Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides the passive shutdown device and the control method thereof, and the passive emergency shutdown device for the lead-based fast reactor changes the mode that the traditional rod dropping device drops the rod by gravity, and designs the floating passive shutdown device by utilizing the characteristic of large density of a lead-based fast reactor coolant.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the purpose of the invention is realized by the following technical scheme:
a passive shutdown device comprises a control rod, an ejection device, a stabilizer, a constraint device, a driving device, a logic circuit and a guide device;
one end of the control rod is provided with the stabilizer, and the other end of the control rod is arranged in the guide device; an ejection device is arranged below the stabilizer, one end of the restraint device is connected with the stabilizer, and the other end of the restraint device penetrates through the ejection device and is connected with the controller.
The material of the control rod is B4C, the control rod is in a lead-based fast reactor coolant environment;
the stabilizer is a counterweight device containing ferromagnetic metal, an electromagnetic device is arranged at the bottom of the ejection device, when the emergency shutdown is not triggered, the electromagnetic device is electrified, the stabilizer is magnetically connected with the electromagnetic device, and the ejection device is in a compressed state.
As a further development of the invention, the ejection device comprises a spring which is in a compressed state when the scram is not triggered.
As a further improvement of the invention, the restraining means is a flexible metal chain.
As a further improvement of the present invention, the controller includes a driving device and a logic circuit;
the driving device is connected with the restraining device;
and the logic circuit is electrically connected with the driving device and the electromagnetic device.
As a further improvement of the present invention, the driving device is a motor.
As a further development of the invention, the guide means comprise at least one coaxial ring or cylindrical sleeve.
A control method of a passive shutdown device comprises the following steps:
when a passive emergency shutdown signal is triggered, the loop of the electromagnetic device is powered off, the electromagnetic force of the stabilizer disappears, and the control rod is ejected out by the spring;
when the nuclear reactor is restarted by triggering, the starting mechanism works to withdraw the restraint device, the stabilizer is electrified to generate electromagnetic force to fix the control rod at the bottom, and the driving device releases the restraint device after the fixation is completed, so that the tension of the restraint device disappears.
As a further improvement of the invention, the method specifically comprises the following steps:
s1, when the passive emergency shutdown is not triggered, the stabilizer fixes the control rod at the bottom of the nuclear reactor by using electromagnetic force, and the restraint device has no tension at the moment;
s2, when a passive emergency shutdown is triggered, the electromagnetic force of the stabilizer disappears, the ejection device ejects the control rod, the attitude of the control rod is stabilized by the guide device at the initial stage after the control rod is ejected, the attitude and the motion track of the control rod can be well maintained under the action of initial kinetic energy, and the control rod is inserted into the reactor along a preset track;
s3, in the middle period after the control rod is ejected, the stabilizer is used as a balance weight to change the gravity center position of the control rod so as to adjust the posture of the control rod, and the middle section where the control rod is inserted needs to be jointly participated in controlling the posture and the movement track of the control rod by a guide device and the stabilizer;
s4, at the tail end of the control rod after being ejected, the constraint device provides tension and the stabilizer to jointly participate in controlling the posture and the motion trail of the control rod;
s5, after the passive emergency shutdown is completed, the system should be kept stable and static, and the system is prepared to be recovered after the power supply is recovered;
and S6, after the power supply is recovered and the restart signal is received, the control rod is pulled back by the traction restraining device of the driving device, in the process, the guide device is used for keeping the control rod posture in the initial stage of the recovery process, the guide device and the stabilizer are used for keeping the control rod posture in the middle stage of the recovery process, and the stabilizer and the restraining device are used for keeping the control posture in the end stage of the recovery process and finally stabilizing the control rod at the bottom of the reactor core to wait for the next task.
Compared with the background art, the invention has the following beneficial effects:
the passive emergency shutdown device for the lead-based fast reactor changes the mode that the traditional rod dropping device drops the rod by gravity, and designs the floating passive shutdown device by utilizing the characteristic of large density of a lead-based fast reactor coolant. The invention can solve the problem of passive shutdown of the lead-based fast reactor. Considering that the liquid metal has high viscosity, three control rod stabilizing devices are designed for restraining the posture and the track of the control rods at different stages of the control rod movement, and finally, a driving mechanism is designed to enable the passive shutdown device to recover the original position and wait for the next task when the nuclear reactor is restarted. The device can automatically reset, and reduces the preparation work for restarting the nuclear reactor in the later period compared with the traditional rod dropping device. The invention comprises a device for stabilizing the movement of the control rod, can well complete rod insertion and has high reliability.
