Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

1 Publication
Simulation of postulated accidents in pressurized water reactors using coupled 3D neutron kinetic/thermal hydraulic code systems
Kliem, S.; Rohde, U.; Weiss, F.-P.;
Coupled code systems consisting of 3D neutron kinetics in combination with advanced thermal hydraulic plant models have been developed for an improved analysis of the whole reactor system. At Forschungszentrum Dresden-Rossendorf, the 3D neutron kinetic core model DYN3D, developed in house, was coupled with the advanced thermal hydraulic system code ATHLET of the German Gesellschaft für Anlagen- und Reaktorsicherheit.
Analyses of a hypothetical boron dilution event were carried out using that coupled code system. For that purpose a validated coolant mixing model was implemented into the code. Transient calculations for the bounding scenario of the start-up of one main coolant pump with the maximum size of a deborated slug showed a significant reactivity insertion and over-criticality. However, according to the calculations, even an over-criticality of about 2 $ did not lead to safety-relevant consequences. The power excursion is mitigated and stopped by fuel temperature feedback.
Anticipated transients without SCRAM are a second application area of the coupled code systems. In such transients with a postulated failure of the control rod insertion, the core power behavior is determined exclusively by the neutron kinetic feedback of the fuel and the moderator. The DYN3D/ATHLET code was used to investigate the influence of the core loading on the safety parameters during the transient: “Loss of main feedwater at running main coolant pumps”. It was shown that the variation of the number of mixed oxide (MOX) fuel elements in the reactor core has a remarkable influence on the fuel temperature and the moderator density feedback, which influences through the core power the primary coolant pressure. Increasing the number of MOX fuel elements decreases the calculated pressure maximum.
  • Lecture (Conference)
    IEEE Dresden 2008, 19.-25.10.2008, Dresden, Germany

Publ.-Id: 11598 - Permalink