In nuclear power plants (NPPs), the reliability of sensor signals is important for operators’ situational awareness and for ensuring safe operation. Operators make decisions based on information collected from various instrumentation sensors, which serve as inputs for artificial intelligence (AI)-based operator support systems. However, signal faults caused by sensor malfunctions, aging, and environmental factors can occur in actual operating environments. These faults may delay accident recognition or cause misdiagnosis, increasing human error risk. Signal integrity is particularly important in emergency situations, where rapid decision-making is imperative. This study proposes an AI-based algorithm for effective identification and restoration of sensor signal faults during emergencies in NPPs. First, the algorithm verifies the input signals to detect faults. Subsequently, it selectively restores only faulty signals. The restored signals are then used for accident diagnosis, preventing performance degradation caused by faulty inputs. The algorithm was evaluated using artificially generated data for three types of faults: bias, drift, and stuck. Results demonstrated high accuracy in fault detection and restoration. Additionally, restored signals enabled accurate accident classification. This study is expected to enhance NPP safety and reliability by mitigating the impact of signal faults on AI-based operator support systems and decision-making.
Renormalization group methods generate low-resolution Hamiltonians that are more diagonal and easier to solve. This chapter reviews the similarity renormalization group for nuclear Hamiltonians, which is a popular method for generating low-resolution nuclear forces. It presents the similarity renormalization group flow equations, analyzes how the similarity renormalization group drives the Hamiltonian towards the diagonal, and studies the effect of induced many-body interactions. It concludes by highlighting the progress in first-principles calculations of nuclei driven by low-resolution nuclear Hamiltonians.
Enung Nurlia, Rahayu Kusumastuti, Abdul Aziz
et al.
The secondary cooling pipes of RSG-GAS utilize AISI-1010, facilitating water circulation directed to the cooling tower after heat absorption from the primary coolant in the heat exchanger. The subsequent dissipation of heat through the cooling tower into the ambient air aims to uphold the primary coolant's temperature below 40°C. This study focuses on evaluating the impact of inhibitor compounds on the corrosion behavior of AISI 1010. Employing FTIR and GCMS techniques, the inhibitor compounds were analyzed, complemented by visual and SEM examinations for surface morphology. The corrosion rate, influenced by the inhibitor, was quantified using a potentiostat. FTIR analysis revealed a spectrum of functional groups, encompassing O-H, N-H, aromatic compounds, C=O, C-O, and phosphate. Nitrogen, oxygen, and phosphorus elements within the inhibitor exhibited binding interactions with iron in the material. GCMS identified prominent compounds like 1H-Benzotriazole (RTs 14.4469 & 14.7746) - which is a major corrosion inhibitor indicated by its high peak and area percentage, Trans-1-methyl-2-nonyl-cyclohexane (RT 6.6834) as primary constituents of the inhibitor. Visual inspection post-immersion in a 150-ppm inhibitor solution showcased a lack of corrosion products on AISI 1010, contrasting with visible corrosion on the material without an inhibitor. SEM analysis confirmed a protective layer formation. The addition of the inhibitor at 150 ppm significantly enhanced AISI 1010's corrosion resistance, evidenced by a 46.71% reduction in the corrosion rate. This underscores the efficacy of the inhibitor in mitigating corrosion effects on AISI 1010, contributing valuable insights for materials in similar cooling system applications.
The decommissioning of nuclear facilities, a critical and hazardous process due to radiation exposure, necessitates the advancement of radiological measurement techniques concerning safety and efficiency. This study presents an optimized back-projection method, integrating a novel single-layer Compton camera and 3D camera setup with the Timepix3 readout chip to improve the precision and efficiency of gamma-ray source localization in decommissioning scenarios. Implementing ‘twin addition’ and ‘twin multiplication’ techniques addressed data ambiguities that arise from event selection in the Compton camera, enhancing the reliability of localization. Introducing a zoom function significantly improved computational efficiency, achieving 163 times faster computation times without sacrificing accuracy. Our method demonstrated enhanced precision with a median angular error of 1.41°, outperforming traditional methods and showing competitive advantages over state-of-the-art technologies, including the Caliste-HD detector. The feasibility of integrating this methodology onto mobile robotic platforms suggests a promising avenue to minimize human radiation exposure and optimize decommissioning tasks, ensuring safer and more effective nuclear facility decommissioning.
