guaranteed.

[Object of the invention] The present invention has been made in response to such conventional circumstances,
We aim to provide a radioactive gas deposit layer thickness monitoring device that can easily measure the thickness of the radioactive gas deposit layer and improve the safety and reliability of radioactive gas waste treatment. It is something.

[Summary of the Invention 1 In other words, the present invention provides a radioactive gas deposited layer thickness monitoring device for measuring the thickness of a radioactive gas deposited layer of a radioactive gas fixing member having a radioactive gas deposited layer to which a radioactive gas is fixed. a radiation generating device disposed on the side of the radioactive gas fixing member and radiating beam-shaped radiation to the radioactive gas fixing member; and a radiation generating device disposed opposite to the radiation generating device via the radioactive gas fixing member. a radiation detector that detects radiation that has passed through the radioactive gas fixing member; an amplifier that amplifies the signal detected by the radiation detector; and a signal amplified by the amplifier that is transmitted to the radiation generating device and the radioactive gas fixing member. and a calculation device that inputs the information stored in the storage device and calculates the thickness of the radioactive gas deposited layer formed on the radioactive gas fixing member. This is a radioactive gas deposit layer thickness monitoring device.

[Embodiment of the Invention] The details of the present invention will be described below with reference to an embodiment shown in the drawings.

FIG. 4 shows an embodiment of the radioactive gas deposited layer thickness monitoring device of the present invention, and in the figure, reference numeral 3 indicates a circumferential electrode. Inside this circumferential electrode 3, an extremely thin inner cylinder 8 made of, for example, tungsten, molybdenum, etc., which has good C absorption for X-rays or γ-rays, is disposed. A radiation source 9 of a radiation generating device that generates X-rays or γ-rays is disposed on the left side of the circumferential electrode 30, and this radiation source 9 is focused into a narrow beam by an aperture 9a.

A collimator 10 having a thin slit 10a is disposed on the right side of the circumferential electrode 3 in the figure, facing the radiation source 9. Inside this collimator 10, for example, a germanium detector, a semiconductor detector, a scintillator, a photoelectron detector, etc. A radiation detector 11 consisting of a multiplier tube or the like is housed.

In the figure, numerals 12 and 13 indicate a preamplifier and a linear amplifier that amplify the signal from the radiation detector 11. In the figure, reference numeral 14 indicates a discriminator that discriminates noise from the signal inputted from the linear amplifier 13, and reference numeral 15 indicates a scaler 15 that counts a count value. In the figure, reference numeral 16 includes a storage device that inputs a signal from the scaler 15 and stores this signal, and an arithmetic device that processes this signal and calculates the thickness of the radioactive gas deposition layer 7 fixed to the circumferential electrode 3. A computer 16 is shown.

In the radioactive gas deposition/layer thickness monitoring device configured as described above, the radiation [9] and the collimator 10, which are disposed opposite to each other on both sides of the circumferential electrode 3, are scanned in the direction of arrow A in the figure. At this time, the counting rate of the radiation transmitted through the circumferential electrode 3 changes as shown in FIG. 5 according to the scanning distance.

That is, in FIG. 5, the absorption shoulder a is the signal when the radiation passes through the upper and lower ends of the circumferential electrode 3, and the absorption peak b is the signal when the radiation is absorbed by the radiation inscribed in the circumferential electrode 3. This is the count value when passing the upper and lower ends of the inner cylinder 8 having a large coefficient. And the absorbed waste C is Kr that you want to measure.
It shows the count value when radiation passes through layer 7 of -85.

In this way, the radiation that has passed through the circumferential electrode 3 is converted into an electrical signal by the radiation detector 11, amplified by the preamplifier 12 and linear amplifier 13, noise-discriminated by the discriminator 14, and then by the scaler 15. The count value is counted.

In this manner, the signals counted by the scaler 15 are stored in the memory of the computer 16 along with the information of the counted IC locations.

By one such scan, the total thickness of the deposited layer 7 in the direction perpendicular to the direction of radiation transmission can be approximately ff1ll. Next, the circumferential electrode 3 is rotated by a small angle, for example in the direction of arrow B in the figure, and the same scanning is repeated, and the scaler 15
The generated signals are stored in the storage device of the computer 16.

In this way, after scanning along the circumferential electrode 3,
The computer 16 performs information reconstruction processing using the arithmetic unit of the computer 16 based on the information stored in the storage device of the computer 16, thereby accurately determining the thickness of the deposited layer 7 in two dimensions. can be done.

In the embodiments described above, an example in which krypton was used as the radioactive gas was explained.
Of course, it can also be applied to 'fj19A-)J gases such as helium and tritium.

[Effects of the Invention] As described above, according to the radioactive gas deposited layer thickness monitoring device of the present invention, the thickness of the deposited layer to which radioactive gas is fixed can be accurately measured two-dimensionally. The safety and reliability of waste treatment can be significantly improved compared to conventional methods.

[Brief explanation of the drawing]

Figure 1 is a longitudinal cross-sectional view showing a conventional krypton fixation device;
Figures 2 and 3 are a cross-sectional view of the Knobton immobilization device shown in Figure 1, and Figure 4 (11
J, Block diagram showing the copper gas deposit layer thickness monitoring device, No. 5
The figure is a schematic diagram showing representative measurement data. 2... Center electrode 3... Circumferential electrode 7... Deposit layer 8... ......Inner tube 9...Radiation source 10...Collimator 11...
...... Radiation detector 12 ......
・・・Preamplifier 13・・・・・・・・・・・・Linear amplifier 14・・・・・・・・・Discriminator 15・・・・・・・・・Counter 16・・・・・・
・・・・・・Computer agent patent attorney Suyama
Sa -

Claims (1)

[Claims] (1) In a radioactive gas deposited layer thickness monitoring device that measures the thickness of the radioactive gas deposited layer of a radioactive gas fixing member having a radioactive gas deposited layer to which a radioactive gas is fixed, the side of the radioactive gas fixing member is provided. a radiation generating device that is disposed in the air and emits a beam-shaped radiation to the radioactive gas fixing member; and a radiation generating device that is disposed opposite to the radiation generating device via the radioactive gas fixing member and that passes through the radioactive gas fixing member. a radiation detector that detects a radiation detector; an amplifier that amplifies a signal detected by the radiation detector; and a signal amplified by the amplifier;
a storage device that stores the positional relationship with the JJ gas fixing member; and a calculation device that inputs the information stored in the storage device and calculates the thickness of the radioactive gas deposited layer formed on the radioactive gas fixing member. A radioactive gas deposit layer thickness monitoring device comprising: