An experimental apparatus for simulating the transient occurrence and response of a criticality accident

Abstract

The application discloses an experimental device for simulating instantaneous occurrence and response of a critical accident, comprising a source module, a source shielding shutter module, a shielding and moderating collimation module and a detection module, wherein the source module is used for generating neutrons / photons; the source shielding shutter module is arranged outside the source module and is used for shielding the source module in a non-triggering state and removing the shielding of the source module in a triggering state while automatically starting timing; the shielding and moderating collimation module is arranged outside the source module and the source shielding shutter module and is used for moderating and collimating the neutrons generated by the source module or collimating the photons; and the detection module is arranged outside the shielding and moderating collimation module and is electrically connected with the source shielding shutter module and is used for generating a response to the moderated and collimated neutrons / photons and interlocking the source shielding shutter module to automatically terminate timing when a response signal is generated. The application can effectively simulate the instantaneous occurrence and response of a critical accident under laboratory conditions.

Description

Technical Field

[0001] This invention belongs to the field of nuclear engineering technology, specifically relating to an experimental device for simulating the instantaneous occurrence and response of critical accidents. Background Technology

[0002] Preventing criticality accidents is a crucial aspect of nuclear safety when handling, processing, storing, and processing fissile materials. When relevant control measures fail or unexpectedly exceed limits, the system may introduce significant positive reactivity, resulting in an effective multiplication factor greater than 1.0. This leads to an uncontrolled neutron chain fission reaction, triggering a criticality accident. After a criticality accident, the number of fissions increases rapidly within a short period, releasing large amounts of energy and heat, accompanied by intense neutron and gamma-ray transient radiation and the release of fissile gas. Therefore, areas where criticality accidents cannot be ruled out must be equipped with detection, alarm, and mitigation measures to protect personnel from excessive radiation exposure. Experimental testing of criticality accident detection, alarm, and mitigation systems or devices requires simulating the instantaneous occurrence and response conditions of a criticality accident.

[0003] Currently, while some progress has been made in the critical safety design of facilities for the storage, handling, and processing of easily fissile materials outside the reactor, the intense neutron and gamma-ray transient radiation generated during a critical accident makes it impossible to directly reproduce a real critical accident under laboratory conditions due to limitations in source strength requirements. Therefore, it is necessary to design appropriate devices to simulate the effects of the transient generation of source terms. While there are existing testing methods for using reactor neutron sources to simulate the transient generation of source terms for critical accident alarm devices, these methods still suffer from high experimental costs, limited space, and poor experimental flexibility. At present, there is still a lack of dedicated experimental devices capable of simulating the transient generation of neutron and photon source strength during a critical accident under laboratory conditions. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an experimental device for simulating the instantaneous occurrence and response of critical accidents, which is in response to the above-mentioned deficiencies of the existing technology and can effectively simulate the instantaneous occurrence and response of critical accidents under laboratory conditions.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is:

[0006] This invention provides an experimental apparatus for simulating the instantaneous occurrence and response of a critical accident, comprising a source module, a source-shielded shutter module, a shielded slowing-down collimation module, and a detection module, wherein:

[0007] The source module is used to generate neutrons / photons;

[0008] The source shielding shutter module is located outside the source module and is used to shield the source module in the untriggered state and remove the shielding of the source module in the triggered state, while automatically starting the timer.

[0009] The shielding slowing-down collimation module is located outside the source module and the source shielding shutter module, and is used to slow down and collimate the neutrons generated by the source module or to collimate the photons.

[0010] The detection module is located outside the shielded slowing-down collimation module and is electrically connected to the source shielded shutter module. It is used to respond to the slowed-down collimated neutrons / photons and to interlock the source shielded shutter module to automatically stop timing when a response signal is generated.

