Relative Power Distribution Research Articles

Photodamage prediction model and optimal lighting system for polychrome artworks in museum

When lighting polychrome artworks in museum, the light sources are required not only to provide high-quality visual performance, but also to minimize the photodamage. Currently, though there are mature methods to calculate visual performance, how to predict the degree of photodamage remains a challenge, which leads to a lack of light sources satisfying both visual and protection requirements. Our study conducted a series of 294 accelerated aging experiments spanning over 11 years for materials commonly used in Chinese polychrome artworks, using isoenergetic white-light D55 and 10 different wavelengths of narrow-band light as experimental light sources. The mathematical model predicting the photodamage degree caused by intensity (I), exposure time (t), the relative spectral power distribution of the light source (S(λ)), and the irradiated material's relative spectral responsivity (P(λ)) to polychrome artworks was established, and the mean absolute percentage error of the model, as verified by experiments, was 11.63 %. Combined with the existing visual performance calculation methods, an optimal lighting algorithm that simultaneously meets high-quality visual performance and minimum photodamage was developed, followed by developing a new Spectrally Tunable White LEDs (STWLEDs) lighting system with 10 LED chips. It is found that the STWLEDs can adjust and output the optimal spectra and recommended illuminance according to the characteristics of polychrome artworks, thus realizing lighting with minimum photodamage, meanwhile, satisfying high-quality visual performance. After testing, as well as satisfying the requirements of visual performance, the average photodamage is reduced by 40.95 % with STWLEDs compared with the traditional WLEDs.

Application of the PSI cycle check-up methodology for full-core Monte Carlo simulations verified using pin power estimates and validated for hot zero power conditions

Monte Carlo (MC) based neutron transport codes provide high-fidelity numerical solutions to problems beyond the modelling capabilities of conventional core simulation methods. However, performing core-follow calculations with MC codes remains challenging due to the necessity of incorporating thermal-hydraulic feedback and generating evolved fuel composition for the cycle of interest by taking into account the entire irradiation history of loaded fuel assemblies over previous cycles. Nevertheless, at PSI, the neutronic version of a cycle check-up methodology (CHUP) is under development to address this challenge. This methodology involves extracting operating conditions and nuclide compositions from validated reference deterministic core-follow models (CASMO5/SIMULATE5/SNF), subsequently generating MC neutron transport models for selected operating points. This article presents the verification and validation performed for a hot zero power operating condition of a Swiss pressurised water reactor using the updated CHUP methodology, which automates information extraction from reference core models to minimise human intervention. The MC models were verified by assessing their deviation from criticality, consistently found to be supercritical within the [10,60] pcm range. Additionally, radial relative power distribution verification yield deviations in the [−5,4] % range compared to validated nodal results. Finally, additional validation was performed using start-up measurements from two successive cycles. Eight MC models were found to be subcritical, on average by 51 pcm, with a standard deviation of 25 pcm.

Assemblies design and modeling analysis of a new fine mesh neutronics/thermal-hydraulics coupling benchmark for plate-type PWR core

In order to support the verification of neutronics/thermal-hydraulics coupling calculation method or simulation codes at the fine mesh for plate-type pressurized water reactor (PWR) with high parameters (which the ratio of power to mass flow rate is greater than 235 kW/kg, the core outlet enthalpy exceeds 1500 kJ/kg), a set of coupling calculation of plate-type PWR based on high parameters (COPHP) is design by Nuclear Power Institute of China (NPIC). Multiple industry research teams, including Tsinghua University, Xi'an Jiaotong University, and Huazhong University of Science and Technology, participated in the production of COPHP benchmark. This article provides a detailed explanation of the completed assembly design and modeling calculations, and provides the keff, pin-by-pin wise fine mesh relative power distribution, and deviation results calculated for 10 conditions of 6 assemblies using RMC, OpenMC, and KYLIN V2 software. The results show that: 1) when using the same cross-sectional library, the OpenMC calculation results are in good agreement with the RMC results. Taking ENDF/B-VII.1 as an example, the maximum deviation of keff in the entire burnup process of all assemblies is −157pcm, the maximum deviation of relative power is −1.13 %, and the maximum power weight error(PWE) is 0.226 %. 2) Compared between KYLIN V2 and the RMC by using ENDF/B-VII.1, the maximum deviation of keff is −468pcm, the maximum deviation of relative power is −1.49 %, and the maximum PWE is 0.316 % when calculating the standard assemblies with all control rod out(ARO) condition and two burnable poison assemblies. The maximum deviation of keff is −795pcm, the maximum deviation of relative power is 1.81 %, and the maximum PWE is 0.369 % when calculating the standard assemblies with all control rod inserted(ARI) conditions.

