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Conference Article: Development of an inactive heat removal system for high temperature reactors

Kugeler, K. (Rheinisch-Westfaelische Technische Hoschschule, Aachen (Germany)); Sappok, M.; Beine, B. (Siempelkamp Giesserei GmbH und Co., Krefeld (Germany)); Wolf, L. (Battelle-Institut e.V., Frankfurt am Main (Germany))

Abstract

Growing public and political interests towards incorporating passive safety features in nuclear installations, let Siempelkamp in late 1987 propose a solution consisting of a prestressed cast-iron pressure vessel and a passive heat removal system, integrated in the reactor cell surrounding the vessel. This solution combines the inherent safety of a prestressed metallic pressure vessel with the advantages of a passive heat removal system and thus constitutes a major step towards the goal of further reducing potential residual risks. The design had to meet the boundary conditions for reactor core and reactor building of the modular 200 MWth pebble bed reactor of Siemens/-KWU. The engineering design showed that many input parameters needed for the finite-element-analysis of the overall structure required a verification by measurements in a well scaled test setup. This was especially required for the heat transfer from the liner of the prestressed cast-iron pressure vessel to the natural convection cooling system in the cell and forward to the outer surface of the cell. The data of six experiments provided a sound basis for demonstrating the feasibility of the proposed design and for deducing important thermal input parameters for code predictions. Furthermore, it could be demonstrated that the heat can be transported from the core via the natural convection system to the outside for all normal and emergency conditions up to the depressurization accident without exceeding the allowable temperatures for the various structural components. This holds also for a failure of the embedded cooling system. For comparison, a reference test with a steel pressure vessel wall proved that the differences in maximum temperatures between steel wall and prestressed cast iron pressure vessel wall were smaller than anticipated. A comparison paper provides details of experimental and analytical results.

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key words: Gas Cooled Reactor, Nuclear Technology
Reference:
Specialists meeting on decay heat removal and heat transfer under normal and accident conditions in gas cooled reactors. Juelich (Germany). 6-8 Jul 1992
International Atomic Energy Agency, Vienna (Austria)
IAEA-TECDOC--757, pp:131-139