This paper is devoted to the construction of a tabular method for calculating critical heat fluxes in fuel-element assemblies with a square arrangement. The method consists of a basic table and a system of correctional functions, describing the dependence of the critical heat flux on the important independent parameters. Experience in developing such a method for triangular assemblies is used. The method is compared with experimental data and other computational methods. The advantages of the new method are shown: maximum width of the range of parameters, possibility of taking account of the influence of the most important parameters, possibility of using in cell-by-cell (channelwise) calculations, and high accuracy of the description.The publication in 1997 of the international version of the tables for critical heat fluxes in pipes [1] laid the foundation for the development of similar tables for critical heat fluxes in other channels. The tables for pipes are the core in describing a crisis in channels and are the basis for developing tabular methods for describing and calculating a crisis in many channels with a complicated cross-section and in fuel-element assemblies. Subsequent works performed at the Physics and Power-Engineering Institute developed methods for tabular description and calculation of critical heat fluxes in ring [2] and other single channels [3], in triangular assemblies of cylindrical fuel elements [4,5], and in the assemblies with a mixed arrangement of fuel elements [6].Tabular methods for calculating critical heat fluxes in channels have substantial advantages over conventional methods and are widely used in practical calculations using approaches based on an analytical (in the form of formulas) description of experimental data. Tabular methods make it possible to describe a wider range of parameters, and are based on a wider experimental base, give a continual description of critical heat fluxes in the entire field of parameters, and are convenient for estimating the aggregate influence of the parameters and for monitoring the results of calculations.The Tabular Method of the Physics and Power Engineering Institute for Assemblies with a Square Arrangement of Fuel Elements. The following have been used in developing a method for PWR, BWR, RBMK, and other assemblies with a square arrangement of fuel elements: 1) experience in constructing tables for pipes, ring channels, and assemblies with a triangular arrangement of fuel elements [4,5] and 2) developments, presented in [7], where it is shown that critical heat fluxes in assemblies with triangular and square arrangements of fuel elements differ substantially from one another. Experimental data arrays for assemblies from the database at the Physics and Power Engineering Institute were used [8]. These data are published in [9][10][11][12][13][14][15][16][17]. Unfortunately, the extensive data of Columbia University [18-20] are inaccessible. The following parameters characterize the array used in the present paper: the number of experimenta...