First experimental time-of-flight-based proton radiography using low gain avalanche diodes

Objective. Ion computed tomography (iCT) is an imaging modality for the direct determination of the relative stopping power (RSP) distribution within a patient’s body. Usually, this is done by estimating the path and energy loss of ions traversing the scanned volume utilising a tracking system and a separate residual energy detector. This study, on the other hand, introduces the first experimental study of a novel iCT approach based on time-of-flight (TOF) measurements, the so-called Sandwich TOF-iCT concept, which in contrast to any other iCT systems, does not require a residual energy detector for the RSP determination. Approach. A small Sandwich TOF-iCT demonstrator was built based on low gain avalanche diodes (LGADs), which are 4D-tracking detectors that allow to simultaneously measure the particle position and time-of-arrival with a precision better than 100 μm and 100 ps, respectively. Using this demonstrator, the material and energy-dependent TOF was measured for several homogeneous PMMA slabs in order to calibrate the acquired TOF against the corresponding water equivalent thickness (WET). With this calibration, two proton radiographs (pRads) of a small aluminium stair phantom were recorded at MedAustron using 83 MeV and 100.4 MeV protons. Main results. Due to the simplified WET calibration models used in this very first experimental study of this novel approach, the difference between the measured and theoretical WET ranged between 37.09% and 51.12%. Nevertheless, the first TOF-based pRad was successfully recorded showing that LGADs are suitable detector candidates for Sandwich TOF-iCT. Significance. While the system parameters and WET estimation algorithms require further optimization, this work was an important first step to realize Sandwich TOF-iCT. Due to its compact and cost-efficient design, Sandwich TOF-iCT has the potential to make iCT more feasible and attractive for clinical application, which, eventually, could enhance the treatment planning quality.

Is QEEG an effective biomarker in predicting cognitive decline?

AbstractBackgroundAlterations in EEG traces are observed in synaptic failure with a reduction in the background α rhythm and an increase in slow frequencies (θ‐δ). The aim of the study is to evaluate whether quantitative EEG (QEEG) can be a reliable biomarker of neuro‐cognitive disorders (NCD), able to identify patients with mild and major‐NCD, and to reflect the clinical course over time.Method63 donors from the Abbiategrasso Brain Bank were included in the study. According to our protocol, the subjects were evaluated longitudinally (2015‐21) through a multidimensional assessment, and divided into 3 groups age and sex matched (NOLD for normal old, mild‐NCD and major‐NCD). A selection of 12 donors was further divided into 3 groups based on the change of the clinical state over time (NOLD>NOLD; NOLD>mild‐NCD and mild‐NCD>major‐NCD). The QEEG analysis was performed considering the relative power distribution (RPD) of band frequency (β, α, θ, δ) and the peak frequency (PF), as synthetic index. The Kruskall Wallis test, with post hoc analysis, and change analysis through one‐way ANOVA were used for the comparison between groups. Kendall’s TAU was used for correlations.ResultThe RPD of the different frequency bands as well as the PF were significantly different in the NOLD, mild‐NCD and major‐NCD groups (p<0.001); α‐RPD and PF decreased, while θ and δ‐RPD increased. NOLDs and mild‐NCDs were always different from major‐NCDs (p<0.001), while NOLDs were statistically different from mild‐NCDs only for θ‐RPD (p = 0.019), b+a‐RPD (p = 0.028) and q+d‐RPD (p = 0.025). A strong correlation between PF and MMSE (p<0.001) was present. Change analysis demonstrated that PF was lower in the NOLD>mild‐NCD group compared to the NOLD>NOLD group (p = 0.049). Interestingly, PF did not present any correlation with depression using CES‐D score (Center Epidemiological Studies‐Depression).ConclusionThe RPD is able to distinguish NOLDs from mild‐ and major‐NCDs. If determined from the initial stages of the disorder, PF may be a promising biomarker for mild‐NCD diagnosis discriminating initial cognitive impairment from depression, and it may be useful to follow the evolution of dementia. PF appears to be a synthetic and simple quantitative index, easily obtained from a standard digital EEG, and widely applicable.

