The increasing digitalization of Instrumentation and Control (I&C) systems in Nuclear Power Plants (NPPs) has improved operational efficiency while introducing cybersecurity vulnerabilities. Conventional network-based intrusion detection systems (IDS) face limitations in detecting sophisticated cyber threats targeting safety-critical controllers. To address these challenges, this study proposes a process information-driven cyber threat detection methodology based on real-time process data analysis and control logic consistency, enabling non-intrusive threat identification. The proposed methodology was examined through simulation and experimental testing using an APR-1400 Reactor Protection System (RPS) testbed. A cyber attack scenario targeting the High Pressurizer Pressure (HPP) Trip function was designed to assess the effectiveness of the detection mechanism. Simulation results demonstrated the detection algorithm's ability to identify unauthorized modifications to the trip setpoint, indicating the potential to detect cyber threats affecting reactor trip logic. Furthermore, experimental testing using the Safety Data Acquisition & Detection System (SDDS) demonstrated real-time anomaly detection while maintaining system integrity. These findings suggest that the proposed process-driven detection technique can enhance the cybersecurity resilience of NPPs without disrupting operational stability.
The performance of an atomic facility depends on the efficient supply of electricity, particularly emergency loads like monitoring and control equipment, radiation safety systems, and emergency lights. Most nuclear facilities rely on diesel generators to supply emergency loads during grid outages. Due to the diesel generator's imperfections, such as its starting time, it may fail to deliver power because it is unavailable due to maintenance, failure to start, or failure to run and supply the load. It cannot immediately supply the critical loads, resulting in a blackout and the release of radioactive substances into the environment. To address the previous issues, this paper proposes an improved method to enhance the reliability of nuclear facilities for providing electricity to safety and critical consumers during normal and emergency operating modes. The approach incorporates a photovoltaic (PV) system/battery, and its robustness and performance are tested using load flow and transient stability analysis. The simulation results demonstrated the effectiveness and speed of the proposed method when compared to the traditional method, as the emergency consumers were successfully powered within a very short time without fluctuations, and the voltage reduction and frequency were within the nominal values. The electrical transient analyzer program (ETAP) is used to validate these results.
mproving the reliability of welded rotors (under conditions of increasing operating loads) is an urgent task in nuclear power engineering. The solution to this problem was achieved by automatic welding of rotors in optimized welding mode parameters using new welding materials. It resulted in obtaining welded rotors with improved quality characteristics of their output structure and without defects, such as pores and non-metallic inclusions. The austenite grains in the structure of the welded joints became much smaller in size. The new austenite decomposition products in the area of incomplete recrystallization of the heat-affected zone were sorbite and troostite, rather than pearlite, which was obtained during the standard automatic welding process. Thus, automatic welding of 25Х2НМФА steel rotors in optimized modes and the use of new welding materials ensured the production of the welded joints with improved quality characteristics of their output structure, which increased the reliability of rotor operation
A theoretical framework is presented for free vibration of a flexible horizontal rectangular vessel, whether it is partially or fully filled with a fluid. The vibrational modal patterns of the vessel, whether dry or wet, are classified into symmetric and antisymmetric modes. The theoretical model conceptualizes the vessel as an unfolded plate with line supports simulating the vessel's corners. The motion of contained fluid is described using displacement potentials that adhere to the Laplace equation and fluid boundary conditions. Importantly, the proposed analytical approach accounts for the dynamic interaction between the vessel and the fluid, ensuring compatibility along their contacting surfaces. The Rayleigh-Ritz method is employed to formulate an eigenvalue problem, considering entire kinetic and strain energies of the fluid-filled vessel. The accuracy of the theoretical approach is checked by conducting finite element analyses. Remarkably, the natural frequencies obtained through commercial software align closely with the theoretical predictions for both dry and fluid-filled vessels. In instances of fully fluid-filled vessels, we can discern the presence of fluid contact at the vessel's upper plate by examining the natural frequencies and mode shapes. The proposed method offers applicability in dynamically analyzing water-filled spent fuel casks, enhancing safety during transportation.
Motivated by recent experimental breakthroughs toward a realization of a solid-state Thorium-229 nuclear clock, we review the technology, basic physics motivation, and limitations of the present generation of atomic clocks. We then discuss prospects for a new generation of clocks based on an anomalous low-energy 8.4 eV nuclear transition in Th-229, with an extremely long lifetime of 641 seconds when doped into CaF crystals. To realize such solid-state nuclear clocks one must confront basic nuclear, AMO, and solid state physics questions. Key challenges are understanding and minimizing the effects of inhomogeneous broadening, associated with strains and electric field gradients due to both the Th dopants and intrinsic crystal defects.
