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Burn up physics; Physique des combustibles irradies

Abstract

The present communication is devoted to a body of theoretical and experimental work carried out at the C.E.A. with the aim of adding to the current knowledge on the evolution of the reactivity (during fuel irradiation) in natural or slightly enriched Uranium reactors. The difficulties of performing direct experiments on large amounts of irradiated fuels are reviewed - especially in operating power reactors - and the necessity is underlined for fundamental research in two directions: on one hand, the change in the composition of the fuels (chains of heavy nuclei, fission products), and on the other hand the effect of changes in composition on the neutron balance. Before presenting three types of experiments which have been carried out, the importance of the problems associated with the neutron spectra is stressed and the practical methods used for the calculations are briefly described. The systematic irradiation of several types of fuel, followed by their chemical and isotopic analysis has been going on for several years. An outline of the experimental programme is given with a description of the methods employed: {alpha}, {beta}, {gamma} chain for the preparation of samples determination of the plutonium content by coulometry and double isotopic dilution, separation of  More>>
Authors:
Tretiakoff, O [1] 
  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-2658
Resource Relation:
Other Information: 11 refs
Subject:
22 GENERAL STUDIES OF NUCLEAR REACTORS; BURNUP; FISSION PRODUCTS; POST-IRRADIATION EXAMINATION; REACTIVITY; SPENT FUELS; URANIUM
OSTI ID:
20668352
Research Organizations:
CEA Saclay, 91 - Gif-sur-Yvette (France)
Country of Origin:
France
Language:
French
Other Identifying Numbers:
TRN: FR05R2658107053
Availability:
Available from INIS in electronic form
Submitting Site:
FRN
Size:
21 pages
Announcement Date:
Dec 14, 2005

Citation Formats

Tretiakoff, O. Burn up physics; Physique des combustibles irradies. France: N. p., 1964. Web.
Tretiakoff, O. Burn up physics; Physique des combustibles irradies. France.
Tretiakoff, O. 1964. "Burn up physics; Physique des combustibles irradies." France.
@misc{etde_20668352,
title = {Burn up physics; Physique des combustibles irradies}
author = {Tretiakoff, O}
abstractNote = {The present communication is devoted to a body of theoretical and experimental work carried out at the C.E.A. with the aim of adding to the current knowledge on the evolution of the reactivity (during fuel irradiation) in natural or slightly enriched Uranium reactors. The difficulties of performing direct experiments on large amounts of irradiated fuels are reviewed - especially in operating power reactors - and the necessity is underlined for fundamental research in two directions: on one hand, the change in the composition of the fuels (chains of heavy nuclei, fission products), and on the other hand the effect of changes in composition on the neutron balance. Before presenting three types of experiments which have been carried out, the importance of the problems associated with the neutron spectra is stressed and the practical methods used for the calculations are briefly described. The systematic irradiation of several types of fuel, followed by their chemical and isotopic analysis has been going on for several years. An outline of the experimental programme is given with a description of the methods employed: {alpha}, {beta}, {gamma} chain for the preparation of samples determination of the plutonium content by coulometry and double isotopic dilution, separation of Boron used in some cases for the measurement of integrated neutron densities. The interpretation of the measurements is discussed with some examples. A second and more recent series of experiments deals with the investigation of lattices, using synthetic fuels (Uranium-Plutonium alloys) as compared to slightly depleted or enriched Uranium Various experiments are considered on heavy water and on cold graphite, then on graphite heated up to 500 C Some results already obtained are listed. These experiments, requiring nearly a metric ton of each type of fuel cannot be pursued in a systematic manner. This is why is developed since several years a method of differential measurement by oscillation, which requires samples of the order of several kilograms only. The relationships between these measurements and the investigations of lattices are discussed, and an outline is given of the way of carrying out the systematic study of fuels of various compositions. The method has been successfully applied to the systematic study of irradiated fuels (analysed independently by the methods mentioned above) thus giving the possibility of measuring in situ the absorption of fission products. (author) [French] Cette communication expose un ensemble d'etudes theoriques et d'experiences, effectuees au CEA et destinees a faire progresser la connaissance de l'evolution de la reactivite (au cours de l'irradiation du combustible) dans les reacteurs a uranium naturel ou faiblement enrichi.,. On rappelle les difficultes de l'experimentation directe sur des masses importantes de combustible irradie - en particulier dans les reacteurs de puissance en fonctionnement - et on souligne la necessite d'experiences a caractere fondamental distinguant: d'une part l'evolution de la composition des combustibles (chaines de noyaux lourds, produits de fission), d'autre part l'effet des modifications de composition sur le bilan de neutrons. Avant de presenter trois categories d'experiences que l'on est conduit a entreprendre, on rappelle l'importance des problemes lies aux spectres de neutrons et on decrit rapidement les methodes pratiques de calcul utilisees. L'irradiation systematique de quelques types de combustibles, suivie de leur analyse chimique et isotopique est en cours depuis plusieurs annees. On donne un apercu de l'ensemble du programme experimental et on decrit les moyens et les methodes mis en oeuvre: chaine {alpha}, {beta}, {gamma} pour la preparation des echantillons, dosage du Plutonium par coulommetrie et double dilution isotopique, separation du Bore utilise dans certains cas pour la mesure des densites de neutrons integrees. On discute sur quelques exemples l'interpretation des mesures. Une deuxieme serie d'experiences, plus recente, porte sur l'etude de reseaux utilisant des combustibles reconstitues (alliages Uranium - Plutonium), compares a de l'Uranium legerement appauvri ou enrichi. On decrit les experiences prevues (eau lourde, graphite a froid puis jusqu'a 500 C) et on expose les resultats deja obtenus. Ces experiences, necessitant pres d'une tonne de combustible de chaque espece, ne peuvent se preter a des etudes systematiques. C'est pourquoi on a poursuivi depuis quelques annees la mise au point d'une methode de mesure differentielle par oscillation, ne necessitant que des echantillons de l'ordre de quelques kilogrammes. On discute les relations entre ces mesures et les etudes de reseaux et on montre comment est effectuee l'etude systematique de compositions de combustible variees. La methode a pu etre appliquee avec succes a l'etude systematique de combustibles irradies (soumis par ailleurs aux analyses citees dans la premiere partie) donnant ainsi la possibilite de mesurer in situ l'absorption des produits de fission. (auteur)}
place = {France}
year = {1964}
month = {Jul}
}