FACULTY OF PHYSICS & ENGINEERING PHYSICS

DEPARTMENT OF NUCLEAR PHYSICS - NUCLEAR ENGINEERING - MEDICAL PHYSICS

An improved semi-empirical procedure for Compton scattering technique applied to measure pipeline thickness

Vo Hoang Nguyen, Nguyen Huu Bao, Huynh Dinh Chuong, Nguyen Duy Thong, Tran Thien Thanh & Chau Van Tao 

Journal of Radioanalytical and Nuclear Chemistry (2021)

Abstract:

This study aims to formulate semi-empirical processing applied to analyze simulated and experimental scattering spectra on pipeline samples for estimating the intensity of the single scattering component for the Compton scattering technique. Firstly, a procedure has been developed based on probability density functions of each scattering component, which are obtained by GEANT4. Secondly, sixteen targets are simulated with MCNP6 to validate the proposed procedure. It is shown that the relative deviation for all samples is under 3%. Thirdly, the nine calculated thickness of pipeline samples is determined with a maximum relative deviation lower than 5% in comparing to calibration thickness.

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An Assessment of External Dose From Natural Radioactivity in Building Materials by Using Simulation Monte Carlo

Le Quang Vuong, Tran Thi Bao Ngoc, Le Thi Ai Van, Tran Thien Thanh, Chau Van Tao

IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 72, NO. 4, APRIL 2025

Abstract:

Aside from the natural background ionizing radiation that humans are constantly exposed to, there is a significant risk of elevated radiation levels from building materials with enhanced radioactivity. Given the time individuals spend indoors, this study is crucial in assessing the external radiation dose from commonly used construction materials. A room model with dimensions of 5×4×2.8 m and walls of 20 cm thick was developed to simulate radiation doses from materials such as cement, brick, sand, and rock collected from suppliers in Ho Chi Minh City, Vietnam. Absorbed dose rates from radionuclides, specifically 238U, 232Th, and 40K, were calculated using the Monte Carlo N-Particle Transport code version 6.1 (MCNP6), with phantom water used to represent the dose absorption medium. The results indicate that the external radiation doses ranged from 0.11 to 0.64 mSv/y for sand, 0.47–0.79 mSv/y for cement, and 1.07–1.58 and 1.00 mSv/y for brick and rock, respectively. While most measured doses were below the reference value, specific brick samples exceeded these thresholds. In addition, a comparative analysis was conducted using the Residual Radioactive Material – Building (RESRAD-BUILD) code, with dosimetric data derived from the international commission on radiological protection 38 (ICRP 38) library. The comparison between MCNP6 and RESRAD-BUILD results showed a good agreement with relative deviations of less than 12%, underscoring the accuracy and reliability of the model. These findings suggest that the proposed methodology provides a reliable and efficient approach for quantifying external radiation doses from building materials, thus contributing to improved radiation safety assessments in indoor environments.

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AMBIGUITIES FROM NUCLEAR INTERACTIONS IN THE 12C(p,2p)11B REACTION

Nguyen Tri Toan Phuc, Kazuyuki Ogata, Nguyen Hoang Phuc, Bui Duy Linh, Vo Hong Hai and Le Xuan Chung

Communications in Physics, Vol. 32, No. 2 (2022), pp. 117-132

Abstract:

We investigate the impact of ambiguities coming from the choice of optical potentialsand nucleon-nucleon scattering cross sections on the spectroscopic factors extracted from the 12C( p,2p)11B reaction. These ambiguities are evaluated by analyzing the cross sections of the 12C( p,2p)11B reaction at 100 and 200 MeV within the framework of the distorted-wave impulseapproximation with realistic choices of nuclear inputs. The results show that the studied ambigui-ties are considerably large in this energy region and careful choices of nuclear inputs used in thereaction calculations are required to extract reliable structure information

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Activity Concentrations of Natural Radionuclides in Soil and Water Around Some Quarries and Potential Human Health Effects

