Abstract
Safety analysis is a major part during licensing a nuclear power plant. This paper presents coupled neutronic thermal-hydraulic calculations for a MOX/UOX mixed core loading of the Westinghouse AP1000 pressurized water reactor concept. Originally, the initial core loading of the reactor has three types of UO2 fuel assemblies with U235 enrichments are: 2.35 w/o, 3.40 w/o and 4.45 w/o. In this paper, it is assumed that one-third of fuel assemblies is replaced by MOX assemblies. The steady state conditions are calculated with the code QUARK. QUARK is a 3D neutronic kinetics code coupled to core thermal hydraulics code. The required cross-section data for QUARK were generated using WIMSD5. The results of the steady state analysis show that both core loading schemes can be used in AP1000 as the safety criteria mentioned in design control document are met.
Kurzfassung
Sicherheitsanalysen sind ein wesentlicher Bestandteil des Genehmigungsprozesses eines Kernkraftwerks. Die Autoren führen gekoppelte Rechnung eine MOX/UOX-Mischkernbeladung durch, wobei sie den Kern in Anlehnung an das Design eines Kerns eines Westinghouse AP1000 Druckwasserreaktors definieren. Während die Originalkernbeladung des Reaktors aus drei unterschiedlich angereicherten UO2-Brennstoffgruppen (U235-Anreicherungen von 2,35 w/o, 3,40 w/o und 4,45 w/o) besteht, wird in diesem Beitrag angenommen, dass ein Drittel der Brennelemente durch MOX-Brennelement ersetzt werden. Für diese Mischkernbeladung werden stationäre Kernrechnungen mit dem Programm QUARK durchgeführt. QUARK ist eine 3D Neutronenkinetik-Berechnung, die an den Code der thermischen Kernhydraulik gekoppelt ist. Die erforderlichen Querschnittsdaten für QUARK wurden mit Hilfe von WIMSD5 generiert. Die Ergebnisse der stationären Analyse zeigen, dass beide Kernbelastungsschemata in AP1000 verwendet werden können, da die Sicherheitskriterien, die im Entwurfskontrolldokument erwähnt werden, erfüllt sind.
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