[0011] Optionally, the source shielding shutter module includes a shielding component and a quick-removal mechanism; the shielding component is located on the periphery of the source module and is used to shield the source module; the quick-removal mechanism is connected to the shielding component and is used to remove the shielding component from the periphery of the source module and automatically start timing in a triggered state; the quick-removal mechanism is also electrically connected to the detection module and is used to automatically terminate timing when the detection module generates a response signal.

[0012] Optionally, the shielding component includes a shielding body and an outer shell; the shielding body is used to shield neutrons and / or photons; the outer shell is wrapped around the shielding body and has a connector thereon, the connector being used to connect a quick removal mechanism.

[0013] Optionally, the shielding component is a windowless shielding component or a windowed shielding component; the windowless shielding component is used to obtain a step source signal; the windowed shielding component is used to obtain a pulse source signal to simulate the fission peak of a critical accident.

[0014] Optionally, the shielding, slowing down, and collimating module includes a housing, a detection channel, and a slowing down pad. The housing contains a source placement channel, and the source module is located within this channel. The detection channel is located on the side wall of the housing and is opposite to the target direction of the detection module. It is used to collimate the neutrons / photons generated by the source module in the target direction of the detection module, ensuring that the target direction of the detection module generates a count rate that meets the measurement and statistical requirements. The slowing down pad is located within the detection channel and is used to slow down the neutrons to optimize the detection efficiency of the detection module.

[0015] Optionally, the enclosure is provided with a shielding shell.

[0016] Optionally, the source module includes a neutron source / photon source and a source support column, wherein the neutron source / photon source is disposed on the source support column.

[0017] Optionally, the neutron source is one or more of californium source, americium-beryllium source, americium-lithium source, and antimony-beryllium source; the photon source is one or more of cobalt-60 source, cesium-137 source, iridium-192 source, americium-241 source, iron-55 source, selenium-75 source, and plutonium-238 source.

[0018] Optionally, the source support column is a pluggable box structure, which is provided with a plunger or inlet for placing a neutron source / photon source, and a shield is provided in the insertion direction of the plunger or inlet, and a neutron moderator is provided in the target direction of the detection module.

[0019] Optionally, the detection module includes a detector and a shielded slowing housing, with the detector disposed within the shielded slowing housing.

[0020] Optionally, the shielding and moderation shell is made of shielding material and moderation material; the shielding body, the shielding shell, and the shielding component are all made of shielding material; the box and the neutron moderation component are all made of moderation material; the shielding material includes neutron absorbing material and photon shielding material; the neutron absorbing material is cadmium, gadolinium, boron carbide, boron-containing polyethylene, boron-containing concrete, boron-containing resin, boron steel, boron aluminum, gadolinium hydride, elemental boron, or boron-containing materials. The photon shielding material is one or more of the following: silicate, boron-containing titanate, gadolinium oxide, samarium oxide, hafnium oxide, europium oxide, hafnium carbide, samarium hafnium oxide, europium hafnium oxide, dysprosium titanate, samarium titanate, hafnium titanate, europium titanate, dysprosium ferrite, terbium titanate, dysprosium aluminate, gadolinium aluminate, and terbium aluminate; the photon shielding material is one or more of the following: stainless steel, lead, tungsten, cast iron, and concrete; the moderating material is one or more of the following: polyethylene, polyoxymethylene, graphite, beryllium oxide, and beryllium carbide.

[0021] Beneficial effects:

[0022] (1) Through the synergistic effect of the source shielding shutter module and the shielding slowing collimation module, the shielding of the neutron / photon source in the source module can be quickly removed in the triggered state. Without using the critical accident level source strength, the dose level or count rate detected by the detection module in the non-triggered state and the triggered state of the device will produce a significant difference, achieving the effect of the instantaneous generation of the critical accident source term. Thus, the instantaneous occurrence and response of the critical accident can be effectively simulated under laboratory conditions. Compared with the existing related experimental tests that use large facilities such as reactors, it can reduce costs, shorten the cycle, avoid site restrictions and other problems, and greatly reduce the experimental threshold.