The International Atomic Energy Agency in Vienna has initiated a worldwide project developing PC based nuclear power plant simulators intended for nuclear professionals education. Participation in training workshops on these simulators began for the teachers in the nuclear Power Plants Department, in the Power Production and Use Department of the Power Engineering Faculty of Politehnica University of Bucharest since 2005. In May 2023 University Politehnica of Bucharest launched the first NuScale Power Energy Exploration Center (E2 Center) in Europe, hosting the control room simulator for NuScale’s VOYGR™ small modular reactor (SMR) power plant. Both type of simulators can be used in personnel training on control systems, process systems response to transients that can appear in normal operation, abnormal behavior and accidental operation of the power plant. In this paper, we report on our experience in nuclear power plant personnel training using PC based simulators and full scope simulators.
M.I. Sayyed, Abdelmoneim Saleh, Anjan Kumar
et al.
Investigations were conducted on the addition of barium's impact on the radiation shielding and physical attributes of five different glasses, designated S1–S5, with varying BaO contents. Using two point sources namely Co60 and Cs137 along with a scintillation detector [NaI(TL)], experimental measurements were made of the shielding parameters of γ-rays, namely the effective atomic number (Zeff), electron density (Nel), half-value layer (HVL), linear attenuation coefficient (μ), mass attenuation coefficient (μm), mean free path (λ), and radiation protection effectiveness at the energies of 0.664, 1.177, and 1.334 MeV, and comparisons made with recently considered glasses as well as frequently employed materials for γ-ray shielding. The results show that the examined glasses' physical and radiation shielding qualities are improved by the addition of BaO. The μ values increased from 0.245 to 0.275 cm−1 (0.662 MeV), from 0.174 to 0.198 cm−1 (1.173 MeV), and from 0.161 to 0.189 (1.332 MeV). The observed values of HVL decreased from 2.83, 3.98, and 4.3 cm to 2.5, 3.5, and 3.62 cm at 0.662, 1.173, and 1.332 MeV, respectively, for the samples S1 and S5. In addition, the S5 glass sample was determined to have the best protection against photon among all the samples that were evaluated, as well as against recently considered glasses and those materials often utilized for gamma-ray shielding purposes.
Gerald Pintsuk, Emanuele Cacciotti, Francesco Crea
et al.
Divertor components for ITER and even beyond will be subjected to cyclic steady state heat loads with a duration of several minutes to hours, repeatedly occurring slow transients during reattachment or ramp-up and down, as well as heat loads during ELMs applying a combination of low cycle fatigue and creep as well as high cycle fatigue via thermal shock loads. While for the qualification of components the duration of the fatigue cycles up to now has been kept small, i.e., close to the required time to reach thermal saturation which is 10 s for typical divertor components, creep in these components has not yet been assessed.In this study divertor tungsten monoblock mock-up manufactured via hot radial pressing in the ITER-like geometry consisting of 4 monoblocks and quality checked via ultrasonic testing are exposed to high heat flux loads in the electron beam facility JUDITH 2 using a high temperature cooling circuit with controlled water chemistry. Thereby, cyclic loads up to 1000 cycles with a duration of 10 to 600 s and a power density of 20 MW/m2 were applied, representing strike point loading conditions in DEMO during strike point sweeping scenarios. Each of the tungsten monoblocks is loaded individually providing the possibility to study different scenarios on one single mock-up. The aim is to assess the performance and degradation of performance due to the applied loads, which is supported by characterization via metallography, profilometry, SEM and hardness testing after the high heat flux tests.
The dangers associated with the entanglement of nuclear and conventional forces have become an area of increasing concern. In this article, I survey the growing nuclear-conventional entanglement risks in Northeast Asia as well as the ways in which entanglement is driving a new era of nuclear arms racing in response. In order to better manage the risks of nuclear crises occurring, I outline the need for a greater emphasis on assurance policies to match the current focus on making deterrent threats. Given the high chance of such crisis nevertheless occurring in Northeast Asia in the years ahead, I make the case for developing what I call “crisis management interoperability” between allies armed with nuclear and strategic non-nuclear weapons. Such interoperability is aimed at ensuring that the difficult task of crisis signalling is not further complicated by alliances with entangled nuclear and conventional forces.