Detailed Description
In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the drawings in the embodiment of the present invention, and it is obvious that the described embodiment is only a part of the embodiment of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, shall fall within the scope of protection of the present invention.
It will be understood that when an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a single embodiment.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings and specific embodiments, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the invention without making creative efforts, fall within the scope of the invention.
As shown in fig. 1 and 2, the passive shutdown device of the present invention utilizes the large buoyancy generated by the high density of the lead-based fast reactor coolant. The method adopts the modes of ejection, buoyancy, restriction and recovery to complete the emergency shutdown task when the shutdown device is powered off so as to prevent accidents of the nuclear reactor.
The passive shutdown device comprises: the control rod control device comprises a control rod 1, an ejection device 2, a stabilizer 3, a constraint device 4, a driving device 5, a logic circuit 6 and a guide device 7;
one end of the control rod 1 is provided with the stabilizer 3, and the other end is provided with a guide device 7; an ejection device 2 is arranged below the stabilizer 3, one end of a restraint device 4 is connected with the stabilizer 3, and the other end of the restraint device penetrates through the ejection device 2 to be connected with a controller.
The material of the control rod 1 is B4C, the control rod 1 is in a lead-based fast reactor coolant environment;
the stabilizer 3 is a counterweight device containing ferromagnetic metal, the electromagnetic device is arranged at the bottom of the ejection device 2, when the emergency shutdown is not triggered, the electromagnetic device is electrified, the stabilizer 3 is magnetically connected with the electromagnetic device, and the ejection device 2 is in a compressed state.
The functions and functions of the specific structures are as follows:
wherein, the control rod 1 has good neutron absorption capacity, and B is generally adopted as the control rod 14C material and lead-based fast reactor coolant density ratio control rod material B4The density of the C is much larger, the control rod can bear large buoyancy in the coolant, so that the passive shutdown can not be carried out by adopting the traditional free falling body mode.
The ejection device 2 has a spring as a core component, and is in an energy storage state when the emergency shutdown is not triggered, namely the spring is in a compression state. The current exists in the loop during the normal operation of the nuclear reactor, the electromagnetic device of the stabilizer 3 is used for fixing the control rod 1 at the bottom of the nuclear reactor, and the ejection device is in an energy storage state.
Stabilizer 3, the stabilizer is the counter weight device that is located control rod 1 lower extreme ferruginous metal, and the stabilizer has two effects in passive shutdown device:
the method has the following effects: stabilizing a control rod 1 at the bottom of a nuclear reactor by utilizing electromagnetic force during normal operation of the nuclear reactor;
the second action is as follows: after triggering the passive shutdown, the control rod 1 is popped up, and in the process of upward movement under the action of buoyancy, the gravity center position of the control rod 1 is changed to keep the attitude of the control rod 1 stable.
The restraining device 4 is a flexible metal chain, the flexibility of the restraining device 4 is that the restraining device 4 does not have obvious influence on the operation of the control rod 1 when the control rod 1 is ejected, and the metal material prevents the corrosion of high-temperature coolant. The effect has two:
the method has the following effects: after the control rod is popped out, the control rod is pulled by tension force to keep a vertical state;
the second action is as follows: and after the shutdown task is completed, the control rod is returned by the traction of the driving device 5.
The driving device 5 is a motor and is used for providing power when the scram is finished, and the control rod 1 is reset through the traction restraining device 4.
The guide device 7 is characterized in that two coaxial circular rings can be replaced by cylindrical sleeves in the guide mode, the restraining device keeps the posture of the control rod 1 after being ejected out by limiting the degree of freedom of the control rod, and the control rod 1 is returned when the reactor is restarted by matching with the driving device 5 after the work is finished.
