KR100449150B1 - A Calibrator Of Neutron Direct Reading Pocket Dosimeter - Google Patents

Abstract

The present invention is provided with a hollow cylinder guide rod in the center of the paraffin-filled cylindrical main shield and provided with a cylinder using a compressed air at the bottom of the neutron source along the inner circumference of the cylinder guide rod to the neutron in the individual exposure dosimeter Neutron personal exposure dosimeter calibrator that is shielded by neutron emission and controlled remotely by a controller. To this end, the main shield is filled with paraffin inside the cylindrical shielding the neutron emission to the outside; A hollow cylinder guide rod provided with a predetermined length from an inner lower portion to an outer upper portion of the main shielding body; A mounting plate provided at a predetermined position of the upper end of the cylinder guide rod and having a plurality of mounting holes for fitting the individual exposure dosimeter along a rim of a circular panel; A cylinder which receives compressed air with an air pipe and vertically transports the neutron source along the inner circumference of the cylinder guide rod; A variable shield provided inside the main shield and having a semi-cylindrical structure, the rotating shaft being rotated by a motor to shield a passage of the hollow cylinder guide rod; And a controller provided with an air valve control switch and a timer for controlling the rising and falling of the cylinder and the driving of the motor.

Description

Neutron Direct Exposure Pocket Dosimeter

The present invention relates to a device for calibrating a neutron personal exposure dose meter, and more particularly, a hollow cylinder guide rod is provided in the center of a paraffin-filled cylindrical main shield, and a cylinder using a compressed air is provided at the bottom of the cylinder guide rod. A neutron personal exposure dosimeter calibrating device that is neutron source rises along the inner periphery, irradiates the neutrons to the individual exposure dosimeter and descends to shield the neutron emission and is remotely controlled by the controller.

Radiometers are generally divided into two types, one of which is an area monitor type, which specifies the radiation dose in a certain area, and the other is a personal exposure dosimeter which measures the radiation dose to a human body. .

In particular, the so-called Pocket Doismeter (PD), which is classified as a direct exposure dosimeter, is manually performed and has many difficulties such as weakness in the radiation protection of the calibrator and prolongation of the calibration time.

These direct reading pocket dosimeters are the most common and widely used equipments because they are inexpensive, simple, lightweight, and can instantly read the exposure dose in the field as a radiation protective instrument for the human body.

The calibration procedure of the conventional personal exposure dosimeter first reads the personal exposure dosimeter requested by the eye with a PD Recharger and makes a zero adjustment. A neutron was irradiated to the individual exposure dosimeter using a method of directly removing the Am-Be neutron source by hand from the neutron source storage tank located in the neutron irradiation room and moving it to the center of the personal exposure dose meter.

In this case, the personal exposure dosimeter is divided into two types, one for measuring a thermal neutron and one for measuring fast neutrons and gamma rays.

First, a personal exposure dosimeter for measuring thermal neutrons is a fast neutron released by inserting an Am-Be neutron source into a polyethylene retarder with a radius of 10 cm. To examine the thermal neutrons.

In addition, personal exposure dosimeters that measure fast neutrons and gamma rays are directly irradiated with personal exposure dosimeters by releasing Am-Be neutron sources.

In addition, the calibration cycle of the direct exposure type personal exposure dosimeter required by the Korea Metrology Association is recommended as 6 months. The use of neutrons in the industry is diverse, and nuclear power plants are the most frequently used.

According to the current situation of the domestic nuclear industry, the use of radiation measurement is increasing in the process of covering 50% of domestic electricity production by nuclear power by national policy. In addition, the number of radiation users in the industry is increasing by 15% every year, and the demand for the use and calibration of the radiometer is increasing rapidly.

Therefore, a calibration automation development project is very necessary to meet these demands. In particular, the development of a calibration automation device for neutron personal exposure dosimeters that are manually calibrating can be of great necessity and relevance, including the efficiency of radiation protection and calibration service work and the reduction of calibration time.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and the first object of the present invention is to employ a cylinder using a compressed air, so that there is almost no failure and the position is easily adjusted so that the neutron is always constantly positioned. It is to provide a neutron personal exposure dosemeter calibration device that can be calibrated remotely without having to be located in the calibration room by the accurate time interval and long time neutron irradiation with a timer and a controller.