Nuclear engineering. Atomic power, International relations
The high-temperature low-cycle fatigue (LCF) behaviour of Incoloy 800H and its weldments with Haynes 230 and Inconel 82 filler metals, which were fabricated with the gas tungsten arc welding (GTAW) technique, was investigated and compared at 760 °C. The results revealed that the Incoloy 800H weldments showed lower fatigue lifetimes compared to the base metal. However, the weldments with the Haynes 230 filler metal demonstrated an improved fatigue life at the low strain amplitude compared to both Incoloy 800H and the weldment with the Inconel 82 filler metal. The Incoloy 800H base metal showed pronounced initial cyclic hardening with hardening factors increasing with strain amplitudes. In contrast, the weldments with Haynes 230 and Inconel 82 filler metals displayed short initial cyclic hardening and saturation stages, followed by long continuous cyclic softening. The fractography and microstructure after LCF the tests were characterized with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Transgranular fracture with multiple crack initiations was the predominant failure mode on the fracture surfaces of both Incoloy 800 base metal and the weldments. TEM examination revealed that planar dislocation slips at the low strain amplitude evolved to wavy slips, eventually forming a cell structure at high strain amplitudes in the Incoloy 800H material as the strain amplitudes increased. However, the weld metal exhibited a planar slip mode deformation mechanism regardless of cyclic strain amplitude in the weldment specimens. The differing cyclic hardening and softening behaviours between Incoloy 800H and its weldments are attributed to the higher strength of the weldment specimens compared to the base metal. In the Incoloy 800H base material specimens, the reverse strains during LCF created wavy dislocation structures, which could not fully recover due to the non-reversible nature of the microstructure. As a result, cells or subgrains formed within the microstructure once created. In contrast, the higher strength of the weld metal in the weldment specimens significantly suppressed the formation of wavy dislocation structures, and deformation primarily manifested as planar arrays of dislocations.
DRHBc Mass Table Collaboration, Peng Guo, Xiaojie Cao
et al.
The mass table in the deformed relativistic Hartree-Bogoliubov theory in continuum (DRHBc) with the PC-PK1 density functional has been established for even-$Z$ nuclei with $8\le Z\le120$, extended from the previous work for even-even nuclei [Zhang $\it{et.~al.}$ (DRHBc Mass Table Collaboration), At. Data Nucl. Data Tables 144, 101488 (2022)]. The calculated binding energies, two-nucleon and one-neutron separation energies, root-mean-square (rms) radii of neutron, proton, matter, and charge distributions, quadrupole deformations, and neutron and proton Fermi surfaces are tabulated and compared with available experimental data. A total of 4829 even-$Z$ nuclei are predicted to be bound, with an rms deviation of 1.477 MeV from the 1244 mass data. Good agreement with the available experimental odd-even mass differences, $α$ decay energies, and charge radii is also achieved. The description accuracy for nuclear masses and nucleon separation energies as well as the prediction for drip lines is compared with the results obtained from other relativistic and nonrelativistic density functional. The comparison shows that the DRHBc theory with PC-PK1 provides an excellent microscopic description for the masses of even-$Z$ nuclei. The systematics of the nucleon separation energies, odd-even mass differences, pairing energies, two-nucleon gaps, $α$ decay energies, rms radii, quadrupole deformations, potential energy curves, neutron density distributions, and neutron mean-field potentials are discussed.
The spin polarization of 87Rb and 129Xe atomic ensemble has great impact on the signal intensity of a nuclear magnetic resonance gyroscope. The coupled spin polarization modelling process for 87Rb and 129Xe atoms ensemble is presented in detail. Three dimensional spatial distribution of the spin polarization field is obtained by numerical solution and is in good agreement with the experiment results. Influencing factors including temperature, power and detuned frequency of the pumping laser, average collision times of anti-relaxation coatings and partial pressure of gas composition are investigated. The work presents an indirect method to estimate the average collision times given the Xe polarization with different temperatures. It is found the average collision times of the 129Xe atoms with the inner surface of a bare glass cell of 3×3×3mm3 can reach up to about 2.7×105 times. It is also found that the pumping frequency corresponding to the maximum polarization of the Xe atoms polarized by spin exchange of Rb atoms is not consistent with the D1 line of the 87Rb atom when the temperature of the cell is above a certain temperature, but is detuned at a certain frequency. Quantitative analysis of the effect of anti-relaxation coatings on the spin polarization suggests that the appropriate average number of collisions of the Rb atoms with the inner surface of the cell is about 1500 times.
Since tungsten (W) was considered as the most promising plasma facing materials (PFMs) in fusion reactors, there has been extensive research on the physical performance of W-PFMs. It is found that under the extreme conditions in a fusion reactor, W-PFMs should be in a nonequilibrium state of high electronic temperature and low ionic temperature. This leads to the possibility of non-thermal phase transitions, where the crystal structure of the tungsten material may change from body-centered cubic (bcc) phase to hexagonal close-packed (hcp) phase or face-centered cubic (fcc) phase. Consequently, it is necessary to investigate the relevant physical properties of hcp-W and fcc-W under the electron-excited state. In this work, the fundamental physical properties, including atomic structures, electronic structures, elastic constants, and vacancy formation energies, of bcc-W, hcp-W and fcc-W, were theoretically calculated at various electronic temperatures. The mechanical stability of these three phases was also systematically analyzed under varying electronic temperatures. The results of this research are expected to provide a certain guidance in the optimization of W-PFMs in future fusion reactors.
