An apparatus and method for simulating rapid strain failure behavior of nuclear fuel cladding
By designing a simulation device that includes a support structure, a load loading system, and an experimental measurement system, the problem of rapid strain failure of the cladding in off-pile simulation tests was solved, and accurate simulation and evaluation under near-plane strain stress state were achieved, improving test safety and data accuracy.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XI AN JIAOTONG UNIV
- Filing Date
- 2023-09-20
- Publication Date
- 2026-07-28
AI Technical Summary
Existing off-pile simulation test schemes are difficult to accurately simulate the rapid strain failure behavior of nuclear fuel cladding in the reactor, especially the failure evaluation criteria under uniaxial stress state are not conservative enough, and in-pile tests are costly and dangerous to operate.
A simulation device was designed, comprising a support structure, a load loading system, and a testing and measurement system. Through hydraulic loading and data acquisition, the rapid failure behavior of the shell under near-plane strain stress was simulated. A powerful electromagnet and chain protection were used, and the drive tube material had high yield strength, with a clearance fit to prevent relative displacement.
It enables accurate simulation of rapid strain failure performance of the cladding outside the reactor core, obtains evaluation criteria that are closer to the actual stress state inside the reactor core, reduces the influence of friction, and improves test safety and data accuracy.
Smart Images
Figure CN117275772B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of nuclear fuel and material performance testing technology, specifically relating to an apparatus and method for simulating the rapid strain failure behavior of nuclear fuel cladding. Background Technology
[0002] Fuel rod cladding is the first barrier in a reactor to contain radioactive materials, and its integrity is closely related to the stability and safety of reactor operation. Under certain accident conditions, such as reactivity-introduced accidents, power pulses occur in fuel pellets within millisecond timescales. Energy deposition causes the pellets to expand rapidly and come into contact with the cladding, forcing the cladding to undergo rapid strain failure. Existing research results indicate that the rapid strain failure behavior of the cladding within the reactor is a strain failure behavior dominated by near-isobaxial stress under the dual influence of displacement and internal pressure. Furthermore, the stronger the biaxiality of the cladding stress, the lower the values of its failure stress and failure strain.
[0003] There are two main methods for studying the rapid strain failure behavior of cladding: in-core testing and off-core simulation testing. In-core testing requires a dedicated test reactor, which is costly. Operators are in direct contact with radioactive materials and the environment, and the number of reactors supporting in-core testing is extremely limited, significantly restricting the feasibility of such methods. The challenge of off-core simulation testing lies in simulating the actual state of the fuel cladding within the reactor using a well-designed testing scheme. The key is to reproduce the stress state experienced by the cladding during rapid strain failure within the reactor. Existing off-core simulation testing schemes, such as compression-expansion tests, uniaxial tensile tests, and mandrel tests, primarily employ uniaxial stress states. In-core test results show that the rapid strain failure performance of the cladding decreases with increasing biaxial stress, thus the cladding failure evaluation criteria obtained under uniaxial stress states are insufficiently conservative. Therefore, developing new off-core simulation testing schemes to improve the biaxiality of stress experienced by the cladding during rapid strain failure, evaluating the failure performance of the cladding under this stress state, and proposing corresponding cladding failure performance evaluation standards have significant engineering and theoretical value. Summary of the Invention
[0004] To address the shortcomings in current research, the present invention aims to provide an apparatus and method for simulating the rapid strain failure behavior of nuclear fuel cladding, which can simulate the rapid failure behavior of cladding under near-plane strain stress state, and simultaneously obtain the evaluation criteria for cladding failure behavior under this state.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] A device for simulating rapid strain failure behavior of nuclear fuel cladding includes a support structure, a load loading system, and a testing and measurement system;
[0007] The support structure includes a movable platform A and a hoisting device B mounted on the movable platform A. The movable platform A supports the load loading system and the testing and measurement system. The hoisting device B is connected to the movable platform A and is used to hoist the load loading system.
[0008] The load loading system includes a fixed frame C, a powerful electromagnet D, a limiting device E, a counterweight F, and a guide column G. One end of the guide column G is connected to the movable base A of the platform, and the other end is connected to the fixed frame C to fix the load loading path. One side of the powerful electromagnet D is connected to the fixed frame C, and the other side cooperates with the counterweight F to load external loads. The counterweight F is movably connected to the guide column G, and the limiting device E is assembled on the guide column G to limit the height at which the counterweight is lifted.