A high-performance liquid chromatography(HPLC) was established for the determination of stabilizer(gentisic acid, vitamin C) content in lutetium[177Lu] oxodotreotide injection. The liquid chromatographic parameters were finally confirmed by the optimization experiments of the chromatographic column, mobile phase, elution gradient and UV wavelength. The chromatographic column(4.6 mm×250 mm×5 μm) filled with octadecylsilane bonded organic hybrid silica gel was used, and the mobile phase was 0.82 g/L sodium acetate solution(pH was adjusted to 3.50 with glacial acetic acid) and methanol(gradient elution). The detector system was ultra-violet visible spectroscopic detector(detection wavelength was 295 nm) and radioactive flow detector connnected in series. The column temperature was 25 ℃, the injection volume was 5 μL, the running time was 20.0 min, and the flow rate was 1.00 mL/min with gradient elution. The method can effectively separate gentisic acid and vitamin C, and the resolution meets the requirement of greater than 1.5. The linear ranges of gentisic acid and vitamin C are 0-1.50 g/L and 0-30.0 g/L, respectively. The correlation coefficient r are 1.000 and 0.998, respectively. When the chromatographic conditions of column temperature, flow rate and mobile phase pH are changed, the relative standard deviation(sr) of vitamin C and gentisic acid in the sample solution are 1.62% and 1.16%(n=9) respectively, meet the requirement of less than 2.0%. The sr of the retention and content of gentisic acid in six samples are 0.10% and 0.13%, respectively. The sr of the retention and content of vitamin C in six samples are 0.06% and 0.19%, respectively. The sr of the retention and content of gentisic acid in twelve samples are 0.18% and 0.30%, respectively. The sr of the retention and content of vitamin C in twelve samples are 0.10% and 1.49%, respectively. The above sr results all meet the requirement of less than 2.0%. The rate of recovery of gentisic acid meets the requirement of 90%-108%, and the rate of recovery of vitamin C meets the requirement of 92%-105%. This method can accurately determine the contents of gentianic acid and vitamin C without diluting the sample, improving measurement accuracy and reducing radiation dose. The method has good durability, accuracy, and precision. The HPLC method is simple, rapid, sensitive, and accurate, which can be used for the accurate determination of gentisic acid and vitamin C in lutetium[177Lu] oxodotreotide injection, and provide guidance for the optimization of the process of these drugs.
Nuclear engineering. Atomic power, Chemical technology
The ITER re-baseline proposes changing the first wall material from beryllium to tungsten and incorporating a boronization system to mitigate plasma operation risks associated with tungsten. This system aims to deposit a 50 nm boron coating on plasma facing surfaces by fuelling diborane with a carrier gas (He, H2, or D2) in a glow discharge, based on the extensive experience from present devices. This paper analyzes the optimal number and distribution of anodes and gas injection locations for achieving a uniform boron coating in ITER. Using Monte Carlo simulations of diborane molecules in the ITER glow discharge plasma, the study examines the spatial distribution of diborane ionization and dissociation reactions, for different anode and gas injection configurations, neutral pressure, and hydrogen versus helium carrier gas concentration. The glow discharge plasma backgrounds are obtained by adapting an existing axisymmetric glow model to simulate helium–hydrogen gas mixtures. The simulation results, initially conducted with a maximum of 2 anodes, are scaled to represent a realistic anode configuration for the ITER equatorial plane. Key findings include that a low hydrogen content in helium, achieved with 5 % diborane in the carrier gas, and a low total pressure yields the best uniform boron deposition. However, thinner layers are expected where ports cannot accommodate additional anodes. Uniform gas injection points, including at the high field side, and separation of gas injection points from anodes are crucial for uniform coatings. These modeling efforts support the design of the ITER boronization system and justify expanding the ITER GDC hardware to include more anodes and gas feed points. Despite the widespread use of boronization in modern tokamaks, boron layer uniformity and its impact on plasma performance remains under-researched, highlighting the need for dedicated experiments and model benchmarking against results from current devices.
