Optical fiber neutron detector

Abstract

The utility model relates to the technical field of neutron detection, in particular to an optical fiber neutron detector, which comprises a probe, a first optical fiber, a joint mechanism, a second optical fiber and an electronics system, the first optical fiber is arranged at one end of the probe, the second optical fiber is arranged at one end of the first optical fiber, and the first optical fiber and the second optical fiber are connected through the joint mechanism. The optical fiber neutron detector is small in size, simple in structure, resistant to irradiation, resistant to interference and high in sensitivity, thermal neutron detection can be achieved when the material of the probe part is set to be 6LiF, fast neutron detection can be achieved when the material of the probe part is set to be 232 Th, the optical fibers are replaced with the metal coating optical fibers, and the cost is reduced. Real-time online detection under high-temperature and high-pressure conditions is realized by matching with high-temperature optical cement, the optical fiber is distributed in a manner of spirally winding the main core with the auxiliary core and is tightly combined, and macro-bending loss is reduced by matching with the stainless steel metal ring on the surface of the optical fiber.

Description

TECHNICAL FIELD

[0001] The utility model belongs to neutron detection technical field, concretely relates to a kind of optical fiber neutron detector. BACKGROUND

[0002] Optical fiber neutron detector is a kind of advanced equipment combined with optical fiber technology and neutron detection technology, is widely used in nuclear physics, nuclear medicine, industrial nondestructive testing, reactor detection and security inspection etc., utilizes optical fiber to transmit neutron signal to remote reading device, with high sensitivity, low background noise and good spatial resolution etc.Advantages.

[0003] Generally, when optical fiber neutron detector detects, the probe of optical fiber neutron detector is directly exposed to high temperature and high dose radiation environment, in long-term use process, it can cause detection accuracy to drop, even damage problem, while the probe structure of existing optical fiber neutron detector is complex, bulky, and when the probe of optical fiber neutron detector is damaged, it is difficult to quickly replace, which affects detection efficiency. UTILITY MODEL CONTENTS

[0004] The utility model aims at solving above -mentioned problem and provides a kind of optical fiber neutron detector with simple structure and reasonable design.

[0005] The utility model realizes the above-mentioned purpose by the following technical scheme:

[0006] A kind of optical fiber neutron detector, including probe, one optical fiber, joint mechanism, second optical fiber and electronics system, the probe one end is provided with one optical fiber, one optical fiber one end is provided with second optical fiber, and one optical fiber and second optical fiber are connected by joint mechanism, second optical fiber one end is connected with electronics system.

[0007] The probe includes protective shell and neutron scintillator, neutron scintillator is arranged in the protective shell, neutron scintillator is connected with second optical fiber, and high temperature sealant is filled outside the connecting place of protective shell and second optical fiber, and neutron scintillator is cylindrical.

[0008] Preferably, the joint mechanism includes a plug-in sleeve fixedly sleeved on the first optical fiber and a fixed sleeve fixedly sleeved on the second optical fiber, the plug-in sleeve is hollow, and the core of the first optical fiber is located in the plug-in sleeve, the fixed sleeve is fixedly sleeved with a fixing ring outside, two guide rods are fixedly connected to the side of the fixing ring close to the plug-in sleeve, two positioning holes are formed on the side of the plug-in sleeve close to the fixing ring, and the guide rods are slidingly connected in the positioning holes.

[0009] Preferably, the side of the fixed sleeve close to the plug-in sleeve is rotationally connected with a threaded sleeve, the side of the plug-in sleeve away from the first optical fiber is fixedly connected with a threaded cylinder, and the threaded sleeve is threadedly connected to the threaded cylinder.

[0010] Preferably, two fixing plates are symmetrically fixedly connected to the side of the fixing ring near the plug sleeve, and a second locking block is fixedly connected to the side of each fixing plate away from the fixing ring. Two L-shaped arms are symmetrically fixedly connected to both sides of the plug sleeve, and a first locking block that engages with the second locking block is fixedly connected to the side of each L-shaped arm near the fixing ring. Rubber pads are fixedly connected to the edges of both sides of the plug sleeve near the fixing ring, and the rubber pads are in contact with the fixing plates.

