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Experimental studies of some of the physical features of beryllium-moderated intermediate reactors; Etude experimentale de quelques particularites physiques des reacteurs a neutrons intermediaires, ralentis au beryllium; Ehksperimental'ny e issledovaniya nekotorykh fizicheskikh osobennostej promezhutochnykh reaktorov s berillievym zamedlitelem; Estudios experimentales de algunas caracteristicas fisicas de los reactores intermedios moderados con berilio

Conference:

Abstract

This paper is devoted to a review of the results obtained from a number of experiments carried out on the PF-4 critical assembly (intermediate-physical assembly), which is designed for detailed studies of the physical characteristics of intermediate reactors. The cores and reflectors of the various critical assemblies were comprised of compact units of steel or aluminium tubes, in which discs of various materials were placed. By combining 90%-enriched uranium discs with moderating materials in various proportions, and also by introducing moderating layers of different thicknesses into the reflector, it was possible to alter the spectrum of the fission-inducing neutrons within a very broad range. This paper describes the PF-4 critical assembly and its various subassemblies. The relative efficiency of internal and external moderation is analysed for reactors with a very low ratio of moderator nuclei to uranium nuclei in the core. The experiments show that even when thick moderating reflectors are used, this low ratio (the ratio of beryllium nuclei to uranium-235 nuclei being {partial_derivative}Be/{partial_derivative}U{sup 235}{approx_equal}1) leads to an increase of the critical mass. A considerable part of the paper is devoted to an analysis of heterogeneous effects in intermediate reactors. It is shown that for reactors with {partial_derivative}Be/{partial_derivative}U{sup 235}=30-40  More>>
Authors:
Lejpunskij, A I; Kuznetsov, V A; Artyukhov, G Ya; Mogil'ner, A I; Prokhorov, Yu A; Steklovski, V M; Chernov, L A [1] 
  1. Akademiya Nauk, Moskva, Union of Soviet Socialist Republics (Russian Federation)
Publication Date:
Mar 15, 1962
Product Type:
Conference
Report Number:
IAEA-SM-18/90
Resource Relation:
Conference: Seminar on Physics of Fast and Intermediate Reactors, Vienna (Austria), 3-11 Aug 1961; Other Information: 9 refs, 5 figs, 5 tabs; Related Information: In: Physics of Fast and Intermediate Reactors. V. I. Proceedings of the Seminar on the Physics of Fast and Intermediate Reactors. V. I| 500 p.
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; ALUMINIUM; BERYLLIUM; BORON CARBIDES; CRITICAL MASS; EXPERIMENTAL DATA; FISSION NEUTRONS; HETEROGENEOUS EFFECTS; HIGHLY ENRICHED URANIUM; INTERMEDIATE REACTORS; MODERATOR-FUEL RATIO; NEUTRON DENSITY; NEUTRON FLUX; NEUTRON REACTIONS; NEUTRON REFLECTORS; NEUTRON SPECTRA; REACTIVITY; REACTOR CORES; STEELS; URANIUM 235; ZERO POWER REACTORS
OSTI ID:
22072711
Research Organizations:
International Atomic Energy Agency, Vienna (Austria)
Country of Origin:
IAEA
Language:
Russian
Other Identifying Numbers:
Other: ISSN 0074-1884; TRN: XA12S0202032446
Submitting Site:
INIS
Size:
page(s) 327-343
Announcement Date:
Mar 14, 2013

Conference:

Citation Formats

Lejpunskij, A I, Kuznetsov, V A, Artyukhov, G Ya, Mogil'ner, A I, Prokhorov, Yu A, Steklovski, V M, and Chernov, L A. Experimental studies of some of the physical features of beryllium-moderated intermediate reactors; Etude experimentale de quelques particularites physiques des reacteurs a neutrons intermediaires, ralentis au beryllium; Ehksperimental'ny e issledovaniya nekotorykh fizicheskikh osobennostej promezhutochnykh reaktorov s berillievym zamedlitelem; Estudios experimentales de algunas caracteristicas fisicas de los reactores intermedios moderados con berilio. IAEA: N. p., 1962. Web.