The TRPO process is a treatment methodology for high-level waste liquid that has been independently developed in China. This process uses TRPO as an extractant to remove long-lived isotopes such as transuranic elements and highly toxic isotopes such as strontium and cesium from high-level waste liquid. However, TRPO undergoes a series of physical and chemical changes after irradiation, resulting in a decrease in quality and affecting extraction performance. Nevertheless traditional alkali washing and water washing methods are ineffective in removing the strong complex products generated by irradiation in TRPO. Consequently, the issue of retention of heavy metal nuclides, such as plutonium, resulting from these strong complex products cannot be adequately addressed through alkali and water washing alone. To significantly reduce both the costs and the volume of radioactive waste, it is essential to purify the dirty TRPO solvent generated during this process for potential reuse. The resin-fixed bed is emerged as an effective approach for purifying the dirty TRPO solvent. When designing a resin-fixed bed, it is necessary to accurately determine the penetration time under varying operational conditions. However, the high-level radioactivity poses a challenge in acquiring a sufficient quantity of radiation-degraded dirty solvents, making it difficult to ascertain penetration times through extensive testing. To address this challenge, a differential bed technique was employed utilizing a minimal amount of radiation-degraded dirty solvent. Through limited experimental trials, key thermodynamic and kinetic parameters for resin purification adsorption were determined, specifically the resin adsorption equilibrium curve and the mass transfer coefficient of the adsorption process. Based on these parameters, a mass transfer model for resin-fixed beds adsorption was established, through which a series of pentration curves were obtained. Furthermore, a mass transfer model available for resin-fixed beds was established, which facilitates the generation of penetration curves. The effects of resin-fixed bed length, feed rate, and feed concentration on the dynamic evolution of resin-fixed bed adsorption and penetration time were systematically examined through a total of 120 simulations in this study. A linear relationship between penetration time (tp) and resin saturation adsorption time (ts) was determined which is tp=3.94ts−9.64×103. The resin adsorption saturation time can be calculated based on operational conditions. In addition, the adsorption equilibrium curve and the liquid-solid mass transfer coefficient can be expressed as q=8.017×10−4+0.1804co−7.390×10−3
+1.177×10−4
and εKLa=−0.021+1.32U−5.56U2, respectively. The novel method proposed in this research offers a solution to circumvent radioactive limitations and rapidly determine penetration time of resin-fixed bed during the dirtty TRPO solvent purification.
The Organization for Economic Cooperation and Development (OECD) Working Party on Nuclear Criticality Safety (WPNCS) proposed a benchmark exercise to assess the performance of current nuclear data adjustment techniques applied to nonlinear applications and experiments with low correlation to applications. This work introduces Bayesian Inverse Uncertainty Quantification (IUQ) as a method for nuclear data adjustments in this benchmark, and compares IUQ to the more traditional methods of Generalized Linear Least Squares (GLLS) and Monte Carlo Bayes (MOCABA). Posterior predictions from IUQ showed agreement with GLLS and MOCABA for linear applications. When comparing GLLS, MOCABA, and IUQ posterior predictions to computed model responses using adjusted parameters, we observe that GLLS predictions fail to replicate computed response distributions for nonlinear applications, while MOCABA shows near agreement, and IUQ uses computed model responses directly. We also discuss observations on why experiments with low correlation to applications can be informative to nuclear data adjustments and identify some properties useful in selecting experiments for inclusion in nuclear data adjustment. Performance in this benchmark indicates potential for Bayesian IUQ in nuclear data adjustments.
