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Adams, R.J.; Baerg, A.P.

Standardization of Radionuclides. Proceedings of a Symposium on Standardization of Radionuclides

Standardization of Radionuclides. Proceedings of a Symposium on Standardization of Radionuclides

AbstractAbstract

[en] In the general coincidence formulae used to determine the absolute decay rate by 4π β-γ coincident methods N

_{β}= N_{0}F(N_{c}/N_{γ}) and N_{β}N_{γ}/N_{c}= N_{0}G(N_{γ}/N_{c}) the functions F and G can be found experimentally by suitable variation of the beta-detector efficiency. To determine N_{0}therefore, it is necessary to fit an n-th order polynomial to the data, since, although these functions are often approximately linear, in general this is not the case. As a least-squares fitting criterion is employed, it is necessary that the order of the function be determined and that the deviations of the data about the final regression curve be randomly distributed. The order is found by calculating that polynomial about which the observations are distributed to a degree consistent with the precision of the measurements (using the x^{2}test for goodness of fit). A set of N observations (y_{1}, y_{2}, x_{2}....y_{N}, x_{N}) yields a polynomial experimentally defined as y_{i}= f(x_{i}, a, b, c...m) (N > m) where, in this case, y_{i}= N_{β}and x_{i}= N_{c}/N_{γ}or y_{i}= N_{β}N_{γ}/N_{c}and x_{i}= Nγ/N_{c}. Since the function is linear in the coefficients (a, b, c . . . m) their experimental evaluation is achieved by the usual least-squares method of minimizing the sum of the weighted residuals. This is equivalent to the minimization of x^{2}, i.e. x^{2}= Σ_{i}(W_{i}V^{2}_{i})/o^{2}= Σ_{i}(V_{i}/o_{i})^{2}where the residual V_{i}= y_{i}- f(x_{i}), w_{i}is the weight associated with the observed residual and o the variance of the residual of unit weight. The variance of this residual function is obtained in terms of the independent experimental parameters P_{j}from o_{i}^{2}= Σ_{j}(δ(y-f(x))/δP_{j})^{2}_{i}(ΔP_{j})^{2}_{i}As these variance calculations for individual measurements depend on the functions F or G and these depend on weights which are themselves variance functions, the final solution is based on an iterative procedure. This results in a successively closer approximation to the final best fit. (author)Primary Subject

Source

International Atomic Energy Agency, Vienna (Austria); 763 p; Mar 1967; p. 123-127; Symposium on Standardization of Radionuclides; Vienna (Austria); 10-14 Oct 1966; IAEA-SM--79/25; ISSN 0074-1884; ; 7 refs.

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Todt, F.W.

Organisation for Economic Co-Operation and Development, Nuclear Energy Agency - OECD/NEA, Le Seine Saint-Germain, 12 boulevard des Iles, F-92130 Issy-les-Moulineaux (France)

Organisation for Economic Co-Operation and Development, Nuclear Energy Agency - OECD/NEA, Le Seine Saint-Germain, 12 boulevard des Iles, F-92130 Issy-les-Moulineaux (France)

AbstractAbstract

[en] 1 - Nature of physical problem solved: This infinite-medium depletion program performs fuel cycle calculations on reactors employing partial refueling. The burnup of up to 12 discrete fuel compositions (regions or stages of irradiation) may be followed simultaneously. The burnup calculation may be interrupted periodically to remove the contents and to refuel one or more regions. Fuel may be partially or completely recycled. 2 - Method of solution: All regions are assumed to be subjected to the same neutron flux and the depletion calculations are performed with a series of short time-steps. After each time-step the flux amplitude is renormalized to the power and the spectrum may be recalculated after a specified series of these steps. 3 - Restrictions on the complexity of the problem: Maximum number of energy groups = 15; Maximum number of fuel compositions or regions = 12; Maximum number of nuclides per region = 35; Maximum number of moderator nuclides with thermal transfer matrix = 3. 2 fixed heavy nuclide chains are always present

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1 Oct 1966; [html]; Available on-line: http://www.nea.fr/abs/html/nesc0223.html; Country of input: International Atomic Energy Agency (IAEA); 1 ref.

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Noyes, R.C.; Morgan, J.G.; Cappel, H.H.

