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Uncertainty and sensitivity analysis with respect to the hydrogen production determined by MELCOR 1.8.4 code during a severe accident

  • J. Kronenberg
Published/Copyright: March 14, 2022
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Abstract

For the selection and design of measures to scope with the hydrogen which will be produced in the course of a severe accident in LWRs a simple postulate – e. g. 75 % zircaloy oxidation of all fuel rod claddings – is not appropriate. In our opinion, realistic (best estimate) analyses with indication of the uncertainties are substantially more suitable. However, the problem thereby lies in the determination of these uncertainties. The current work presents a method, which determines the uncertainty band for the in-vessel hydrogen production calculated with the MELCOR program using a mathematical-statistic method (SUSA). For the exercise a “Total loss of the alternating current supply” for the planned European Pressurised Water Reactor (EPR) has been chosen as a representative scenario. Besides the actual uncertainties of the computational program concerned with such an analysis also the sensitive parameters can be identified.

Abstract

Für die Auswahl und Auslegung von Maßnahmen zur Beherrschung des bei schweren Störfällen in LWR produzierten Wasserstoffs ist ein einfaches Postulat – z. B 75 %ige Oxidation aller Zircaloy Brennstab-Hüllrohre – nicht zielföhrend. Realistische (best-estimate) Analysen mit Angaben der Unsicherheiten sind unseres Erachtens wesentlich geeigneter. Die Problematik dabei liegt in der Ermittlung dieser Unsicherheiten. In der vorliegenden Arbeit wird eine Methode vorgestellt, die am Beispiel einer Analyse eines „Vollständigen Ausfalls der Wechselstromversorgung“ beim geplanten Europäischen Druckwasserreaktor (EPR) mit dem Programm MELCOR das Unsicherheitsband bezüglich der in-vessel Wasserstofferzeugung unter Verwendung einer mathematisch-statistischen Methode (SUSA) ermittelt. Neben den eigentlichen Unsicherheiten des betreffenden Rechenprogramms können mit einer derartigen Analyse auch die sensitiven Einflussgrößen (Parameter) ermittelt werden.

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Received: 2001-01-22
Published Online: 2022-03-14

© 2001 Carl Hanser Verlag, München

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