Research On Deformation Law Of Prestressed Concrete Containment Under The Action Of Comprehensive Environmental Factors And Optimal Arrangement Of Sensor

In the event of a nuclear accident at a nuclear power plant,the containment structure of the nuclear reactor is extremely important as a last protective barrier against the release of fission products into the environment,ensuring its integrity.In the containment structural integrity test of nuclear power plants,the deformation of the containment structure is mainly caused by the test pressure,and is affected by comprehensive environmental factors such as ambient temperature and solar radiation,so it needs to be reasonably corrected in order to improve the accuracy of the test deformation measurement.Therefore,it is necessary to study the deformation law of prestressed concrete containment structure under the action of comprehensive environmental factors,clarify the sensitivity of concrete material parameters and environmental parameters to the deformation of containment structure during the test,and propose a new method for correcting the deformation measurement during the integral test of containment structure.The displacement sensor is the basis for collecting the deformation data of the containment structure in the integrity test of the containment structure,and it is also the basis for reconstructing the overall deformation of the containment structure based on the interpolation method and further realizing the overall performance evaluation of the containment structure.The number and location of the displacement sensor will directly affect the accuracy of the above problem solving.Therefore,it is necessary to study the optimal placement of the displacement sensor during the containment structure integrity test.In this paper,prestressed concrete containment is the research object,and the main research contents and conclusions are as follows:(1)Based on theoretical analysis and finite element method,the influence of ambient temperature,solar radiation,radiant heat transfer and different thermal boundary conditions on the deformation of containment structure was studied.The displacement of the containment structure varies approximately sinusoidally with the ambient temperature,but the lag is about 2h behind the ambient temperature change.When ignoring solar radiation,the average amplitude of the vertical displacement of the dome decreased by about 49%,and the average amplitude of the horizontal radial displacement of the barrel decreased by about 21%,indicating that the ambient temperature and solar radiation were the main environmental factors affecting the deformation of the containment structure.Radiant heat transfer is a secondary environmental factor affecting the deformation of containment structure,and it is recommended to consider the influence of this factor in order to ensure the simulation accuracy.With different thermal boundary condition application methods,the containment structure deformation is almost identical.(2)Based on the finite element method and the modified Morris screening method,the sensitivity of concrete material parameters and environmental parameters to structural deformation during the integrity test of containment structure was studied.The expansion coefficient is a highly sensitive parameter,the specific heat capacity and density are sensitive parameters,the elastic modulus is an insensitive parameter,the thermal conductivity and Poisson’s ratio are inconsistent due to the different structural parts of the containment shell,the dome top position is an insensitive parameter,and the barrel part is a medium sensitive parameter.Solar radiation and wind speed are sensitive parameters,the daily temperature difference is inconsistent due to the different parts of the containment structure,the dome top position is sensitive parameters,and the barrel part is highly sensitive parameters.The average amplitude of the displacement of containment structure was positively correlated with the expansion coefficient,negatively correlated with the specific heat capacity and density,and the correlation with the elastic modulus,Poisson’s ratio and thermal conductivity was not clear.The average amplitude of the displacement of the containment structure was positively correlated with solar radiation,daily temperature difference and wind speed.(3)Based on the machine learning regression prediction algorithm,a structural deformation prediction model under the action of multiple factors of ambient temperature and solar radiation during the overall test of containment structure is constructed,and the prediction error is compared with the structural deformation prediction model under the action of single factor of ambient temperature and the traditional linear regression structural deformation prediction model.A new method for correcting the deformation measurement during the integrity test of containment structure is proposed.The prediction error of the structural deformation prediction model under the action of multiple factors is lower than that of the ambient temperature single-factor and linear regression structural deformation prediction model,which effectively improves the correction accuracy of the deformation measurement during the integrity test of the containment structure,and realizes the automatic correction of the deformation measurement value during the integrity test of the containment structure.(4)Based on finite element method,Kriging interpolation and intelligent algorithm,the optimal arrangement of displacement sensor of containment structure is studied.Through finite element simulation,the deformation response of the containment structure under the action of the design internal pressure is obtained,and the deformation data of the finite element measurement point of a randomly generated displacement sensor layout scheme is used to reconstruct the structural deformation by Kriging,taking the smallest mean square error of the two as the optimization criterion,taking the mean square error as the objective function,and solving the objective function through genetic algorithm to realize the optimal arrangement of the displacement sensor of the containment structure.The optimized layout scheme of the displacement sensor of the containment structure can not only reflect the overall deformation of the structure,but also have certain economy.The initial state of the population has a certain influence on the calculation results and convergence rate at the beginning of the iteration,but has little effect on the final calculation results.