The shut-down of the Barseback 1 BWR: A unique opportunity to measure the power distribution in nuclear fuel rods
2006 (English)In: Annals of Nuclear Energy, ISSN 0306-4549, E-ISSN 1873-2100, Vol. 33, no 13, 1091-1101 p.Article in journal (Refereed) Published
Reactor poolside measurements of gamma radiation specific for the fission product La-140 (1596 keV) have been used for an experimental determination of axial power distributions in 55 nuclear fuel rods irradiated in the Barseback 1 BWR nuclear power plant. The measurements take advantage of the unique situation of a very short last reactor cycle of only three months due to the out-phasing of the reactor unit at November 30 1999. La-140 whose decay is controlled by the mother nuclide Ba-140 with the half-life 12.75 days reflects an average power distribution, representative for the latest weeks of core operation (in this case basically during November 1999). The measured intensities have been transformed into a 25 nodal representation to allow a precise and direct comparison with the corresponding calculated power distribution. The 55 rods were selected from two different fuel assemblies with average burn-ups of 1.9 and 9.7 MWd/ kgU, respectively (that is one fresh bundle and one slightly more than one cycle bundle). The stability and the linearity of the measurement system were evaluated. The linearity was checked using the two-source method. The stability was checked by recurrent measurements on a reference fuel rod. The results have been used in the validation of the pin power reconstruction model of Westinghouse 3D core simulator POLCA-7. The deviation between measured and calculated Ba-140 concentration (expressed as radial error) is typically a few percent on rod level. Results indicate that also Gd-rods are properly modelled over a broad range of conditions. It is indicated that predictions for fuel rods in their first month of operation are less accurate than for the rest of the rods.
Place, publisher, year, edition, pages
2006. Vol. 33, no 13, 1091-1101 p.
IdentifiersURN: urn:nbn:se:uu:diva-94563DOI: 10.1016/j.anucene.2006.07.007ISI: 000242114100003OAI: oai:DiVA.org:uu-94563DiVA: diva2:168451