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Heat transfer at the step of a CANDU calandria during a severe accident

Wärmeübertragung an der Stufe der Calandria eines CANDU-Reaktors während eines schweren Unfalls
R. David
From the journal Kerntechnik


During the in-vessel stage of a severe accident in a CANDU 6 reactor, decay heat from a collapsed core would be rejected through the calandria walls into the surrounding water. At the step in the calandria wall, the subshell and annular plate meet at a right angle pointing into the calandria. The geometry at this joint could concentrate the exiting heat flux, potentially leading to calandria failure. Finite element analysis is used to study the heat transfer near the welded joint. Different weld profiles, boundary conditions, and decay heat characteristics are considered, and the local concentration of exiting heat flux is calculated.


Während eines schweren Unfalls in einem CANDU 6-Reaktor wird eine Phase erreicht, während der im Reaktorbehälter die Nachzerfallswärme eines kollabierten Kerns durch die Wände der Calandria in das umgebende Wasser abgeleitet wird. An der Stufe in der Calandriawand treffen die Unterschale und die ringförmige Platte in einem rechten Winkel aufeinander, der in die Calandria zeigt. Die Geometrie an dieser Verbindungsstelle könnte den austretenden Wärmestrom verstärken, was zu einem Versagen der Calandria führen könnte. Mit Hilfe der Finite-Elemente-Analyse wird der Wärmeübergang in der Nähe der Schweißnaht untersucht. Es werden verschiedene Schweißprofile, Randbedingungen und Zerfallseigenschaften berücksichtigt und die lokale Konzentration des austretenden Wärmestroms berechnet.


I thank J.H. Spencer and J.R. Buell for critical review of the manuscript. This work was funded by Atomic Energy of Canada Ltd. under the Federal Nuclear Science and Technology program.


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Received: 2021-03-24
Published Online: 2021-10-23

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