Numerical Modeling of RBMK-1000 Graphite Stack Distortion

Abstract

Engineering and detailed three-dimensional models of the RBMK-1000 graphite stack for modeling of its distortions caused by the appearance of longitudinal cracks in the blocks owing to the nonuniformity of the temperature and fluence distributions are described. As the neutron fluence accumulates and the limit longitudinal deflection of the graphite columns is reached, the graphite stack is repaired by cutting the graphite blocks. The developed models make it possible to evaluate the accumulation of deflection of the columns before and after repairs and the effectiveness of various repair schemes. The developed models are used to calculate the maximum deflection of the stack columns in the No. 1 unit of the Leningradskaya NPP for different operating conditions after repairs.