Simulation of xenon transition processes based on data of reactor experiments and metric analysis

The report presents a new scheme for modeling xenon transient processes, based on the use of accumulated information on the parameters of the core state in the reactor operation. The proposed scheme uses an interpolation algorithm for functions of many variables, constructed on the basis of metric analysis. Approbation of the developed algorithm for searching for the most probable set of model parameters was carried out using the example of solving a series of model problems. The search for a posteriori probability density was carried out by the Monte Carlo method according to the Markov chain scheme. To construct a posteriori probability density, the construction of a Markov chain involving several hundred thousand links is required. For each link of the Markov chain, it is necessary to calculate the values of the functionals. When constructing the Markov chain, the values of the sets of functionals corresponding to different sets of parameters were determined by using the interpolation algorithm between the reference points, based on the metric analysis scheme. To improve the accuracy of the interpolation procedure, on one hand, and to maintain an acceptable volume of calculations, on the other hand, a procedure was developed to supplement the set of reference points with new calculation points. The main idea of such a procedure is that the asymptotic density of points in the Markov chain corresponds to the density of the unknown a priory probability density. The scheme allows us to refine the values of the initial parameters of the calculation model on the basis of the information accumulated during the operation of the reactor and, thereby, to calculate the transient processes with greater accuracy. © Copyright 2017 for the individual papers by the papers' authors.