[en] Two radial conduction models, one for steady state and another for unsteady state, in a nuclear power reactor fuel element are developed. The objective is to obtain the temperatures in the fuel pellet and the cladding. The lumped-parameter hypothesis are adopted to represent the system. Both models are verified and their results are compared with similar ones. A method to calculate the conductance in the gap between the UO₂ pellet and the clad and its associated uncertainty is included in the steady state model. (author)

[en] For the 500 MWe Prototype Fast Breeder Reactor (PFBR), 20% CW D9 has been chosen as the material for fuel clad and wrapper. A peak burnup of 100,000 MWd/t is targeted for the fuel. While experimental data on irradiation behaviour of this material will be generated by irradiation in the test reactor FBTR, presently in operation, correlations have been derived from data available in literature for neutron induced void swelling and creep. The derived data has been used in assessing the deformation in hexagonal wrapper and clad and for optimising core restraint system design. This paper presents results of sensitivity studies carried out in respect of the above data. The parameters considered are hexcan dilation, differential deformation between hexcan and pin bundle and core deformation parameters. It is observed that the fluence parameter has the highest influence on the design parameters. (author)

[en] Four tube-sets constructed from a combination of three lots of HT9 and two heat-treatments were examined after irradiation in FFTF-MOTA at four different temperatures between 400 and 600 deg. C. Diametral measurements indicated that small amounts of swelling occurred at 400 deg. C, with the magnitude of the swelling varying from tube-set to tube set. At 495, 550, and 600 deg. C no indications of swelling were observed. Over a limited stress range that decreased with increasing irradiation temperature, the irradiation creep was found to be proportional to the stress level and mirrored the swelling behavior, confirming the B_o + DS creep model. The creep compliance, B_o, appears to be about half of the observed in austenitic steels, whereas the creep-swelling coupling coefficient D, appears to be comparable to that of austenitics. At the highest stress levels examined, the value of the stress exponent became much greater than 1.0. Higher irradiation temperatures resulted in creep behavior with pronounced thermal creep characteristics: a primary creep transient was observed at the three higher irradiation temperatures and increased in magnitude with increasing irradiation temperature, while a stress exponent between 1.0 and 2.0 was observed at 550 deg. C. (author)

[en] Electromagnetic nondestructive techniques are usually applied to solve many inspection problems in industry. In particular, eddy currents are used for the detection of defects and the characterization of physical properties of metallic materials and components. One such application is the measurement of thickness of non conductive layers on a conducting substrate. A laboratory device for the quantitative determination of those thicknesses was developed at our laboratory. It works in the range from 0 to 100 μm and was calibrated with a micro metre screw. This task involved the design and construction of the sensors their characterization (working frequency, resolution, sensitivity, etc.) and the setup of the mechanical system and the electronic signal generation and measurement circuit. (author)

[en] The nuclear power plants steam generators have different types of structural supports. One of these types are the antiseismic supports, which are intended to be under stress only if a seismic event takes place. Nevertheless, the antiseismic supports lugs, that are welded to the steam generator vessel, are subjected to thermal fatigue because of the temperature cycles related with the shut down and start up operations performed during the life of the nuclear power plant. In order to evaluate the stresses that the lugs are subjected to, several strain gages were welded on two supports lugs, positioned at two heights of one of the Embalse nuclear power plant steam generators. In this paper, the instrumentation used and the strain measurements obtained during two start up operations are presented. The influence of the plant start up operation parameters on the lugs strain evolution is also analyzed. (author)

[en] During the design steps of a fuel bundle for a nuclear reactor, some vibration tests are usually necessary to verify the prototype dynamical response characteristics and the structural integrity. To perform these tests, the known hydrodynamic loop facilities are used to evaluate the vibrational response of the bundle under the different flow conditions that may appear in the reactor. This paper describes the tests performed on a 19 plate fuel bundle prototype designed for a low power research reactor. The tests were done in order to know the dynamical characteristics of the plates and also of the whole bundle under different flow rate conditions. The paper includes a description of the test facilities and the results obtained during the dynamical characterization tests and some preliminary comments about the tests under flowing water are also presented. (author)

[en] This paper illustrates developments in and prospects for the application of nuclear science technology in the fields of food and agriculture, industry and environmental protection, in connection with the IAEA's activities

[en] Gamma scanning of trayed and packed columns is widely used to obtain density profiles and identify on-line problems such as: damaged tray or packing, foaming, flooding, maldistribution, weeping and entrainment, etc. However, scanning of large diameter tray or packed columns requires expertise in handling high intensity gamma sources along with thorough understanding of distillation engineering. Engineers India Limited and the Bhabha Atomic Research Centre undertook scanning of two such large diameter (8.4 m and 7.4 m) trayed and packed refinery vacuum distillation columns and successfully diagnosed the problems and suggested remedial actions. Radiography testing of small diameter columns can be used to confirm gamma scanning results. One such example for ammonia separator column is given

[en] Isotope tracers have been used successfully in the well-to-well tracer test because of their unique properties, high sensitivity, wide range of choice, easy for in-situ operation and reasonable price thus are getting the broad applications in China recently. Basic methodology has been developed for the design and completion of a test. Methods and equipment for new tracer development and tracer property evaluation have been established. Many field tests were carried out during the past years. As 87% of the total oil reserve are exploited by water drive, water tracer test is much more concerned. Tracers for steam and gas tracing are also reviewed. For water drive, tritiated water (THO) is the most commonly used tracer. Tritiated methanol, tritiated ethanol, ³⁵S tagged thiourea and ⁶⁰Co tagged K₃[Co(CN)₆] have been used in some field tests as water tracers; ⁵¹Cr-EDTA, ¹²⁵I-NaI, and some activable tracers (rare earth 1 elements tagged EDTA complex) have also been tried for water tracing in the fractured or a channelling reservoir; the results obtained were encouraging. For steam tracing, THO was used for that of gases, tritium, tritiated methane and krypton (⁸⁵Kr) were employed. Three field application examples are described in this paper. The first example is about water tracing by use of gamma radiotracers; the second, a typical example of steam tracing by use of THO; and the 1 third introduces the application of activable tracers in water tracing. Current trends of the well-to-well tracer test are the use of partitioning tracers to determine S residual oil saturation of the reservoir, development of new tracers, optimization of the tracer analysis methods, and the development of data interpretation method and software

[en] The inventory of fusion reactors mainly consists of deuterium and tritium. The amount of tritium of each reactor is equal to the natural inventory of the earth's atmo- and hydrosphere. Elementary tritium (HT) itself is not dangerous to man, for it is hardly dissolved in water, that is neither taken up by human tissues nor metabolized anywhere in our body. In contrast to HT the tritiated water HTO quickly exchanges with any wet surface and with the humidity of air. After an accidental release into the atmosphere the main pathway of intake into the human body is as HTO via the lung; its surface is comparable to a soccer playground. HT released into air will be quickly oxidised within the upper centimetres of the soil when the plume touches the ground. Each soil tested by us until now had oxidized HT, that had shown hydrogenase activity. Neither the biological function nor the catalytic system wee identified yet. The hypothesis of a correlation between hydrogenase activity and soil nitrogen fixation could not be confirmed (nitrogen fixation shows a leakage of hydrogen): nitrogen fixing plants (nodules) do not oxidize HT. The presentation will summarize ten years of work in the laboratory and in the field. A concise picture of the radioecological behaviour of elementary tritium after an accidental release could be obtained. The work was partly done as cooperation within the frame of the EU or within the International Union of Radioecology