[0011] Preferably, the second optical fiber includes a stainless steel metal ring, a main core, and a secondary core. Several secondary cores are spirally wound around the main core. The main core and secondary cores are covered by a stainless steel metal ring, and high-temperature sealant is filled between the stainless steel metal ring, the main core, and the secondary cores.

[0012] Preferably, the neutron scintillation screen material is 6 LiF+ZnS(Ag) or 232 Th+ZnS(Ag).

[0013] Preferably, the first and second optical fibers are metal-coated optical fibers or wavelength-shifted optical fibers.

[0014] Preferably, the electronic system includes a preamplifier, a linear amplifier, an analog-to-digital converter, and a multi-channel pulse amplitude analyzer, and the preamplifier, linear amplifier, analog-to-digital converter, and multi-channel pulse amplitude analyzer are connected in sequence.

[0015] The beneficial effects of this utility model are as follows:

[0016] 1. The fiber optic neutron detector of this invention is small in size, simple in structure, radiation resistant, anti-interference, and highly sensitive, and can realize neutron detection in confined spaces.

[0017] 2. Set the material of the probe part as follows: 6 Thermal neutron detection can be achieved using LiF, by setting the material of the probe portion as... 232 Fast neutron detection can be achieved at Th time.

[0018] 3. Replacing the optical fiber with a metal-coated optical fiber, along with high-temperature optical adhesive, enables real-time online detection of neutrons inside the reactor core under high temperature and high pressure conditions. Replacing the optical fiber with a wavelength-shifting optical fiber enables long-distance transmission.

[0019] 4. The optical fiber of this utility model adopts a spiral winding method of secondary core and main core, which is tightly coupled. With the stainless steel metal ring on the surface of the optical fiber, the bending resistance of the optical fiber is improved and the macro bending loss is reduced. Moreover, the connector mechanism enables quick replacement of probes, which is convenient for changing different probes according to different detection environments, thus improving the practicality of the equipment. Attached Figure Description

[0020] Figure 1 is the overall structure perspective view of the utility model;

[0021] Figure 2 is the partial sectional view of the utility model probe;

[0022] Figure 3 is the utility model's No. 1 optical fiber, joint mechanism and No. 2 optical fiber perspective view;

[0023] Figure 4 is the partial sectional view of the utility model No. 2 optical fiber;

[0024] Figure 5 is the utility model's Figure 4 A area enlarged schematic view in the middle.

[0025] In the figure: 1, probe;11, protective shell;12, neutron scintillation screen;2, No. 1 optical fiber;3, joint mechanism;30, plug-in sleeve;31, guide rod;32, threaded sleeve;33, fixed sleeve;34, fixed ring;35, fixed plate;36, rubber pad;37, No. 1 locking block;38, No. 2 locking block;39, L-shaped arm;4, No. 2 optical fiber;41, stainless steel ring;42, main core;43, auxiliary core;5, electronic system;51, preamplifier;52, linear amplifier;53, analog-digital converter;54, multi-channel pulse amplitude analyzer. DETAILED DESCRIPTION

[0026] It is necessary to point out here that the following detailed description is only used to further illustrate the application and can not be understood as limiting the scope of the application, and the skilled in the art can make some non-essential improvements and adjustments to the application according to the above application content.

[0027] EMBODIMENT

[0028] Please refer to Figure 1 A kind of optical fiber neutron detector, including probe 1, No. 1 optical fiber 2, joint mechanism 3, No. 2 optical fiber 4 and electronic system 5, probe 1 one end is provided with No. 1 optical fiber 2, No. 1 optical fiber 2 one end is provided with No. 2 optical fiber 4, and No. 1 optical fiber 2 and No. 2 optical fiber 4 are connected by joint mechanism 3 between, No. 2 optical fiber 4 one end is connected with electronic system 5, No. 1 optical fiber 2 and No. 2 optical fiber 4 are wavelength displacement optical fiber or metal coating optical fiber.

[0029] The joint mechanism 3 is used to realize the connection between the probe 1 and the second optical fiber 4, realizes the quick installation and replacement of the probe 1, facilitates the replacement of different probes 1 according to the actual use condition, adopts the metal coated optical fiber in cooperation with the use of high temperature optical glue, facilitates the real-time online detection of the neutrons in the reactor core under the high temperature and high pressure conditions, and when the wavelength displacement optical fiber is used, the long distance transmission can be realized.