[0023] (2) Through the modular architecture design of the source module, source shielding shutter module, shielding slowing collimation module and detection module, the device configuration can be flexibly adjusted according to experimental requirements, greatly improving experimental flexibility and repeatability, and supporting the research and development iteration and routine testing and verification of critical accident detection alarm and mitigation system.

[0024] (3) By using windowless or windowed shielding components, the windowless shielding component can be selected to obtain the step source signal to simulate the instantaneous step characteristics of the critical accident, or the windowed shielding component can be selected to obtain the pulse source signal to simulate the fission peak characteristics of the critical accident. At the same time, the configuration of neutron source and photon source is flexible and diverse, which can be adapted to different experimental scenarios, meet different testing and verification requirements, and expand the simulation application range of the device.

[0025] (4) By adopting a pluggable box structure design for the source support column, the source can be quickly replaced and radiation safety protection can be achieved during operation, further improving the flexibility and safety of the experiment. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the experimental apparatus for simulating the instantaneous occurrence and response of a critical accident in an embodiment of the present invention.

[0027] In the diagram: 1-Source support column; 2-Neutron source / photon source; 3-Source shielded shutter module; 4-Box; 5-Slowing down pad; 6-Detection module; 7-Detection channel; 8-Shielding shell; 9-Source placement channel. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0029] In the description of this invention, it should be noted that the terms "above" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience and simplification of the description and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0030] In the description of this invention, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0031] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connection," "setting," "installation," "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection, an indirect connection through an intermediate medium, or a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0032] It is understood that, without conflict, the various embodiments and features in the embodiments of the present invention can be combined with each other.

[0033] It is understood that, for ease of description, only the parts related to the present invention are shown in the accompanying drawings, while the parts unrelated to the present invention are not shown in the drawings.

[0034] Example 1

[0035] like Figure 1 As shown, this embodiment discloses an experimental apparatus for simulating the instantaneous occurrence and response of a critical accident, including a source module, a source-shielded shutter module 3, a shielded slowing-down collimation module, and a detection module, wherein:

[0036] The source module contains a neutron / photon source for generating neutrons / photons.

[0037] The source shielding shutter module 3 is located outside the source module and is used to shield the neutron source / photon source in the source module in the non-triggered state. That is, it maintains the shielded source state in the non-triggered state and removes the shielding of the neutron source / photon source in the triggered state, and automatically starts timing.

[0038] The shielding slow-down collimation module is located outside the source module and the source shielding shutter module 3. It is used to slow down and collimate the neutrons generated by the neutron source in the source module or to collimate the photons generated by the photon source.

[0039] The detection module is located outside the shielded slowing-down collimation module and is electrically connected to the source shielded shutter module 3. It is used to generate a response to the slowed-down collimated neutrons / photons and to interlock the source shielded shutter module to automatically stop timing when a response signal is generated, thereby measuring the response time.

[0040] In some implementations, the source module includes a neutron source / photon source 2 and a source support column 1, with the neutron source / photon source 2 disposed on the source support column 1.

[0041] Specifically, the neutron source is one or more of the following: californium source, americium-beryllium source, americium-lithium source, and antimony-beryllium source; the photon source is one or more of the following: cobalt-60 source, cesium-137 source, iridium-192 source, americium-241 source, iron-55 source, selenium-75 source, and plutonium-238 source. These will not be elaborated on here.

[0042] In some embodiments, the source support column 1 is a pluggable box structure, which is provided with a plunger or inlet for placing the neutron source / photon source 2, and a shield is provided at the end of the plunger or inlet in the insertion direction. A neutron moderator is provided in the target direction of the detection module 6, but no shield is provided, so as to improve the detection efficiency and avoid the loss of neutrons / photons reaching the detection module 6 due to the shield after the source shield shutter module 3 is removed, thereby weakening the effect that the response after the source shield shutter module is removed is much greater than that when it is not removed.

