Three dimensional computation of PWR reactivity accidents induced by thermal-hydraulic transients

摘要

Reactivity accidents due to thermalhydraulic transients as steam line break or boron dilution accidents in a Pressurized Water Reactor are characterized by large asymmetric reactivity effects in the reactor core. A best estimate calculation of the consequences of such accidents requires the coupling of three dimensional and time dependent neutronic and thermalhydraulic computations in the reactor core. Furthermore in order to compute the time variation of core inlet and outlet boundary conditions, the thermalhydraulic transient in the reactor coolant primary loops and in the reactor vessel has to be also computed. This paper describes the possibilities of the SAPHYR system (Reactor PHYsics Analysis computer code System) to calculate these transients, by coupling neutron kinetics and thermal hydraulics in the reactor core and the primary system. The first part of the paper gives a description of the CRONOS-2, FLICA-4 and FLICA-S computer codes and coupling methods. The second part of the communication deals with a Steam Line Break calculation performed with the SAPHYR system. (authors). 15 figs., 6 refs. (Atomindex citation 26:037808)