[0009] The test and measurement system includes a punch H, a plunger I, a guide sleeve J, a piston cylinder K, a cylinder L, a hydraulic oil chamber M, a pressure sensor N, a drive pipe mounting flange O, a lock nut P, a drive pipe Q, a casing tube R, and a data acquisition device S. The punch H is located below the counterweight F. The counterweight F falls and impacts the punch H. The punch H drives the plunger I to move along the guide sleeve J and the piston cylinder K. The cylinder L contains a hydraulic oil chamber M, which is filled with hydraulic oil. The movement of the plunger I compresses the hydraulic oil, thus pressurizing the hydraulic oil chamber M. Pressure sensor N is placed on the side wall of hydraulic oil chamber M to measure the internal pressure of hydraulic oil chamber M. Data acquisition device S is used to collect and record data during the test. Drive tube mounting flange O and locking nut P are placed at the bottom of cylinder body L to fix drive tube Q. Shell tube R is placed outside drive tube Q. Hydraulic oil chamber M is connected to drive tube Q. The increase of hydraulic oil pressure causes drive tube Q to deform rapidly, which in turn forces shell tube R to deform rapidly, realizing the simulation of rapid strain failure behavior of shell tube (R).
[0010] As described above, in the device for simulating rapid strain failure of nuclear fuel cladding, the material used for the drive tube Q has a yield strength greater than 925 MPa and a minimum wall thickness greater than 0.475 mm.
[0011] As described above, in the device for simulating rapid strain failure of nuclear fuel cladding, the drive tube Q and the cladding tube R are fitted with a clearance, with a clearance size not exceeding 50 μm.
[0012] As described above, in order to prevent the counterweight F from falling due to an accidental power failure of the powerful electromagnet D, the counterweight F is connected to the fixed frame C by a chain.
[0013] The test method corresponding to the apparatus for simulating the rapid strain failure behavior of nuclear fuel cladding is as follows:
[0014] First, install the casing tube R. Insert the casing tube R into the lower end of the drive tube Q, and then use the lock nut P to lock the lower end of the drive tube Q.
[0015] The second step is to fill the hydraulic oil chamber M with hydraulic oil and continuously circulate the hydraulic oil to remove air from the oil circuit until the air removal is completed.
[0016] The third step is to adjust the plunger I stroke to the value required for the test conditions.
[0017] The fourth step is to adjust the hoisting height of the counterweight F to the value required for the test conditions.
[0018] Fifth step: Turn on the data acquisition device S to record the test data;
[0019] Step 6: Cut off the power supply to the powerful electromagnet D, release the counterweight F, and the counterweight F falls freely along the guide column G and applies a load to the punch H, thereby forcing the hydraulic oil inside the hydraulic oil chamber M to pressurize and realize the rapid strain failure simulation of the casing tube R.
[0020] Step 7: Save all data from the experiment.
[0021] Compared with the prior art, the present invention has the following advantages:
[0022] 1. The experimental apparatus and method described in this invention can simulate the failure behavior of the cladding under different strain rates by adjusting the falling height of the counterweight and the stroke of the plunger. It can accurately record the response relationship between the internal pressure and strain of the cladding over time under rapid strain conditions, thereby enabling the evaluation of the rapid strain failure performance of the cladding.
[0023] 2. The off-core simulation test scheme proposed in this invention can simulate the rapid failure behavior of the cladding under near-plane strain stress. Compared with common test schemes, it has stronger stress biaxiality and is closer to the actual stress state of the cladding inside the reactor.
[0024] 3. To prevent the counterweight from falling due to a sudden power failure of the powerful electromagnet, a chain is used to connect it to the fixed frame, which has a mechanical protection effect.
[0025] 4. The off-core simulation test scheme proposed in this invention can eliminate the influence of friction on the cladding strain failure behavior and obtain good response curves of driving tube internal pressure and cladding strain over time. Attached Figure Description
[0026] Figure 1 This is a schematic diagram of the device of the present invention.
