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[en] The paper deals with the effect of atmospheric conditions - relative humidity, wind velocity, temperature and temperature gradient on the visible plume. For estimating cooling tower plumes, used was made of verified mathematical model. (author)
[en] The effect of water vapor concentration on the current vs. voltage curve in an air filled ionization chamber was investigated. Experimental conditions included a parallel plate chamber with a plate spacing of 6 cm, ionization rates of 3.6 x 10-3 esu/cm3/sec or 0.45 x 10-3 esu/cm3/sec and collecting potentials ranging from zero to ± 500V. Over the range of water vapor concentration from 6400 ppm (∼30% relative humidity) to 100 ppm no significant change in the current vs. voltage curve was observed. (author)
[en] The various radiations encountered in radiological protection cover a wide range of energies and radiation measurements have to be carried out under an equally broad spectrum of environmental conditions. This report is one of a series intended to give information on the performance characteristics of radiological protection instruments, to assist in the selection of appropriate instruments for a given purpose, to interpret the results obtained with such instruments, and, in particular, to know the likely sources and magnitude of errors that might be associated with measurements in the field. The radiation, electrical and environmental characteristics of radiation protection instruments are considered together with those aspects of the construction which make an instrument convenient for routine use. To provide consistent criteria for instrument performance, the range of tests performed on any particular class of instrument, the test methods and the criteria of acceptable performance are based broadly on the appropriate Recommendations of the International Electrotechnical Commission. The radiations in the tests are, in general, selected from the range of reference radiations for instrument calibration being drawn up by the International Standards Organisation. Normally, each report deals with the capabilities and limitations of one model of instrument and no direct comparison with other instruments intended for similar purposes is made, since the significance of particular performance characteristics largely depends on the radiations and environmental conditions in which the instrument is to be used. The results quoted here have all been obtained from tests on instruments in routine production, with the appropriate measurements being made by the NRPB. This report deals with a battery-powered exposure rate meter with digital display manufactured by Scanary Ltd., Bletchley, Milton Keynes
[en] Energy release associated with sodium spray combustion was determined and a computer code was developed to analyze combustion of sodium particles in the atmosphere depleted of oxygen. Liquid sodium heated at 300∼500 deg. C was injected as much as 400 gr into a closed vessel of 2 m3. Atmosphere in the vessel was controlled by mixing nitrogen gas with dry air and wet air 0∼21% in oxygen concentration and 0∼75 in humidity. Temperatures and pressure of the atmosphere were recorded to observe their rises and drops with time during and after sodium injection. Peak pressure rose with increases in oxygen concentration and temperature of injected sodium being more sensitive to the concentration than the temperature. The peak pressure did not reach a level which was obtained from theoretical energy release from sodium spray combustion because of incomplete combustion and heat transfer to the vessel wall. It was assumed in the computer code that heat and mass transfer was controlled respectively by heat conduction and mass diffusion inside a reaction zone and the transfer was governed by convection outside the reaction zone. Calculation results revealed that combustion rate per unit area on the sodium particle was in proportion to oxygen concentration in the ambient gas but in reverse to the particle sizes, and that decreasing rate of square of particle sizes was about 7x10-4 cm2/s, being smaller in one order of the value of fuel oils. Change in the pressure obtained from the calculation was on the whole in agreement with that observed in the experiment. (author)
[en] The increased Agency assistance for transfer of nuclear technology is essential for the developing countries and especially Africa. It would have a beneficial effect on the implementation of training programmes. The introduction of teaching in nuclear physics at universities in Nigeria, Tanzania and Madagascar should be extended to other universities in order further to orientate African students towards nuclear sciences. In the peaceful uses of atomic energy the African States are concentrating their activities in the spheres of agriculture and medicine. The Agency assists these countries in programmes in agriculture and the exploitation of natural resources, including water. The introduction of radioisotope techniques should be accelerated at all existing agricultural research centres. Services of this kind exist in a few countries, including Senegal, Kenya, the Ivory Coast, Morocco and the Sudan. Radioisotopes employed there make it possible, in particular, to trace the movement of fertilizers from soil to plant and to measure soil humidity. Ionizing radiations can be used to produce genetic effects for the purpose of creating hew varieties of important crop plants and selecting varieties requiring less water for their growth. Such activities are naturally of the greatest interest to the African continent which, as a whole, lives basically from agriculture. The guarantee of food supplies during the next decade is a subject of concern for Africa, and the prevention of losses of foodstuffs is one of the main objectives of African policy.Food irradiation projects are being conducted in Ghana (on cocoa beans) and in Nigeria (on sweet potatoes) with the support of Agency research projects. The Agency's project on the radiation preservation of fish, at present being implemented in countries in Asia, could - provided that the results are satisfactory - have important economic repercussions for the African countries.In the medical sphere, the improvement in health facilities and services has recently been facilitated by advances in nuclear medicine, and laboratories and dispensaries able to use radioisotopes have been set up with the Agency's assistance at numerous African medical centres
[en] This work on textile hibiscus was undertaken for two reasons: to contribute by physical mutagenesis methods to the genetic improvement of these species and especially to obtain the genetic diversity which is seriously lacking in the species sabdariffa var. altissima; to add to research on the effects of mutagenic seed treatments and thus to help towards a better definition of optimum seed irradiation conditions. These two purposes have been fulfilled. The main results may be summed up as follows. - Concerning the improvement of textile hibiscus. Many strains with various new features were selected at the second generation and may lead either to new varieties or at least to interesting precursors for selection programmes. In the second generation derived from Hibiscus saddariffa var. THS 22 some plants were observed with one or more of the following characteristics specific to the edible form: ramified bearing - fleshy calix - smooth leaf. - Concerning the study of mutagenic seed treatment effects. Our experiments showed up the importance of the seed water content and its effect on the response of first-generation plantlets to cobalt 60 γ-ray treatments.
