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Languages : en
Pages : 7
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This paper reports the results from a study conducted to determine the effect of electron energy on the dose-to-amorphization of Zr{sub 3,}Fe at 23--30 K. Zr3Fe samples were irradiated in the HVEM at Argonne National Laboratory, at 200 to 900 keV. Amorphization occurred at electron energies from 900 keV down to 250 keV. Three distinct regions were observed: between 900 and 700 key amorphization occurred at a constant low dose of (approximately) 4 x 1021 e cm−2; a higher plateau at 1022 was observed between 600 and 400 keV, and finally there was a sharp increase in the dose-to-amorphization below 400 key, so that at 250 key the necessary dose was an order of magnitude higher than that at 900 keV. In the region below 400 keV there was evidence of a dependence of the dose-to-amorphization on the orientation of the sample with respect to the electron beam. The results can be analyzed in terms of a composite displacement cross section dominated at high energies by displacements of Zr and Fe atoms, by displacements of Fe atoms at intermediate energies and of secondary displacements of lattice atoms by recoil impurities at low energies.
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Category :
Languages : en
Pages : 7
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This paper reports the results from a study conducted to determine the effect of electron energy on the dose-to-amorphization of Zr{sub 3,}Fe at 23--30 K. Zr3Fe samples were irradiated in the HVEM at Argonne National Laboratory, at 200 to 900 keV. Amorphization occurred at electron energies from 900 keV down to 250 keV. Three distinct regions were observed: between 900 and 700 key amorphization occurred at a constant low dose of (approximately) 4 x 1021 e cm−2; a higher plateau at 1022 was observed between 600 and 400 keV, and finally there was a sharp increase in the dose-to-amorphization below 400 key, so that at 250 key the necessary dose was an order of magnitude higher than that at 900 keV. In the region below 400 keV there was evidence of a dependence of the dose-to-amorphization on the orientation of the sample with respect to the electron beam. The results can be analyzed in terms of a composite displacement cross section dominated at high energies by displacements of Zr and Fe atoms, by displacements of Fe atoms at intermediate energies and of secondary displacements of lattice atoms by recoil impurities at low energies.
Author: A. T. Motta
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Languages : en
Pages : 0
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Results of pre-test analyses of fuel element thermal-mechanical behaviour and fission product (fp) release during the btf-105 experiment are discussed in this report. a detailed twenty-segment eloca nodalization is used to reflect axial variations of the element behaviour during the test. the range of simulations conducted accounts for the effects of several experimental uncertainties, including the behaviour of a pre-defected element, the effects of fuel pellet eccentricity inside the sheath and fuel-to-sheath axial gap distribution. a prototype post-failure version of eloca.mk5 is used to investigate the consequences of element failure with rupture sizes ranging from large burst to a small pin hole. the simulation results show that the element will fail by over-strain at about 916 s from the start of transient. at the end of the transient, the volume-averaged fuel temperature is calculated to be about 1830 degrees c, with an end-to-end area-averaged fuel temperature variation of about 270 degrees c and a radial temperature difference of 355 degree c. complete sheath oxidation is predicted by the end of the transient for the hottest segments (at the bottom of the element). stable gas and cs-137 releases of over 50 percent of the element inventory are predicted. a coupled eloca-cathena simulation is recommended to improve the accuracy of these predictions. the effect of rupture size on the final sheath strain, fuel temperature and fp release is found to be insignificant. while fuel pellet eccentricity leads to higher fuel-sheath heat transfer and thus lower fuel temperature and fp release, the effect of varying the distribution of fuel-to-sheath axial gap appears to be negligible. for a pre-defected element, a small sheath strain would be maintained throughout the experiment, hence the final fuel temperature and fp release are significantly lower than those predicted for an intact element.
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Languages : en
Pages : 7
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Book Description
This paper reports the results from a study conducted to determine the effect of electron energy on the dose-to-amorphization of Zr{sub 3,}Fe at 23--30 K. Zr3Fe samples were irradiated in the HVEM at Argonne National Laboratory, at 200 to 900 keV. Amorphization occurred at electron energies from 900 keV down to 250 keV. Three distinct regions were observed: between 900 and 700 key amorphization occurred at a constant low dose of - 4 × 1021 e cm{sup −2}; a higher plateau at 1022 was observed between 600 and 400 keV, and finally there was a sharp increase in the dose-to-amorphization below 400 key, so that at 250 key the necessary dose was an order of magnitude higher than that at 900 keV. In the region below 400 keV there was evidence of a dependence of the dose-to-amorphization on the orientation of the sample with respect to the electron beam. The results can be analyzed in terms of a composite displacement cross section dominated at high energies by displacements of Zr and Fe atoms, by displacements of Fe atoms at intermediate energies and of secondary displacements of lattice atoms by recoil impurities at low energies.
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Category : Power resources
Languages : en
Pages : 544
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Author:
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Category :
Languages : en
Pages : 16
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0.9 MeV electron irradiations were performed at 28--220 K in a high-voltage electron microscope (HVEM). By measuring onset, spread and final size of the amorphous region, factoring in the Guassian distribution of the beam, a kinetic description of the amorphization in terms of dose, dose rate and temperature was obtained. The critical temperature for amorphization by electron irradiation was found to be (approximately)220 K, compared to 570--625 K for 4°Ar ion irradiation. Also, the dose-to-amorphization increased exponentially with temperature. Results indicated that the rate of growth of the amorphous region under the electron beam decreased with increasing temperature and the does-to-amorphization decreased with increasing dose rate. The size of the amorphous region saturated after a region dose, the final size decreasing with increasing temperature, and it was argued that this is related to the existence of a critical dose rate, which increased with temperature, below which no amorphization occurred. The above observations can be understood in the framework of the kinetics of damage accumulation under irradiation.
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Category : Aeronautics
Languages : en
Pages : 652
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Author: Atomic Energy of Canada Limited
Publisher:
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Category :
Languages : en
Pages : 80
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Author: A. T. Motta
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Category :
Languages : en
Pages : 0
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Author: Kurt E. Sickafus
Publisher: Springer Science & Business Media
ISBN: 1402052952
Category : Science
Languages : en
Pages : 593
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Book Description
This is a comprehensive overview of fundamental principles and relevant technical issues associated with the behavior of solids exposed to high-energy radiation. These issues are important to the development of materials for existing fission reactors or future fusion and advanced reactors for energy production; to the development of electronic devices such as high-energy detectors; and to the development of novel materials for electronic and photonic applications.
Author: Ian M. Robertson
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 600
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Book Description
The focus of the symposium, which was held at the 1994 MRS Fall Meeting, was on the changes produced in the microstructure of metals, ceramics, and semiconductors by irradiation with energetic particles. This proceedings volume contains invited and contributed papers. Among the topics are computer simulation of displacement cascade damage in metals; radiation effects in ceramic insulators; and computer simulation of thermal annealing effects of self implanted silicon. Annotation copyright by Book News, Inc., Portland, OR