Atomistic simulations using ab initio density functional theory and machine-learned potentials have been employed to map the structural, thermodynamic, and kinetic properties of the T-WOx system (x = 0 to 3). The simulations reveal that the T permeability is low in WO2, intermediate in W, and relatively high in WO3. Diffusion of T is slowest in WO2. Vacancies and self-interstitials are strong traps for T. Oxygen vacancies in WO2 are very strong traps for a few T atoms, while vacancies in bulk W can trap up to ten T atoms. Segregation to WO2 surfaces is energetically favourable. However, segregation of T to WO3 surfaces is energetically unfavourable at high surface coverage.
Seo-Yoon Choi, Hyung-Kyu Kim, Min-Seop Song
et al.
A high-fidelity numerical analysis methodology was proposed for evaluating the fuel rod cladding integrity of a Prototype Gen IV Sodium Fast Reactor (PGSFR) during normal operation and Design basis events (DBEs). The MARS-LMR code, system transient safety analysis code, was applied to analyze the DBEs. The results of the MARS-LMR code were used as boundary condition for a 3D computational fluid dynamics (CFD) analysis. The peak temperatures considering HCFs satisfied the cladding temperature limit. The temperature and pressure distributions were calculated by ANSYS CFX code, and applied to structural analysis. Structural analysis was performed using ANSYS Mechanical code. The seismic reactivity insertion SSE accident among DBEs had the highest peak cladding temperature and the maximum stress, as the value of 87 MPa. The fuel cladding had over 40 % safety margin, and the strain was below the strain limit. Deformation behavior was elucidated for providing relative coordinate data on each active fuel rod center. Bending deformation resulted in a flower shape, and bowing bundle did not interact with the duct of fuel assemblies. Fuel rod maximum expansion was generated with highest stress. Therefore, it was concluded that the fuel rod cladding of the PGSFR has sufficient structural safety margin during DBEs.
BackgroundMulti-Wires detector (MW) is widely used in beam profile measurements. However, wire deformation and even wire broken have also happened frequently during the MW operation due to beam power deposition on the wire under high beam power environment.PurposeThis study aims to investigate the influences of the beam parameters and detector design, especially wire tension structure, on the wire temperature and wire deformation arising therefrom.MethodsFirstly, based on the backward Euler method with adaptive steps, a numerical algorithm was developed to conduct temperature simulation of MW. Then, verification experiments with various beam parameters and detector design of MW were performed in an ion source platform at Institute of Modern Physics (IMP), Chinese Academy of Sciences, and the wire deformation caused by temperature was reproduced and observed at HIMMWW (Heavy Ion Medical Machine at WuWei city, China) complex. Finally, comparative analysis was conducted on the relevant results to find the appropriate beam parameters and detector design.Results & ConclusionsExperimental results show that temperature plays an essential role on wire deformation if none tension mechanism is implemented on wire structure. Based on numerical simulations, experiments verifications and operation experiences, a fixed wire tension maintained by welding is appropriate while the wire temperature is below 1 300 K, which also provides a simple construction and a low cost. After exceeding 1 300 K, pre-tensioning by a spring is essential to support the wire with a constant tension to avoid deformation.
Optical atomic clocks$^{1,2}$ use electronic energy levels to precisely keep track of time. A clock based on nuclear energy levels promises a next-generation platform for precision metrology and fundamental physics studies. Thorium-229 nuclei exhibit a uniquely low energy nuclear transition within reach of state-of-the-art vacuum ultraviolet (VUV) laser light sources and have therefore been proposed for construction of the first nuclear clock$^{3,4}$. However, quantum state-resolved spectroscopy of the $^{229m}$Th isomer to determine the underlying nuclear structure and establish a direct frequency connection with existing atomic clocks has yet to be performed. Here, we use a VUV frequency comb to directly excite the narrow $^{229}$Th nuclear clock transition in a solid-state CaF$_2$ host material and determine the absolute transition frequency. We stabilize the fundamental frequency comb to the JILA $^{87}$Sr clock$^2$ and coherently upconvert the fundamental to its 7th harmonic in the VUV range using a femtosecond enhancement cavity. This VUV comb establishes a frequency link between nuclear and electronic energy levels and allows us to directly measure the frequency ratio of the $^{229}$Th nuclear clock transition and the $^{87}$Sr atomic clock. We also precisely measure the nuclear quadrupole splittings and extract intrinsic properties of the isomer. These results mark the start of nuclear-based solid-state optical clock and demonstrate the first comparison of nuclear and atomic clocks for fundamental physics studies. This work represents a confluence of precision metrology, ultrafast strong field physics, nuclear physics, and fundamental physics.