Organisation for Economic Co-Operation and Development, Nuclear Energy Agency - OECD/NEA, Le Seine Saint-Germain, 12 boulevard des Iles, F-92130 Issy-les-Moulineaux (France)

Organisation for Economic Co-Operation and Development, Nuclear Energy Agency - OECD/NEA, Le Seine Saint-Germain, 12 boulevard des Iles, F-92130 Issy-les-Moulineaux (France)

AbstractAbstract

[en] 1 - Nature of physical problem solved: TRANS-FUGUE1 is a transient single channel, two-phase flow, and heat transfer code for analysis of postulated reactor incidents involving boiling. The code is based on a homogeneous hydrodynamic model which assumes equal phase temperatures and velocities. It assumes vapor generation to be heat transfer limited only, and calculates axial distribution of velocity, void fraction, pressure, coolant temperature, and fuel temperature. Transients simulating power excursions, loss of flow, loss of pressure and channel plugging can be studied. 2 - Method of solution: Each transient starts from some steady-state condition derived from input parameters. One of these selected by the user varies with time and the program calculates the response of the system to this driving function. The heat balance equations are solved by use of finite difference techniques and the momentum equation is derived assuming constant vapor density and saturation temperature, eliminating pressure feedback. Numerical instabilities resulted when attempts were made to remove these limitations. The code is set up to provide use of a smaller time-step for the momentum equation than that used for the heat balance and mass equations if requested. 3 - Restrictions on the complexity of the problem: Maximum of - 100 spatial nodes

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1 Sep 1968; [html]; Available on-line: http://www.nea.fr/abs/html/nesc0268.html; Country of input: International Atomic Energy Agency (IAEA); 2 refs.

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Drittler, K.

Nuclear data for reactors. Proceedings of a conference on nuclear data - microscopic cross-sections and other data basic for reactors. V. 1

Nuclear data for reactors. Proceedings of a conference on nuclear data - microscopic cross-sections and other data basic for reactors. V. 1

AbstractAbstract

[en] From the formalism of Van Hove, a formula is derived from which the influence of chemical binding on neutron cross-sections at higher energies can be calculated. The cross-section is equal to that of free atoms only if strongly inharmonic binding forces are not present. But strongly inharmonic binding forces are to be expected in crystals. Therefore, crystals with atoms of middle and high mass numbers should still show effects of the crystal binding on the cross-section up to a few thousand eV. Since these effects are comparatively small and nearly temperature-independent, it is difficult to measure them. Therefore, with the anisotropic properties of the chemical binding in crystals, the transmissions of copper single crystals for two different crystallographic orientations were measured from 9 to 3000 eV. From a comparison of these results for the two it is obvious that with great probability there is an influence of the chemical binding. The significance of these effects for reactor calculations is briefly discussed. (author)

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International Atomic Energy Agency, Nuclear Data Unit, Vienna (Austria); 594 p; Apr 1967; p. 155; Conference on nuclear data - microscopic cross-sections and other data basic for reactors; Paris (France); 17-21 Oct 1966; IAEA-CN--23/80; ISSN 0074-1884; ; Abstract only

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Uttley, C.A.; Newstead, C.M.; Diment, K.M.

Nuclear data for reactors. Proceedings of a conference on nuclear data - microscopic cross-sections and other data basic for reactors. V. 1

Nuclear data for reactors. Proceedings of a conference on nuclear data - microscopic cross-sections and other data basic for reactors. V. 1

AbstractAbstract

[en] Neutron total cross-section measurements have been made between 100 eV and 1 MeV on nuclei near the mass 100 and mass 240 p-wave size resonances using the Harwell 'booster' pulsed neutron source and the 120-m and 300-m spectrometers. The s-wave strength function s

_{0}and distant level parameter R_{0}^{∞}have usually been separately determined at lower energies and the corresponding p-wave parameters are obtained from a least-squares fit to the higher energy (> 10 keV) total cross-section using the average collision function expression from R-matrix theory. The d-wave strength function is also determined using plausible assumptions on the average parameters of the higher partial waves. The nuclei studied are^{93}Nb_{41},^{98}Mo_{42},^{100}Mo_{42},^{103}Rh_{45}and^{232}Th_{90},^{233}U_{92},^{235}U_{92},^{238}U_{92}and^{239}Pu_{92}. (author)Primary Subject

Source

International Atomic Energy Agency, Nuclear Data Unit, Vienna (Austria); 594 p; Apr 1967; p. 165-174; Conference on nuclear data - microscopic cross-sections and other data basic for reactors; Paris (France); 17-21 Oct 1966; IAEA-CN--23/36; ISSN 0074-1884; ; 15 refs, 3 figs, 1 tab

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D WAVES, EV RANGE 100-1000, KEV RANGE, LEAST SQUARE FIT, MASS, MOLYBDENUM 100, MOLYBDENUM 98, NEUTRON SOURCES, NEUTRONS, NIOBIUM 93, NUCLEAR DATA COLLECTIONS, P WAVES, PLUTONIUM 239, R MATRIX, RHODIUM 103, S WAVES, SPECTROMETERS, STRENGTH FUNCTIONS, THORIUM 232, TOTAL CROSS SECTIONS, URANIUM 233, URANIUM 235, URANIUM 238

