نتایج جستجو برای: neutron shield
تعداد نتایج: 53966 فیلتر نتایج به سال:
In this study, a flexible composite shield with a combination of polyethylene, tungsten and boron carbide has been designed and constructed for neutron-gamma mixed fields. For this purpose, theoretical studies were conducted using the multi-purpose MCNPX Code. According to the results of simulation studies, a multi-purpose composite was constructed using a combination of a solid phase of boron ...
background: changes in body composition may be used for monitoring progression/ regression of a disease. prompt γ-rays in vivo neutron activation analysis (ivnaa) has been widely used for the measurement of body composition in recent years. objective: in this paper, we tried to improve the safety of ivnaa operator. methods: the most important factor for reducing the operator receiving dose is t...
Background: Several landmine detection methods, based on nuclear techniques, have been suggested during the recent years. Neutron energy moderation, neutron-induced gamma emission, neutron and gamma attenuation, and fast neutron backscattering are nuclear-based methods used for landmine detection. The aim of this study is to use backscattered neutron for landmine detection. Materials ...
Neutron Generators (NG) are used as a neutron source for different applications. During recent years, major efforts are underway to develop a high yield compact NG. In this way, radiation protection aspects need to be considered during the operation of these high yield NGs. In this paper the neutron effective dose of a NG operator has been calculated using MCNPX Monte Carlo code. The results sh...
In order to simulate neutron shields, MCNP5 calculation code was used and three types of homogeneous and separated shield multilayer arrangement, irradiated with 241Am-Be neutron sources were investigated. In these shields, the polyethylene (C2H4) and polystyrene (C8H8) were used as moderator material, and the boron carbide (B4C), as a thermal neutron absorber material and stainless steel as a ...
INTRODUCTION The Tokai Power Station (Tokai 1), a 166MWe gas-cooled graphite-moderated reactor of advanced Calder-Hall type, ceased commercial operation in March 1998 after 32 years of service, and spent fuels are being discharged from the core at present for preparation of decommissioning the reactor. Plans for the decommissioning that include future dismantling work, have been studied since t...
Neutron dose-equivalent buildup factors were calculated for point isotropic neutron sources irradiating infinite slablike shields of lead, iron and water using the MCNP code. The factors are presented for some source neutron energies in the range from 0.025 eV to 14 MeV, and for shield thicknesses from 0.5 to 10 mfp. Since the MCNP code considers all kinds of neutron interactions with matter, a...
Neutron howitzers are routinely used in universities to activate samples for instructional laboratory experiments on radioactivity. They are also a convenient source of neutrons and gammas for research purposes, but they must be used with caution. This paper describes the modeling, design, construction, and testing of a portable, economical shield for a 1.0 Curie neutron howitzer. The Monte Car...
Background: Changes in body composition may be used for monitoring progression/ regression of a disease. Prompt γ-rays in vivo neutron activation analysis (IVNAA) has been widely used for the measurement of body composition in recent years.Objective: In this paper, we tried to improve the safety of IVNAA operator.Methods: The most important factor for reducing the operator receiving dose is th...
In this paper, we describe the performance of the Los Alamos spallation-driven solid-deuterium ultra-cold neutron (UCN) source. Measurements of the cold neutron flux, the very low energy neutron production rate, and the UCN rates and density at the exit from the biological shield are presented and compared to Monte Carlo predictions. The cold neutron rates compare well with predictions from the...
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