One of the simplest nuclear fission reactor designs is the soliton reactor. In these reactors, neutrons reduce the toxicity of fissile materials in a manner that allows new vital areas appear successively. Therefore, the spatial dependence of the neutron flux, specific power density, and associated particle density exhibit wave phenomena of solitons and emerge from the solution of nonlinear partial differential equations, preserving their shape during propagation. The velocity of the burnup Soliton Wave (SW) is related to the density of the initial Nuclear Fuel (NF) in each Neutron Absorber (NA) in the medium. These nonlinear waves can be described by equations describing the atomic flux and density in terms of time and space in the medium. The soliton wave can also be observed in advanced nuclear power systems. Burnup SWs in a propagation medium can be analyzed using the spatial coordinates and position of the NA in a propagation region. The aim of this work is to investigate the burnup SW characteristics by selecting various isotopic neutron absorbers in the slab reactor core. Our computational findings show that the SW burning rate is affected by increasing the diffusion coefficient. However, both the diffusion length and the Length of Transient (LOT) increase with increasing the diffusion coefficient. Interestingly, the ratio of LOT to diffusion length remains constant. Furthermore, while increasing the diffusion coefficient leads to a higher Transient of Time (TOT), the ratio between TOT and characteristic time remains constant. (c) 2026 Atom Indonesia. All rights reserved
In this research, the radiological contamination caused by the Station Blackout (SBO) accident in the Advanced Power Reactor 1400 (APR 1400) reactor was investigated. The results of the investigation of the Fukushima accident in Japan showed that such an event can lead to severe radioactive pollution in the environment surrounding a nuclear power plant. This research assumes that the SBO accident happened at one of the reactors of Unit 1 at the Baraka Nuclear Power Plant. This research mainly focuses on the type and quantity of radioactive materials released into the environment after containment failure occurs. MELCOR 1.8.6 code calculations show that it takes approximately 77.56 hours from the onset of the accident until the failure of the reactor containment building and the subsequent release of radioactive materials. According to these calculations, the largest mass of released radioactive materials is related to noble gases, with about 364.98 kg entering the environment and 5.426 kg of cesium iodide aerosol are released as well. These results demonstrate that the extent of radioactive contamination depends strongly on the type of radioactive species released. (c) 2026 Atom Indonesia. All rights reserved
This study evaluates the proton radiation shielding efficacy of various materials, with a focus on ALON, for satellite solar arrays in LEO across the 0.1-200 MeV energy range using SRIM/TRIM simulations. Key metrics, ion penetration, vacancies per ion, range, displacements per atom, non-ionizing energy loss, Bragg curves, and transmission, were analyzed for aluminum, SiO2, polyimide, ALON, and Ta2O5/Al2O3 at thicknesses from 0.01 mm to 4 mm. ALON demonstrates moderate stopping power and damage resistance, with penetration exceeding 20 & micro;m and 100 & micro;m at 0.5 MeV and 5 MeV, respectively, and 2000 & micro;m and 4000 & micro;m providing protection up to 50 MeV and 100 MeV, while maintaining high optical clarity (>80%) for photovoltaic (PV) applications. Thinner layers mitigate highenergy proton damage but are vulnerable to low-energy (<1 MeV) peaks in DPA and NIEL, whereas thicker layers offer broader shielding at the cost of increased damage accumulation. Multi-criteria decision analysis highlights ALON's suitability for LEO, balancing mass, radiation protection, and optical functionality. These findings, validated with 5% agreement with literature, suggest ALON as a promising PV shield, with future research needed to address high-energy protons and secondary particle effects. (c) 2026 Atom Indonesia. All rights reserved
Hybrid Statistical Iterative Reconstruction (H/SIR) is a method for Computed Tomography (CT) image reconstruction that provides optimal diagnostic images while reducing radiation doses compared to the standard protocol using Filtered Back Projection (FBP). This work aims to assess the image quality metrics; Signal to Noise Ratio (SNR) and Contrast-to-Noise Ratio (CNR) of Low-Dose Computed Tomography (LDCT) examination with different vendors H/SIR algorithms. Three CT scanners from different manufacturers (Philips, GE, and Siemens) were used in this work. A total of 218 clinical images were analysed. The SNR and CNR of LDCT+H/SIR images were compared with standard protocol combined with FBP. The quantitative assessments were achieved by IndoQCT software. Results showed that H/SIR preserved image quality while radiation dose was minimized. (c) 2026 Atom Indonesia. All rights reserved
Radiological examinations are essential for medical diagnostics, but accurate estimation of dose deposition is crucial for patient safety, particularly in pediatric patients. This study employs Monte Carlo simulations with the MCNP code and a newly developed custom program, Irradose, to analyze photon dose deposition in a cylindrical phantom representing the thorax of a 10-year-old child. Two tissue-equivalent compositions were modeled: water and a more realistic HCNO-based soft tissue mixture. Depth-dose distributions obtained with Irradose were compared to MCNP results. Both codes predicted a maximum dose at 2 cm depth, followed by exponential fall-off, with deviations remaining below 5% across the depth range. These results validate Irradose as a reliable and computationally efficient tool for pediatric chest dosimetry in phantom studies. While limited to simplified geometries, this work demonstrates the potential of Irradose for use in preliminary dose assessments and as a complement to established Monte Carlo codes.
