[en] Visual inspection makes easier to ensure the integrity and safety of spent nuclear fuel (SNF) than any classical techniques. Various classical techniques have been applied but there are no reliable methods to qualitatively and quantitatively verify spent fuel in dry storage. Thus, the present authors have developed the prototype safeguards apparatus for dry storage employing the array of He-4 gas scintillation detectors (S670E, Arktis Radiation Detectors Ltd., Switzerland), newly designed to simultaneously measure thermal and fast neutrons without any moderators. The S670E detector has a cylindrical shape with a diameter of 52 mm and active length of 600 mm (total length: 875 mm). The detector is filled by He-4 gas with an approximate pressure of 180 bar for fast neutron detection, and its inner wall is coated by Li-6 for thermal neutron detection. The scintillation lights generated via Li-6 nuclear reaction and elastic scattering are collected by 24 SiPMs linearly paired at the center of the detector. The detector delivers a TTL (Transistor-Transistor Logic) output for pulse readout and UART (Universal Asynchronous Receiver Transmitter) for device control. In order to assess feasibility of the apparatus, an experimental system has been designed, built, and optimized via computational studies. Cf-252 neutron sources and linearly arrayed detectors, working as a single detector, were occupied for this study due to the difficulties in working with SNF. The laboratory scale cask (diameter: 0.67 m, height: 1.5 m), minimized by a factor of 10 compared to the actual thickness of a commercial TN-32 cask, was also manufactured. The detector array was designed to rotate the lab-scale cask and obtain 36 image profiles at every 10 degrees. All profiles were aligned in single frame image called a sinogram, and the cross-sectional image was then fabricated by the inverse radon transform algorithm. These experiments have been repeated with different configurations and numbers of sources. Some gamma-ray sources were also measured with neutron sources in order to distinguish between neutron and gamma-ray pulses. Basically, a He-4 detector is designed to run on Linux OS so it is difficult to directly apply to Windows-based equipment widely used in S. Korea. Therefore, a new data acquisition board working on Windows OS was designed and built. The board mainly consists of FPGA (Field Programmable Gate Array) and SoC (System on Chip) for TTL pulse readout, sorting measured data, and transferring data to a user interface. In conclusion, the tomographic system at lab-scale has shown considerable potential to detect a partial or gross defect of encapsulated assemblies in dry storage. Next steps of this study will be to 1) repeatedly carry out experiments to demonstrate scientific reliability and validity, and 2) numerically integrate signals with weight factors to enhance the image quality since the suggested system based on passive interrogation method requires longer measurement time. Finally, the system will apply to a commercial dry storage phased out soon in S. Korea. (authors)

[en] For the denuclearization, nuclear activities must be reported and the reported documents must be confirmed through nuclear disarmament verification process. Sampling from undeclared area is an essential task of the verification to obtain information about the concealment of nuclear material. However, it is not possible to get the environmental radioactivity information of undeclared areas, so the safety of workers for sampling cannot be guaranteed. Therefore, before collecting samples, it is necessary to secure the information about radioactivity of the sampling region through the radiation measurement. In this study, we propose a compact gamma detection probe that can be transported by drones and distributed over a wide area in a short period of time. A plastic scintillator was applied to reduce weight and increase efficiency. In addition, the total weight and power consumption of the probe were optimized by applying a measurement method that counts photons generated from the scintillator. The performance of the probe was evaluated under the same dose conditions as the actual measurement environment. It was confirmed that the probe developed in this study exceeded more than twice the count value of background radiation at 25 meters. In addition, it was confirmed that the count value increased at a linear rate as the dose rate. As a result, it is possible to estimate the dose rate from the measured count value

[en] The Republic of Korea is expected to participate in the denuclearization verification activities by the International Atomic Energy Agency (IAEA) in case any neighboring countries declared denuclearization. In this study, samples for the verification of nuclear activities in undeclared areas were selected for the denuclearization of neighboring countries, and the appropriateness of the procedures was considered. If a country with nuclear weapons declares denuclearization, it must be accompanied by the IAEA’s verification regarding nuclear materials and weapons in the declared and undeclared areas. The analysis of the process samples or on-site environmental samples and the verification of undeclared nuclear facilities and materials aid in uncovering any evidence of concealment of nuclear activity in undeclared areas. Therefore, a methodology was established for effective sampling and analysis in accordance with proper procedures. Preparations for sampling in undeclared areas were undertaken for various potential scenarios, such as, the establishment of zones according to radiation dose, methods of supplying electricity, wireless communication networks, targets of sampling according to characteristics of nuclides, manned sampling method, and unmanned sampling method. Through this, procedures were established for pre- and post-site settings in preparation for hazards and limiting factors at nuclear inspection sites

