Effect of Cell-Boundary Currents on the Fuel Burnup Characteristics of VVER-1000 Light-Water Reactor

The results of a computational study of the effect of nonzero currents at FA boundaries on the characteristics of fuel burnup in VVER-1000 are presented. A variant with 1/3 mixed fuel loaded into the core was studied. The TRIFON 2.1 code was used to calculate the time dependence of the characteristics of FA with uranium and mixed fuel and the SHERHAN code was used for computational modeling of three-dimensional burnup; the codes were modified on the basis of an improved heterogeneous method. It is shown by a computational method that in VVER-1000 with a mixed fuel load nonzero currents at FA boundaries, matched with their conditions inside the reactor, give a moderate effect in the multiplication coefficient – ≤0.2–0.35%, in the coefficient of nonuniformity of the power distribution – ≤1.5%, and in the burnup of uranium and mixed fuel in FA over a fuel cycle – ≤0.6%.