[0030] Please refer to Figure 1 and Figure 2 , the probe 1 comprises a protective shell 11 and a neutron scintillation screen 12, the neutron scintillation screen 12 is arranged in the protective shell 11, the neutron scintillation screen 12 is connected with the second optical fiber 4, the outside of the connection position of the protective shell 11 and the second optical fiber 4 is filled with high temperature sealing glue, the neutron scintillation screen 12 is in a cylindrical shape, and the material of the neutron scintillation screen 12 is 6 LiF+ZnS(Ag) or 232 Th+ZnS(Ag), 6 When LiF is used as the material, the probe 1 can detect thermal neutrons, and when 232 Th is used as the material, the probe 1 can detect fast neutrons.

[0031] When the probe is used, first, the protective shell 11 is processed, the protective shell 11 is processed into a cylindrical shape with one end open and the other end closed, the size of the protective shell is 12 mm in outer diameter, 9.5 mm in inner diameter and 6 mm in height, the bottom has a 1 mm thick bottom sealing, and the inside is 5 mm deep; the protective shell 11 is in clearance fit with the first optical fiber 2, after the protective shell 11 is processed and formed, the inside of the protective shell 11 needs to be polished, the inside wall of the protective shell 11 is polished through three steps of rough grinding, fine grinding and grinding, and finally the inside wall of the protective shell 11 is polished by using polishing paste, so that the inside is smooth and clean.

[0032] Then, the neutron scintillation screen 12 is processed, the neutron conversion material and the scintillator material are mixed in a ratio of 1:1, the neutron conversion material is 6 LiF particles, the scintillator material is ZnS(Ag) particles, after being mixed uniformly, optical glue is added, the optical glue is epoxy optical glue, after being mixed uniformly again, the optical glue is filled into the polished protective shell 11, the filling depth is 3 mm, that is, there is a 2 mm gap at the top of the protective shell 11, after the mixed material is solidified, the neutron scintillation screen 12 is formed;

[0033] After the neutron scintillation screen 12 and the protective shell 11 are processed, the two are formed as a whole, the protective shell 11 is left with a 2mm deep gap at the top end, and after the optical glue is coated on one end face of the first optical fiber 2, the first optical fiber 2 is inserted into the protective shell 11, the inner diameter of the protective shell 11 is 9.5mm, the outer diameter of the first optical fiber 2 is 9mm, and there is a 2mm empty space in the protective shell 11, and a gap can be formed between the two, and the sealing glue is used to seal the connection between the first optical fiber 2 and the protective shell 11, and after the first optical fiber 2 and the protective shell 11 form a stable structure, the installation of the probe 1 is completed.

[0034] Please refer to Figure 1 and Figure 3 The joint mechanism 3 comprises a plug-in sleeve 30 fixedly sleeved on the first optical fiber 2 and a fixed sleeve 33 fixedly sleeved on the second optical fiber 4. The plug-in sleeve 30 is hollow inside, and the core of the first optical fiber 2 is located inside the plug-in sleeve 30. The fixed sleeve 33 is fixedly sleeved with a fixed ring 34 outside. The fixed ring 34 is fixedly connected with two guide rods 31 on the side close to the plug-in sleeve 30. The plug-in sleeve 30 is provided with two positioning holes on the side close to the fixed ring 34, and the guide rods 31 are slidingly connected in the positioning holes. The fixed sleeve 33 is rotatably connected with a threaded sleeve 32 on the side close to the plug-in sleeve 30. The plug-in sleeve 30 is fixedly connected with a threaded cylinder on the side away from the first optical fiber 2, and the threaded sleeve 32 is threadedly connected with the threaded cylinder.

[0035] Please refer to Figure 1 and Figure 3 The fixed ring 34 is fixedly connected with two fixed plates 35 on the side close to the plug-in sleeve 30, and the two fixed plates 35 are fixedly connected with two second locking blocks 38 on the side away from the fixed ring 34. The plug-in sleeve 30 is fixedly connected with two L-shaped arms 39 on the two sides, and the two L-shaped arms 39 are fixedly connected with a first locking block 37 on the side close to the fixed ring 34. The first locking block 37 is clamped with the second locking block 38. The edges of the plug-in sleeve 30 close to the fixed ring 34 are fixedly connected with rubber pads 36, and the rubber pads 36 are attached to the fixed plates 35.