The reactivity value of the RSG-GAS research reactor fuel with different burnup levels has been measured. The primary objective of this study is to establish the burnup calibration curve using the equilibrium core reactivity method of the RSG-GAS reactor. The reactivity value of each fuel element was measured at the same position within the reactor core to ensure that the measured burnup corresponds to the experimental core. The reactivity value of each fuel element was then extrapolated with the known burnup of the fuel element. The total control rod worth measurement was compared with Monte Carlo Serpent2 code calculations. The experimental fuel reactivity results were compared with the calculation results, showing a maximum discrepancy of-4.88%. Based on the reactivity measurement and calculation results, a fuel burnup calibration curve was successfully developed, which can be used to determine the burnup fraction of the RSG-GAS reactor. (c) 2026 Atom Indonesia. All rights reserved
Microorganisms from high natural radiation environments hold potential as bioremediation agents for radioactive waste. In this study, isolation and selection of fungi from Mamuju high natural radiation soil was done for radioactive bioremediation. The methods included fungal isolation from soil samples, radiosensitivity tests, sensitivity tests to uranium and thorium, and absorption tests under gamma radiation (100 Gy hour-1-1). Results revealed three fungal isolates with high growth ratios and resistance to gamma radiation: Talaromyces flavus (A3), Gongronella butleri (A4), and Aspergillus sp sp. (F1). Isolates A3 and A4 survived up to 2 kGy, while F1 endured up to 8 kGy. At 24 hours, A3 absorbed uranium at 96% with a biomass of 0.73 g and thorium at 84% with 0.98 g biomass. A4 achieved the highest uranium absorption of 97% (biomass 4.11 g) and thorium absorption of 100% (biomass 0.74 g). F1 demonstrated 96% uranium absorption (biomass 1.29 g) and 87% thorium absorption (biomass 2.17 g). These isolates exhibited significant potential for bioremediation of uranium and thorium-contaminated environments, showing unique adaptations to high radiation conditions and effective radioactive metal uptake. (c) 2026 Atom Indonesia. All rights reserved
An alternative approach to estimate the Tissue Phantom Ratio (TPR) at depths of 20 cm and 10 cm (TPR20,(1)(0)) under non-reference conditions is required to address situations where a 10 & times; 10 cm & sup2; field size is not achievable on a specific Linear Accelerator (LINAC) during a beam quality test. This study aims to estimate the TPR20,10 under non-reference conditions using a geometric sequence approach, and to compare it with the TPR20,(1)(0) under non-reference conditions estimated using the Sauer method, the Palmas method, a linear fit approach, as well as with the TPR20,(1)(0) under reference conditions calculated using the TRS-398 protocol. The first step in this study was measuring the percentage depth dose (PDD), D20cm, and D10cm with field size variations from 4 & times; 4 cm & sup2; to 10 & times; 10 cm & sup2; for both 6 MV and 10 MV X-ray beams. The PDD were used to estimate the TPR20,(1)(0) using a geometric sequence approach, the Sauer method, the Palmans method, and a linear fit approach, and to calculate the TPR20,(1)(0) using the TRS-398 protocol. The D20cm and D10cm were also used to calculate the TPR20,(1)(0) using the TRS-398 protocol. The TPR20,(1)(0) for 6 MV and 10 MV X-ray beams estimated using the geometric sequence approach were 0.683 +/- 0.004 and 0.742 +/- 0.005, respectively. The level of precision that could be reached by the geometric sequence approach is potentially equivalent to the TRS-398 protocol, the Sauer method, the Palmans method, and the linear fit approach. The TPR20,(1)(0) for 6 MV and 10 MV X-ray beams estimated using the geometric sequence method did not show a significant difference compared with the TPR20,(1)(0) calculated using the TRS-398 protocol. However, the TPR20,(1)(0) for 6 MV and 10 MV X-ray beams estimated using the geometric sequence approach showed a significant difference compared with those TPR20,(1)(0) estimated using the Sauer method and the Palmans method.