[0043] Specifically, the shielding components are made of shielding materials used to shield neutrons and photons. More specifically, the shielding materials include neutron-absorbing materials and photon-shielding materials, wherein: the neutron-absorbing materials are one or more of cadmium, gadolinium, boron carbide, boron-containing polyethylene, boron-containing concrete, boron-containing resin, boron steel, boron aluminum, gadolinium hydride, elemental boron, borosilicate, boron titanate, gadolinium oxide, samarium oxide, hafnium oxide, europium oxide, hafnium carbide, samarium hafnium oxide, europium hafnium oxide, dysprosium titanate, samarium titanate, hafnium titanate, europium titanate, dysprosium ferrite, terbium titanate, dysprosium aluminate, gadolinium aluminate, and terbium aluminate; the photon-shielding materials are one or more of stainless steel, lead, tungsten, cast iron, and concrete.

[0044] The neutron moderator is made of solid neutron moderator materials, such as polyethylene, polyoxymethylene, graphite, beryllium oxide, beryllium carbide, or other materials containing light elements, or one or more of these materials.

[0045] In some embodiments, the source-shielded shutter module 3 includes a shielding component and a quick-removal mechanism. The shielding component is located on the periphery of the source module and is used to shield the neutron / photon source within the source module. The quick-removal mechanism is connected to the shielding component and is used to quickly remove the shielding component from the periphery of the source module in a triggered state and automatically start timing; the quick-removal mechanism is also electrically connected to the detection module 6 and is used to automatically stop timing when the detection module generates a response signal, thereby measuring the response time.

[0046] Specifically, the shielding component includes a shielding body and an outer shell. The shielding body is designed in the shape of a circular cylinder, square cylinder, etc., to shield neutrons and / or photons. The outer shell is wrapped around the shielding body and has connectors for connecting a quick-removal mechanism. The shielding body is made of a shielding material including neutron-absorbing material and / or photon-shielding material; when shielding a neutron source, neutron-absorbing material is preferred; when shielding a photon source, photon-shielding material is preferred. The specific neutron-absorbing material and photon-shielding material are the same as those in the shielding component described above, but the materials can be the same or different in the same embodiment, which will not be elaborated here. The material and size of the shielding body should be matched so that the dose rate / count rate of the detection module is much smaller (e.g., differing by an order of magnitude) than the dose rate / count rate of the detection module when the shielding material is removed, to simulate the dose level when a critical accident has not occurred. The outer shell is made of stainless steel.

[0047] The rapid removal mechanism can be implemented manually or automatically. For example, the rapid removal mechanism can be a rapid clamp. The outer end of the rapid removal mechanism is equipped with the aforementioned shielding material, which includes neutron absorbing material and photon shielding material. However, the materials of the two materials can be the same or different in the same embodiment, which will not be described in detail here, to ensure that the shielding effect of the entire device is not weakened by the action of the rapid removal mechanism.

[0048] In some implementations, the shielding component is either a windowless shielding component or a windowed shielding component with windows of varying lengths in several intermediate sections. The specific shielding component can be selected according to the simulation requirements. The windowless shielding component is used to obtain a step source signal; the windowed shielding component is used to obtain a pulse source signal to simulate the fission peak of a critical accident. By using windowed shielding components with different window lengths and controlling the removal speed of the shielding components, pulse source signals with different pulse durations can be obtained.