Lejpunskij, A I, Kuznetsov, V A, Artyukhov, G Ya, Mogil'ner, A I, Prokhorov, Yu A, Steklovski, V M, & Chernov, L A. Experimental studies of some of the physical features of beryllium-moderated intermediate reactors; Etude experimentale de quelques particularites physiques des reacteurs a neutrons intermediaires, ralentis au beryllium; Ehksperimental'ny e issledovaniya nekotorykh fizicheskikh osobennostej promezhutochnykh reaktorov s berillievym zamedlitelem; Estudios experimentales de algunas caracteristicas fisicas de los reactores intermedios moderados con berilio. IAEA.
Lejpunskij, A I, Kuznetsov, V A, Artyukhov, G Ya, Mogil'ner, A I, Prokhorov, Yu A, Steklovski, V M, and Chernov, L A. 1962. "Experimental studies of some of the physical features of beryllium-moderated intermediate reactors; Etude experimentale de quelques particularites physiques des reacteurs a neutrons intermediaires, ralentis au beryllium; Ehksperimental'ny e issledovaniya nekotorykh fizicheskikh osobennostej promezhutochnykh reaktorov s berillievym zamedlitelem; Estudios experimentales de algunas caracteristicas fisicas de los reactores intermedios moderados con berilio." IAEA.
@misc{etde_22072711,
title = {Experimental studies of some of the physical features of beryllium-moderated intermediate reactors; Etude experimentale de quelques particularites physiques des reacteurs a neutrons intermediaires, ralentis au beryllium; Ehksperimental'ny e issledovaniya nekotorykh fizicheskikh osobennostej promezhutochnykh reaktorov s berillievym zamedlitelem; Estudios experimentales de algunas caracteristicas fisicas de los reactores intermedios moderados con berilio}
author = {Lejpunskij, A I, Kuznetsov, V A, Artyukhov, G Ya, Mogil'ner, A I, Prokhorov, Yu A, Steklovski, V M, and Chernov, L A}
abstractNote = {This paper is devoted to a review of the results obtained from a number of experiments carried out on the PF-4 critical assembly (intermediate-physical assembly), which is designed for detailed studies of the physical characteristics of intermediate reactors. The cores and reflectors of the various critical assemblies were comprised of compact units of steel or aluminium tubes, in which discs of various materials were placed. By combining 90%-enriched uranium discs with moderating materials in various proportions, and also by introducing moderating layers of different thicknesses into the reflector, it was possible to alter the spectrum of the fission-inducing neutrons within a very broad range. This paper describes the PF-4 critical assembly and its various subassemblies. The relative efficiency of internal and external moderation is analysed for reactors with a very low ratio of moderator nuclei to uranium nuclei in the core. The experiments show that even when thick moderating reflectors are used, this low ratio (the ratio of beryllium nuclei to uranium-235 nuclei being {partial_derivative}Be/{partial_derivative}U{sup 235}{approx_equal}1) leads to an increase of the critical mass. A considerable part of the paper is devoted to an analysis of heterogeneous effects in intermediate reactors. It is shown that for reactors with {partial_derivative}Be/{partial_derivative}U{sup 235}=30-40 various thicknesses of highly enriched uranium, ranging from 0.023 g/cm{sup 2} to 32 g/cm{sup 2}, have an identical effect on the reactivity of the system. The causes underlying compensation of the neutron-flux screening effect by thick layers of uranium are analysed. The interesting fact that the efficiency of uranium increases in the neighbourhood of the absorbing rods, which was experimentally revealed in an assembly with {partial_derivative}Be/{partial_derivative}U{sup 235}{approx_equal}200, is discussed in the paper. This fact is explained by the sharp decline in the importance of neutrons absorbed by the uranium. The paper provides data, derived from the same assembly, on the efficiency of rods made of various absorbing materials. It gives the experimentally measured distribution of neutron density for neutrons of various energies in the neighbourhood of a boron-carbide rod, and the density of neutron captures by a 1/v detector within the