Accurate neutron flux measurement is essential for reactor characterization and utilization. At the RSG-GAS reactor, previous flux measurements relied on the foil activation method. While this method provides high accuracy, it lacks real-time capability due to its requirement for irradiation, post-irradiation cooling, and subsequent gamma spectroscopy for activity assessment. Direct online measurements of thermal neutron flux in the RSG-GAS reactor irradiation positions were performed using a Sub-Miniature Fission Chamber (SMFC) detector, where the flux was determined from the detector's output current proportional to fission events. This approach offers a viable alternative to the conventional foil activation technique by eliminating its time-consuming process and multiple uncertainty sources. After applying a correction factor obtained from gold foil activation reference measurements and the combined measurement uncertainty was quantified as f 4.0%, results showed an axial flux distribution peaking at 200 mm height from the bottom of the core with maximum values of 4.997 x 1012 f 0.199 x 1012 n/cm2.s at central iradiation position (CIP E7), 6.212 x 1012 f 0.248 x 1012 n/cm2.s at iradiation position (IP B6), and 2.096 x 1012 f 0.083x1012 n/cm2.s at reflector element with plug (BS+ A2) under 200 kW operation. Radial mapping at 600 mm height from the bottom of the core revealed a maximum flux of 1.230 x 1012 f 0.049 x 1012 n/cm2.s at IP (G7). These results demonstrate that the Sub-Miniature Fission Chamber (SMFC) enables real-time neutron flux monitoring and provides a viable alternative to the conventional foil activation technique. (c) 2026 Atom Indonesia. All rights reserved
This study delivers the first full probabilistic liquefaction hazard assessment, filling a major gap in current geotechnical risk evaluation techniques for nuclear infrastructure. We want to assess liquefaction risk under seismic loading in the Serpong region, by integrating seismic hazard data and geotechnical site characteristics. The technique includes Probabilistic Seismic Hazard Analysis (PSHA), Ground Motion Prediction Equations (GMPEs), disaggregation curves, and soil characteristics extracted from 18 boreholes, such as SPT-N values, fines content, and groundwater level changes. Liquefaction triggering is assessed using Cyclic Stress Ratio (CSR), Cyclic Resistance Ratio (CRR), and associated factors (MSF, Rd), followed by probabilistic validation. Over a 50-year exposure period, the total liquefaction probability ranges from 0.5676 to 0.594, with the maximum vulnerability seen in water-saturated sandy layers at depths of 1-6 meters. These findings emphasize localized seismic susceptibility and have direct implications for risk-informed nuclear installation foundation design and regulatory safety evaluations. Furthermore, the findings can be integrated into Probabilistic Safety Assessment (PSA) frameworks to help with quantitative risk indicators like Core Damage Frequency (CDF) and Large Early Release Frequency (LERF). This study provides a reproducible methodology for assessing liquefaction at nuclear plants in other seismically active regions. (c) 2026 Atom Indonesia. All rights reserved
This study investigates the microdosimetric characteristic of Boron Neutron Capture Therapy (BNCT) using high-fidelity Monte Carlo simulations to quantify the energy deposition distributions of alpha and lithium-7 particles within cellular structures. The Geant4 toolkit is utilized to model various physics lists and water representations, aiming to optimize the accuracy of BNCT simulations. Dosimetric and microdosimetric studies using these Monte Carlo techniques are conducted to examine the behavior of the produced alpha and lithium-7 particles and their energy deposition in different cellular compartments. Our findings contribute to the understanding of BNCT's effects at the cellular level, which is crucial for advancing treatment planning and minimizing side effects. (c) 2025 Atom Indonesia. All rights reserved
Due to the complexity of radiotherapy techniques, rigorous Patient-Specific Quality Assurance (PSQA) is crucial to ensure the accuracy of treatment plans. This study aims to evaluate the performance of the Treatment Planning System (TPS) by comparing its dose distribution calculations with those obtained from the PRIMO Monte Carlo simulation. Treatment plans for 3D-CRT, IMRT, and VMAT were generated for a Rando breast phantom using the TPS. Subsequently, the dose distributions from the TPS were compared with those obtained from the PRIMO Monte Carlo simulation. Key metrics, including Homogeneity Index (HI) and Conformity Index (CI), were calculated to assess the quality of dose distribution. Furthermore, the dose constraints on OARs were