[0049] In some embodiments, the shielded, slowing-down, and collimating module includes a housing 4, a detection channel 7, and several slowing-down pads 5. The housing has a source placement channel 9 inside, and the source support column 1 in the source module is located within the source placement channel 9. The detection channel 7 is located on the side wall of the housing 4 and is opposite to the target direction of the detection module 6. It is used to collimate the neutrons / photons generated by the neutron source / photon source 2 in the source module in the target direction of the detection module 6, so that the target direction of the detection module 6 generates a sufficient count rate (e.g., above 10 cps, where cps is an abbreviation for counts per second) to meet the count rate requirements for measurement statistics. The moderation pad 5 is detachably installed in the detection channel 7 and can be flexibly installed and removed. It is used to moderate neutrons. Specifically, it can not only moderate and collimate neutrons generated by the neutron source in the target direction of the detection module 6 and shield them in other directions, but also collimate photons generated by the photon source in the target direction of the detection module 6 and shield them in other directions. The number of moderation pads 5 can be one or more. The specific number can be adjusted according to the experimental requirements, the thickness of the moderation material of the source support column 1, and the thickness of the moderation material at the detection module 6 to optimize the detection efficiency of the detection module.

[0050] In some embodiments, the interior of the housing 4 is also provided with space for placing removal materials and components, or in other words, the source placement channel 9 has sufficient space, that is, in addition to placing the source support column 1 in the source module, the interior of the housing 4 can also place shielding components and quick removal mechanisms during removal.

[0051] In some embodiments, the housing 4 is provided with a shielding shell. The shielding shell, like the shielding components mentioned above, is also made of shielding materials including neutron absorbing materials and photon shielding materials. However, the materials of the two can be the same or different in the same embodiment, which will not be described in detail here, so that the dose rate in areas other than the target direction of the detection module 6 does not affect the personnel's experimental operations.

[0052] In some embodiments, the housing 4 is made of a moderation material. Specifically, the housing 4, like the neutron moderator, is also made of a solid neutron moderation material. However, the materials of the two can be the same or different in the same embodiment, which will not be elaborated here. This is to improve the neutron detection efficiency of the detection module and the neutron absorption efficiency of the neutron shielding material of the housing shell.

[0053] In some embodiments, the detection module 6 includes a detector and a shielding and slowing-down housing, with the detector housed within the shielding and slowing-down housing. The detector may be a neutron detector or a photon detector, selected according to experimental requirements, and its position and angle are arranged to maximize detection efficiency. The shielding and slowing-down housing is used to shield against interference from other directional sources, depending on the detector selection.

[0054] Specifically, the shielding and moderating shell is made of shielding material and moderating material, with the shielding material in the non-detection direction and the moderating material in the detection direction. The shielding materials include neutron-absorbing materials and photon-shielding materials. Neutron-absorbing materials are one or more of the following: cadmium, gadolinium, boron carbide, boron-containing polyethylene, boron-containing concrete, boron-containing resin, boron steel, boron aluminum, gadolinium hydride, elemental boron, boron silicates, boron titanates, gadolinium oxide, samarium oxide, hafnium oxide, europium oxide, hafnium carbide, samarium hafnium oxide, europium hafnium oxide, dysprosium titanate, samarium titanate, hafnium titanate, europium titanate, dysprosium ferrite, terbium titanate, dysprosium aluminate, gadolinium aluminate, and terbium aluminate. Photon-shielding materials are one or more of the following: stainless steel, lead, tungsten, cast iron, and concrete. Moderator materials are one or more of the following: polyethylene, polyoxymethylene, graphite, beryllium oxide, and beryllium carbide.

[0055] Example 2

[0056] This embodiment discloses an experimental apparatus for simulating the instantaneous occurrence and response of a critical accident. Compared with Embodiment 1, the difference is as follows:

[0057] The neutron source is a californium-252 spontaneous fission neutron source with a source intensity of approximately 3.0E+05n / s;

[0058] The source support column 1 is made of polyethylene with a thickness of 1.0 cm in the detector direction, and a 0.5 cm thick stainless steel is provided at the end of the column in the insertion direction to shield photons.

[0059] The shielding material (i.e., the shielding body in the shielding component) in the source shielding shutter module 3 is made of 10.0cm thick boron-containing polyethylene and 0.5cm thick cadmium.