[fr]Nous avions en entreprenant ces travaux sur les hibiscus textiles deux objectifs: par la voie de la mutagenese physique, contribuer a l'amelioration genetique de ces especes et notamment obtenir la diversite genetique qui fait gravement defaut a l'espece sabdariffa var. altissima; apporter notre contribution a l'etude des effets des traitements mutagenes sur les semences et aider ainsi a une meilleure definition des conditions optimales d'irradiation des semences. Ces deux objectifs ont ete atteints. Nous resumons les principaux resultats. - En ce qui concerne l'amelioration des Hibiscus textiles. De nombreuses souches presentant divers caracteres nouveaux ont ete selectionnees a la deuxieme generation et sont susceptibles d'aboutir sinon a de nouvelles varietes du moins a des geniteurs interessants pour les programmes de selection. Dans la deuxieme generation issue d'Hibiscus sabdariffa var. THS 22 on a observe des plantes presentant l'un ou l'autre ou plusieurs des caracteres suivants propres a la forme alimentaire: port ramifie - calice charnu - feuille lisse. - En ce qui concerne l'etude des effets des traitements mutagenes sur les semences. Nos experiences ont mis l'accent sur l'importance de la teneur en eau des semences et son influence sur la reponse des plantules de premiere generation aux traitements par les rayons gamma du cobalt 60.
[en] The main objective of this research thesis which deals with meteorite study, is to develop an experimental technique to measure the hydrogen isotopic rate in the case of very low quantities of hydrogen, notably in samples in which water content is hundred or thousand times less than in reported experiments, in order to study mechanisms of alteration of chondrites. The author reports an attempt to reconcile obtained results for isotopic rates as well as for water contents with those of the main existing models of chondrite formation. He proposes a detailed description of isotopic exchange mechanisms at low temperature, and shows that this mechanism is not in disagreement with literature published on chondrites
[en] It is of important to study the extension of shelf-life at ambient temperature. This study would be of significant in the case of non- refrigerated transport, practices within the country and transhipment to distant countries. studies have therefore extended to assess the shelf-life of irradiated banana stored under-room temperature. Extension of shelf -life have been achieved by many methods, the most modern one is using gamma irradiation as a promising technology for developing nations. the aim of this investigation is to study the biochemical effects of gamma irradiation on Gros Michel mature green banana fruits and also to determine the optimum dose level and the optimum storage conditions which resulted in, keeping the organoleptic qualities as it is and maximum extension in shelf-life
[en] Experiments have been conducted in one of ECN's aerosol chambers using Exploding Wire produced sodium oxide aerosol under dry air conditions (100 ppm H2O). Electron microscope analysis of particles immediately after sampling revealed the typical appearance of metal oxide smoke particles, viz. aggregates of large numbers of solid primaries. The diameters of the primary particles were distributed log normally with a geometric median diameter of 0.085 micrometers and a geometric standard deviation of 1.5. Spiral centrifuge analysts yielded dynamic shape factors κ between 2 and 4 for aggregates of aerodynamic diameters between 0.57 and 0.92 micrometers resp. The relation between κ and the number of primaries per aggregate was found to fit nicely the ECN-model for such aggregates, which model has been validated previously experimentally with aerosols of Fe-oxide, Au, U3O8 and Cu-oxide. This model with the Na-oxide primaries input data leads to aerodynamic diameter values of about 1.5 micrometers for a 10 g.m-3 aerosol after 15 minutes of dominant Brownian coagulation. This is in reasonable accordance with some experimental observations. Increased humidity or sampling artefacts will lead to compaction of the fluffy aggregates resulting in an increased aerodynamic diameter of about 4 micrometers or more
[en] Geothermal and geochemical monitoring of the volcano La Soufriere, la Guadeloupe was carried out in 1974-1975, especially thanks to the earliest prototypes of automatic measurement beacons, and the results were evaluated. The devices used are described and their development is considered in the light of the information supplied by field experience. (authors)
[fr]Cette note fait le point des resultats obtenus en matiere de surveillance geothermique et geochimique du volcan La Soufriere en Guadeloupe, en 1974 et 1975 grace notamment aux premiers prototypes de balises de mesures automatiques. Elle contient une description des materiels utilises et envisage leur evolution a partir des enseignements fournis par l'experience sur le terrain. (auteurs)