ACTINIDE NUCLEI, ALPHA DECAY RADIOISOTOPES, BARYONS, CROSS SECTIONS, ELEMENTARY PARTICLES, ENERGY RANGE, EV RANGE, EVEN-EVEN NUCLEI, EVEN-ODD NUCLEI, FERMIONS, FUNCTIONS, HADRONS, HEAVY ION DECAY RADIOISOTOPES, HEAVY NUCLEI, INTERMEDIATE MASS NUCLEI, INTERNAL CONVERSION RADIOISOTOPES, ISOMERIC TRANSITION ISOTOPES, ISOTOPES, MATHEMATICAL SOLUTIONS, MATRICES, MAXIMUM-LIKELIHOOD FIT, MEASURING INSTRUMENTS, MINUTES LIVING RADIOISOTOPES, MOLYBDENUM ISOTOPES, NEON 24 DECAY RADIOISOTOPES, NIOBIUM ISOTOPES, NUCLEI, NUCLEONS, NUMERICAL SOLUTION, ODD-EVEN NUCLEI, PARTIAL WAVES, PARTICLE SOURCES, PLUTONIUM ISOTOPES, RADIATION SOURCES, RADIOISOTOPES, RHODIUM ISOTOPES, SPONTANEOUS FISSION RADIOISOTOPES, STABLE ISOTOPES, THORIUM ISOTOPES, URANIUM ISOTOPES, YEARS LIVING RADIOISOTOPES

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Miessner, H.; Arai, E.

Nuclear data for reactors. Proceedings of a conference on nuclear data - microscopic cross-sections and other data basic for reactors. V. 1

Nuclear data for reactors. Proceedings of a conference on nuclear data - microscopic cross-sections and other data basic for reactors. V. 1

AbstractAbstract

[en] Effective capture and transport cross-sections which are fundamental for Doppler coefficient calculations in fast reactor design have been measured on lead, uranium and tantalum in the low keV region. In this energy range the resonances of the cross-sections of fertile and fissile materials and of most structural materials are separated but are still experimentally unresolved. For the following measurements the pulsed method which has been proved in the thermal energy range for measuring capture and transport cross-sections is extended to the keV region. A short burst (1 or 10 ns) of nearly monoenergetic neutrons with energies below the threshold for inelastic scattering is injected into assemblies of lead, uranium and tantalum (parallelepipeds of 10 to 20 cm side length) and the decay of the neutron field in the block is measured. Moderation effects during the decay are small for materials as heavy as lead, uranium and tantalum and can be eliminated from each decay spectrum by a calculated moderation correction function F(t), which corrects the measured neutron density N(t) in the following way: N(t) / F(t) ∼e

^{-α}0^{t}The corrected neutron density decays exponentially with a decay constant α_{0}= v_{0}Σ_{e}^{ff}_{a}+ v_{0}/ 3Σ^{eff}_{tr}B^{2}+ C^{B4}_{T}. v_{0}is the neutron injection velocity, B^{2}the buckling of the assembly and C_{T}a correction term due to transport theory. α_{0}is measured as a function of B^{2}and in this way Σ^{eff}_{a}and Σ^{eff}_{tr}are obtained. The effective cross-sections are related to 'infinite dilution' average values <Σ_{a}> and <Σ_{tr}> by self-shielding factors f_{a}and f_{t}, which have been calculated for many nuclides by Abagjan and others. The measured effective cross-sections are compared with self-shielding factors and <Σ> values measured by other authors. Further dilution effects in mixtures of a resonance absorber (^{238}U) and a potential scatterer (Pb) are investigated. (author)Primary Subject

Source

International Atomic Energy Agency, Nuclear Data Unit, Vienna (Austria); 594 p; Apr 1967; p. 502; Conference on nuclear data - microscopic cross-sections and other data basic for reactors; Paris (France); 17-21 Oct 1966; IAEA-CN--23/8; ISSN 0074-1884; ; Abstract only

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ACTINIDE NUCLEI, ACTINIDES, ALPHA DECAY RADIOISOTOPES, BARYONS, BOSONS, ELEMENTARY PARTICLES, ELEMENTS, ENERGY RANGE, EPITHERMAL REACTORS, EVEN-EVEN NUCLEI, FERMIONS, FISSIONABLE MATERIALS, HADRONS, HEAVY NUCLEI, ISOTOPES, MATERIALS, METALS, NUCLEI, NUCLEONS, RADIOISOTOPES, REACTIVITY COEFFICIENTS, REACTORS, REFRACTORY METALS, SCATTERING, SPONTANEOUS FISSION RADIOISOTOPES, TRANSITION ELEMENTS, URANIUM ISOTOPES, YEARS LIVING RADIOISOTOPES

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Stupegia, D.C.; Keedy, C.R.; Schmidt, M.; Madson, A.A.