Le Binh An, Van Thang Nguyen, Nguyen Phong Thu Huynh, Huynh Thi Yen Hong, Truong Huu Ngan Thy, Huynh Truc Phuong, Cong Hao Le

Water Air Soil Pollut (2023) 234:122

Abstract:

In this study, radioactivity levels were measured in surface soil and water around some large quarries and quarry lakes in Binh Duong Province, Vietnam. Natural radionuclides (226Ra, 232Th, and 40K) in the collected soil and water samples were analyzed by gamma spectroscopy equipped with a high-purity germanium (HPGe) detector. A method was introduced to assess the radiological risks to the local population. It was based on the effective dose that was estimated by a sum of the individual doses. Some major exposure pathways including (1) external exposure by gamma rays, (2) internal exposure by drinking water, and (3) internal exposure by ingestion of food crops and fishes in the area were considered. For the estimation of natural radioactivity in other relevant environments such as food crops and fish, some estimation models based on soil-to-crops transfer factors and water-to-fish concentrations ratios were used. It was found that most of the radioactivity levels in soil and water were within the ranges of the concentrations in the world and Vietnam. The effective dose due to the ingestion of food exceeds the recommended limitation of 300 μSv y−1. However, the ingestion dose was estimated with the assumption that the ingestion rate is the average rate of people in the study area.

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Vu Ngoc Ba, Van Thang Nguyen, Bui Ngoc Thien, Huynh Nguyen Phong Thu, Truong Thi Hong Loan

Journal of Radioanalytical and Nuclear Chemistry

Abstract:

The aim of this study is to determine activity concentrations of natural radionuclides (226Ra, 232Th, 40K and 222Rn) and radiological risks due to the contamination of radionuclides in surface soil in Ho Chi Minh City, Vietnam. Based on the activity concentration of 226Ra in the surface soil, we proposed a method for estimation of the radon concentration in the indoor air. The assessments of radiation dose and excess lifetime cancer risk show that the utilization of surface soils for human residences or routine activities in the studied area poses no risk to the public health.

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Van Thang Nguyen, Nguyen Phong Thu Huynh, Cong Hao Le

Journal of Environmental Management 271 (2020) 111001

Abstract:

In topsoils, the activity concentrations of natural radionuclides (hereafter NRs) increase due to the addition of NRs from fertilizers, irrigation water, and air dust pollution. On the other hand, various physical-chemical and environmental processes such as radioactive decay, volatilization, leaching, erosion, and plant uptake were responsible for the decrease of the activity concentrations of NRs in the topsoils. In this study, behaviours of 40K, 210Pb, 226Ra, 238U, and 232Th in topsoils were modelled by the CEMC soil model and the HYDRUS-1D model. An exponential equation was proposed for estimating the accumulation rates of these radionuclides in the topsoils. Long-term accumulation of radionuclides was assessed for water spinach (Ipomoea Aquatica Forssk.) soil (here-after VES) and rice (Oryza sativa L.) soil (hereafter RIS). We found that the current agricultural practices caused the increase of 40K activity concentration in the water spinach soil, and 40K, 210Pb, 226Ra, and 232Th activity concentrations in the rice soil. The accumulation rates of radionuclides were in the order 238U <232Th <226Ra <210Pb <40K. 25 years of cultivation with water spinach can increase/decrease +(165 +/- 6) Bq of 40K, (8.2 +/-0.7) Bq of 210Pb, (4.3 +/-0.2) Bq of 226Ra, (7 0.3 +/-0.3) Bq of 238U, and (1.8 +/-0.1) Bq of 232Th in 1 kg soil. For rice cultivation, these values are +(1004 +/-39), +(3.3 +/-0.2), +(3.0 +/-0.2), (5.1 +/-0.3), (2.2 +/-0.1) Bq kg-1 for 40K, 210Pb, 226Ra, 238U, and 232Th, respectively.

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