In addition, the second object of the present invention is to easily attach and detach polyethylene spheres, so that both thermal neutrons, fast neutrons, and gamma-ray personal exposure dosimeters can be calibrated, and by using an Am-Be neutron source having a very long half-life (432 years). It is to provide a device for calibrating neutron personal exposure dosimeters, which has an almost infinite service life and a very small reduction in neutron emission, which is easy to calculate uncertainty.

In addition, the third object of the present invention is to improve the accuracy of calibration, to prevent radiation exposure of the calibration worker, and to automate the calibration of the radiation personal exposure dosimeter which is in increasing use, neutron personal exposure dosimeter calibration that can facilitate the external calibration service To provide a device.

Such, the object of the present invention, the main shield to shield the neutron emission to the outside is filled with paraffin in a cylindrical shape;

A hollow cylinder guide bar provided at a central portion of the main shield and provided at a predetermined length from an inner lower portion to an outer upper portion of the main shield;

A mount having a plurality of mounting holes provided at a predetermined position at an upper end of the cylinder guide rod and configured to mount the personal exposure dose meter along a rim of a circular panel;

A cylinder configured at a lower end of the cylinder guide rod and receiving compressed air with an air pipe to move the neutron source up and down along the inner circumference of the cylinder guide rod;

A variable shield provided in the middle of the cylinder guide rod provided inside the main shield and having a semi-cylindrical structure, the rotating shaft rotated by a motor to shield the passage of the hollow cylinder guide rod after the neutron source descends. ; And

The controller is provided with an air valve control switch and a timer for controlling the rising and falling of the cylinder and the driving of the motor.

In addition, a polyethylene sphere is further inserted into the upper end of the cylinder guide rod to change the neutron emitted from the neutron source into a thermal neutron.

In addition, the variable shield is characterized in that it is further provided with a semicircular guide groove and a protruding rod that is rotated along the guide groove is provided on one side of the upper end of the variable shield so as to operate limited to a rotation radius of 180 °.

Other objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and the preferred embodiments associated with the accompanying drawings.

1 is a perspective view of a device for calibrating a neutron personal exposure dose meter of an embodiment according to the present invention;

Figure 2a is a cross-sectional view of the device for calibrating the neutron personal exposure dose meter according to the present invention,

Figure 2b is a plan view of the neutron personal dose dosimeter calibration apparatus according to the present invention,

3 is a perspective view of a device for calibrating a neutron personal exposure dose meter of another embodiment according to the present invention.

<Description of the symbols for the main parts of the drawings>

10: calibration device 20: individual exposure dosimeter

30: main shield 32: paraffin

40: cylinder guide rod 50: mounting table

52: mounting hole 60: cylinder

62 air pipe 70 neutron source

80: variable shield 82: rotating shaft

85: motor 86: protrusion bar

88: guide groove 90: controller

92: air valve control switch 94: timer

100: polyethylene ball

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

The apparatus for calibrating a neutron personal exposure dose meter of the present invention is a device for finding a calibration constant value by finding a measurement error with respect to a standard amount of a measured value indicated by the personal exposure dose meter by irradiating a neutron having a standard amount on the personal exposure dosimeter. The personal exposure dosimeter displays the value accumulated according to the amount of neutrons to be irradiated on a scale.

1 is a perspective view of a neutron personal exposure dose meter calibration apparatus according to an embodiment of the present invention, Figure 2a is a cross-sectional view of the neutron personal exposure dose meter calibration apparatus according to the present invention, Figure 2b is a neutron personal exposure dosimeter calibration apparatus according to the present invention Top view of the.

As shown in Figures 1 and 2a, 2b, the personal exposure dosemeter calibration apparatus 10 according to the present invention is provided in the central portion of the main shield 30 made of a cylindrical shape, the inside of the main shield 30 A hollow cylinder guide rod 40 is provided on the outer upper portion of the main shield 30 from a lower portion as a predetermined length.