And the logic circuit 6 is used for triggering the passive shutdown device and a control circuit for recovering after the passive shutdown device is completed. The circuit logic is as follows: when a non-energy passive emergency shutdown signal is triggered, the loop is powered off, the electromagnetic force of the stabilizer 3 disappears, and the control rod is ejected out by the spring. When the nuclear reactor is restarted by triggering, the starting mechanism works to withdraw the restraint device 4, the stabilizer 3 is electrified to generate electromagnetic force to fix the control rod at the bottom, and the driving device 5 releases the restraint device after the fixation is completed, so that the tension of the restraint device 4 disappears to ensure that the control rod 1 can be effectively ejected when the nuclear reactor is in emergency shutdown next time.
As shown in fig. 4, the passive emergency shutdown device is stationary at the bottom of the nuclear reactor when the nuclear reactor is not triggering the passive emergency shutdown device. The lower end of the control rod is provided with a stabilizer and a restraint device, wherein the stabilizer is a counterweight device with ferromagnetic metal. During normal operation of the nuclear reactor, the passive emergency shutdown device is powered on, the device with the electromagnet adsorbs the stabilizer and fixes the control rod at the bottom of the nuclear reactor, and the ejection device is in a compressed state.
The magnitude of the electromagnetic force should be:
Fmagnetic field=ξ(FFloating body+FBullet-FHeavy load)
Wherein FMagnetic fieldIs an electromagnetic adsorption force, FHeavy loadTotal weight of control rod, stabilizer and restraint, FFloating bodyIs a control rod and is stableAnd restraining the total buoyancy received, FBulletThe elasticity of the spring, xi is a safety coefficient, and 1 is taken<ξ≤2。
When triggering passive emergency shutdown signal, the system cuts off the power supply, and the electromagnetic force disappears, and control rod atress is unbalanced this moment, and the control rod flies out from bottom to top under buoyancy and spring force effect, and acceleration during the fly-out is:
where a is the acceleration at which the control rod flies out, MStickIs the total mass of the control rod, the stabilizer and the restraint device. To ensure the smooth insertion of the control rods into the core, a guide is disposed at the bottom of the core for restraining the initial movement direction of the control rods, and the guide should be not higher than the tips of the control rods in the non-operating state as shown in fig. 1. The guide device can adopt a cylindrical tube structure or a double-ring structure, and the length of the cylindrical tube and the distance between the double rings are selected according to the length of the control rod. It should not be too large or too small. When the control rods are fully inserted into the core, the guide should not be lower than the bottom ends of the control rods, as shown in FIG. 2.
The ejection system ejects the control rod out of the control rod, the control rod does not take the elastic force action of the ejection device any more, the resistance borne by the control rod is gradually increased along with the increase of the speed of the control rod, the control rod reaches the maximum speed when the resultant force is 0, and then the control rod rises at the constant speed. The maximum speed of the control rod is:
wherein VmaxFor the maximum possible speed of the control rod, ε is the drag coefficient, which is related to the kinematic viscosity of the coolant.
When the control rod moves to the middle section, the guide means is weakened, and a stabilizer is disposed at the bottom end of the control rod in order to maintain the attitude and the movement direction of the control rod. The working principle of the stabilizer is shown in fig. 3, the stabilizer is a counterweight device with ferromagnetic metal, the density of the counterweight device is as much as possible greater than that of the control rod, so that the lower end of the control rod is subjected to small resultant force, the upper end of the control rod is subjected to large resultant force, and when the control rod tilts in a reaction mode, the upper end resultant force generates larger torque to enable the control rod to restore to the vertical state again.
As shown in fig. 2, when the control rods move to the end, the guide means is substantially deactivated, and the restraining means is connected to the bottom ends of the control rods in addition to the stabilizer in order to restrain the final state of the control rods. The restraining means maintains the position of the control rods after the control rods are inserted into the core so as not to be deflected or float, and the lower end of the restraining means is flexibly restrained so as to maintain the stable state of the balloon, in analogy to the floating state of the balloon in the air. And the lead-based fast reactor has higher operating temperature and certain corrosivity, and common materials are difficult to apply to the environment. The metal wire is too thin and easily broken, and too thick and flexible to easily interfere with the movement of the control rod at the control rod lifting stage, so a chain structure should be adopted.