evaluated to assess the impact on surrounding healthy tissues. To further validate the TPS, dose distributions from the linac log file (Dynalog) for VMAT were reconstructed within the PRIMO environment. These reconstructed distributions were then compared with the dose distributions calculated directly by the TPS. Gamma index analysis was employed to evaluate the agreement between these two sets of data. The comparison between TPS and Monte Carlo simulations revealed that 3D-CRT plans exhibited smaller deviations in HI and CI compared to IMRT and VMAT plans. However, a significant improvement in HI and CI values was observed in both IMRT planning simulations and Dynalog VMAT file simulations, indicating enhanced plan quality. The dose received by OARs in all treatment plans remained within the acceptable dose thresholds, demonstrating effective sparing of surrounding healthy tissues. For the PSQA procedure, the 3D-CRT technique is still the safest due to its lower level of complexity compared to IMRT and VMAT. More complex treatments should consider the robustness of treatment transfer information from TPS to linac to avoid dosimetry errors. (c) 2025 Atom Indonesia. All rights reserved
The use of Low-Dose Computed Tomography (LDCT) protocols has garnered significant attention, particularly in detecting cancerous lesions in high-risk populations. However, the drawback of low-dose CT protocols results in image noise. Solutions introduced, such as the use of reconstruction techniques, tend to be time-inefficient, complex, and costly. This paper aims to explain the design and construction of an approach for evaluating the quality of lung cancer lesion imaging that is adequate and easily implementable. In this study, a custom-designed in-house phantom is required to simulate lung cancer lesions. The inhouse phantom was constructed from organ or tissue-equivalent materials and equipped with various Hounsfield Unit values and lesion diameter sizes, which were determined based on data from 73 patients, consisting of both males and females, using contrast. Scans were performed on the phantom using standard-dose and low-dose protocol parameters. The results demonstrated that the low-dose protocol was able to detect small lesions at lower radiation levels. The contrast difference is quite good with a Signal Difference to Noise Ratio (SDNR) value >= 5. The image was optimum with a relatively high Figure of Merit (FOM). Additionally, Noise Power Spectrum (NPS) measurements provided accurate results within a specific range of spatial frequencies. (c) 2025 Atom Indonesia. All rights reserved
The development of nuclear science presents multifaceted benefits across diverse sectors, including energy, health, construction, agriculture, and food production. However, the proliferation of nuclear technology introduces the complex challenge of dual-use, encompassing both constructive applications and potential misuse for nefarious purposes such as terrorism. Indonesia, like many nations, faces this dual-use dilemma, necessitating robust defense mechanisms to safeguard against nuclear terrorism threats. This study aims to investigate and enhance Indonesia's defense system against nuclear terrorism by emphasizing integration and strategic intelligence within its defense components. The primary objective is to analyze the integration and coordination mechanisms among the main, supporting, and reserve components of Indonesia's defense system to strengthen strategic analysis and intelligence efforts in combating nuclear terrorism threats. Through a qualitative research methodology employing an analytical approach, data collection encompasses expert interviews, observations, and an extensive literature review. The study identifies various threat risks and potential initiators of nuclear terrorism attacks, highlighting the critical role of integrated defense components in addressing these threats effectively. Findings reveal the indispensable roles of the main, supporting, and reserve components in executing intelligence functions, including investigation, security, and information gathering, to mitigate the threat of nuclear terrorism. Despite their distinct roles, these components require seamless integration and coordination to maximize strategic analysis efforts and intelligence sharing. The research identifies several constraints hindering the effective implementation of integration and strategic intelligence within Indonesia's defense components. These constraints necessitate targeted improvements to enhance the nation's capability to mitigate the threat of nuclear terrorism effectively. In conclusion, this study underscores the significance of integration and strategic intelligence within Indonesia's defense system to confront the evolving threat landscape of nuclear terrorism. By addressing research gaps and proposing actionable recommendations, this research contributes to strengthening Indonesia's defense posture against nuclear terrorism, thereby ensuring national security and global stability. (c) 2025 Atom Indonesia. All rights reserved
