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CN-121997660-A - Gas diffusion-deformation-fracture coupling simulation method, model construction, electronic equipment and program product in nuclear fuel UO2 service process

CN121997660ACN 121997660 ACN121997660 ACN 121997660ACN-121997660-A

Abstract

The invention discloses a gas diffusion-deformation-fracture coupling simulation model in the service process of nuclear fuel UO2, which comprises, ; ; ; . The invention solves the problem that the existing simulation model only can consider one or two of the problems of gas diffusion, deformation and fracture in the nuclear fuel UO 2 , and the simulation model simultaneously considers three physical elements of gas diffusion, deformation and fracture.

Inventors

  • ZHAO CHENLONG
  • LIU GUISEN
  • Tan Peiyin
  • ZHANG ZIKANG
  • SHEN YAO

Assignees

  • 上海交通大学

Dates

Publication Date
20260508
Application Date
20260127

Claims (10)

  1. 1. A method for constructing a gas diffusion-deformation-fracture coupling simulation model in the service process of a nuclear fuel UO 2 is characterized in that the simulation model is described by the following set of control equations (7) - (10),
  2. 2. The method of claim 1, wherein the weak form of control equations (8) - (11) comprises the following set of control equations (11) - (15):
  3. 3. the method of claim 2, wherein the control equations (11) - (15) are solved using a finite element multi-level crossover optimization algorithm.
  4. 4. The method of claim 3, wherein the finite element multi-level cross optimization algorithm calculation process is organized by an outer loop, and in each outer loop iteration step, the calculation process is divided into two steps by interleaving, (1) Calculating a concentration field by adopting a residual Newton method through a diffusion sub-solver Chemical potential field Bubble phase field ; (2) The mechanical field is calculated by internal staggered circulation processing through a displacement-crack sub-solver.
  5. 5. The method of claim 4, wherein step (2) updates the displacement field with the residual-based newton solver under conditions where the diffusion state remains unchanged, the internal loop first ; Then, at a fixed displacement field On the premise of adopting a PETSc's SNES variation inequality solver to update the crack phase field 。
  6. 6. A method for simulating gas diffusion-deformation-fracture coupling in a nuclear fuel UO 2 service process, which is characterized in that a model as claimed in claim 1 is adopted to simulate the gas diffusion-deformation-fracture coupling problem in the nuclear fuel UO 2 service process, and the simulation process is optimized through finite element multi-level crossing.
  7. 7. The method according to claim 6, characterized in that it is used for the design of nuclear fuel rods with pellet-cladding structure.
  8. 8. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor runs the computer program to implement the method of any one of claims 1 to 7.
  9. 9. A storage medium having stored thereon a computer program which, when executed by a processor, implements the method of any of claims 1 to 7.
  10. 10. A computer program product comprising a computer program, characterized in that the computer program is executed by a processor to implement the method of any one of claims 1 to 7.

Description

Gas diffusion-deformation-fracture coupling simulation method, model construction, electronic equipment and program product in service process of nuclear fuel UO 2 Technical Field The disclosure belongs to the technical field of nuclear material design, and particularly relates to a gas diffusion-deformation-fracture coupling simulation method, a model construction method, a nuclear fuel rod design, electronic equipment and a program product in a nuclear fuel UO 2 service process. Background Uranium dioxide (UO 2) has been a cornerstone of the commercial nuclear power industry for decades and is the primary fuel for worldwide Light Water Reactors (LWRs) and fast neutron breeder reactors (FBRs). During the operational life of a reactor, the fuel is subjected to a combination of extreme conditions that, in combination, induce complex microstructural and material property changes and ultimately affect its performance. These conditions include neutron irradiation and stress, among other factors, which induce many different physical processes. Under irradiation conditions, fission gases such as xenon (Xe) and krypton (Kr) are generated in the nuclear fuel. These gases have very low solubility in the UO 2 matrix and therefore migrate by diffusion. This migration and subsequent aggregation results in nucleation and growth of intra-and inter-crystalline fission bubbles. When the bubble growth and connection reach a threshold, gaseous fission products are released from the fuel pellet into the pellet-cladding gap. Such fission gas release can reduce the thermal conductivity of the gap and exert significant pressure on the inner wall of the enclosure, which can lead to creep deformation and failure. Under stress conditions, such as those caused by temperature gradients, UO 2 may deform and crack inside the fuel pellet. The formation and propagation of such cracks is deeply affected by the presence and distribution of fissile bubbles. The formation of a network of cracks reduces the thermal conductivity within the fuel pellets, resulting in fuel-cladding interactions and causing fuel repositioning. In addition, the crack network may also alter the communicating percolation path of the fission gas release and alter the gas diffusion behavior. These phenomena indicate that these physical processes, including diffusion, deformation and fracture, are far from independent, but are tightly coupled. In view of the extreme conditions under which nuclear fuels are in service, it is almost impossible to experimentally study the coupling of these factors in situ for the performance of nuclear fuels such as UO 2, and a number of numerical methods and models have been developed to try to solve the problems of gas diffusion, deformation and fracture in UO 2 on various scales. For example, molecular dynamics methods can be used on a microscopic scale to study the diffusion behavior of different types of atoms and vacancies in a nuclear fuel matrix. On mesoscopic scale, the phase field method is widely used for researching evolution of a gas concentration field and growth and connection of bubbles, deformation research relates to material constitutive development considering factors such as irradiation and creep under different conditions, fracture problems on microscopic and atomic scale can be researched by a molecular dynamics method, and crack evolution on macromesoscopic can be researched by a phase field fracture method, a cohesive force unit, an expansion finite element and other models. Disclosure of Invention In one aspect of the present disclosure, a finite element multi-level crossover optimization method for diffusion, deformation and fracture coupling problems in nuclear fuel UO 2. The gas diffusion-deformation-fracture coupling problem in the service process of the nuclear fuel UO 2 is simulated through a simulation model, and the simulation process is optimized through finite element multi-level crossing. The simulation model is described by the following set of control equations (7) - (10), In one aspect of the disclosure, a method for simulating gas diffusion-deformation-fracture coupling in a nuclear fuel UO 2 service process is provided, the simulation model is adopted to simulate the gas diffusion-deformation-fracture coupling problem in the nuclear fuel UO 2 service process, and the simulation process is optimized through finite element multi-level crossing. In one aspect of the disclosure, an electronic device includes a memory, a processor, and a computer program stored on the memory and executable on the processor, the processor running the computer program to implement the gas diffusion-deformation-fracture coupling simulation method described above during service of the nuclear fuel UO 2. In one aspect of the disclosure, a storage medium has a computer program stored thereon, which when executed by a processor, implements the gas diffusion-deformation-fracture coupling simulation method described above for n