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Atomic Transport Problems of Interest in Nuclear Systems; Problemes de Transport Atomique Presentant un Interet dans les Systemes Nucleaires; Problemy perenosa atomov, predstavlyayushchie interes v yadernykh sistemakh; Problemas de Transporte Atomico de Interes para la Ingenieria Nuclear

Conference:

Abstract

Several problems encountered in the application of basic diffusion data to systems of practical interest such as those encountered in nuclear engineering will be discussed. These problems will include isothermal diffusion experiments, thermal gradient diffusion and radiation effects on diffusion processes. Most of the reliable information on diffusion in solids has been obtained from cases where there is essentially no concentration gradient of the diffusing species. In systems of interest to nuclear engineers, however, concentration gradients are almost invariably present. Thus, a working knowledge of the relation between self- and chemical-diffusion coefficients is necessary in order to estimate the proper coefficients to use in a given situation. Knowledge of thermodynamic activity coefficients as functions of compositions is necessary additional information. Recently it has been clearly demonstrated that indiscriminate use of an Arrhenius-type expression to describe the temperature dependence of diffusion data may lead to large errors in the prediction of diffusion coefficients. The ramifications of this finding will be discussed with emphasis on refractory, body-centred cubic systems. We have studied, both theoretically and experimentally, the effect of a thermal gradient on the redistribution of substitutional impurities in a metal. Such work has led to an increased appreciation of the importance  More>>
Authors:
Lundy, T. S.; Winslow, F. R. [1] 
  1. Oak Ridge National Laboratory, TN (United States)
Publication Date:
Feb 15, 1966
Product Type:
Conference
Report Number:
IAEA-SM-66/59
Resource Relation:
Conference: Symposium on Thermodynamics with Emphasis on Nuclear Materials and Atomic Transport in Solids, Vienna (Austria), 22-27 Jul 1965; Other Information: 31 refs., 7 figs.; Related Information: In: Thermodynamics. Vol. II. Proceedings of the Symposium on Thermodynamics with Emphasis on Nuclear Materials and Atomic Transport in Solids| 673 p.
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ATOM TRANSPORT; BCC LATTICES; CONCENTRATION RATIO; DIFFUSION; DISLOCATIONS; INTERSTITIALS; RADIATION EFFECTS; SOLIDS; TEMPERATURE DEPENDENCE; TEMPERATURE GRADIENTS; THERMODYNAMIC ACTIVITY; VACANCIES
OSTI ID:
22121901
Research Organizations:
International Atomic Energy Agency, Vienna (Austria); International Union of Pure and Applied Chemistry, Commission on Thermodynamics and Thermochemistry, Research Triangle Park, NC (United States)
Country of Origin:
IAEA
Language:
English
Other Identifying Numbers:
Other: ISSN 0074-1884; TRN: XA13M2396078012
Submitting Site:
INIS
Size:
page(s) 23-41
Announcement Date:
Aug 27, 2013

Conference:

Citation Formats

Lundy, T. S., and Winslow, F. R. Atomic Transport Problems of Interest in Nuclear Systems; Problemes de Transport Atomique Presentant un Interet dans les Systemes Nucleaires; Problemy perenosa atomov, predstavlyayushchie interes v yadernykh sistemakh; Problemas de Transporte Atomico de Interes para la Ingenieria Nuclear. IAEA: N. p., 1966. Web.
Lundy, T. S., & Winslow, F. R. Atomic Transport Problems of Interest in Nuclear Systems; Problemes de Transport Atomique Presentant un Interet dans les Systemes Nucleaires; Problemy perenosa atomov, predstavlyayushchie interes v yadernykh sistemakh; Problemas de Transporte Atomico de Interes para la Ingenieria Nuclear. IAEA.
Lundy, T. S., and Winslow, F. R. 1966. "Atomic Transport Problems of Interest in Nuclear Systems; Problemes de Transport Atomique Presentant un Interet dans les Systemes Nucleaires; Problemy perenosa atomov, predstavlyayushchie interes v yadernykh sistemakh; Problemas de Transporte Atomico de Interes para la Ingenieria Nuclear." IAEA.
@misc{etde_22121901,
title = {Atomic Transport Problems of Interest in Nuclear Systems; Problemes de Transport Atomique Presentant un Interet dans les Systemes Nucleaires; Problemy perenosa atomov, predstavlyayushchie interes v yadernykh sistemakh; Problemas de Transporte Atomico de Interes para la Ingenieria Nuclear}
author = {Lundy, T. S., and Winslow, F. R.}
abstractNote = {Several problems encountered in the application of basic diffusion data to systems of practical interest such as those encountered in nuclear engineering will be discussed. These problems will include isothermal diffusion experiments, thermal gradient diffusion and radiation effects on diffusion processes. Most of the reliable information on diffusion in solids has been obtained from cases where there is essentially no concentration gradient of the diffusing species. In systems of interest to nuclear engineers, however, concentration gradients are almost invariably present. Thus, a working knowledge of the relation between self- and chemical-diffusion coefficients is necessary in order to estimate the proper coefficients to use in a given situation. Knowledge of thermodynamic activity coefficients as functions of compositions is necessary additional information. Recently it has been clearly demonstrated that indiscriminate use of an Arrhenius-type expression to describe the temperature dependence of diffusion data may lead to large errors in the prediction of diffusion coefficients. The ramifications of this finding will be discussed with emphasis on refractory, body-centred cubic systems. We have studied, both theoretically and experimentally, the effect of a thermal gradient on the redistribution of substitutional impurities in a metal. Such work has led to an increased appreciation of the importance of this effect in systems of interest in the nuclear field. The enhancement of diffusion by radiation fields remains a problem of justified interest. We have made the first successful direct measurements of the effect of fast-particle bombardment on diffusion in a metal. Our results correlate well with predictions based on a model of the annihilation of excess point defects (vacancies and interstitials) by three mechanisms - migration to homogeneously-distributed fixed sinks such as dislocations, migration to a free surface, and recombination of defects. (author) [French] Les auteurs discutent plusieurs problemes qui surgissent lorsqu'on veut appliquer les constantes fondamentales de diffusion a des systemes presentant un interet pratique, notamment a ceux que l'on rencontre dans le genie nucleaire. Ces problemes comprennent des experiences de diffusion isotherme, la diffusion sous gradient thermique et les effets de rayonnements sur les processus de diffusion. La plupart des donnees dignes de foi sur la diffusion dans les solides ont ete obtenues a partir de cas dans lesquels il n'y avait essentiellement pas de gradient de concentration des especes diffusantes. Toutefois, dans les systemes qui presentent un interet pour les specialistes du genie nucleaire, il y a presque invariablement des gradients de concentration. C'est pourquoi il faut avoir une connaissance pratique de la relation entre les coefficients d'autodiffusion et de diffusion chimique pour pouvoir determiner les coefficients applicables dans chaque cas d'espece. En outre, il faut egalement connaitre les coefficients d'activite thermodynamique en fonction de la composition. Recemment, il a ete clairement demontre qu'il est dangereux d'utiliser aveuglement une expression d'Arrhenius pour decrire les variations de la diffusion selon la temperature, car cela peut entrainer des erreurs considerables dans le calcul theorique des coefficients de diffusion. Les auteurs discutent les consequences qui en decoulent, particulierement pour les systemes cubiques centres refractaires. Ils ont etudie, tant theoriquement qu'experimentalement, l'effet d'un gradient thermique sur la distribution des impuretes de substitution dans un metal. Ces travaux ont permis de mieux apprecier l'importance de cet effet dans des systemes presentant un interet du point de vue nucleaire. L'accroissement