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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Analysis of axisymmetric heat conduction pertaining to a new axial power monitor for nuclear reactors

Get access (open in a dialog) DOI: 10.1615/IHTC12.4230
6 pages

Résumé

A new type of axial power monitor (APM) for nuclear reactors was recently tested in a laboratory under electrical heating in two different modes, 1) passing an electric current through its bulk ("Joule heating") and 2) passing an electric current through a heating wire along its axis ("internal heating"). The test results showed good agreement between the thermocouple voltages for the two heating modes. However, a physical explanation for the good agreement was missing and the applicability of the test results to reactor operation, whereby the heating is due to gamma and neutron irradiation ("gamma heating"), needed to be examined. Earlier investigations provided a physical explanation for the good agreement of the above test results as well as insight into the axisymmeric heat conduction in the "hot zone" of an APM sensor segment. However, the effects of non-uniform heat flux at the recess surrounding a "hot zone" on the important temperature differentials remained to be investigated. In the present paper, axisymmetric heat conduction in the "hot zone" of an APM sensor segment is investigated, assuming a parabolic radial heat flux at the recess, the radial heat flux being maximum at the hottest cross section (plane of symmetry of the "hot zone") and decreasing to a negligible value at the coldest cross section (end of the "hot zone"). For both "internal heating" and "gamma/Joule heating", the partial differential equations for axisymmetric heat conduction under the new boundary conditions at the recess were solved. The new results show small deviations from those of the earlier investigations.