The uranium-containing wastewater produced from uranium ore mining and uranium separation/purification processes may present a serious pollution to environment and ecosystem. The separation of U(Ⅵ) from uranium-containing wastewater by adsorption can not only effectively recover uranium resources, but also reduce environmental pollution. For the high-efficiency separation of U(Ⅵ) in uranium-containing wastewater, the ion-imprinted chitosan/carbon (ICC) nanotube composite membranes were prepared by combining ion-imprinted and chemical cross-linking technologies, and the adsorption performance of ICC for U(Ⅵ) in aqueous solution was investigated by static adsorption method. The results of comprehensive characterization such as SEM, XRD, FT-IR and XPS suggest that the ICC has a porous structure and abundant functional groups (amino, carboxyl), and the CNT is uniformly dispersed in the chitosan matrix. The results of adsorption experiments show that among the ICC prepared with different mass ratios of raw materials, ICC-2 with a mass ratio of CS to CNT of 1∶0.3 has the best adsorption performance for U(Ⅵ), owing to its rich pore structure and the presence of abundant cavities produced by ion-imprinted which can match with uranyl ions and thus are favorable for the adsorption of U(Ⅵ). The adsorption isotherms could be fitted by the Langmuir model, indicating mono-layer adsorption of U(Ⅵ) onto ICC, and the maximumad adsorption capacity reaches 215.83 mg/g at pH=5.0 and 298 K. The adsorption kinetics could be described by the pseudo-second-order model, indicating that chemisorption is the rate-controlling step. ICC-2 could selectively remove U(Ⅵ) in aqueous solution, and the adsorption of U(Ⅵ) is a spontaneous endothermic process. The U(Ⅵ)-loaded ICC-2 could be desorbed and regenerated by 0.2 mol/L HNO3, with the desorption efficiency of 95.2%. ICC-2 could also maintain a high adsorption capacity after multiple adsorption-desorption cycles, indicating its good reusability. The XPS analysis indicates that the main mechanism for U(Ⅵ) adsorption onto ICC is related to U(Ⅵ) chelation by the functional groups, which accounts for 73.6% of total U(Ⅵ) adsorption. The ICC-2 presents high adsorption capacity, fast adsorption rate, and good selectivity for U(Ⅵ), and thus it could be potentially used for the effective treatment of radioactive wastewater.
The potential for recriticality and sub-critical boron concentrations is analyzed during the relocation of the fuel rods in the assembly, which we call late phase of a severe accident, via coupling between MELCOR and whole-core Monte Carlo analyses by Serpent 2. The recriticality, initiated during the early phase, is found to maintain when the fuel assemblies containing intact fuel rods are submerged by the cooling water. It is also found that the effect of the negative reactivity insertion via remaining fission products in the fuel debris increases as the burnup increases. The sub-critical boron concentrations during the late phase are found to be 76∼544 ppm lower than those during the early phase. Therefore, it can be concluded that the boron concentration that prevents recriticality not only during the early phase but also during the late phase is the sub-critical boron concentration during the early phase.