de la diffusion par les champs de rayonnements demeure toujours un probleme d'un interet reel. Les auteurs ont fait les premieres mesures directes de l'effet du bombardement par des particules rapides sur la diffusion dans un metal. Leurs resultats sont en bon accord avec les calculs theoriques fondes sur un modele de 1)annihilation de l'excedent de defauts ponctuels (lacunes et interstices) par trois mecanismes, savoir la migration vers des puits fixes dont la distribution est homogene tels que les dislocations, la migration vers une surface libre et la recombinaison de defauts. (author) [Spanish] Se analizan en la memoria varios problemas encontrados al aplicar los datos basicos sobre difusion a sistemas de interes practico para la ingenierfa nuclear. Estos problemas se refieren a experimentos de difusion isotermica, difusion por gradiente termico y efectos de la radiacion sobre los procesos de difusion. La mayor parte de la informacion fidedigna sobre la difusion en solidos proviene de casos donde no existe, en esencia, gradiente alguno de concentracion de las especies que se difunden. Los sistemas que interesan a los ingenieros nucleares, en cambio, presentan casi invariablemente gradientes de concentracion. Asf, pues, para evaluarlos coeficientes adecuados es necesario contar con un conocimiento practico de la relacion existente entre los coeficientes de autodifusiOn y de difusion quimica. Ademas, es preciso conocer los coeficientes de actividad termodinamica como funciones de la composicion. Recientemente se ha demostrado sin lugar a dudas que el uso indiscriminado de una expresion del tipo de la de Arrhenius para describir la manera en que los datos de difusion dependen de la temperatura, puede introducir graves errores en el calculo de los coeficientes de difusion. Se analizan en la memoria las consecuencias de ese hecho, haciendo especial hincapie en los sistemas cubicos centrados en el cuerpo/ del tipo refractario. Los autores han estudiado teorica y experimentalmente el efecto de un gradiente termico sobre la redistribucion de impurezas sustitutivas en un metal. Ese trabajo ha contribuido a un mejor conocimiento de la importancia de este efecto en los sistemas de interes en la esfera nuclear. El fomento de la difusion por los campos de radiacion sigue siendo un problema de justificado interes. Los autores han hecho las primeras mediciones directas del efecto que el bombardeo con particulas rapidas ejerce sobre la difusion en un metal. Los resultados guardan una correlacion satisfactoria con los pronosticos basados en un modelo de la aniquilacion de los defectos puntiformes (huecos e intersticios) excesivos en virtud de tres mecanismos: migracion hacia trampas fijas y homogeneamente distribuidas tales como dislocaciones, migracion hacia una superficie libre, y recombinacion de defectos. (author) [Russian] Obsuzhdajutsja nekotorye problemy, voznikajushhie pri ispol'zovanii osnov- nyh dannyh otnositel'no diffuzii v sistemah, predstavljajushhih prakticheskij interes, napri- mer v sistemah, vstrechajushhihsja v jadernoj tehnike. V chislo jetih problem vkljucheny jeksperi- menty v oblasti izotermicheskoj diffuzii, problemy diffuzii temperaturnogo gradienta i vlijanija radiacii na processy diffuzii. Bol'shaja chast' nadezhnoj informacii otnositel'- no diffuzii v tverdyh telah poluchena v teh sluchajah, kogda po sushhestvu gradient koncen- tracii diffundirujushhih obrazcov otsutstvuet. V sistemah, predstavljajushhih interes dlja inzhenerov-atomnikov, odnako, gradienty koncentracii pochti vsegda prisutstvujut. V svja- zi s jetim neobhodimy rabochie znanija po voprosu o svjazi mezhdu kojefficientami samodiffu- zii i himicheskoj diffuzii, chtoby dat' ocenku sootvetstvujushhih kojefficientov s cel'ju ispol'zovanija v opredelennoj situacii. Znanie kojefficientov termodinamicheskoj aktivnosti kak funkcii struktury predstavljaet soboj neobhodimuju dopolnitel'nuju informaciju. Nedavno bylo jasno pokazano, chto pri nediskriminacionnom primenenii vyrazhenija tipa Arheniusa dlja opisanija temperaturnoj zavisimosti dannyh otnositel'no diffuzii mozhno dopu- stit' znachitel'nye oshibki v predskazanii kojefficientov diffuzii. Obsuzhdajutsja varianty jetogo vyvoda s uporom na refrakcionnye ob{sup e}mno-centrirovannye kubicheskie sistemy . Izuchalis' teoreticheski i jeksperimental'no voprosy vlijanija temperaturnogo gradienta na pereraspre- delenie sushhestvennyh primesej v metalle. Rezul'taty priveli k bolee vysokoj ocenke vazhnosti jetogo jeffekta v sistemah, predstavljajushhih interes v oblasti atomnoj jenergii. Usilenie diffuzii radiacionnymi poljamijeto po-prezhnemu problema, interes k koto- roj opravdan. Provedeno pervoe uspeshnoe neposredstvennoe izmerenie stepeni vlijanija bombardirovki bystrymi chasticami na velichinu diffuzii v metalle. Poluchennye rezul'- taty horosho soglasujutsja s predpolozhenijami, osnovannymi na modeli annigiljacii izbytochnyh defektov (vakansii i vnedrennye atomy) s ispol'zovaniem treh mehanizmov migracija v gomogenno raspredelennye fiksirovannye rakoviny, naprimer dislokacii, migracija na svobodnuju poverhnost' i rekombinacija defektov. (author)}
place = {IAEA}
year = {1966}
month = {Feb}
}