High-flux reactor

Actinides occurrence and preparation. With the exception of U and Th, the availability of the actinides of the first half of the series ranges from the g to kg scale that of the elements of the second half of the series from the mg scale for Cf to the sub-mg scale for Es. Isotopes of Np, Pu, Am, Cm can be available as byproducts of nuclear fuel processing other elements such as Ac, Cf, Bk, Es can be obtained by irradiation of selected isotopes in high flux reactors, or by reprocessing large quantities of ore (Pa). 

Traditional neutron sources for SANS have been nuclear reactors, such as the High Flux Reactor at Institut Laue-Langevin (ILL), Grenoble. As a neutron source, it is necessary that a reactor should have a high neutron flux, not necessarily a high power. 

The study of the 0 decay of 0.59s 145Cs was conducted at the TRISTAN mass separator on-line to the high flux reactor at BNL. A detailed description of the TRISTAN facility can be found in reference [GIL81]. The radioactive samples were produced by fissioning a uranium target integrated in a positive surface ionization source.[PI084] In this experiment, the usual Re surface ionizer was replaced with a Ta ionizer. The lower work function of Ta ensured no independent production of Ba from the ion source at a low power operation ( 1200°C). 

Institut Laue-Langevin, Neutron Research Facilities at the High Flux Reactor, Institut... 

A serious problem, however, for both paramagnetic and coherent magnetic scattering measurments, at least until higher reflectivity polarizers are available or alternative techniques of polarization analysis are developed, is the low intensity obtained after reflection from the sample as well as from two polarizing crystals. Even for location of apparatus at a high flux reactor, with current techniques the measurement of covalent spin reductions in powder samples can be made as efficiently by profile analysis of a conventional powder diffraction pattern as by polarization analysis. Polarized beam methods including polarization analysis will however, be essential for the determination of form factors. 

Neutron Beam Facilities at the high flux reactor, available to users. Institute Laue Langevin, Grenoble, France, (1994). 

The D2O ice samples investigated in this context were prepared inside vanadium sample cans inside an Orange Cryostat on the constant wavelength neutron powder diffractometers D2B (wavelength 1.6 A) and (wavelength 2.4 A), based at the high-flux reactor of... 

All of these factors tend to lead to more accurate structure factors, better internal agreement, and ultimately to lower crystallographic R factors and somewhat more precise atomic parameters, hence the best accuracy for neutron single-crystal structure determination. Constant wavelength single-crystal diffraction is the method of choice if ultimate precision is required in an individual structure determination. The high-flux reactor sources are currently favored for larger unit cells or smaller crystals. 

If this explanation made sense, then an inspection of the chart of nuclei showed that the mother had to be 6.68 hr [iodine] and the daughter 9.13 hr [xenon]Within an hour Fermi arrived with detailed reactivity data which checked this assignment. Within three hours two additional conclusions were clear, (a) The cross section for absorption of thermal neutrons by Xe was roughly 150 times that of the most absorptive nucleus previously known, [cadmium], (b) Almost every Xe nucleus formed in a high flux reactor would take a neutron out of circulation. Xenon had thrust itself in as an unexpected and unwanted extra control rod. To override this poison more reactivity was needed. 

Thus, by the summer of 1946 , the design for the experimental high-flux reactor had evolved from an initially homogeneous-fluid reactor to an all-metallic rigid machine aside from the cooling fluid (ordinary water). 

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