JPH09101372A - Radioactive ray shielding structure of radioactive ray measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the dimension of a radioactive ray shielding structure for reducing the weight and to reduce the raw material cost and machining cost by arranging an inner shielding body consisting of a radioactive ray shielding member in the rear of a sensor in a detector case. SOLUTION: An object 2 to be measured is, for example, a filtering paper 22 for capturing dust placed on a measurement dish 21 and a semiconductor sensor 4 and an amplification transmission circuit 5 for amplifying and shaping the detection signal before outputting is stored in a detector case 6 in a radioactive ray detector 3. An inner shielding body 11 made of, for example, lead is provided in the rear region of the sensor 4 within the detector case 6. Since the detection signal of a semiconductor radioactive ray detection element 41 is extremely weak, a head amplifier 42 in a simple circuit configuration is adhered to a substrate where the detection element 41 is placed. When the radiation detector 3 is placed to a shielding container 12, the inner shielding body 11 is connected to the shielding member of the detector insertion hole part of the shielding container 12, thus constituting the radioactive ray shielding structure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation shielding structure used for shielding environmental radiation that interferes with measurement in a radioactivity measuring device.

[0002]

2. Description of the Related Art Radiation emitted by radioactive substances as to the amount of extremely small amounts of radioactive substances contained in wastewater and exhaust gas from radiation facilities or the amount of radioactive substances contained in atmospheric dust collected on filter paper. In a radioactivity measuring device that measures by detecting, the radiation emitted by the radioactive substance to be measured is extremely weak, so background radiation (BG that naturally exists at the location where the radioactivity measuring device is installed interferes with the measurement). ).

Therefore, in order to reduce the background radiation so that only the radiation emitted by the object to be measured can be captured by the detector, in a radioactivity measuring device for measuring a very small amount of radioactivity, the object to be measured and the radiation are measured. The detector and the radiation shielding structure, which is a thick container made of radiation shielding material such as lead and iron, are housed in the radiation shielding structure for measurement, and FIG. 2 shows the concept of the radiation shielding structure based on the conventional technique. .

In FIG. 2, reference numeral 2 is a measurement target of radioactivity consisting of, for example, a sample 22 contained in a sample pan 21 and reduced in weight by ashing. The sensor 4 and the sensor 4 for detecting radiation and transmitting an electric signal. The sensor 4 of the radiation detector 3 including an amplification transmission circuit that amplifies and outputs the detection signal is the measurement target 2
It is placed so as to face the radiation shielding structure 1 made of a lead member having a wall thickness of, for example, about 100 mm.

[0005]

A conventional radiation shielding structure in which a radiation detector and a measurement objective are housed as a whole is formed of a thick wall shielding member that secures an internal space for housing an object to be accommodated. Therefore, the volume dimension becomes large, and a large amount of the shielding member is required, resulting in a heavy weight and the problem that the device cannot be easily moved is inherent.

An object of the present invention is to provide a radiation shielding structure that effectively shields BG radiation with a small amount of shielding member, and solves the problems in the radiation shielding structure based on the above-mentioned prior art.

[0007]

SUMMARY OF THE INVENTION In order to effectively shield BG radiation with a small amount of shielding member, in the present invention, the radiation shielding structure of the radiation measuring device detecting and measuring section is placed in the detector case of the radiation detector. An internal shield made of a radiation shielding member arranged in the rear portion of the sensor, and a shield provided with an insertion hole for mounting the radiation detector made of a radiation shielding member for accommodating a sensor portion of the detector and an object to be measured. When the radiation detector is attached to the detector insertion hole of the shielded container, the internal shield placed inside the detector case is connected to the wall of the detector insertion hole area of the shielded container. Make the shielding structure valid.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A radiation detector used in a radioactivity measuring apparatus amplifies a sensor that captures radiation and emits an electric signal and a detection signal emitted by the sensor, and outputs the amplified signal as a signal suitable for transmission. It is composed of two elements of an amplification transmission circuit, and these two elements are integrally housed in a detector case for the purpose of preventing ingress of moisture and noise and convenience of mounting.

Meanwhile, while the sensor is sensitive to radiation, the direct radiation sensitivity of the amplification transmission circuit is much lower than that of the sensor. Therefore, in the present invention, a shielding member made of a heavy metal such as lead is arranged in a region surrounding a portion other than the measurement window facing the measurement object of the sensor in the detector case of the radiation emitter, and the shielding in the detector case is arranged. A radiation shielding structure is configured by providing a shielding container that accommodates the measurement target so as to be connected to the member.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a cross section of one embodiment of a radiation shielding structure constructed by disposing a radiation shielding member in a detection case of a radiation detector having a semiconductor radiation detecting element as a sensor according to the present invention. In FIG. 1, 2 is a measuring object such as a filter paper 21 that collects dust placed on a measuring dish 22, and 3 is a sensor 4 which is a semiconductor radiation detecting element and an amplification shaping of the detection signal of the sensor 4. Amplification and transmission circuit 5
Is a radiation detector housed in a detector case 6, and a detector internal shield 11 made of lead or the like is arranged in a region behind the sensor 4 of the detector case 6. Since the detection signal of the semiconductor radiation detection element 41 is extremely weak, a head amplifier 42 having a simple circuit configuration may be provided in close contact with the mounting substrate of the detection element 41. In this case, the detection element 41 and the head amplifier 42 are It is considered that the sensor 4 is configured by. Reference numeral 12 denotes a shielding container provided with an insertion hole for the radiation detector 3. When the radiation detector 3 is mounted on the shielding container 12, the inner shield 11 is connected to the shielding member of the detector insertion hole portion of the shielding container 12. The radiation shielding structure 1 is configured as a result.

[0011]

According to the present invention, an internal shield is provided in the radiation detector, and when the detector is mounted on the shield container, the internal shield and the shield container wall are connected to form a radiation shield structure. As a result, the size is reduced and the weight is reduced as compared with the radiation shielding structure that houses the entire detector. As a result, the portability of the radiation shielding structure is improved, and the strength requirement for the structure such as the desk and the table to be installed and installed is reduced.
Since the amount of the shielding member used is also small, the effect of reducing the raw material cost and the processing cost can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of a radiation shielding structure according to the present invention.

FIG. 2 is a sectional view of a conventional radiation shielding structure.

[Explanation of symbols]

 1 Radiation Shielding Structure 11 Inner Shielding Body 12 Shielding Container 2 Object to be Measured 21 Sample Dish 22 Sample 3 Radiation Detector 4 Sensor 41 Semiconductor Radiation Detection Element 42 Head Amplifier 5 Amplification Transmission Circuit 6 Detector Case 7 Connector 71 Cable 8 Detection Measurement Department

Claims (2)

[Claims] 1. A radiation shielding structure which constitutes a detection and measurement unit of a radioactivity measuring apparatus, comprising a radiation shielding member which is arranged at a rear portion of a sensor in a detector case of a radiation detector which constitutes the detection and measurement unit. And a shielding container provided with an insertion hole for mounting the radiation detector, which is a radiation shielding member for accommodating a sensor portion of the radiation detector and an object to be measured. The radiation shield structure is configured such that the inner shield disposed inside the detector case when attached to the detector insertion hole of the shielding container is connected to the wall body in the detector insertion hole region of the shield container. A radiation shielding structure for a radioactivity measuring device, comprising: 2. The radiation detector is a semiconductor radiation detector composed of a semiconductor sensor and a widening circuit, and an internal shield is arranged between the semiconductor sensor and the widening circuit. Radiation shielding structure of radioactivity measuring device.