CALCULATION OF MINIMUM DNBR IN NUCLEAR REACTOR CORE BASED ON STATISTICAL MODELS NEUTRON - PHYSICAL AND THERMOHYDRAULIC PROCESSES

A. Ryzhov, D. Oleksyuk, A. Pinegin, National Research Centre “Kurchatov Institute”, Moscow, Russia

22nd Symposium of AER on VVER Reactor Physics and Reactor Safety (2012, Průhonice, Czech Republic)
ENGINEERING FACTORS

Abstract

In the paper is represented the method of statistical account of uncertainties to obtain
estimation of DNBR and value of heat flux per rods length unit. The method is based on the
special developed FA model which includes mathematical models of energy field
calculations, FA thermomechanical deformations, thermohydraulics and technological
processes. FA thermohydraulics calculations carry out using cell by cell thermohydraulic code
SC-1 ¹. In these calculations were taken into account deviations in different parameters
Statistical properties of DNBR minimum value in FA and in specified rods, statistical
properties of heat flux from the surface of the fuel rods and coolant heating in specified cells
is determined using statistical simulation of large number of random parameters affecting this
values. It have been estimated the value of reducing factor for DNBR and this value was
analyzed for sensitivity to different factors: FA power, relative axial heat flux profiles, rods
energy distribution, the law of statistical distribution random parameters, the number of ?hot?
fuel assemblies. Also the estimation of engineering safety factors for coolant heating and local
heat flux have been obtained.

Presentation / full paper