An upper end of the cylinder guide rod 40 is provided with a mounting table 50 of the individual exposure dosimeter 20 around the cylinder guide rod 40. The mounting table 50 is a circular panel, and a plurality of mounting holes 52 are formed to mount the personal exposure dose meter 20 along the edge thereof.

The cylinder guide rod 40 extends into the cylindrical main shield 30 provided with the cylinder guide rod 40, and the cylinder 60 is provided at the lower end of the cylinder guide rod 40. do.

The cylinder 60 is to transport the neutron source 70 up and down, the neutron source 70 is provided at the upper end of the cylinder 60 is vertically moved along the inner circumference of the cylinder guide rod 40 hollow It is possible. The cylinder 60 is operated by using compressed air, and is provided with an air pipe 62 for outflow and inflow of compressed air to the outside of the main shielding body 30.

In addition, since the neutron source 70 uses an Am-Be neutron source 70 having a very long half-life (432 years), the service life is almost infinite, and the amount of reduction in neutron emission is very small, which is very easy to calculate the uncertainty. have.

The main shield 30 is filled with a paraffin 32 for preventing the emission of neutrons from the neutron source 70. That is, when the neutron source 70 is not calibrated, the neutron source 70 is installed at the center of the cylindrical shield filled with paraffin 32 so as not to be released to the outside.

In addition, the intermediate portion of the cylinder guide rod 40 provided in the cylindrical main shield 30 is rotated to prevent the release of neutrons along the cylinder guide rod 40 after the neutron source 70 is lowered. This possible Cylindrical Polyethylene Variable Shield 80 was fitted.

The variable shield 80 is a semi-cylindrical structure having a rotating shaft 82 at the center and the rotating shaft 82 is rotated by a motor 85 to shield or open the passage of the hollow cylinder guide rod 40. can do. At this time, the rotation shaft 82 is protruded to the upper portion of the main shield 30 and the motor 85 is mounted on one side of the upper portion of the main shield 30 so that the rotation shaft 82 and the motor 85 is a chain or It is connected as a belt to transmit the driving force.

The variable shield 80 is provided in the semicircular guide groove 88 and the upper end side of the variable shield 80 so as to operate at a limit of the rotation radius of 180 ° protruding rods that rotate along the guide groove (88) ( 86).

In addition, a controller 90 connected to an air pipe 62 for driving the cylinder 60 and a motor 85 for driving the variable shield 80 is provided to remotely control the cylinder ( 60 and the motor 85 can be driven.

That is, the controller 90 is provided with an air valve control switch 92 and a timer 94 to raise the neutron source 70 attached to the upper end of the cylinder 60 by using a compressed air to the timer 94. It is safe to control the neutron irradiation time by remotely controlling the calibration start and stop of the personal exposure dosimeter 20.

In particular, the connecting passage in the upper portion of the neutron source 70 while entering the center of the shield by the variable shield 80 made of cylindrical polyethylene on the cylinder of the main shield 30 filled with paraffin 32 It is safe to prevent the neutron coming out to the phosphorus cylinder guide rod 40.

Here, the neutron source 70 enters the interior and at the same time a signal from the relay switch is sent to the controller 90 so that the variable shield 80 rotates 180 ° to completely block the intermediate passage of the cylinder guide rod 40. .

In addition, the neutron personal exposure dosimeter calibration device 10 can be a simple conversion of the thermal neutron personal exposure dosimeter 20 and the fast neutron and gamma radiation personal exposure dosimeter 20.

3 is a perspective view of a device for calibrating a neutron personal exposure dose meter of another embodiment according to the present invention.

As shown in Figure 3, by inserting the polyethylene sphere 100 in the cylinder guide rod 40 protruding to the upper portion of the mounting 50 can neutron emitted from the neutron source 70 have.

This is because the calibration device of one embodiment shown in FIG. 1 generally makes the calibration of the fast neutron and gamma-ray personal exposure dosimeters 20, while the calibration device of the other embodiment shown in FIG. A correction is made.

