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Behaviour of uranium under irradiation; Comportement de l'uranium sous irradiation

Abstract

The main results obtained in a study of the formation of defects caused in uranium by fission at low temperature are reported. By irradiation at 20 K. it was possible to determine the number of Frenkel pairs produced by one fission. An analysis of the curves giving the variations in electrical resistivity shows the size of the displacement spikes and the mechanism of defect creation due to fission. Irradiations at 77 K gave additional information, showing behaviour differences in the case of recrystallised and of cold worked uranium. The diffusion of rare gases was studied using metal-rare gas alloys obtained by electrical discharge, and samples of irradiated uranium. Simple diffusion is only responsible for the release of the rare gases under vacuum in cases where the rare gas content is very low (very slightly irradiated U). On the other hand when the concentration is higher (samples prepared by electrical discharge) the gas is given off by the formation, growth and coalescence of bubbles; the apparent diffusion coefficient is then quite different from the true coefficient and cannot be used in calculations on swelling. The various factors governing the phenomenon of simple diffusion were examined. It was shown in particular that  More>>
Authors:
Adda, Y; Mustelier, J P; Quere, Y; [1]  Commissariat a l'Energie Atomique, Fontenay-aux-Roses (France). Centre d'Etudes Nucleaires]
  1. Commissariat a l'Energie Atomique, Saclay (France). Centre d'Etudes Nucleaires
Publication Date:
Jul 01, 1964
Product Type:
Technical Report
Report Number:
CEA-R-2671
Subject:
36 MATERIALS SCIENCE; CRACKS; DISLOCATIONS; ELECTRIC CONDUCTIVITY; FRENKEL DEFECTS; MOLYBDENUM; PHYSICAL RADIATION EFFECTS; URANIUM
OSTI ID:
20668365
Research Organizations:
CEA Saclay, 91 - Gif-sur-Yvette (France); CEA Fontenay-aux-Roses, 92 (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR05R2671107066
Availability:
Available from INIS in electronic form
Submitting Site:
FRN
Size:
20 pages
Announcement Date:
Dec 14, 2005

