BẢN TIN KHOA HỌC

Effects of soil erosion on natural radioactivity in water in a typical quarry lake in Vietnam based on model assessment

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

Journal of Radioanalytical and Nuclear Chemistry

Abstract:

A quarry lake is a quarry that is filled with water after abandonment. In the lake water, natural radionuclides contaminate with a certain level, as a result of atmospheric deposition, groundwater diffusion, soil erosion, and sediment–water–air interaction. In this study, ⁴⁰K, ²²⁶Ra, and ²³²Th were analysed for surface soil and water in a specific quarry lake in Vietnam. The seasonable variation of radioactivity in water was investigated. It was found that the activity concentration correlated with the TDS of water and the higher activity concentration was found in the wet season. The RUSLE model was used to predict the average annual rate of soil erosion in the study site. Based on the model prediction, the inflow rate of ⁴⁰K, ²²⁶Ra, and ²³²Th in water were 4.73, 36.75, and 768.5 GBq y⁻¹ respectively.

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Effects of single-particle overlap function on the ¹⁶O(p,2p)¹⁵N reaction

Nguyen Tri Toan Phuc, Vo Hong Hai

Science & Technology Development Journal 2023, 26(2):2838-2847

Abstract:

Introduction: The proton-induced nucleon knockout reactions have been widely used in recent years to explore the single-particle properties of various nuclei. In this study, we examine the effects of the single-particle overlap function on the cross sections and spectroscopic factors of the ¹⁶O(p,2p)¹⁵N reactions.

Methods: These effects are extensively studied through an analysis of the cross sections of the ¹⁶O(p,2p)¹⁵N reaction at incident energies of 392 and 505 MeV. The evaluation is carried out within the framework of the distorted-wave impulse approximation (DWIA), utilizing overlap function inputs from different structure calculations and potential prescriptions.

Results: The analysis reveals that, for the ¹⁶O(p,2p)¹⁵N reaction and the chosen incident energies, the ambiguities arising from different selections of the overlap function are small but non-negligible.

Conclusion: Given the existence of these theoretical uncertainties, it is important that careful and consistent choices of single-particle overlap functions are made in systematics knockout reactions analyses to ensure the extraction of reliable structure information.

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Vu Ngoc Ba , Bui Ngoc Thien, Truong Thi Hong Loan

Nuclear Engineering and Technology Available online 2 July 2020

Abstract:

In this work, self-absorption correction factor related to the variation of the composition and the density of soil samples were evaluated using the p-type HPGe detector. The validated MCNP5 simulation model of this detector was used to evaluate its Full Energy Peak Efficiency (FEPE) under the variation of the composition and the density of the analysed samples. The results indicates that FEPE calculation of low gamma ray is affected by the composition and the density of soil samples. The self-absorption correction factors for different gamma-ray energies which was fitted as a function of FEPEs via density and energy and fitting parameters as polynomial function for the logarithm neper of gamma ray energy help to calculate quickly the detection efficiency of detector. Factor Analysis for the influence of the element composition in analysed samples on the FEPE indicates the FEPE distribution changes from non-metal to metal groups when the gamma ray energy increases from 92 keV to 238 keV. At energies above 238 keV, the FEPE primarily depends only on the metal elements and is significantly affected by aluminium and silicon composition in soil samples.

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Effects of agricultural activities on long‐term accumulations of ²²⁶Ra and ²¹⁰Po in topsoil

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

Journal of Radioanalytical and Nuclear Chemistry(2022)

Abstract:

In this study, long-term changes in radioactivity levels in the agricultural soil were assessed by a method in which the major processes contributing to the accumulations of radionuclides in the topsoil were taken into account. Four agricultural regions with different crops and agricultural conditions were investigated. The results indicated that long-term cultivation caused the accumulations of ²²⁶Ra and ²¹⁰Po in the topsoil and the rates correlated strongly to plant types, fertilization, and irrigation features. This research is used as the pre-primary base to decide the cultivation method that is relevant to the selection of plant varieties, fertilization and irrigation methods.

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Lê Quang Vương, Phan Long Hồ, Lê Công Hảo, Trần Thiện Thanh, Châu Văn Tạo

Những tiến bộ trong Vật lý Kỹ thuật và Ứng dụng – CAEP VI

Tóm tắt:

Trong công việc này, phương pháp Monte Carlo với chương trình mô phỏng MCNP-CP và phương pháp tất định sử dụng phần mềm ETNA được áp dụng để tính toán hệ số hiệu chỉnh trùng phùng của nguồn RGU dạng trụ, với các chiều cao mẫu là 0,99 cm, 1,53 cm, 2,01 cm, 2,59 cm, 2,89 cm, 3,69 cm. Các kết quả thể hiện sự phù hợp tốt giữa hai phương pháp với độ sai biệt tương đối nhỏ hơn 2%. Ngoài ra, hệ thực nghiệm với đầu dò HPGe loại p và các nguồn RGU được sử dụng đo phổ gamma và xác định hiệu suất ghi đỉnh năng lượng toàn phần trong khoảng năng lượng từ 46,5 keV đến 2447,9 keV. Đối với nguồn RGU có chiều cao 0,99 cm, ở năng lượng gamma 768,5 keV của đồng vị 214Bi, giá trị hiệu suất ghi đỉnh khi có hiệu chỉnh trùng phùng có độ sai biệt tương đối lớn nhất là 25% so với giá trị không có hiệu chỉnh trùng phùng. Điều đó chứng minh rằng hệ số hiệu chỉnh trùng phùng có đóng góp quan trọng và không thể bỏ qua trong các nghiên cứu về hiệu suất ghi đỉnh sử dụng hệ phổ kế gamma.

Nguyễn Anh Tuấn, Châu Văn Tạo

Tạp chí Phát triển Khoa học và Công nghệ – Khoa học Tự nhiên, 4(4):737-743

Tóm tắt:

Chùm electron năng lượng cao phát ra từ các máy gia tốc ngày càng được ứng dụng rộng rãi trong xử lý thực phẩm, y tế, biến tính vật liệu, đổi màu đá bán quý và xử lý môi trường gồm nước thải, khí thải và bùn thải. Chùm electron phát ra từ máy gia tốc chỉ hữu hiệu trong việc xử lý bề mặt vì khả năng xuyên sâu thấp, do đó khi cần xử lý khối vật liệu có mật độ mặt cao chùm electron được bắn vào bia nặng để chuyển đổi sang tia X theo cơ chế phát bức xạ hãm. Trong báo cáo này, hiệu suất chuyển đổi tia X được xác định bằng thực nghiệm đo liều hấp thụ gây ra bởi chùm electron và chùm photon kết họp mô phỏng MCNP4c2 cho các bia khác nhau, với các mức năng lượng chùm electron tới bia 5 MeV, 7,5 MeV và 10 MeV. Kết quả mô phỏng MCNP4c2 và đo thực nghiệm đo liều bằng liều kế phim cho thấy hiệu suất chuyển đổi phụ thuộc vào vật liệu bia và năng lượng chùm electron tới. Hiệu suất chuyển đổi cao nhất khi sử dụng bia hỗn hợp Ti – H20 – Pb, với kết quả tương ứng với các mức năng lượng 5,0 MeV, 7,5 MeV và 10,0 MeV là 5,57 %, 7,12 % và13,54 %. Bia hỗn hợp Ti – H2O – Pb có tính ứng dụng thực tế cao vì bia được cấu tạo với 3 lớp vật liệu vở bọc Ti có chức năng chịu lực, chịu nhiệt, nước giải nhiệt được luân chuyển giữ lớp Ti và Pb để giải nhiệt cho bia.

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