When the passive emergency shutdown device finishes the restart stage after the shutdown task, the driving device can retract the restraint device through the driving motor, the guide device, the restraint device and the stabilizer still keep the original functions in the retraction process, and then the ejection device is compressed under the traction of the driving device and the restraint device to be in an energy storage state and fixed at the bottom end through the electromagnet. The motor stops working, the restraint device is released, and the system recovers the initial state. It is to be noted that the containment device should be in a relaxed state after it has been restored to its initial condition, in order to ensure that the control rods are inserted into the core as quickly as possible during a passive emergency shutdown.
As shown in fig. 3, the present invention further provides a control method of a passive shutdown device, comprising the following steps:
when a non-energy passive emergency shutdown signal is triggered, the loop of the electromagnetic device is powered off, the electromagnetic force of the stabilizer 3 disappears, and the control rod is ejected out by the spring;
when the nuclear reactor is restarted by triggering, the starting mechanism works to withdraw the restraint device 4, the stabilizer 3 is electrified to generate electromagnetic force to fix the control rod 1 at the bottom, and the driving device 5 releases the restraint device 4 after the fixation is completed, so that the tension of the restraint device 4 disappears.
Triggering a logic circuit of the passive shutdown device, the passive ejection device, posture correction, posture and position restraint and completing system restoration after passive shutdown; the passive shutdown device comprises the following working steps:
s1, in the initial stage, namely when the passive emergency shutdown is not triggered, the stabilizer 3 fixes the control rod at the bottom of the nuclear reactor by using electromagnetic force, and at the moment, the restraint device 4 has no tension;
s2, when a passive emergency shutdown is triggered, the electromagnetic force of the stabilizer 4 disappears, the ejection device 2 ejects the control rod, the attitude of the control rod 1 is stabilized by the guide device 7 at the initial stage after the control rod 1 is ejected, the attitude and the motion track of the control rod 1 can be well maintained under the action of initial kinetic energy, and the control rod 1 is inserted into the reactor along a preset track;
s3, in the middle period after the control rod 1 is popped up, the slender control rod 1 easily loses the vertical posture under the action of buoyancy, the stabilizer is used as a counterweight to change the gravity center position of the control rod so as to adjust the posture of the control rod, and the middle section where the control rod 1 is inserted needs to be jointly participated in controlling the posture and the movement track of the control rod 1 by the guide device 7 and the stabilizer 3;
s4, at the end of the control rod 1 after being ejected, the constraint device 4 provides tension and the stabilizer 3 to jointly participate in controlling the posture and the motion trail of the control rod 1;
s5, after the passive emergency shutdown is completed, the system should be kept stable and static, and the system is prepared to be recovered after the power supply is recovered;
and S6, after the power supply is recovered and the restarting signal is received, the driving device 5 pulls the restraint device 4 to pull back the control rod 1, in the process, the guide device 7 is used for keeping the control rod 1 in the posture at the initial stage of the restoration process, the guide device 7 and the stabilizer 3 are used for keeping the control rod 7 in the posture at the middle stage of the restoration, and the stabilizer 3 and the restraint device 4 are used for keeping the control rod 7 in the posture at the end stage of the restoration and finally stabilizing the control rod at the bottom of the reactor core to wait for the next task.
The above embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention, and all simple modifications, changes and equivalent structural changes made to the above embodiments according to the technical spirit of the present invention still fall within the protection scope of the technical solution of the present invention.
It should be noted that, in the description of the present invention, the terms "first", "second", and the like are used for descriptive purposes only and for distinguishing similar objects, and no precedence between the two is considered as indicating or implying relative importance. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.
It is to be understood that the above description is intended to be illustrative, and not restrictive. Many embodiments and many applications other than the examples provided would be apparent to those of skill in the art upon reading the above description. The scope of the present teachings should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. The disclosures of all articles and references, including patent applications and publications, are hereby incorporated by reference for all purposes. The omission in the foregoing claims of any aspect of subject matter that is disclosed herein is not intended to forego such subject matter, nor should the applicant consider that such subject matter is not considered part of the disclosed subject matter.