In general, thermal neutrons must be thermal neutrons by colliding neutrons with hydrogen atoms, causing them to lose energy. Polyethylene, which contains a lot of hydrogen atoms, is used as such a material and is called a moderator. Therefore, the polyethylene sphere 100 generates thermal neutrons as a polyethylene material containing a lot of hydrogen atoms.

That is, the neutron collides with the hydrogen atom to lose energy, thereby thermally neutronizing to generate thermal neutrons. The polyethylene sphere 100 converts the neutrons emitted from the neutron source 70 into thermal neutrons. As a result, the apparatus for calibrating the thermal neutron personal exposure dosimeter 10 which generates thermal neutrons and irradiates the thermal neutron personal exposure dosimeter 20 is obtained.

In particular, everyone who enters the reactor periphery of a nuclear power plant is required to wear a thermal neutron personal exposure dosimeter (20). The core of a nuclear reactor containing uranium fuel rods, which emit neutrons from nuclear power plants, is immersed in water in a pool for neutron shielding, which is why neutrons leaking out of the water are likely to be thermal neutron regions.

As described above, the calibration device 10 of the neutron personal exposure dose meter according to the present invention employs a cylinder 60 using compressed air, so that there is almost no failure and the position is easily adjusted so that the neutron is constantly positioned. The controller 90 is provided with a timer 94 to enable accurate time intervals and long-term neutron irradiation and to enable calibration remotely without the calibration worker being located in the calibration room.

In addition, it is possible to calibrate both the thermal neutron, the fast neutron, and the gamma-ray personal exposure dosimeter 20 by simply attaching and detaching the polyethylene sphere 100, and the Am-Be neutron source 70 having a very long half-life (432 years) The use of this method provides a neutron personal exposure dosimeter calibrator 10, which has an almost indefinite service life and a very small decrease in neutron emission, which is easy to calculate uncertainty.

In addition, by increasing the accuracy of the calibration, preventing the radiation exposure of the calibration worker and by automating the calibration of the radiation personal exposure dosimeter 20 that is increasing in use, it is possible to facilitate the external calibration service.

Although the present invention has been described in connection with the above-mentioned preferred embodiments, various other modifications and variations may be made without departing from the spirit and scope of the invention. Accordingly, it is intended that the appended claims cover such modifications and variations as fall within the true scope of the invention.

Claims (3)

Paraffin 32 is filled in a cylindrical shape to the main shield 30 to shield the neutron emission to the outside; A hollow cylinder guide rod 40 provided at a central portion of the main shield 30 and provided at a predetermined length from an inner lower portion to an outer upper portion of the main shield 30; Mounting unit 50 is provided at a predetermined position of the upper end of the cylinder guide rod 40 and a plurality of mounting holes 52 are formed to be fitted to the individual exposure dosimeter 20 along the rim as a circular panel; A cylinder 60 configured at the lower end of the cylinder guide rod 40 and receiving a compressed air to the air pipe 62 to vertically transfer the neutron source 70 along the inner circumference of the cylinder guide rod 40; The rotating shaft 82 provided at the center portion of the cylinder guide rod 40 provided in the main shield 30 and rotated in the center of the semi-cylindrical structure is rotated by driving by the motor 85 so that the neutron source 70 A variable shield (80) for shielding the passage of the hollow cylinder guide rod (40) after the descending; And And a controller (90) provided with an air valve control switch (92) and a timer (94) to control the rise and fall of the cylinder (60) and the driving of the motor (85). Neutron personal exposure dosimeter calibration device. The apparatus of claim 1, wherein a polyethylene sphere (100) is further inserted into the upper end of the cylinder guide bar (40) to change the neutrons emitted from the neutron source (70) into thermal neutrons. According to claim 1, The variable shield 80 is provided with a semicircular guide groove 88 and the upper end side of the variable shield 80 to operate at a radius of rotation of 180 ° the guide groove 88 Neutron personal exposure dosimeter calibration device, characterized in that is further provided with a protruding rod (86) to rotate along.