Analysis of calculation of fuel rods for strength under transient and steady-state operating conditions

Abstract

The operating conditions are analyzed, mechanical characteristics are calculated pertaining to the 4-year cycle fuel rods of VVER-1000. The fuel rod strength characteristics are considered as applied to steady-state and transient conditions of reactor operation.The analysis of the per – fuel rod calculations covering a part of fuel assemblies in the VVER-1000 core under steady-state and several transient operating conditions allows one to assess the mechanical state of fuel claddings, the fulfillment of the design criteria of acceptance and to gain the understanding of the effect produced by the reactor control methods on the strength characteristics.Given are the results of computer modelling the stress-strained condition of present-day fuel rod claddings upon the four-year operation within the VVER-1000 core both under steady-state and transient conditions.The calculations involved transients with the application of different control systems, namely, only the boric system and its combination with mechanical organs of control. The calculations evidence that in terms of the strength criteria these algorithms ensure the tolerable local distortions of power rating fields.