rod. The paper also discusses methods used and the results obtained from experiments designed to assess the efficiency of recompensation, cylinders placed on the boundary between core and reflector. (author) [French] Le memoire analyse les resultats de plusieurs experiences effectuees sur l'ensemble critique PF-4, qui est destine a l'etude detaillee des particularites physiques des reacteurs a neutrons intermediaires. Les coeurs et les reflecteurs des differents esembles critiques etaient constitues par un assemblage compact de tubes en acier ou en aluminium dans lesquels etaient inseres des diques de diverses matieres. En combinant selon differentes proportions les disques d'uranium enrichi a 90% et les matieres de ralentissement et en introduisant dans le reflecteur des couches de ralentisseur de diverses epaisseurs, on a pu obtenir de grandes modifications du spectre des neutrons provoquant la fission. Le memoire decrit l'ensemble critique PF-4 et les differents assemblages qui le composent. Les auteurs analysent l'efficacite relative du ralentissement interieur et exterieur pour des reacteurs dans lesquels le rapport noyaux du ralentisseur noyaux d'uranium dans le coeur est tres peu eleve. Il ressort des experiences que, meme lorsqu'on emploie des reflecteurs tres epais, la faible dilution de l'uranium par le ralentisseur (le rap- port entre les noyaux du beryllium et de l'uranium-235 etant: {partial_derivative}Be/{partial_derivative}{sup 235}U{approx_equal}1) entraine un accroissement de la masse critique. Une partie importante du memoire est consacree a une analyse des effets hetero- genes produits dans les reacteurs a neutrons intermediaires. U est demontre que pour une reacteur dans lequel {partial_derivative}Be/{partial_derivative}{sup 235}U = 30 a 40, diverses epaisseurs d'uranium fortement enrichi, allant de 0,023 a 32 g/cm{sup 2}, exercent une action egale sur la reactivite du systeme. Les auteurs analysent les causes qui donnent lieu a une compensation de l'effet d'ecran du flux de neutrons par des couches epaisses d'uranium. Le memoire signale comme fait interessant l'augmentation de l'efficacite de l'uranium a proximite des barreaux absorbants, qui a ete constatee experimentalemen t dans un ensemble ou {partial_derivative}Be/{partial_derivative}{sup 235}U{approx_equal}200. On explique ce fait par une diminution brusque de la quantite de neutrons absorbee par l'uranium. Pour la meme installation, le memoire cite des donnees relatives a l'efficacite de barreaux composes de diverses matieres absorbantes. Il indique la distribution, mesuree experimentalement, de la densite des neutrons de differentes energies a proximite d'un barreau en carbure de bore, ainsi que la densite de capture des neutrons par un detecteur 1/v, place a l'interieur du barreau. Le memoire expose egalement les methodes appliquees et les resultats obtenus dans des experiences destinees a evaluer l'efficacite des cylindres de compensation installes a la limite du coeur et du reflecteur. (author) [Spanish] Los autores examinan algunos resultados experimentale s obtenidos en el conjunto critico PF-4, que se destina al estudio detallado de las caracteristicas fisicas de los reactores de neutrones intermedios. Los cuerpos y los reflectores de los diversos conjuntos criticos estan formados por un denso haz de tubos de acero o de aluminio, que contienen discos de distintos materiales. La combinacion de discos de uranio (enriquecido al 90 por ciento) y de materiales moderadores en proporcion variable, asi como la introduccion de capas moderadoras de distintos espesores en el reflector, permiten modificar dentro de limites muy amplios los espectros de los neutrones causantes de la fision. En la memoria se describe el conjunto critico y sus diversas partes. Analizan los autores la eficacia comparada de la moderacion interna y externa, para reactores en que la razon de nucleos de moderador a nucleos de uranio, en el cuerpo, es muy pequena. Los experimentos demuestran que, arm. en el caso de los reflectores moderadores de gran espesor, esta baja razon ({partial_derivative}Be/{partial_derivative}{sup 235}U{approx_equal}1) conduce