[0027] Figure 2 This is a schematic diagram of the testing and measurement system.
[0028] Figure 3 This is a flowchart of the experimental method. Detailed Implementation
[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0030] like Figure 1 As shown, the present invention provides an apparatus for simulating the rapid strain failure behavior of nuclear fuel cladding, including a support structure, a load loading system, and a test and measurement system;
[0031] The support structure includes a movable platform A and a hoisting device B. The movable platform A supports the load loading system and the testing and measurement system. The hoisting device B is connected to the movable platform A and is used to hoist the load loading system.
[0032] The load loading system includes a fixed frame C, a powerful electromagnet D, a limiting device E, a counterweight F, and a guide column G. One end of the guide column G is connected to the movable base A of the platform, and the other end is connected to the fixed frame C to fix the load loading path. One side of the powerful electromagnet D is connected to the fixed frame C, and the other side cooperates with the counterweight F to load external loads. The counterweight F is movably connected to the guide column G, and the limiting device E is assembled on the guide column G to limit the height at which the counterweight is lifted.
[0033] like Figure 2 As shown, the test and measurement system includes a punch H, a plunger I, a guide sleeve J, a piston cylinder K, a cylinder L, a hydraulic oil chamber M, a pressure sensor N, a drive pipe mounting flange O, a locking nut P, a drive pipe Q, a casing tube R, and a data acquisition device S. A counterweight F falls and impacts the punch H, causing the plunger I to move along the guide sleeve J and the piston cylinder K. The cylinder L contains a hydraulic oil chamber M filled with hydraulic oil. The movement of the plunger I compresses the hydraulic oil, increasing the pressure in the hydraulic oil chamber M. The pressure sensor N is placed on the side wall of the hydraulic oil chamber M to measure the internal pressure. The data acquisition device S is used to collect and record data during the test. The drive pipe mounting flange O and the locking nut P are placed at the bottom of the cylinder L to fix the drive pipe Q. The casing tube R is placed outside the drive pipe Q. The hydraulic oil chamber M is connected to the drive pipe Q. The increased hydraulic oil pressure causes the drive pipe Q to deform rapidly, which in turn forces the casing tube R to deform rapidly, thus simulating the rapid strain failure behavior of the casing tube (R).
[0034] In this embodiment, the material selected for the drive tube Q has a yield strength greater than 925 MPa and a minimum wall thickness greater than 0.475 mm. The purpose is to prevent necking failure of the cladding and reduce the internal pressure of the drive tube when the cladding fails.
[0035] In this embodiment, to facilitate the installation of the cladding sample, the drive tube Q and the cladding tube R are fitted with a clearance, with a clearance size not exceeding 50 μm, to prevent axial relative displacement between the drive tube and the cladding.
[0036] In this embodiment, to prevent the counterweight F from falling due to an accidental power failure of the powerful electromagnet D, a chain is used to connect the counterweight F to the fixing frame C.
[0037] like Figure 3 As shown, a test method corresponding to a device for simulating the rapid strain failure behavior of nuclear fuel cladding is described:
[0038] First, install the casing tube R. Insert the casing tube R into the lower end of the drive tube Q, and then use the lock nut P to lock the lower end of the drive tube Q.
[0039] The second step is to fill the hydraulic oil chamber M with hydraulic oil and continuously circulate the hydraulic oil to remove air from the oil circuit until the air removal is completed.
[0040] The third step is to adjust the plunger I stroke to the value required for the test conditions.
[0041] The fourth step is to adjust the hoisting height of the counterweight F to the value required for the test conditions.
[0042] Fifth step: Turn on the data acquisition device S to record the test data;
[0043] Step 6: Cut off the power supply to the powerful electromagnet D, release the counterweight F, and the counterweight F falls freely along the guide column G and applies a load to the punch H, thereby forcing the hydraulic oil inside the hydraulic oil chamber M to pressurize and realize the rapid strain failure simulation of the casing tube R.
[0044] Step 7: Save all data from the experiment.
[0045] The above description is a further detailed explanation of the present invention in conjunction with specific preferred embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of patent protection determined by the submitted claims.
