LOKET - a gamma-ray spectroscopy system for in-pool measurements of thermal power distribution in irradiated nuclear fuel
2006 (English)In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, Vol. 569, no 3, 872-882 p.Article in journal (Refereed) Published
An important issue in the operations of nuclear power plants is the independent validation of core physics codes like e.g. Westinghouse PHOENIX-4/POLCA-7. Such codes are used to predict the thermal power distribution down to single node level in the core. In this paper, a dedicated measurement system (LOKET) is described and experimental results are discussed. The system is based on a submergible housing, containing a high-resolution germanium detector, allowing for measurements in-pool. The system can be transported to virtually any nuclear power plant's fuel storage pool for measurements in-pool during outage. The methodology utilises gamma radiation specific for La-140, whose decay is governed by the parent Ba-140, reflecting a weighted average power distribution, representative for the last weeks of operation of the core. Good agreements between measured power distribution and core physics calculations (Ba distribution) have been obtained during a series of experiments at Leibstadt NPP in Switzerland and Cofrentes NPP in Spain (BWRs) for both fuel assemblies and single fuel rods. The system has proven as a very useful tool for the experimental validation of core calculations also for the most complex fuel designs and challenging core configurations. Experimental errors (on the 1 - sigma level), has been demonstrated below +/- 2% on nodal level for assembly measurements.
Place, publisher, year, edition, pages
2006. Vol. 569, no 3, 872-882 p.
Ba/La, core simulator, gamma-ray spectroscopy, LOKET, thermal power distribution, validation
IdentifiersURN: urn:nbn:se:uu:diva-146653DOI: 10.1016/j.nima.2006.08.103ISI: 000243176300028OAI: oai:DiVA.org:uu-146653DiVA: diva2:398703