Alkali residue was dissolved by the ammonium hydrogen fluoride method, in which the uranium content is determined to be (16.7±0.3)%(n=6) by inductively coupled plasma optical emission spectrometry(ICP-AES). By means of XRD and SEM-EDS, the main uranium occurrence form of alkali residue was determined. It includes UO3, fluoride(CaF2, NaF, MgF2, UF4, etc), SiO2-P2O5-UO3, Cr2O3-Fe2O3 and other solid melts, and the forms of UO3 being wrapped by the above solid melts. Using TBP-HNO3 as complexing agent, the effects of various parameters were investigated on the lab-scale supercritical CO2 fluid extraction facility. The extraction parameters are optimized: the particle size is 0.250-0.420 mm, saturated Al(NO3)3 solution of w=25% alkali residue is used as salting agent, the mole ratio of TBP-HNO3/U is ≥50, the extraction temperature is 50 ℃ and the pressure is 20 MPa. Under these conditions, the extraction rate of uranium in the alkali residue reaches as high as 98.5% within 2 h. This work provides a new method for the recovery of uranium in alkali residue.
Nuclear engineering. Atomic power, Chemical technology
Liquid lithium wettability has been investigated on novel zirconium-alloyed porous tungsten fabricated by the place-holder spark plasma sintering technique. This paper investigates the wetting properties of liquid lithium on the substrates by in vacuo contact angle measurements of lithium droplets at Penn State’s IGNIS-2 facility. X-ray Photoelectron Spectroscopy analysis was performed on the samples to investigate the role of the surface chemistry in the contact angle behavior of lithium on the substrates. It was seen that hydrated and hydroxylated states of the surface play a key role in affecting the lithium affinity of the surface.
The stability of engineered barriers in high-level radioactive waste disposal systems can be influenced by the decay heat generated by the waste. This study focuses on the thermal analysis of various canister designs to effectively lower the maximum temperature of the engineered barrier. A numerical model was developed and employed to investigate the heat dissipation potential of copper rings placed across the buffer. Various canister designs incorporating copper rings were presented, and numerical analysis was performed to identify the design with the most significant temperature reduction effect. The results confirmed that the temperature of the buffer material was effectively lowered with an increase in the number of copper rings penetrating the buffer. Parametric studies were also conducted to analyze the impact of technical gaps, copper thickness, and collar height on the temperature reduction. The numerical model revealed that the presence of gaps between the components of the engineered barrier significantly increased the buffer temperature. Furthermore, the reduction in buffer temperature varied depending on the location of the gap and collar. The methods proposed in this study for reducing the buffer temperature hold promise for contributing to cost reduction in radioactive waste disposal.
Using the relativistic Hartree-Bogoliubov framework with separable pairing force coupled with the latest covariant density functionals, i.e., PC-L3R, PC-X, DD-PCX, and DD-MEX, we systematically explore the ground-state properties of all isotopes of Z=8-110. These properties consist of the binding energies, one- and two-neutron separation energies ($S_\mathrm{n}$ and $S_\mathrm{2n}$), root-mean-square radius of matter, of neutron, of proton, and of charge distributions, Fermi surfaces, ground-state spins and parities. We then predict the edges of nuclear landscape and bound nuclei for the isotopic chains from oxygen (Z=8) to darmstadtium (Z=110) based on these latest covariant density functionals. The number of bound nuclei predicted by PC-L3R, PC-X, DD-PCX, and DD-MEX, are 9004, 9162, 6799, and 7112, respectively. The root-mean-square deviations of $S_\mathrm{n}$ ($S_\mathrm{2n}$) yielded from PC-L3R, PCX, DD-PCX, and DD-MEX are 0.962 (1.300) MeV, 0.920 (1.483) MeV, 0.993 (1.753) MeV, and 1.010 (1.544) MeV, respectively. The root-mean-square deviations of charge radius distributions of comparing the available experimental values with the theoretical counterparts resulted from PC-L3R, PC-X, DD-PCX, and DD-MEX are 0.035 fm, 0.037 fm, 0.035 fm, and 0.034 fm, respectively. We notice pronounced differences between the empirical and theoretical root-mean-square radii of neutron at nuclei near the neutron drip line of the Mg, Ca, and Kr isotopic chains, suggesting the possible existence of the halo or giant halo phenomena.