x���mO�0��W�w���D�~~�P@LtB�^M{��"uA W. Goodell et al., Phys. Neutron attenuation measurements showed that thin ToGa concrete samples had 16% greater neutron absorption in comparison with the reference concrete (density of 2.35 g/cm3). An experiment was performed at tbe Lid Tank Shielding Facility to determine the dependence of the neutron attenuation of a structaral concrete shield on the amount and placement of water hydrogen throughout the shield. In this work, B4C is added into concrete as fine aggregates to test the attenuation properties by getting the attenuation coefficient of the concrete/ B4C. loaded Portland concrete has higher total absorption dose rate than 20% colemanite loaded concrete. The simulation results confirm that borated Portland concrete sample has higher attenuation effects for lower neutron energy from 3.5 MeV. Much lower bremsstrahlung production than lead or bismuth when beta radiation is present. & Sychev, B.S. Source terms and attenuation lengths for neutron attenuation in a concrete shield were calculated starting from experimental neutron… Cheap. This is a preview of subscription content, log in to check access. to prevent neutrons from causing unacceptable activation of the environment. ]ȁ>@�B�Q��D��,ʦf3UP���;���Lq��m7�� e�j�W:�}��>c,����G��^��)� �Q� Moreover neutron attenuation is more effective when fast neutrons are made to collide with lightweight atoms (typically hydrogen) so hydrous aggregates are to be preferred for neutron shielding; hydrous aggregates are in fact capable of increasing the fixed-water content of concrete or retaining their water of crystallization at high temperatures. AN SSSR,” seriya fiz.,19. Low density requires 10-20x thickness as lead or bismuth for gamma attenuation. 4 0 obj 573 (1955). Slow down neutrons (the same principle as the neutron moderation). 22-25. The Soviet Journal of Atomic Energy Keywords: Boron carbide, concrete, shielding, neutron, attenuation. Borated & Pure Polyethylene Neutron Shielding. Thicker and heavier shields needed to achieve same attenuation of lead, bismuth or tungsten. Tax calculation will be finalised during checkout. Subscription will auto renew annually. A Hurst dosimeter was used to measure the fast-neutron dose rate. The aim of the present work is to extend the available computational shielding data to high-energy neutrons produced by heavy ion beams (uranium and carbon) of 1 GeV/u slowed down in a thick iron target. Rev.,89, 724 (1953). Note that the calculation can significantly underestimate absorption due to resonance effects, but resonant neutron absorption rarely occurs in powder diffraction measurements. Typical neutron spectra at high energy electron accelerators outside concrete shielding of various thicknesses (at ~90 degrees) have been calculated at three electron energies (0.1, 1 and 10 GeV) with the FLUKA code. Borated Polyethylene 30 is available in slabs, bricks, and cylinders. Neutron Excitation Function – A plot of cross section vs neutron energy for a given neutron-target system. Concrete Streaming Streaming – Door Design Streaming – Labyrinth Contents 6 Shine Appendices ... u is the linear attenuation coefficient (e.g., cm-1). For high energy neutrons (E > 20 Mev) produced by proton charge exchange, the flux attenuation follows an exponential law for concretes of various compositions in thicknesses exceeding 20–40 cm. Such an erroneous idea sometimes gains seeming economic advantage for the use of high density concrete because of savings in area and volume, and better building components on the whole [8]. hydrogen atoms), such as water, polyethylene, and concrete. One can see from this figure that dose attenuation in reality differs from the exponential low (2) with depth d. It turned out that the dependences in Fig. Immediate online access to all issues from 2019. 1 at normal hitting by neutrons the concrete shielding The results have provided useful information about neutron attenuation lengths and the Figure 6 shows the corresponding dose equivalent attenuation profiles in concrete for neutrons. 10, 399 (1961). 1 0 obj Part of Springer Nature. neutrons. 2 0 obj https://doi.org/10.1007/BF01481311, Over 10 million scientific documents at your fingertips, Not logged in %PDF-1.5 Neutrons can be made less harmful through a combination of elastic and inelastic scattering, and most neutron barriers are constructed with material… Neutrons the concrete increased the neutron attenuation in concrete attenuation coefficient while it decreased the neutron removal cross-section for and. 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