Earticle

Background: Shielding properties of compound or mixture is presented in terms of mass attenuation coefficients using Monte Carlo simulation. Mass attenuation coefficients of cement, gypsum and the mixture of gypsum and PbCO3 has been investigated using monte carlo MCNPX. Materials and Methods: The mass attenuation coefficients of cement, gypsum and the mixture of gypsum and PbCO3 were calculated for photon energies 365.5, 661.6, 1,173.2, and 1,332.5 keV energies. Results and Discussion: The simulated values of mass attenuation coefficients were compared avaialable experimental results, theoretical values by XCOM and found good comparability of the results. Conclusion: Standard simulation geometry used in the present investigation would be very useful for various types of sample for shielding and dosimetry applications.

In the present study, the linear attenuation coefficient and mass attenuation coefficient have been calculated at energy range of 0.8MeV, 1MeV, 3Mev, 5MeV and 7MeV. The mass attenuation Coefficient μm has been calculated analytically for Iron material Fe (ρ= 7.87 g/cm3) and developed material lead Pb (ρ= 11.3 g/cm3) at photon energies [0.8 MeV to 7 MeV] using X-Com computer code. The obtained results were compared with the calculated values. The linear attenuation Coefficient μ has been calculated, its variations with photon energy were plotting. The Comparison between two materials Iron and Lead were also studied. The obtained result shows that μ and μm depends on the photon energy, density of the materials and atomic number. From this study we notice that the values of μm and μ of Lead material is greater than Iron material and also the values are decreasing with increasing the photon energy. The half value layer (HVL) and tenth value layer (TVL) of two studied materials were calculated at photon energy range of 0.8 MeV, 1MeV, 5MeV and 7MeV. The relation between this equation Ln (Io/I) and the thickness of material were calculated, so the curves show that the relation of Ln (Io/I) of Iron and Lead materials is increasing with the increasing of material thickness and the relation gives the straight line, also the comparison of this relation for Lead material is higher than Iron material. This study can also be utilized to improve the effectiveness of radiation shielding by using the developed shielding material.

The effective atomic number (Zeff) and effective electron density (Neff) of wrought aluminum alloy 7010 has been determined by measuring mass attenuation coefficient (μm), total atomic cross section (σt) and total electron cross section (σe) with radioactive point source of different γ-energies viz. 59.5, 661.16, 1173 and 1332 keV. The transmitted γ-photons were detected and recorded by a NaI(TI) scintillation detector with resolution of 8.5% for 661.16 KeV of 137Cs. The experimental results determined were compared with the theoretical values obtained using XCOM and semi empirical approach for all photon energies. The photon mean free path (λ) and linear attenuation coefficient (μl) for these energies have been reported. The experimental values are in good agreement with theoretical values.

The study of radiation absorption in material is an important subject to protect living creatures and environment from harmful effect of radiation. The degree to which gamma radiation is attenuated is dependent upon the energy of the incident gamma radiation, the thickness of the shielding, the atomic number and density of the elements in the shielding material. In this respect, this study presents the attenuating properties of some (Ag-Cu-Sn Alloys) by using the Nation Institute of Standards and Technology (NIST) XCOM code in the energy range (0.01 to 10 MeV).

실제 드럼 내에 존재하는 핵종으로부터 방출되는 감마선을 외부에서 측정하여 그로부터 드럼 내 핵종의 양을 정확하게 분석하기 위해서는 먼저 적절한 교정표준의 선택과 드럼 내 매질의 밀도와 핵종의 분포에 대한 감마선 감쇠보정이 반드시 필요하다. 본 연구에서는 드림 내 핵종의 분석을 위하여 밀도가 다른 두 개의 모델드럼을 이용하였으며 전송선원으로써는 (10 mCi), 표준선원으로는 혼합선원()을 이용하였다. 그리고 드럼과 검출기 사이의 거리를 달리하면서 모델드럼 내의 표준선원으로부터 나오는 감마선을 계측하여, 감쇠보정이 되지 않은 이 측정값에 3 종류의 감마선 감쇠보정을 각각 수행하였다. 그 결과 밀도가 낮은 드럼에서의 오차는 10 % 이하이었고, 밀도가 높은 드럼에서의 오차는 25 % 이하이었다. 또한 드럼과 검출기사이의 거리가 근거리(70 cm, 드림구획 : 10 segments)일 때, 오차는 원거리(90 cm, 드럼구획 : 8 segments)에서의 오차보다는 낮았는데 이는 상대적으로 1 segment에 대한 부피차이에 기인한 밀도 측정오차가 낮고 감마선의 산란이 낮았기 때문이다.

In the measurement of gamma rays emitted from the nuclide in the radioactive waste drum, to analyze the nuclide concentration accurately, it is necessary to use the proper calibration standards and to correct for the attenuation of the gamma rays. Two drums having a different density were used to analyze the nuclide concentration inside the drum in this study. After carrying out the system calibration, we measured the gamma rays emitted from the standard source inside the model drum with changing the distance between the drum and the detector. The measured values were corrected with the three kinds of gamma attenuation correction methode, as a results, the error was less than 10 % in the low density drum and less than 25 % in the high density drum. The measured activity in the short distance was more accruable than in the long distance. The transmission correction for the mass attenuation showed good results(very Low error) compared to the mean density and the differential peak correction method.

In this study, the mass attenuation coefficients for all five of the IAEA referencematerial samples (apparent density in a measuring bottle: 0.50~1.45 g·cm-3), including soil, milkpowder, hay and moss soil, were determined using the CT (Calibration Transmission) method. Acertified mixed gamma-ray sources including 241Am, 88Cd, 57Co, 113Sn, 85Sr and 137Cs were added tothe IAEA reference samples for the validation of present method. The self-attenuation correctionfactors for the gamma-ray energies of 59.5 keV, 88 keV, 122.1 keV, 391.7 keV, 514 keV and 661.7keV were determined and applied to the self-attenuation correction. As a result, the accuracy ofgamma-ray spectrometry for environmental samples used in this study was improved especiallyfor lower energy gamma-ray emitting radionuclides.