[en] We investigated the characteristics of recurrence pattern and survival of patients with non-endometrioid endometrial cancer (NEEC) and attempted to identify prognostic and treatment factors affecting disease-free survival (DFS) and overall survival (OS) of these patients. Fifty-seven patients with histologically confirmed International Federation of Gynecology and Obstetrics (FIGO) stage IA-IVA NEEC from February 2003 to December 2021 were retrospectively analyzed. The 5-year DFS and OS rates of the total cohort were 50.6% and 56.1%, respectively. Recurrence occurred in 28 patients (49.1%) during follow-up, and the most common recurrence pattern was distant metastasis (DM; 78.6% of total recurrences). The occurrence of relapse significantly reduced 5-year OS (recurrence group vs. non-recurrence group: 12.5% vs. 100%; p < 0.001). In univariate analysis, adjuvant radiotherapy (RT) group showed significantly higher 5-year DFS (56.7% vs. 37.9%; p = 0.04), local recurrence-free survival (91.6% vs. 50.5%; p = 0.01), and regional recurrence-free survival (88.2% vs. 56.5%; p < 0.01) than the non-RT group. In multivariate analysis, advanced FIGO stage was identified as a negative prognostic factor for DFS and OS. Lymphovascular space invasion (LVSI) and adjuvant RT were independent prognostic factors for DFS. The most common recurrence pattern observed in patients with NEEC was DM. FIGO stage and LVSI were identified as prognostic factors for survival, and RT was identified as a therapeutic modality that could increase DFS. To improve the OS of patients with NEEC, the addition of effective chemotherapy that can reduce DM may be important.

[en] The denuclearization verification process involves the localization of nuclear materials in the area of nuclear inspection. Various methodologies based on detector measurement using CsI(Tl), NaI(Tl) scintillators and Geiger–Müller (GM) counters have been studied to localize a nuclear material, but they are not suitable for application to a wide outdoor range. The Korea Institute of Nuclear Nonproliferation and Control (KINAC) has developed a plastic scintillator-based small gamma-ray instrument (probe). In this study, artificial intelligence-based machine learning was applied to localize radioactive material based on probe measurement values. A localization algorithm model based on a Deep Neural Network (DNN) and Multiple Linear Regression (MLR) which are most used among various machine learning and deep learning algorithms was created. Then, the radioactive material was localized based on the measured value and compared with MCNP6-based simulation data. The performance of the DNN and MLR algorithms was evaluated through a coefficient of determination (R²) and Root Mean Square Error (RMSE). The results for the R² and RMSE of the DNN algorithms model are 0.9488 and 3.5734 m. The R² and RMSE of the MLR algorithm model are 0.8496 and 7.2452 m

[en] Purpose: To evaluate the accuracy of measuring volumes using three-dimensional ultrasound (3D US), and to verify the feasibility of the replacement of CT-MR fusion images with CT-3D US in radiotherapy treatment planning. Methods: Phantoms, consisting of water, contrast agent, and agarose, were manufactured. The volume was measured using 3D US, CT, and MR devices. A CT-3D US and MR-3D US image fusion software was developed using the Insight Toolkit library in order to acquire three-dimensional fusion images. The quality of the image fusion was evaluated using metric value and fusion images. Results: Volume measurement, using 3D US, shows a 2.8 ± 1.5% error, 4.4 ± 3.0% error for CT, and 3.1 ± 2.0% error for MR. The results imply that volume measurement using the 3D US devices has a similar accuracy level to that of CT and MR. Three-dimensional image fusion of CT-3D US and MR-3D US was successfully performed using phantom images. Moreover, MR-3D US image fusion was performed using human bladder images. Conclusions: 3D US could be used in the volume measurement of human bladders and prostates. CT-3D US image fusion could be used in monitoring the target position in each fraction of external beam radiation therapy. Moreover, the feasibility of replacing the CT-MR image fusion to the CT-3D US in radiotherapy treatment planning was verified.

[en] Purpose: The development of breast cancer-related lymphedema (LE) is closely related to the number of dissected axillary lymph nodes (N-ALNs), chemotherapy, and radiation therapy. In this study, we attempted to estimate the risk of LE based on combinations of these treatment-related factors. Methods and Materials: A total of 772 patients with breast cancer, who underwent primary surgery with axillary lymph node dissection from 2004 to 2009, were retrospectively analyzed. Adjuvant chemotherapy (ACT) was performed in 677 patients (88%). Among patients who received radiation therapy (n=675), 274 (35%) received supraclavicular radiation therapy (SCRT). Results: At a median follow-up of 5.1 years (range, 3.0-8.3 years), 127 patients had developed LE. The overall 5-year cumulative incidence of LE was 17%. Among the 127 affected patients, LE occurred within 2 years after surgery in 97 (76%) and within 3 years in 115 (91%) patients. Multivariate analysis showed that N-ALN (hazard ratio [HR], 2.81; P<.001), ACT (HR, 4.14; P=.048), and SCRT (HR, 3.24; P<.001) were independent risk factors for LE. The total number of risk factors correlated well with the incidence of LE. Patients with no risk or 1 risk factor showed a significantly lower 5-year probability of LE (3%) than patients with 2 (19%) or 3 risk factors (38%) (P<.001). Conclusions: The risk factors associated with LE were N-ALN, ACT, and SCRT. A simple model using combinations of these factors may help clinicians predict the risk of LE