AbstractSmall modular reactors (SMRs) could be key to providing developing regions with clean and affordable (and cost-effective) electricity. Deployment of SMRs requires a transparent and balanced legal framework that will define the specifics and boundaries of shared responsibility between the host and supplier country, especially in the case of innovative floating SMR projects. Legal experience in nuclear-powered vessels and nuclear installations can be used in the development of regulatory approaches for floating SMRs. This chapter provides an analysis of the applicability of the existing international conventions, including the 1974 International Convention for the Safety of Life at Sea, the IAEA safeguards agreements, and civil liability instruments, to the floating SMRs. In addition, some considerations for the future development of the legal framework for floating SMRs are proposed.
Recently, a new generation of nuclear forces has been developed in the framework of chiral EFT. An important feature of these potentials is a novel semi-local regularization approach that combines the advantages of a local regulator for long-range interactions with the convenience of an angle-independent nonlocal regulator for contact interactions. The authors discuss the key features of the semi-local two-nucleon potentials and demonstrate their outstanding performance in the two-nucleon sector by showing selected results up to fifth order in the EFT expansion. Also reviewed are applications to heavier systems, which are currently limited to third chiral order. This limitation reflects the conceptual difficulty in constructing a consistently regularized many-body forces and current operators and affects all currently available interactions. The authors outline possible ways to tackle this problem and discuss future directions in the field.
BackgroundThe research of low temperature detergent is of great significance for the operating and decommissioning of nuclear facilities at low temperature environment.PurposeThis study aims to explore the fluid characteristics and decontamination characteristics of polyvinyl butyral detergent at low temperature.MethodsThe low temperature detergent was prepared by using polyvinyl butyral as solute, ethanol and ethyl acetate as solvent and citric acid as decontamination additives. The viscosity, fluidity, sprayability and wettability of the detergent on the surface of different materials were measured in experiment. Four simulated U(VI) contaminated plate samples were prepared by the dyeing of the uranyl nitrate solution on the base of glass, stainless steel, ceramic tile and alkyd paint, respectively. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to characterize the decontamination films on the surface of these four samples, and study the decontamination mechanism. Finally, the decontamination characteristics of the detergent for the simulated U(VI) pollution on surface of different materials were studied at low temperature, and the effects of temperature, detergent dosage and surface roughness on decontamination rate were discussed.ResultsExperimental results show that the decontamination rates of the detergent for the simulated U(VI) pollution on the surface of glass, stainless steel, ceramic tile and alkyd paint board are above 97.3%, 93.6%, 95.5% and 88.9%, respectively, in the temperature range of -15~10 ℃, that the temperature and the detergent dosage have little effect on the decontamination rate and that the decontamination film formed by the detergent have good strippability.ConclusionsThe detergent has a good application potential at the decontamination of radioactive pollution in low temperature environment.
Supardjo Supardjo, Agoeng Kadarjono, Jan Setiawan
et al.
KOMPOSISI, STRUKTUR DAN DENSITAS PADUAN U-7Mo-xSi. Struktural paduan U-7Mo-xSi (x= 1, 2, dan 3%) dipelajari dalam rangka mendapatkan paduan uranium baru yang cocok digunakan sebagai kandidat bahan bakar reaktor riset densitas uranium tinggi. Paduan U-7Mo-xSi dibuat dengan teknik peleburan menggunakan tungku busur listrik, dan pengujian meliputi analisis komposisi kimia, densitas, kekerasan dan struktural fasa yang terdapat di dalamnya. Data uji menunjukkan bahwa dengan kenaikan kadar Si di dalam paduan U-7Mo-xSi kadar U dan densitas menurun dan kekerasanya meningkat. Pola difraksi Sinar-X paduan U-7Mo-xSi dideteksi dari sudut difraksi 25° hingga 95°, teramati adanya fasa U-γ, U3Si2, dan U3Si2Mo. Makin tinggi kadar Si, fasa U3Si2 yang terbentuk semakin banyak dan kekerasannya meningkat karena semakin banyak terbentuknya ikatan antara Si dan Si.
Kata kunci: Paduan U-7Mo-xSi, bahan bakar nuklir densitas tinggi, komposisi, struktur, densitas.