No abstract available

[en] Capture and fission cross sections for ²³⁵U in the ''unresolved resonance'' energy region were evaluated to permit determination of local-average resonance parameters for the ENDF/B-IV cross section file. Microscopic data were examined for infinitely dilute average fission and capture cross sections and also for intermediate structure unlikely to be reproduced by statistical fluctuations of resonance widths and spacings within known laws. Evaluated cross sections, averaged over lethargy intervals greater than 0.1, were obtained as an average over selected data sets after appropriate renormalization. Estimated uncertainties are given for these evaluated average cross sections. The ''intermediate'' structure fluctuations common to a few independent data sets were approximated by straight lines joining successive cross sections at 120 selected energy points; the cross sections at the vertices were adjusted to reproduce the evaluated average cross sections over the broad energy regions. Data sources and methods are reviewed, output values are tabulated, and some modified procedures are suggested for future evaluations. Evaluated fission and capture integrals for the resolved resonance region are also tabulated. These are not in agreement with integrals based on the resonance parameters of ENDF/B versions III and IV. 8 tables, 5 figures

[en] Methods for fission yield determinations at an ISOL-system connected to a nuclear reactor have been developed. The present report contains detailed descriptions both of the experimental techniques and of the method used to correct the experimental yields for the decay of short-lived nuclear species in the delay between production and measurement. The methods have been applied to the determination of the fission yields of 40 fission products including 2 isometric pairs in the light mass region and those of 99 fission products including 25 isometric pairs or triplets in the heavy mass region. For 64 cases this is the first determination published. (author)

[en] In this work we have aimed to determine of fission product yields produced by photofission of ²³⁵U. The enriched uranium (²³⁵U: 5%) target was homogeneously smeared on the thick Al backing. On the uranium target was placed multilayer thin Al foils (every one's thickness is 5 μm) for implantation of fission products. Sandwich from multilayer thin Al foils and U-target was irradiated by gamma-quanta on the electron cyclic accelerator microtron MT-22. Using the HPGe-detector gamma spectrometer the fission products were measured by activation methods. It has been seen that the gamma spectra of uranium target and the first, second and third thin Al foils were almost the same, but the / background for Al foils was rather smaller than background for uranium, especially at low energy region. The fission products weren't observed for the fourth and farther thin Al foils, because the fission fragment maximum range in Al foils is R<20 μm. So, using the gamma spectra were determined a half-life and identified fission products. The results of our measurements were compared with other data from compilations.The formula for determination a nuclides number without the gamma radioactivity is given. We have estimated the relative yield of the some nuclides without the gamma radioactivity, which were on the isobar chain, using the measurement of gamma radioactivity of the fission fragments produced by photo-fission of ²³⁵U

[en] Nuclear fission reaction between Uranium-235 nucleus and thermal neutron caused the high energy fission fragments with uncertainly direction. The particle direction discrimination was determined. The 2.5 x 3.0 mm² polyethylene gratings with 1-6 mm thickness were used. The grating was placed between uranium screen that fabricated from ammonium-diurinate compound and polycarbonate nuclear track film recorder irradiated by neutron from Thai Research Reactor (TRR-1/M1) facility. The nuclear track density was inversely with grating thickness. It's only fission fragments normal to uranium screen pass through film recorder when grating thickness was 4-6 mm

[en] Pb 207 is to be converted to U235 in a steel concrete tower by producing pressures of up to 100.000 atmospheric excess pressure in a He-air atmosphere. (DG)

[en] One of the necessary data for the study of the actinides cores fission process is the fragment configuration at the moment of the split. This configuration corresponds to one determined value of coulomb Energy, which becomes kinetic energy of the primary fragments (before the neutrons emission). However, what is measured corresponds to the secondary fragments (after the neutrons emission)

[en] A suggestion is made to selectively excite certain isotopes of a mixture present as gaseous atomic beam by radiation, to ionize them by further irradiation and to give these ions isotropically distributed recoil pulses. The ions then more in a different direction to the beam and can be captured downstream with relatively easy mechanical separating devices. Several variations of the method are described in detail taking the example of the separation of U sup(235) F₆ from UF₆, whereby photoionization, dissociative electron deposit and matric insulation are treated. (UWI)

No abstract available

[en] On July 4, 2017, maintenance was being performed on an inert gas purification system used on a Research and Test Reactor (RTR) UAlx processing glovebox at the BWX Technologies, Inc. facility in Lynchburg, Virginia (US). The gas purification system has two large canisters filled with purification media. The media has two constituents; one removes moisture and the other removes oxygen from the inert gas. When the canisters were disconnected during maintenance, the operators saw what they believed was UAlx in the canisters. They stopped and notified Nuclear Criticality Safety (NCS) engineers. Preliminary estimates of the mass were potentially in excess of 1 kg ²³⁵U. The Emergency Operations Center was activated. More detailed Non-Destructive Analysis (NDA) measurements were later made and determined that the higher loaded container had less than 722 grams ²³⁵U. This was less than the minimum critical mass in the containers. After 27 hours, the Emergency Operations organization stood down. A Radiation Work Permit (RWP) was developed to guide removal of the material into individual = 2.5 liter bottles. These bottles were then measured on a Material Control and Accountability qualified system and stored for disposal. An investigation was undertaken to determine how material accumulated in these containers, whether these systems were installed elsewhere in the facility, and if similar conditions existed in those systems. Several similar systems were reviewed and evaluated by NDA. No accumulations were found. The investigation established 3 root causes and 18 corrective actions to prevent recurrence. (authors)