Portable beta-ray irradiator for field calibration of photoluminescence fluorescence dosimeterTechnical Field
The invention belongs to the technical field of ionizing radiation dose monitoring, and particularly relates to a portable beta-ray irradiator for field calibration of a photoluminescence fluorescence dosimeter.
Background
The advantages of the photoluminescence fluorescence dosimeter (OSLD) such as stable signal, high sensitivity, wide measuring range and repeatable measurement become an excellent personal dosimeter, and the OSLD is widely applied to the fields of environmental, medical and space radiation monitoring at present. In order to ensure the accuracy of dose monitoring, the fluorogenic dosimeter needs to be calibrated before use, and the common calibration method is as follows: the dosimeter using unit sends the dosimeter to the detecting unit, the detecting unit irradiates by adopting a standard radiation field, then the using unit carries out measurement and reading, and calibration and correction are carried out through the difference between the measurement and reading value and the reference value.
However, for special environments such as radiation dose monitoring during long-term operation of a space station, personal dose monitoring during a nuclear power ocean mission, and dose monitoring under a nuclear emergency, the OSLD and the readout device for personal or environmental monitoring need to be followed for a long time, calibration in a time-scale laboratory is difficult, and reliability of the monitoring value is difficult to guarantee. Therefore, a field calibration device needs to be developed to solve the OSLD tracing problem and ensure the reliability of dose monitoring.
Disclosure of Invention
The invention aims to design a portable beta irradiator for OSLD field calibration, which traces the dosage rate of a reference point of the portable beta irradiator to a standard radiation field by transmitting a standard dosimeter, and then carries the portable beta irradiator to the field to carry out field calibration on the OSLD, thereby solving the problem of the reliability of dosage monitoring under the special environment.
In order to achieve the above object, the technical scheme adopted by the invention is a portable beta-ray irradiator for field calibration of a photoluminescence fluorescence dosimeter, which is used for irradiating an OSLD, wherein the OSLD is the photoluminescence fluorometer and comprises a straight-plate type support provided with a transmission window, an annular shield and a shield plate, wherein the annular shield and the shield plate are oppositely arranged on the two side surfaces of the support, the transmission window is positioned between the annular shield and the shield plate, a radioactive source support is arranged in the annular shield, a radioactive source is arranged in the radioactive source support, an irradiation chamber is arranged between the shield plate and the transmission window, a shutter is arranged between the transmission window and the irradiation chamber, and a sample disc for conveying the OSLD into the irradiation chamber is also included.
Furthermore, the radioactive source support is arranged on the position of the circle center in the annular shielding body in a replaceable mode.
Furthermore, the transmission window is made of beryllium materials, and the radioactive source support is made of brass, aluminum alloy, stainless steel or other copper materials capable of playing a role in shielding.
Furthermore, the annular shielding body is made of brass, aluminum alloy, stainless steel or other copper materials capable of playing a shielding role.
Further, the shutter is controlled to be opened and closed through an electromagnetic valve, the electromagnetic valve is arranged on the support, and the time control precision of the electromagnetic valve on the shutter is 0.01 s.
Further, the radioactive source is an electrodeposition plane source with controllable activity, and the radioactive source is a beta-ray radioactive source.
Furthermore, the shielding plate is made of lead.
Further, the transmission window is located at the center of the annular shield.
Furthermore, the shutter is made of brass, aluminum alloy, stainless steel or other copper materials capable of playing a role in shielding.
The invention has the beneficial effects that:
1. the portable beta-ray irradiator provided by the invention has the overall size not more than 150mm multiplied by 80mm multiplied by 50mm and the weight not more than 3kg, can be conveniently carried to the site to calibrate the OSLD, and solves the problem of site calibration under the special environment of the OSLD.
2. The movable radioactive source bracket is designed, radioactive sources of different types and activities can be replaced at any time according to actual needs, and the application range of the portable beta-ray irradiator is expanded.
3. The electro-deposition plane source with the controllable active region is designed, so that the ray direction in the irradiation chamber tends to be collimated, and the uniformity of the dose rate of the irradiation chamber is improved.
4. A unique shield structure is designed: lead shielding is adopted right below the radioactive source, and brass shielding is adopted in other directions. The portable beta-ray irradiator has the advantages that the whole volume and weight of the portable beta-ray irradiator are reduced while the radiation protection requirement is met, and the portable requirement is met.
5. A brass shutter for blocking rays is designed, the electromagnetic valve is used for controlling the shutter to act, the irradiated dose is accurately calculated by recording the time interval of the on-off of the shutter, and the deviation caused by dose rate change is reduced.
Drawings
FIG. 1 is a schematic diagram of a portable beta ray irradiator for field calibration of a fluorogenic dosimeter according to an embodiment of the invention;
FIG. 2 is a sectional view A _ A of a portable beta ray irradiator for field calibration of a fluorogenic dosimeter according to an embodiment of the invention;
in the figure: the device comprises a 1-annular shield, a 2-shutter, a 3-bracket, a 4-sample disc, a 5-electromagnetic valve, a 6-radioactive source bracket, a 7-fastening device, an 8-transmission window, a 9-radioactive source clamping groove and a 10-shielding plate.