[0036] In use, first, the end face of the first optical fiber 2 away from the probe 1 is inserted into the insertion sleeve 30, and the connection part is connected by sealant, and the fixing sleeve 33 is sleeved on one end of the second optical fiber 4, and the two are also connected by sealant, and the lengths of the first optical fiber 2 and the second optical fiber 4 can be replaced according to actual needs. When the probe 1 needs to be installed or replaced, the guide rod 31 is inserted into the positioning hole on the insertion sleeve 30 to achieve accurate positioning between the first optical fiber 2 and the second optical fiber 4. After insertion, the threaded sleeve 32 is tightened on the threaded cylinder on the insertion sleeve 30 to achieve threaded connection and fixation of the two. At the same time of tightening, the fixing sleeve 33 on the threaded sleeve 32 moves towards the insertion sleeve 30, synchronously driving the fixing ring 34 and the fixing plate 35 on it to move towards the insertion sleeve 30, and driving the second locking block 38 to move towards the insertion sleeve 30, thereby achieving locking between the second locking block 38 and the first locking block 37. In combination with the threaded connection of the threaded sleeve 32 and the threaded cylinder, two-stage fixation is achieved, effectively preventing disconnection and improving the stability of the probe 1 installation. When disassembly is required, the two fixing plates 35 are centered and pressed to loosen the locking between the second locking block 38 and the first locking block 37. The threaded sleeve 32 is reversed to loosen the threaded connection between the threaded sleeve 32 and the threaded cylinder, thereby achieving disassembly of the probe 1. This is conducive to quick installation and disassembly of the probe 1, with high work efficiency.

[0037] Please refer to Figure 1 , Figure 4 and Figure 5 , the second optical fiber 4 includes a stainless steel ring 41, a main core 42 and a secondary core 43, the main core 42 is spirally wrapped with a plurality of secondary cores 43, and the main core 42 and the secondary core 43 are coated with a stainless steel ring 41, and the stainless steel ring 41, the main core 42 and the secondary core 43 are filled with high-temperature sealant.

[0038] The first optical fiber 2 and the second optical fiber 4 both adopt a distribution mode of linear main core 42 and spirally wrapped secondary core 43. This mode combines the main core 42 and the secondary core 43 tightly to form a whole, with high structural strength. In combination with the setting of the stainless steel ring 41 on the surface, the bending resistance of the first optical fiber 2 and the second optical fiber 4 is improved, and the macro-bending loss is reduced.

[0039] Please refer to Figure 1 , the electronic system 5 includes a preamplifier 51, a linear amplifier 52, an analog-to-digital converter 53 and a multi-channel pulse amplitude analyzer 54, and the preamplifier 51, the linear amplifier 52, the analog-to-digital converter 53 and the multi-channel pulse amplitude analyzer 54 are connected in sequence.

[0040] When the connection between the No. 2 optical fiber 4 and the preamplifier 51 needs to be made, the incident window of the preamplifier 51 and the other end face of the No. 2 optical fiber 4 are connected by sealing glue, and the preamplifier 51, the linear amplifier 52, the analog-to-digital converter 53 and the multi-channel pulse amplitude analyzer 54 are sequentially connected.

[0041] It should be noted that, when the optical fiber neutron detector is used, first, the probe 1 is replaced with the required detection, the No. 1 optical fiber 2 and the No. 2 optical fiber 4 are connected by the joint mechanism 3, then the probe 1 is placed in the to-be-detected area, after the neutron is incident to the neutron scintillation screen 12, first, the neutron in the neutron scintillation screen 12 reacts with the neutron conversion material in the neutron scintillation screen 12:

[0042] n+ 6 Li→T+ 4 He+4.786MeV

[0043] The neutron and 6 Li nuclear reaction produces secondary particles α and T, and gives 4.786MeV of energy to the two secondary particles, the neutron and 6 The cross section of the nuclear reaction of the neutron and 6 Li and the thermal neutron has a large cross section, and the fast neutron can react but the cross section is very small, so the 6 The scintillation optical fiber detector made of Li is mainly used for measuring the thermal neutron flux, and the α and T particles act on the ZnS(Ag) scintillator to emit fluorescence, the fluorescence is transmitted to the photocathode of the preamplifier 51 after entering the No. 1 optical fiber 2 and the No. 2 optical fiber 4, then linearly amplified by the linear amplifier 52, then the optical signal is converted into an electrical signal by the analog-to-digital converter 53, and the electrical signal that can be detected is formed by the processing of the multi-channel pulse amplitude analyzer 54, so that the detection of the neutron is realized.