Citation Formats

Adda, Y, Mustelier, J P, Quere, Y, and Commissariat a l'Energie Atomique, Fontenay-aux-Roses (France). Centre d'Etudes Nucleaires]. Behaviour of uranium under irradiation; Comportement de l'uranium sous irradiation. France: N. p., 1964. Web.
Adda, Y, Mustelier, J P, Quere, Y, & Commissariat a l'Energie Atomique, Fontenay-aux-Roses (France). Centre d'Etudes Nucleaires]. Behaviour of uranium under irradiation; Comportement de l'uranium sous irradiation. France.
Adda, Y, Mustelier, J P, Quere, Y, and Commissariat a l'Energie Atomique, Fontenay-aux-Roses (France). Centre d'Etudes Nucleaires]. 1964. "Behaviour of uranium under irradiation; Comportement de l'uranium sous irradiation." France.
@misc{etde_20668365,
title = {Behaviour of uranium under irradiation; Comportement de l'uranium sous irradiation}
author = {Adda, Y, Mustelier, J P, Quere, Y, and Commissariat a l'Energie Atomique, Fontenay-aux-Roses (France). Centre d'Etudes Nucleaires]}
abstractNote = {The main results obtained in a study of the formation of defects caused in uranium by fission at low temperature are reported. By irradiation at 20 K. it was possible to determine the number of Frenkel pairs produced by one fission. An analysis of the curves giving the variations in electrical resistivity shows the size of the displacement spikes and the mechanism of defect creation due to fission. Irradiations at 77 K gave additional information, showing behaviour differences in the case of recrystallised and of cold worked uranium. The diffusion of rare gases was studied using metal-rare gas alloys obtained by electrical discharge, and samples of irradiated uranium. Simple diffusion is only responsible for the release of the rare gases under vacuum in cases where the rare gas content is very low (very slightly irradiated U). On the other hand when the concentration is higher (samples prepared by electrical discharge) the gas is given off by the formation, growth and coalescence of bubbles; the apparent diffusion coefficient is then quite different from the true coefficient and cannot be used in calculations on swelling. The various factors governing the phenomenon of simple diffusion were examined. It was shown in particular that a small addition of molybdenum could reduce the diffusion coefficient by a factor of 100. The precipitation of gas in uranium (Kr), in silver (Kr) and in Al-Li alloy (He) have been followed by measurement of the crystal parameter and of the electrical resistivity, and by electron microscope examination of thin films. The important part played by dislocations in the generation and growth of bubbles has been demonstrated, and it has been shown also that precipitation of bubbles on the dislocation lattice could block the development of recrystallisation. The results of these studies were compared with observations made on the swelling of uranium and uranium alloys U Mo and U Nb strongly irradiated between 400 and 700 C. In the case of Cubic phase alloys (U Nb, U Mo) the size and distribution of the bubbles are greatly influenced by the existence of a polygonization lattice, formed before irradiation, inside the grains. During high temperature annealings the bubbles situated on the polygonization lattice grow much faster than those which are distributed inside the crystal. In the case of uranium the bubbles are either distributed at random, or grouped in flat accumulations which can give rise to transgranular cracks, according to the state of the metal and the irradiation temperature. At high temperature an intergranular de-cohesion is also observed. (authors) [French] On expose les principaux resultats obtenus dans l'etude de la formation des defauts introduits dans l'uranium par la fission a basse temperature. Par irradiation a 20 K on a pu evaluer le nombre de paires de Frenkel produites par une fission. L'analyse des courbes de variation de resistivite electrique a permis de preciser l'etendue des pointes de deplacement (deplacement Spike) et le mecanisme de la creation des defauts dus a la fission. Des irradiations a 77 K ont apporte des precisions supplementaires et indiquent un comportement different de l'uranium recristallise et ecroui. On a etudie la diffusion des gaz rares a partir d'alliages metal-gaz rare obtenus par decharge electrique et d'echantillons d'uranium irradie. Le degagement des gaz rares sous vide n'est controle par un processus de diffusion simple que dans le cas ou la teneur en gaz rare est tres faible (U tres faiblement irradie). Par contre quand la teneur en gaz rare est plus forte (echantillons prepares par decharge electrique) le degagement du gaz se produit par formation, croissance et coalescence de bulles; le coefficient de diffusion apparent est alors tres different du coefficient vrai et ne peut etre utilise dans les calculs de gonflement. Dans le cas d'un processus de diffusion simple on a etudie les differents facteurs qui regissent le phenomene. On a montre en particulier qu'une faible addition de molybdene pouvait reduire d'un facteur 100 le coefficient de diffusion. On a suivi la precipitation de gaz dans l'uranium (Kr), dans l'argent (Kr) et dans l'alliage Al-Li (He) par mesure du parametre cristallin, de la resistivite electrique et par examen de lames minces au microscope electronique. On a mis en evidence le role important des dislocations sur la germination et la croissance des bulles. On a montre en outre que la precipitation de bulles sur le reseau de dislocations pouvait bloquer le developpement de la recristallisation. On a compare les resultats de ces etudes aux observations effectuees sur le gonflement de l'uranium et d'alliages U Mo et U Nb fortement irradies entre 400 et 700 C. Dans le cas des alliages a phase cubique (U Nb U Mo) la repartition et la taille des bulles sont fortement influencees par l'existence a l'interieur des grains d'un reseau de polygonisation forme avant irradiation. Au cours de recuits a haute temperature, les bulles situees sur le reseau de polygonisation croissent beaucoup plus vite que celles qui sont distribuees dans l'interieur du cristal. Dans le cas de l'uranium, suivant l'etat du metal et la temperature d'irradiation, les bulles sont soit reparties au hasard, soit groupees en amas plans qui peuvent donner naissance a des fissures transgranulaires. A haute temperature, on constate en outre une decohesion inter granulaire. (auteurs)}
place = {France}
year = {1964}
month = {Jul}
}