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Proceedings Paper

Mechanical characterization of pressurized water reactor fuel assemblies using laser techniques
Author(s): Pierrette Fardeau; Alain Mattei; Joelle Vallory
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Paper Abstract

The laboratory's test facilities are used to characterize the mechanical behavior of fuel assemblies of Pressurized Water Reactors (PWR). These structures are submitted to the excitation of the cooling fluid whose transverse and axial velocity fields are also measured. Fuel assemblies are made of long fuel rods (approximately 4 m) containing depleted uranium pellets. The rods are maintained together using structural grids located at different elevations. The LHC (Laboratoire d'Hydraulique de Coeur) is equipped with special test sections along with hydraulic loops to test these full scale mockups. In order to make measurement on the tested structure with optical devices, the test sections are equipped with a plexiglas front panel or viewports. The use of non contacting methods of measurement such as laser techniques are imposed by: (1) the inaccessibility of the structure studied due to the containment of the assembly in the test section, (2) the fact that the fluid (source of excitation) flowing around the rods should no be disturbed. A laser vibrometer equipped with optic fibers is used to make velocity measurements on the assemblies at different levels. In order to evaluate the level of vibration of the structure tested (fuel assembly or fuel rod), a differential laser vibrometer is used to measure the relative displacement of the assembly with respect to the test section or the relative displacement of the fuel rod with respect to the structural grids of the assembly. The differential technique is important because the higher structural modes of the assembly are mixed up in terms of frequency with the lower structural modes of vibration of the fuel rods.

Paper Details

Date Published: 8 September 1994
PDF: 12 pages
Proc. SPIE 2358, First International Conference on Vibration Measurements by Laser Techniques: Advances and Applications, (8 September 1994); doi: 10.1117/12.185321
Show Author Affiliations
Pierrette Fardeau, CEA (France)
Alain Mattei, CEA (France)
Joelle Vallory, CEA (France)

Published in SPIE Proceedings Vol. 2358:
First International Conference on Vibration Measurements by Laser Techniques: Advances and Applications
Enrico Primo Tomasini, Editor(s)

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