TY - THES TI - Experimental study of the hydrodynamic instabilities occurring in boiling-water reactors; Etude experimentale des instabilites hydrodynamiques survenant dans les reacteurs nucleaires a ebullition AB - The subjects is an experimental out-of pile loop study of the hydrodynamic oscillations occurring in boiling-water reactors. The study was carried out at atmospheric pressure and at pressure of about 8 atmospheres, in channels heated electrically by a constant and uniform specified current. In the test at 8 atmospheres the channel was a round tube of approximately 6 mm interior diameter. At 1 atmosphere a ring-section channel was used, 10 * 20 mm in diameter, with an inner heating tube and an outer tube of pyrex. It was possible to operate with natural convection and also with forced convection with test-channel by-pass. The study consists of 3 parts: 1. Preliminary determination of the laws governing pressure-drop during boiling. 2. Determination of the fronts at which oscillation appears, within a wide range of the parameters involved. 3. A descriptive study of the oscillations and measurement of the periods. The report gives the oscillation fronts with natural and forced convection for various values of the singular pressure drop at the channel inlet and for various riser lengths. The results are presented in non-dimensional form, which is available, in first approximation, for all geometric scales and for all fluids. Besides the following points were observed: - the wall (nature and thickness) can be an important factor ; - oscillation can occur in a horizontal channel. (author) [French] II a ete effectue une etude experimentale, en boucle hors-pile, des oscillations hydrodynamiques survenant dans les reacteurs a ebullition. L'etude a ete effectuee a la pression atmospherique et a une pression voisine de 8 atmospheres dans des canaux chauffes electriquement a puissance imposee constante et uniforme. Dans les essais a 8 atmospheres le canal etait un tube circulaire de diametre interieur 6 mm environ. A 1 atmosphere le canal etait de section annulaire 10 * 20 mm avec un tube interieur chauffant et un tube exterieur en pyrex. Le fonctionnement etait possible en convection naturelle et en convection forcee avec by-pass du canal d'essai. L'etude comporte 3 parties: 1. L'etablissement prealable des lois de la perte de pression en ebullition. 2. La determination des frontieres d'apparition de l'oscillation, dans une gamme tres large des parametres intervenant. 3. Une etude descriptive des oscillations et la mesure des periodes. Les frontieres de l'oscillation sont fournies en convection naturelle et en convection forcee pour diverses valeurs de la perte de charge singuliere a l'entree du canal et pour differentes longueurs de cheminee. Les resultats sont presentes sous une forme adimensionnelle valable en premiere approximation quelles que soient l'echelle geometrique et la nature du fluide. Enfin on a constate les particularites suivantes: - la paroi (nature et epaisseur) peut jouer un role important; - l'oscillation est possible en canal horizontal. (auteur) AU - "Fabreca, S [Commissariat a l'Energie Atomique, Grenoble (France). Centre d'Etudes Nucleaires]" KW - "21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS" KW - "BOILING" KW - "BORAX-5 REACTOR" KW - "BYPASSES" KW - "CORRELATIONS" KW - "FORCED CONVECTION" KW - "NATURAL CONVECTION" KW - "PRESSURE DROP" KW - "SPERT-4 REACTOR" DO - https://doi.org/ UR - https://www.osti.gov/etdeweb/servlets/purl/20680289 PB - CY - France PY - 1964 DA - 1964-10-01 LA - French J2 - [] VL - C1 - CEA Grenoble, 38 (France); Faculte des Sciences de l'Universite de Grenoble, 38 (France) C2 - C3 - CEA-R-2884 C4 - C5 - Available from INIS in electronic form L3 - Other Information: TH: These sciences; 30 refs ER -