Nuclear data for reactors. Proceedings of a conference on nuclear data - microscopic cross-sections and other data basic for reactors. V. 1

Nuclear data for reactors. Proceedings of a conference on nuclear data - microscopic cross-sections and other data basic for reactors. V. 1

AbstractAbstract

[en] Neutron capture cross-sections over a wide range of mass number are being measured for neutron energies between about 5 keV and 3 MeV. The nuclei studied to date are

^{41}K,^{85}Rb,^{86}Sr,^{87}Rb,^{89}Y,^{98}Mo,^{139}La,^{141}Pr,^{158}Gd,^{170}Er,^{175}Lu, and^{176}Yb. The experimental technique used is the activation method, in which the radioactive capture product formed in the neutron bombardment is measured by beta or gamma counting, and the counters are calibrated against a 4π-beta counter. Monoenergetic neutrons are produced by bombarding lithium or tritium targets with protons from the 4-MeV Van de Graaff accelerator. The neutron intensity is measured with a fission chamber, which counts fissions in a thin deposit of^{235}U. The data are compared with calculations based upon the statistical model of uncorrelated and non-interfering compound nuclear states. This model, which yields the energy averages of resonant or fluctuating compound nuclear cross-sections, was first used to calculate capture cross-sections by Lane and Lynn, and has been developed further by Moldauer. The calculations take into account the variation of radiation width and level density with excitation energy and spin of the compound nucleus, and include the competition of compound elastic and inelastic scattering and the variation of neutron widths from level to level (Porter-Thomas distribution). Neutron widths were calculated from optical model transmission coefficients, with the parameters chosen according to the spherical optical model of Moldauer. Another phenomenon is considered in the calculations. If the compound state, de-exciting through a gamma-ray cascade, ends its de-excitation in a low-lying level of (Z, A + 1), the event is radiative capture, as measured experimentally. If, however, after a gamma-ray decay, the compound system is at an excitation energy above the neutron emission threshold, the gamma-ray cascade may be ended by neutron emission, and the process does not contribute to the capture cross-section. The computations take into account the competition between those two modes of de-excitation. The experimental results are compared with calculations using the model described above. The agreement is good from a few keV to about 1 MeV for^{89}Y,^{98}Mo,^{139}La, and^{141}Pr. The agreement is not as good for the distorted nuclei,^{158}Gd,^{170}Er,^{175}Lu, and^{176}Yb. In all cases, the calculations become uncertain at energies above which the level schemes of the target nuclei are poorly known, since this lack of data introduces uncertainty in the calculation of the competition of inelastic scattering. In the calculations, the influence of the termination of the gamma-ray cascade by neutron emission begins to be appreciable above about 200 keV. The inclusion of this effect in the computations is an important factor in allowing the radiative capture cross-sections to be calculated accurately above that energy. (author)Primary Subject

Source

International Atomic Energy Agency, Nuclear Data Unit, Vienna (Austria); 594 p; Apr 1967; p. 520; Conference on nuclear data - microscopic cross-sections and other data basic for reactors; Paris (France); 17-21 Oct 1966; IAEA-CN--23/51; ISSN 0074-1884; ; Abstract only

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CAPTURE, COMPOUND NUCLEI, CROSS SECTIONS, DE-EXCITATION, ENERGY-LEVEL DENSITY, ERBIUM 170, EXCITATION, FISSION, FISSION CHAMBERS, GADOLINIUM 158, INELASTIC SCATTERING, LANTHANUM 139, LUTETIUM 175, MOLYBDENUM 98, NEUTRON EMISSION, NEUTRON REACTIONS, NUCLEAR DATA COLLECTIONS, OPTICAL MODELS, PORTER-THOMAS DISTRIBUTION, POTASSIUM 41, PRASEODYMIUM 141, RUBIDIUM 85, RUBIDIUM 87, STATISTICAL MODELS, STRONTIUM 86, TRITIUM TARGET, URANIUM 235, VAN DE GRAAFF ACCELERATORS, YTTERBIUM 176, YTTRIUM 89