[0060] The enclosure 4 is made of polyethylene material, and the outer shielding shell of the enclosure 4 is made of stainless steel. Three detection channels 7 are provided on the side wall of the enclosure 4 in the horizontal direction, and each detection channel 7 is provided with a 4.0cm thick polyethylene slowing pad 5.

[0061] The detector uses a He-3 gas neutron detector with a pressure of 200 kPa and a size of φ2.5cm×20cm. The shielding and slowing shell is made of polyethylene with a thickness of 3.75cm. In the non-detection direction, a 0.5cm thick stainless steel is used to shield photons, and a 0.1cm thick cadmium is used to absorb and shield neutrons in the non-detection direction.

[0062] The detector count rate of the experimental apparatus simulating the instantaneous occurrence and response of a critical accident in this embodiment was calculated and analyzed before and after the shielding component was removed: when the shielding component was not removed, the detector count rate was only 70 cps, simulating the background count rate level of the facility when no critical accident occurred; after the triggering device quickly removed the shielding component, the detector count rate increased significantly to about 400 cps, simulating the neutron count rate level generated when the facility experienced a critical accident.

[0063] The experimental apparatus for simulating the instantaneous occurrence and response of critical accidents in Examples 1 and 2 has at least the following effects:

[0064] (1) Through the synergistic effect of the source shielding shutter module and the shielding slowing collimation module, the shielding of the neutron source or photon source in the source module can be quickly removed in the triggered state. Without using the critical accident level source strength, the dose level or count rate detected by the detection module in the non-triggered state and the triggered state of the device will produce a significant difference, achieving the effect of the instantaneous generation of the critical accident source term. Thus, the instantaneous occurrence and response of the critical accident can be effectively simulated under laboratory conditions. Compared with the existing related experimental tests that use large facilities such as reactors, it can reduce costs, shorten the cycle, avoid site restrictions and other problems, and greatly reduce the experimental threshold.

[0065] (2) Through the modular architecture design of the source module, source shielding shutter module, shielding slowing collimation module and detection module, the device configuration can be flexibly adjusted according to experimental requirements, greatly improving experimental flexibility and repeatability, and supporting the research and development iteration and routine testing and verification of critical accident detection alarm and mitigation system.

[0066] (3) By using windowless or windowed shielding components, the windowless shielding component can be selected to obtain the step source signal to simulate the instantaneous step characteristics of the critical accident, or the windowed shielding component can be selected to obtain the pulse source signal to simulate the fission peak characteristics of the critical accident. At the same time, the configuration of neutron source and photon source is flexible and diverse, which can be adapted to different experimental scenarios, meet different testing and verification requirements, and expand the simulation application range of the device.

[0067] (4) By adopting a pluggable box structure design for the source support column, the source can be quickly replaced and radiation safety protection can be achieved during operation, further improving the flexibility and safety of the experiment.

[0068] It is understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An experimental apparatus for simulating the instantaneous occurrence and response of a critical accident, characterized in that, It includes a source module, a source-shielded shutter module, a shielded slow-down collimation module, and a detection module; The source module is used to generate neutrons / photons; The source shielding shutter module is located outside the source module and is used to shield the source module in the untriggered state and remove the shielding of the source module in the triggered state, while automatically starting the timer. The shielding slowing-down collimation module is located outside the source module and the source shielding shutter module, and is used to slow down and collimate the neutrons generated by the source module or to collimate the photons. The detection module is located outside the shielded slowing-down collimation module and is electrically connected to the source shielded shutter module. It is used to respond to the slowed-down collimated neutrons / photons and to interlock the source shielded shutter module to automatically stop timing when a response signal is generated.

2. The experimental apparatus for simulating the instantaneous occurrence and response of a critical accident according to claim 1, characterized in that, The source shielding shutter module includes a shielding component and a quick-removal mechanism. The shielding component is located on the periphery of the source module and is used to shield the source module. The quick-removal mechanism is connected to the shielding component and is used to remove the shielding component from the periphery of the source module and automatically start timing when triggered. The quick-removal mechanism is also electrically connected to the detection module and is used to automatically stop timing when the detection module generates a response signal.