Intensity-Modulated Radiation Therapy (IMRT) requires rigorous dose verification to ensure accurate radiation delivery. This study evaluates point dose verification and 2D dose verification techniques in detecting dose discrepancies due to isocenter shifts in IMRT treatment for post-mastectomy breast cancer cases. Five post-mastectomy breast IMRT plans were retrospectively analyzed, with phantom-based measurements compared against Treatment Planning System (TPS) calculations. The results indicate that point dose verification provides reliable absolute dose measurements, but lacks spatial resolution, whereas 2D verification captures dose variations more effectively. Dose discrepancies remained within acceptable limits for shifts up to +/- 3 mm, but shifts of +/- 5 mm or more resulted in clinically significant deviations. Gamma Passing Rates (GPR) decreased substantially beyond +/- 5 mm shifts, underscoring the importance of precise patient positioning. These findings support the integration of both verification methods to improve IMRT quality assurance, particularly in resource-limited settings. Future advancements in AI-driven dosimetry and real-time in vivo monitoring may further optimize dose verification, enhancing treatment accuracy and patient safety.
Comprehensive dosimetric evaluation of light and heavy ions such as protons, alpha particles, carbon, and oxygen ions is essential for advancements in radiation therapy and space applications. This study employed the Particle and Heavy Ion Transport code System (PHITS) to simulate dose distributions and secondary particle fluence in a water phantom across a range of therapeutic ion energies. A 30 & times; 30 & times; 30 cm3 water phantom with 2.0 & times; 108 primary particles at a Source to Surface Distance (SSD) of 100 cm were irradiated using mono energetic axial source. This simulation study also evaluated particle fluence of secondary particles such as electrons, positrons, and neutrons. Results showed that positron fluence concentrates around the water phantom, dispersing more at higher energy, while neutron flux focuses along the source path. The PHITS generated Percent Depth Dose (PDD) curves illustrate varied dose deposition patterns for each ion at different energies. For the highest energy considered, the simulated Bragg peak positions deviated by not more than 4.55 % from the experimental data, with simulation uncertainties kept below 0.1%, ensuring accurate dose analysis. Helium ions (alpha particles) exhibited favorable treatment characteristics such as lower entrance dose, minimal lateral scattering, and reduced fragmentation consistent with the experimental findings. Additionally, the spatial distributions of electrons, positrons, and neutrons show elevated concentrations near the water phantom, indicating potential benefits for enhancing treatment precision.
The use of passive cooling systems as a reactor safety measure has become a key approach to preventing future incidents similar to the Fukushima Daiichi NPP accident. These systems operate based on natural circulation, a process driven by temperature differences and elevation between the heat source and heat sink. Key design factors, such as the inclination angle of the rectangular loop, significantly influence this circulation. This study aims to investigate the effects of different inclination angles of the rectangular loop and variations in the initial water temperature in the Water Heating Tank (WHT) on the flow rate and heat removal capability. The research was conducted experimentally using a natural circulation rectangular loop facility, FASSIP-04 Ver.0, which has an inner diameter of 26.64 mm, a rectangular loop height of 2280 mm, and a width of 780 mm. The experimental variations were achieved by adjusting the water temperature inside the WHT to 50°C, 70°C, and 90°C. Meanwhile, the inclination angle of the loop was set to 30°, 60°, and 90° mass flow rate and heat removal capability was influenced by both the loop inclination angle and the water temperature in the WHT. The highest values were observed at a 90° inclination angle and a set temperature of 90°C, with a mass flow rate of 0.0241 kg/s, and heat removal rates of qH = 0.791 kW, qC = 0.489 kW. The resulting buoyancy force was stronger under these conditions, leading to greater heat removal through natural circulation compared to free convection, thereby increasing both mass flow rate and heat removal efficiency.