ACCELERATORS, ACTINIDE NUCLEI, ALKALINE EARTH ISOTOPES, ALPHA DECAY RADIOISOTOPES, BARYON REACTIONS, BETA DECAY RADIOISOTOPES, BETA-MINUS DECAY RADIOISOTOPES, ELECTROSTATIC ACCELERATORS, EMISSION, ENERGY-LEVEL TRANSITIONS, ERBIUM ISOTOPES, EVEN-EVEN NUCLEI, EVEN-ODD NUCLEI, GADOLINIUM ISOTOPES, HADRON REACTIONS, HEAVY NUCLEI, INTERMEDIATE MASS NUCLEI, INTERNAL CONVERSION RADIOISOTOPES, IONIZATION CHAMBERS, ISOMERIC TRANSITION ISOTOPES, ISOTOPES, LANTHANUM ISOTOPES, LUTETIUM ISOTOPES, MATHEMATICAL MODELS, MEASURING INSTRUMENTS, MINUTES LIVING RADIOISOTOPES, MOLYBDENUM ISOTOPES, NANOSECONDS LIVING RADIOISOTOPES, NEUTRON DETECTORS, NUCLEAR REACTIONS, NUCLEI, NUCLEON REACTIONS, ODD-EVEN NUCLEI, POTASSIUM ISOTOPES, PRASEODYMIUM ISOTOPES, RADIATION DETECTORS, RADIOISOTOPES, RARE EARTH NUCLEI, RUBIDIUM ISOTOPES, SCATTERING, SECONDS LIVING RADIOISOTOPES, SPONTANEOUS FISSION RADIOISOTOPES, STABLE ISOTOPES, STRONTIUM ISOTOPES, TARGETS, URANIUM ISOTOPES, YEARS LIVING RADIOISOTOPES, YTTERBIUM ISOTOPES, YTTRIUM ISOTOPES

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AbstractAbstract

[en] A method for the evaluation of elastic and inelastic scattering cross-sections for the first collective state of even-even nuclei is described. Some theoretical results are compared with the experimental ones; comparisons are also made with DWBA. (author)

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International Atomic Energy Agency, Nuclear Data Unit, Vienna (Austria); 454 p; May 1967; p. 371; Conference on nuclear data - microscopic cross-sections and other data basic for reactors; Paris (France); 17-21 Oct 1966; IAEA-CN--23/114; ISSN 0074-1884; ; Abstract only

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Fuan, Jacques; Grimont, Bernard; Marin, Roland; Richard, Jean-Pierre

Commissariat a l'energie atomique et aux energies alternatives - CEA, Centre d'Etudes Nucleaires de Saclay, Service de Documentation, BP No.2, 91190 Gif-sur-Yvette (France)

Commissariat a l'energie atomique et aux energies alternatives - CEA, Centre d'Etudes Nucleaires de Saclay, Service de Documentation, BP No.2, 91190 Gif-sur-Yvette (France)

AbstractAbstract

[en] The objective of this document is to describe different measurement methods, and more particularly to present a software for the processing of obtained results in order to avoid interpretation by the investigator. In a first part, the authors define the parameters of integral and differential linearity, outlines their importance in measurements performed by spectrometry, and describe the use of these parameters. In the second part, they propose various methods of measurement of these linearity parameters, report experimental applications of these methods and compare the obtained results

Original Title

Methodes de mesure des distorsions de linearite integrale et differentielle des ensembles de spectrometrie

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May 1969; 110 p; DEG-EI-R--2-518-BG-JF-RM-JPR-CHD; 5 refs.; Available from the INIS Liaison Officer for France, see the 'INIS contacts' section of the INIS website for current contact and E-mail addresses

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Zraick, Samir

Faculte des Sciences de l'Universite de Paris (France); Commissariat a l'energie atomique et aux energies alternatives - CEA-Saclay (France)

Faculte des Sciences de l'Universite de Paris (France); Commissariat a l'energie atomique et aux energies alternatives - CEA-Saclay (France)

AbstractAbstract

[en] A macro-generator is a translator which is able to interpret and translate a programme written in a macro-language. After a first part presenting the main notions and proposing a brief description of the TAS-86 language, the second part of this research thesis reports the development of the macro-generator language, and notably presents the additional functionalities provided by the macro generator. The development is illustrated by logical flowcharts and programming listings

Original Title

Macro generateur recursif pour le langage TAS-86. 1ere partie: le langage du macro generateur. 2eme partie: logique interne du systeme

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16 Nov 1970; 257 p; 8 refs.; Available from the INIS Liaison Officer for France, see the 'INIS contacts' section of the INIS website for current contact and E-mail addresses: http://www.iaea.org/inis/Contacts/; These Docteur-Ingenieur

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