3. The experimental apparatus for simulating the instantaneous occurrence and response of a critical accident according to claim 2, characterized in that, The shielding component includes a shielding body and a housing; The shielding body is used to shield neutrons and / or photons; The outer shell is wrapped around the shielding body and has a connector on it for connecting the quick removal mechanism.

4. The experimental apparatus for simulating the instantaneous occurrence and response of a critical accident according to claim 3, characterized in that, The shielding component is a windowless shielding component or a shielding component with a window; The windowless shielding component is used to obtain the step source signal; The windowed shielding component is used to obtain pulse source signals to simulate the fission peak of a critical accident.

5. The experimental apparatus for simulating the instantaneous occurrence and response of a critical accident according to any one of claims 1 to 4, characterized in that, The shielded slowing-down collimation module includes a housing, a detection channel, and a slowing-down pad; The housing has a source placement channel inside, and the source module is located inside the source placement channel; The detection channel is located on the side wall of the housing and is opposite to the target direction of the detection module. It is used to collimate the neutrons / photons generated by the source module in the target direction of the detection module, so that the target direction of the detection module generates a count rate that meets the measurement and statistical requirements. The moderation pad is located inside the detection channel to moderate neutrons, thereby optimizing the detection efficiency of the detection module.

6. The experimental apparatus for simulating the instantaneous occurrence and response of a critical accident according to claim 5, characterized in that, The enclosure is equipped with a shielding shell.

7. The experimental apparatus for simulating the instantaneous occurrence and response of a critical accident according to claim 6, characterized in that, The source module includes a neutron source / photon source and a source support column, wherein the neutron source / photon source is disposed on the source support column.

8. The experimental apparatus for simulating the instantaneous occurrence and response of a critical accident according to claim 7, characterized in that, The neutron source is one or more of the following: californium source, americium-beryllium source, americium-lithium source, and antimony-beryllium source; The photon source is one or more of the following: cobalt-60 source, cesium-137 source, iridium-192 source, americium-241 source, iron-55 source, selenium-75 source, and plutonium-238 source.

9. The experimental apparatus for simulating the instantaneous occurrence and response of a critical accident according to claim 7, characterized in that, The source support column is a pluggable box structure, which is provided with a plunger or inlet for placing a neutron source / photon source, and a shield is provided in the insertion direction of the plunger or inlet, and a neutron moderator is provided in the target direction of the detection module.

10. The experimental apparatus for simulating the instantaneous occurrence and response of a critical accident according to claim 9, characterized in that, The detection module includes a detector and a shielded slowing-down housing, with the detector located in the shielded slowing-down housing.

11. The experimental apparatus for simulating the instantaneous occurrence and response of a critical accident according to claim 10, characterized in that, The shielding and moderation shell is made of shielding material and moderation material. The shielding body, the shielding shell, and the shielding component are all made of shielding material. The box and the neutron moderation component are all made of moderation material. The shielding material includes neutron-absorbing materials and photon-shielding materials. The neutron-absorbing material is one or more of the following: cadmium, gadolinium, boron carbide, boron-containing polyethylene, boron-containing concrete, boron-containing resin, boron steel, boron aluminum, gadolinium hydride, elemental boron, boron silicate, boron titanate, gadolinium oxide, samarium oxide, hafnium oxide, europium oxide, hafnium carbide, samarium hafnium oxide, europium hafnium oxide, dysprosium titanate, samarium titanate, hafnium titanate, europium titanate, dysprosium ferrite, terbium titanate, dysprosium aluminate, gadolinium aluminate, and terbium aluminate. The photon-shielding material is one or more of the following: stainless steel, lead, tungsten, cast iron, and concrete. The moderating material is one or more of polyethylene, polyoxymethylene, graphite, beryllium oxide, and beryllium carbide.

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