γ-ray self-absorption of cylindrical fissile material

The self-absorption of γ-ray emitted from cylindrical fissile materials, such as ^235U and ^239Pu. does not possess spherical symmetry. The analytical formulae of self-absorption for y-ray throughout the cylinder have been obtained. The intensity of γ-ray is a function of y-ray outgoing directions and cylindrical configorations, accordingly one can acquire the information about geometrical configuration of cylindrical fissile materials through multi-location measurements. Further more. the method is given in this article, The result can be applied to the fissile material safeguard, such as nuclear monitoring and verifying.     

γ-ray Spectroscopy of _Λ~7 Li

TheexperimentisperformedatK6beamlineofPSacceleratorinKEK.Theπ beamof1.05GeV/cisusedtohitthe25cmthick7Litargettoproducetheboundstateof7ΛLibythe7Li(π ,K )7ΛLireaction.ThescatteredK particlesareidentifiedandmomentumanalyzedwiththeSKSspectrometer.Usingala…     

Proposal for a high brightness γ-ray source at the SXFEL

High brightness γ-rays produced by laser Compton scattering(LCS) are ideal probes for the study of nucleon and nuclear structure. We propose such a γ-ray source using the backscattering of a laser from the bright electron beam produced by the linac of the Shanghai Soft X-ray Free-electron Laser(SXFEL) test facility at the Shanghai Institute of Applied Physics(SINAP). The performance is optimized through theoretical analysis and benchmarked with 4D Monte-Carlo simulations. The peak brightness of the source is expected to be larger than2 × 1022photons/(mm2mrad2s 0.1%BW) and photon energy ranges from 3.7 Me V to 38.9 Me V. Its performance, compared to Extreme Light Infrastructure-Nuclear Physics(ELI-NP), and the Shanghai Laser-Electron Gamma-ray Source(SLEGS), is given. The potential for basic and applied research is also briefly outlined.     

γ-ray spectra from the radiation capture of neutrons for even-even radiating nuclei with rotational levels

Using a magnetic Compton spectrometer, we measured the spectra of the -rays arising from the capture of thermal neutrons by nuclei of gadolinium, erbium, hafnium, dysprosium and tantalum in the energy range 0.3–9 Mev. We determined the energies and the intensities of the -lines. For the first three elements, the radiating nuclei are the even-even nuclei₆₄Gd ₉₂ ¹⁵⁶ ,₆₄Gd ₉₄ ¹⁵⁸ ,₆₈Er ₁₀₀ ¹⁶⁸ and₇₂Hf ₁₀₆ ¹⁷⁸ , which have rotational structural levels close to the ground state. The peculiarity of the spectra of these nuclei is the presence of a group of closely placed intense -lines with energies of 1 Mev. These lines are absent in the case of even-odd (for example,₆₆Dy ₉₉ ¹⁶⁵ ) and odd-odd radiating nuclei (for example,₇₃Ta₁₀₉ ¹⁸²). The peculiarities of the -ray spectra noted are due to the structure of the lower nuclear levels.     

On the creep characteristics of β-zircaloy

A recent model of creep deformation in pure materials is compared with published data on β-zirconium and β-zircaloy. It is shown that the zircaloys behave like the pure metal in this phase range and that the model is capable of predicting their creep rates to within a factor of 2 on tubing material. A condition is that the curved Arrhenius plot for diffusion in zirconium represents the intrinsic behaviour of point defects in the lattice and that solute atoms have an insignificant effect on the process. A corollary is that the contribution from dislocation short-circuiting both to diffusion and to creep is negligible.     

Benchmark experiment of large-angle scattering reaction cross section of iron at 14 MeV using two shadow bars – Comparison of experimental results with ENDF/B-VIII –

ABSTRACT

It is important to perform neutron transport simulations with accurate nuclear data in the neutronics design of a fusion reactor. However, absolute values of large-angle scattering cross sections vary among nuclear data libraries even for well-examined nuclide of iron. Benchmark experiments focusing on large-angle scattering cross sections were thus performed to confirm the correctness of nuclear data libraries. The series benchmark experiments were performed at a DT neutron source facility, OKTAVIAN of Osaka University, Japan, by the unique experimental system established by the authors’ group, which can extract only the contribution of large-angle scattering reactions. This system consists of two shadow bars, target plate (iron), and neutron detector (niobium). Two types of shadow bars were used and four irradiations were conducted for one experiment, so that contribution of room-return neutrons was effectively removed and only large-angle scattering neutrons were extracted from the measured four Nb reaction rates. The obtained experimental results were compared with calculations for five nuclear data libraries including JENDL-4.0, JEFF.-3.3, FENDL-3.1, ENDF/B- VII, and recently released ENDF/B-VIII. It was found from the comparison that ENDF/B-VIII showed the best result, though ENDF/B-VII showed overestimation and others are in large underestimation at 14 MeV.     

Investigation of the radiation characteristics of the masonry in the ai uranium–graphite reactor

The results of investigations of the nuclear safety of the masonry in the AI uranium–graphite (Industrial Association Mayak) reactor are presented. It is concluded on the basis of these results that the masonry is nuclear safe and a radiation certificate is composed. The radiation examination made it possible to determine the level, composition, and distribution of the radioactive contamination of the masonry as well as the level and distribution of the neutron and γ radiation, and to construct a forecast of the change in the activity of radionuclides in graphite as a function of the holding time. These data are necessary for safety analysis and for making decisions about the subsequent stages of decommissioning of the reactor. Translated from Atomnaya énergiya, Vol. 105, No. 5, pp. 266–269, November, 2008.     

Metrological system forγ-ray spectrometry measurement of the specific activity and mass fraction of natural radioactive elements in soil and rock samples

All-Russian Scientific-Research Institute of Exploratory Geophysics, VIRG-Rudgeofizika. Scientific and Industrial Association "VNIIM im. D. I. Mendeleeva," Center for Metrological Standards for Ecological Safety. Institute of Radiation Hygiene. Translated from Atomnaya Énergiya, Vol. 75, No. 5, pp. 350-354, November, 1993.     

Radiation protection in the design of λ-ray industrial computed tomography systems

The recent increasing use of γ-rays industrial computed tomography(γ-rays ICT) in various fields has induced greater attention to its performance as well as to considerations of radiation safety. It is understood that radiation protection planning cannot be sacrificed for the sake of CT image quality during the design, manufacture,and layout of γ-rays ICT systems. In the present work, we describe a typical γ-rays ICT system in brief, and, based on experience and pertinent examples, we propose design requirements for ensuring the radiation safety of the sealed radioactive source, source container, and workspace. The design examples and dose rate measurement results illustrate that the proposed design standards are reasonable,feasible, and safe, and are therefore meaningful for the design, manufacture, and layout of γ-rays ICT systems. This paper discussed the predominant measures associated with the radiation protection of γ-rays ICT systems in accordance with the pertinent Chinese standards. In addition, based on experience and pertinent examples, the design requirements for ensuring the radiation safety of a sealed radioactive source, source container, and workspace were defined in detail. The design examples and dose rate measurements conducted in conjunction with a γ-rays ICT system and workspace employing the proposed design standards have illustrated that the proposals provided in this paper are reasonable, feasible, and safe, and are therefore meaningful for the design, manufacture, and layout of γ-rays ICT systems.