Detailed Description
The invention is further described below with reference to the figures and examples.
As shown in fig. 1 and fig. 2, the portable beta-ray irradiator for field calibration of a fluorogenic dosimeter provided by the invention is used for irradiating an OSLD (the OSLD is a fluorogenic dosimeter), and comprises an annular shielding body 1, a shutter 2, a bracket 3, a sample disc 4, anelectromagnetic valve 5, aradioactive source bracket 6, a fastening device 7, atransmission window 8, a radioactivesource clamping groove 9, ashielding plate 10 and other parts.
The bracket 3 is of a straight plate type, and the annular shield 1 and theshield plate 10 are oppositely arranged on the two side surfaces of the bracket 3. The annular shielding body 1 is made of brass, aluminum alloy, stainless steel or other copper materials capable of playing a shielding role; the material of theshielding plate 10 is lead.
Thetransmission window 8 is arranged on the support 3, thetransmission window 8 is positioned between the annular shield body 1 and theshield plate 10, and thetransmission window 8 is made of beryllium material (also called beryllium window). Thetransmission window 8 is located in the center of the annular shield 1.
Theradioactive source bracket 6 is arranged at the position of the circle center in the annular shielding body 1, and a radioactive source is arranged in theradioactive source bracket 6. Theradioactive source support 6 is arranged in the annular shielding body 1 in a replaceable mode. The material of theradioactive source bracket 6 is brass, or aluminum alloy, or stainless steel, or other types of copper materials capable of playing a shielding role. The radioactive source is an electrodeposition plane source with controllable activity, and the radioactive source is a beta-ray radioactive source.
An irradiation chamber is provided between theshielding plate 10 and thetransmission window 8, and the shutter 2 is provided between thetransmission window 8 and the irradiation chamber. The shutter 2 is made of brass, aluminum alloy, stainless steel or other copper materials capable of playing a role of shielding.
A sample tray 4 is provided on one side of the irradiation chamber for transporting the OSLD into the irradiation chamber.
The shutter 2 is controlled to be opened and closed by anelectromagnetic valve 5, theelectromagnetic valve 5 is arranged on the bracket 3, and the time control precision of theelectromagnetic valve 5 on the shutter 2 is 0.01 s.
The invention provides a portable beta-ray irradiator for field calibration of a photoluminescence fluorescence dosimeter, which is designed by the following special design:
1) radiation source part
Electroplating a beta-ray radioactive source with certain activity onto an aluminum alloy substrate by an electrodeposition method to form an electroplating source, and measuring the surface emissivity of the electroplating source by a 2 pi multi-wire proportional counter. Then the electroplating source is fixed on aradioactive source bracket 6 made of copper material, and theradioactive source bracket 6 is loaded on the portable beta-ray irradiator when in use.
2) Irradiated part
The irradiation part comprises atransmission window 8, an irradiation chamber, ashielding plate 10 and an irradiator matrix from inside to outside. When the OSLD is used, the OSLD is placed in an irradiation chamber for irradiation, and the beta ray dose rate of a reference point of the irradiation chamber is calibrated through a beta ray standard responsible field. Wherein thetransmission window 8 is positioned between the irradiation chamber and the radioactive source and is used for preventing an irradiated sample (OSLD) from contacting the radioactive source, the annular shielding body 1 is arranged above thetransmission window 8, and theshielding plate 10 is arranged below the irradiation chamber and is used for preventing radiation leakage.
3) Control section
The change of the 'unirradiated/irradiated' state of the OSLD is realized by the reciprocating motion of a shutter 2 between thetransmission window 8 and the irradiation chamber, that is, when the shutter 2 moves to the position right below thetransmission window 8, the beta rays can be completely blocked, so that the OSLD is in the unirradiated state, and after the shutter 2 is moved away, the OSLD is under the irradiation of the beta rays. The operation of the shutter 2 is controlled by thesolenoid valve 5, and the radiation dose is changed by controlling the time of the OSLD in the beta ray irradiation, and the accuracy of the time control is 0.01 s.
Finally, the practical application of the portable beta-ray irradiator for field calibration of the photoluminescence dosimeter provided by the invention is illustrated.
Prepared by electrodeposition90Sr-90The Y radiation source is loaded onto theradiation source holder 6 with an activity of about 3 MBq. The dosage rates around the portable beta-ray irradiator are measured by a 451P surveying instrument, and the values are all less than 0.25 mu Sv/h and are at the environmental level. The reference point of the portable beta-ray irradiator is determined by transmitting a standard dosimeter and a beta-ray reference radiation field, the dosage rate of an irradiation chamber of the portable beta-ray irradiator is (0.060-0.083) mGy/s, and the standard uncertainty is 6.9%. The OSLD of the same batch was placed in the same position of the irradiation chamber of the portable β -ray irradiator and irradiated with an irradiation dose repeatability of 3.9% (n ═ 10).
The device according to the present invention is not limited to the embodiments described in the specific embodiments, and those skilled in the art can derive other embodiments according to the technical solutions of the present invention, and also belong to the technical innovation scope of the present invention.