a un aumento de la masa critica. Gran parte de la memoria se dedica al analisis de los efectos heterogeneos en los reactores intermedios. Se demuestra que para un reactor en el que la razon {partial_derivative}Be/{partial_derivative}{sup 235}U este comprendida entre 30 y 40 distintos espesores (comprendidos entre 0,023 g/cm{sup 2} y 32 g/cm{sup 2}) de uranio muy enriquecido ejercen un efecto de magnitud constante sobre la reactividad del sistema. Se analizan las causas de la compensacion del efecto de apantallamient o del flujo neutronico por accion de capas de uranio de gran espesor. Los autores senalan un hecho interesante, a saber, el aumento de la eficacia del uranio en la proximidad de las barras de absorcion, que se observo experimentalment e en un conjunto en el que la razon {partial_derivative}Be/{partial_derivative}{sup 235}U era del orden de 200. Este hecho se explica por el acentuado descenso del nivel energetico de los neutrones absorbidos por el uranio. Para el mismo conjunto, presentan tambien datos sobre la eficacia de las barras de absorcion fabricadas con distintos materiales absorbentes. Exponen los resultados de las mediciones experimentales de la variacion de la densidad de los neutrones de distintas energias, en las cercanias de una barra de carburo de boro y la densidad de la captura neutroniea con m detector 1/v colocado en el interior de la barra. Por ultimo se exponen los metodos aplicados y los resultados obtenidos en la evaluacion de la eficacia de los cilindros compensadores giratorios distribuidos en el limite entre el cuerpo y el reflector. (author) [Russian] Doklad posvyashchen obzoru nekotorykh ehksperimen-tal'nykh rezul'tatov, poluchennykh na stende PF-4, prednaznachennom dlya detal'nogo issledovaniya fizicheskikh osobennostej reaktorov, rabotayushchikh na nejtronakh promezhutochnykh ehnergij. Aktivnye zony i otrazhateli razlichnykh kriticheskikh sborok predstavlyali soboj plotnuyu upakovku stal'nykh ili alyuminievykh trub, v kotorykh pomeshchalis' diski iz razlichnykh materialov. Kombinatsiya diskov urana (90%-nogo obogashcheniya) i zamedlyayushchikh materialov v razlichnoj proportsii, a takzhe vvedenie v otrazhatel' zamedlyayushchikh sloev razlichnoj tolshchiny, pozvolilo menyat' spektr nejtronov, proizvodyashchikh delenie, v ochen' shirokikh predelakh. V doklade privedeno opisanie stenda i ego otdel'nykh uzlov. Analiziruetsya sravnitel'naya ehffektivnost' vnutrennego i vneshnego zamedleniya dlya reaktorov s ochen'malym otnosheniem yader zamedlitelya i urana v aktivnoj zone. Ehksperimenty pokazyvayut, chto dazhe v sluchae tolstykh zamedlyayushchikh otrazhatelej maloe razbavlenie urana zamedlitelem (otnoshenie yader berilliya i urana-235 {partial_derivative}Be/{partial_derivative}U{sup 235}{approx_equal}1) privodit k vozrastaniyu kriticheskoj massy. Znachitel'noe mesto v doklade udeleno analizu geterogennykh ehffektov v promezhutochnykh reaktorakh. Pokazano, chto dlya reaktora s {partial_derivative}Be/{partial_derivative}U{sup 235}= 30+40, vysokoobogashchenny j uran v razlichnykh tolshchinakh ot 0,023 g/sm{sup 2} do 32 g/sm{sup 2} okazyvaet odinakovoe vliyanie na reaktiv-nost' sistemy. Analiziruyutsya prichiny, privodyashchie k kompensatsii ehffekta ehkranirovki nejtronnogo potoka tolstymi sloyami urana. V doklade privoditsya interesnyj fakt vozrastaniya ehffektivnosti urana vblizi po- gloshchayushchikh sterzhnej, ehksperimental'n o obnaruzhennyj v sbor kes {partial_derivative}Be/{partial_derivative}U{sup 235}{approx_equal}200. Ehtot fakt ob'yasnyaetsya rezkim snizheniem tsennosti nejtronov, pogloshchaemykh uranom. Dlya ehtoj zhe sborki privodyatsya dannye po ehffektivnosti sterzhnej iz razlichnykh pogloshchayushchikh materialov. Privoditsya ehksperimental'n o izmerennyj khod plotnosti nejtronov razlichnykh ehnergij vblizi sterzhnya iz karbida bora i plotnost' zakhvatov nejtronov ' 1/v-detektorom vnutri sterzhnya. V doklade privoditsya takzhe metodika i rezul'taty ehksperimentov po otsenke ehffektivnosti povorotnykh kompensiruyushchikh tsilindrov, razmeshchennykh na granitse aktivnoj zony i otrazhatelya. (author)}
place = {IAEA}
year = {1962}
month = {Mar}
}