Claims
1. A device for simulating the rapid strain failure behavior of nuclear fuel cladding, characterized in that: This includes the supporting structure, load loading system, and testing and measurement system; The support structure includes a movable platform (A) and a hoisting device (B) mounted on the movable platform (A). The movable platform (A) supports the load loading system and the testing and measurement system. The hoisting device (B) is connected to the movable platform (A) and is used to hoist the load loading system. The load loading system includes a fixed frame (C), a powerful electromagnet (D), a limiting device (E), a counterweight (F), and a guide column (G). One end of the guide column (G) is connected to the platform moving seat (A), and the other end is connected to the fixed frame (C) to fix the load loading path. One side of the powerful electromagnet (D) is connected to the fixed frame (C), and the other side cooperates with the counterweight (F) for loading external loads. The counterweight (F) is movably connected to the guide column (G), and the limiting device (E) is assembled on the guide column (G) to limit the height at which the counterweight is lifted. The test and measurement system includes a punch (H), a plunger (I), a guide sleeve (J), a piston cylinder (K), a cylinder (L), a hydraulic oil chamber (M), a pressure sensor (N), a drive pipe mounting flange (O), a lock nut (P), a drive pipe (Q), a casing tube (R), and a data acquisition device (S). The punch (H) is located below the counterweight (F). The counterweight (F) falls and impacts the punch (H). The punch (H) drives the plunger (I) to move along the guide sleeve (J) and the piston cylinder (K). The cylinder (L) contains a hydraulic oil chamber (M) filled with hydraulic oil. The movement of the plunger (I) compresses the hydraulic oil, causing... The hydraulic oil chamber (M) is pressurized, and the pressure sensor (N) is placed on the side wall of the hydraulic oil chamber (M) to measure the internal pressure of the hydraulic oil chamber (M). The data acquisition device (S) is used to collect and record data during the test. The drive tube mounting flange (O) and locking nut (P) are placed at the bottom of the cylinder (L) to fix the drive tube (Q). The outer shell tube (R) is placed on the outside of the drive tube (Q). The hydraulic oil chamber (M) is connected to the drive tube (Q). The increase in hydraulic oil pressure causes the drive tube (Q) to deform rapidly, which in turn forces the shell tube (R) to deform rapidly, thereby simulating the rapid strain failure behavior of the shell tube (R). By adjusting the falling height of the counterweight and the stroke of the plunger, the failure behavior of the cladding under different strain rates can be simulated.
2. The apparatus for simulating rapid strain failure behavior of nuclear fuel cladding according to claim 1, characterized in that: The material used for the drive tube (Q) has a yield strength greater than 925 MPa and a minimum wall thickness greater than 0.475 mm.
3. The apparatus for simulating rapid strain failure behavior of nuclear fuel cladding according to claim 1, characterized in that: The drive tube (Q) and the casing tube (R) are fitted with a clearance, with a clearance dimension not exceeding 50 μm.
4. The apparatus for simulating rapid strain failure behavior of nuclear fuel cladding according to claim 1, characterized in that: To prevent the counterweight (F) from falling due to an accidental power failure of the powerful electromagnet (D), a chain is used to connect the counterweight (F) to the fixing frame (C).
5. The test method corresponding to the apparatus for simulating the rapid strain failure behavior of nuclear fuel cladding as described in any one of claims 1 to 4, characterized in that: First, install the casing tube (R). Insert the casing tube (R) into the lower end of the drive tube (Q), and then use the lock nut (P) to lock the lower end of the drive tube (Q). The second step is to fill the hydraulic oil chamber (M) with hydraulic oil and continuously circulate the hydraulic oil to remove air from the oil circuit until the air removal is completed. The third step is to adjust the plunger (I) stroke to the value required for the test conditions. The fourth step is to adjust the lifting height of the counterweight (F) to the value required for the test conditions. Fifth step: Turn on the data acquisition device (S) to record the test data; Step 6: Cut off the power supply to the powerful electromagnet (D), release the counterweight (F), and the counterweight (F) falls freely along the guide column (G) and applies a load to the punch (H), thereby forcing the hydraulic oil in the hydraulic oil chamber (M) to pressurize and realize the rapid strain failure simulation of the casing tube (R); Step 7: Save all data from the experiment.