Moderator–collimator-shielding design for neutron radiography systems using 252Cf

Silva, A.X da; Crispim, V.R.

doi:10.1016/s0969-8043(00)00291-8

Cited by 15 publications

(4 citation statements)

References 5 publications

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“…The measurements were recorded at the top side of the "created instrument" (35 cm from the backside of the first sample of 0.5 cm in thickness) for a period of time not exceed ten seconds for each time, and also the procedures were repeated for the cumulative thickness of the samples up to 5 cm. Then investigated via exposing them to 241 Am/Be neutron source with average energy 4.5 MeV [8,15], as shown in Figures (6) and (7). The neutron count rate beyond each paraffin sample was measured after samples exposing.…”

Section: Experimental Workmentioning

confidence: 99%

“…one of the most notable materials employed in nuclear facilities dating back to the famous experiment of James Chadwick that resulted in the discovery of neutrons in 1932, is paraffin (C n H 2n + 2 ) [5]. The high hydrogen content of paraffin, its cheap cost, moldability, and superior electrical insulation make it suitable for use as a neutron moderator and shield [6,7]. Fast neutrons are more difficult to protect against since their absorption cross sections are significantly smaller at higher energy.…”

Section: Introductionmentioning

confidence: 99%

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Design and Creating a Specific Neutron Irradiation Instrument to Decrease the User’s Radiation Exposure Time

Muslim

Al-Mashhadani

2023

Iraqi Journal of Science

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A specialized irradiation instrument "created instrument" was designed and created from various kinds and sizes of available plastic household-waste materials. In addition, a neutron beam collimator with a lid was designed and implemented. The collimator is with dimensions of 25 cm in height and 10 cm in inner diameter, while the lid dimensions are 11.5 cm height and outer diameter of 9.9 cm to perfectly match the inner diameter of the collimator with the possibility of movement (opening and closing), and also the shielding of the radioactive 241Am/Be neutron source with a recent activity of 37.5 mCi. To investigate the efficiency of the "created instrument", ten hydrogenous material samples (ordinary paraffin of chemical structure CnH2n+2) with the same cylindrical dimensions (Ø = 8.5 cm, 0.5 cm thickness) and with the same weight of 20 g ± 0.005 for each, were used with and without the "created instrument". The neutron measurements were slowed (4.7 – 1.58 n/s) when the paraffin sample thickness was progressively increased (0 – 5 cm). Most importantly, the "created instrument" was effectively contributed to reducing the user’s radiation exposure time from approximately 90 seconds to a few seconds no longer than 30 seconds for each measurement with considerable reduction ratio of 66.67% by making the samples of thicknesses ranging from 0.5 cm to 5 cm easier to position on the neutron beam collimator compared without using the "created instrument". It may also be utilized to evaluate the moderation on-site for different materials in neutron source shielding thickness based on the measuring procedures and data gathered. It is predicted that this study will help future improvements to use additional techniques to satisfy more protection related to the radiation field.

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Section: Experimental Workmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Design and Creating a Specific Neutron Irradiation Instrument to Decrease the User’s Radiation Exposure Time

Muslim

Al-Mashhadani

2023

Iraqi Journal of Science

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“…The right-hand side cylinder incorporates the divergent collimator which determines, to a great extent, the quality of the image for a given source type [18]. In the optimization procedure of the collimator, the collimator length L, the inlet aperture D and the diameter of the collimator inlet next to the image plane, D0, were altered in order to achieve the values for which the maximum thermal flux is attained in the image plane [19]. The lining of the collimator is consideredof great importance.…”

Section: 3the Radiography Unit: Design and Materialsmentioning

confidence: 99%

A neutronradiography facility based on an experimental reactor

Dimitrios¹,

Fantidis²,

Nicolaou³

2015

JESTR

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A thermal Neutron Radiography (NR) facility based on the use of thermal neutron flux, generated by the PULSTAR experimental reactor, has been designed and simulated using the MCNPX code. The key objective of the proposed facility is to deliver thermal neutron flux in this range for variable values of L/D ratio, instantaneously with acceptable values for all NR parameters. Thus, with suitable aperture and collimators designs, optimization for the parameters for thermal NR was achieved, for a wide range of the collimator ratio. The short time requirements for obtaining the radiography images justify the use of the proposed system for 'real time radiography'. The system was designed under the limitation that the total Dose Equivalent Rate does not exceed at the external shield surface the limit recommended by ICRP-26.

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“…The optimization parameters, the collimator shape, size and material, has great impact on achieving high quality beam for neutron imaging. The shape of the collimator could be the single segment cylinder [11], single segment truncated cone [12], even multiple segment ones [13] or more complex configurations [14]. The size of the collimator contains source size (𝐷), collimator length (𝐿), outlet size (𝐷 0 ), and thickness of the collimator wall (if the wall is multilayered, it is the thickness of each layers).…”

Section: Introductionmentioning

confidence: 99%

Optimization design of a fast neutron imaging collimator by genetic algorithm

Yan

Liu

et al. 2020

J. Inst.

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Fast neutron imaging, including radiography and computer tomography (CT), has been developed as a useful probe to visualize the inner structure of objects. From large scale neutron facility (like spallation source) to compact neutron source, even to small neutron generator, collimator design is extremely important for achieving high quality images. The main indexes to evaluate the performance of the fast neutron imaging collimator are: collimation ratio (L/D), outlet size (D0), fast neutron intensity (fF), uncollided neutron content (UNC), neutron to gamma ratio (n/γ). At present, the enumeration method is widely used for the collimator design from the reported studies. However, not only one (always several) parameters need to be optimized, as well as multiple optimization objectives should be considered, thus enumeration method can only try an extremely limited number of parameter combinations within the parameter space. In this paper, we proposed an optimization method combining genetic algorithm (GA) with MCNP code for the collimator design. The optimization results show the proposed method can significantly improve its performance compared with those with enumeration method.

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Moderator–collimator-shielding design for neutron radiography systems using 252Cf

Cited by 15 publications

References 5 publications

Design and Creating a Specific Neutron Irradiation Instrument to Decrease the User’s Radiation Exposure Time

Design and Creating a Specific Neutron Irradiation Instrument to Decrease the User’s Radiation Exposure Time

A neutronradiography facility based on an experimental reactor

Optimization design of a fast neutron imaging collimator by genetic algorithm

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