[0044] The above-described embodiments only express several implementation manners of the present application, the description is relatively specific and detailed, but it cannot be understood as the limitation of the patent range of the present application. It should be noted that, for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection range of the present application.

Claims

1. A fiber-optic neutron detector comprising a probe (1), a first optical fiber (2), a joint mechanism (3), a second optical fiber (4) and an electronics system (5), characterized in that: The probe (1) is provided with a first optical fiber (2) at one end, the first optical fiber (2) is provided with a second optical fiber (4) at one end, and the first optical fiber (2) and the second optical fiber (4) are connected through a joint mechanism (3), and the second optical fiber (4) is connected with an electronic system (5) at one end; The probe (1) comprises a protective shell (11) and a neutron scintillation screen (12), the neutron scintillation screen (12) is arranged in the protective shell (11), the neutron scintillation screen (12) is connected with the second optical fiber (4), and the outside of the connecting part of the protective shell (11) and the second optical fiber (4) is filled with high-temperature sealing glue, and the neutron scintillation screen (12) is in a cylindrical shape.

2. The optical-fiber neutron detector of claim 1, wherein: The joint mechanism (3) comprises a plug-in sleeve (30) fixedly sleeved on the first optical fiber (2) and a fixed sleeve (33) fixedly sleeved on the second optical fiber (4), the plug-in sleeve (30) is hollow, and the core of the first optical fiber (2) is located in the plug-in sleeve (30), the fixed sleeve (33) is fixedly sleeved with a fixed ring (34) on the outside, two guide rods (31) are fixedly connected on the side of the fixed ring (34) close to the plug-in sleeve (30), and two positioning holes are formed on the side of the plug-in sleeve (30) close to the fixed ring (34), and the guide rods (31) are slidably connected in the positioning holes.

3. The optical-fiber neutron detector of claim 2, wherein: The fixed sleeve (33) is rotatably connected with a threaded sleeve (32) on the side close to the plug-in sleeve (30), and the plug-in sleeve (30) is fixedly connected with a threaded cylinder on the side away from the first optical fiber (2), and the threaded sleeve (32) is threadedly connected with the threaded cylinder.

4. The optical-fiber neutron detector of claim 2, wherein: The fixed ring (34) is symmetrically fixedly connected with two fixed plates (35) on the side close to the plug-in sleeve (30), two second locking blocks (38) are fixedly connected on the side of the two fixed plates (35) away from the fixed ring (34), two L-shaped arms (39) are fixedly connected on the two sides of the plug-in sleeve (30), and the two L-shaped arms (39) are fixedly connected with a first locking block (37) on the side close to the fixed ring (34), the first locking block (37) is clamped with the second locking block (38), and rubber pads (36) are fixedly connected on the edges of the two sides of the plug-in sleeve (30) close to the fixed ring (34), and the rubber pads (36) are attached to the fixed plates (35).

5. The optical-fiber neutron detector of claim 1, wherein: The second optical fiber (4) comprises a stainless steel ring (41), a main core (42) and a secondary core (43), the secondary core (43) is spirally wound on the outside of the main core (42), and the main core (42) and the secondary core (43) are covered with the stainless steel ring (41), and the stainless steel ring (41), the main core (42) and the secondary core (43) are filled with high-temperature sealing glue.

6. The optical-fiber neutron detector of claim 1, wherein: The neutron scintillator (12) material is 6 LiF + ZnS(Ag) or 232 Th + ZnS(Ag).

7. The optical-fiber neutron detector of claim 1, wherein: The first optical fiber (2) and the second optical fiber (4) are metal-coated optical fibers or wavelength-shifted optical fibers.

8. The optical-fiber neutron detector of claim 1, wherein: The electronic system (5) comprises a preamplifier (51), a linear amplifier (52), an analog-to-digital converter (53) and a multi-channel pulse amplitude analyzer (54), and the preamplifier (51), the linear amplifier (52), the analog-to-digital converter (53) and the multi-channel pulse amplitude analyzer (54) are connected in sequence.

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