The decline of quantitative EEG goes along with neuropathology in Alzheimer’s Disease

AbstractBackgroundFew studies investigate the correlation between the quantitative EEG (QEEG) and the neuropathological picture. The purpose of this study is to explore how QEEG can recognize the type and extent of neuropathological changes.MethodThe EEG traces and brains belonging to 14 donors of the Abbiategrasso Brain Bank were analyzed. The subjects suffered from neurocognitive disorders due to AD, LBD or AD/vascular lesions (mixed dementia‐MD), with different stages of clinical and neuropathological severity. Clinical and neuropathological characterization was performed according to our protocol; biochemical measurements to determine the amount of proteinopathies are in runtime on frozen samples. QEEG analysis considered the relative power distribution (RPD) of the frequency bands (β, α, θ, δ) and the peak frequency (PF), i.e. the most represented frequency considering all the leads. The PF was measured every 2 seconds for 200‐400 samples, and then averaged. The Kruskall‐Wallis test was used for the comparison between groups.ResultThe clinical diagnosis included: 2 MCI, 4 AD, 6 MD, and 2 LBD. The neuropathological definite diagnosis demonstrated frequent co‐pathologies, and some discrepancies compared to the clinical diagnosis. The neuropathological characterization identified 2 cases with low AD pathology (corresponding to the 2 MCI), 8 cases with intermediate or high AD pathology (4 MD with concomitant cerebrovascular disease), and 4 cases with prevalent LBD pathology. Considering both clinical and neuropathological diagnoses, the comparison between groups revealed no significant differences in QEEG parameters. Nonetheless, a trend emerges towards a lower β‐RPD and a higher θ‐RPD in cases with prevalent LBD pathology. Grouping based on the severity of AD pathology (2 low, 4 intermediate, 4 high) demonstrated significant differences depending upon the neuropathological scoring with a progressive decrease of α‐RPD (p = 0.029) and PF (p = 0.019), and an increase of δ‐RPD (p = 0.020).ConclusionRPD and PF show low discriminatory capacity on etiology. Nonetheless, the presence of LBD seems to boost the EEG slowing. The PF slowing down parallels the increase of AD pathology, representing an indicator for the degenerative load. PF is a simple QEEG parameter, easily obtainable through standard digital EEG; it can be useful for monitoring neurodegenerative burden and disease evolution.

Enhancing transmutation rates of minor actinides using Zr and Y hydride and deuteride coatings in an LFR

The possibility of transmutation of minor actinides (MAs) in lead-cooled fast reactors provides an excellent opportunity to reduce the overall repository of radioactive waste. The present work seeks to augment the transmutation rates of six minor actinides (237Np, 241Am, 243Am, 243Cm, 244Cm, and 245Cm) by increasing neutron capture through the use of moderator coatings around the fuel elements. The reference design for the fuel assembly was based on the design concept of ALFRED, the European Lead Cooled Demonstrator Reactor, and consists of 127 fuel elements loaded with 5 wt.% of minor actinides (MAs) homogeneously mixed with MOX (mixed oxide) fuel. Four different moderators (ZrH1.6, ZrD1.6, YH2, and YD2) with five different coating thicknesses (0.01 cm, 0.02 cm, 0.03 cm, 0.04 cm, and 0.05 cm) were selected for this study and variation in kinf, transmutation rates and fuel cycle parameters (employing the linear reactivity model or LRM) were determined. Results showed that both the addition of a moderator and the increase in moderator thickness improved transmutation rates but had a negative impact on fuel cycle parameters. ZrH1.6 resulted in the highest increase in transmutation rate, but also incurred the largest penalties in fuel burnup, and cycle length. For ZrH1.6 coatings of 0.01 cm, the obtained transmutation rates were 13.57%/y for 237Np, 12.6%/y for 241Am, and 9.26%/y for 243Am. The concentration of Cm isotopes increased over time due to neutron capture of Am, U, and Pu. Deuteride moderators minimized the decrease in fuel cycle parameters but compromised transmutation rates. The fuel temperature coefficient (FTC), energy dependent neutron flux, and relative pin power distribution of the reference design and the models were also determined in order to analyze the effect of moderator addition on these factors. Finally, a suggestion of the best model was put forth in consideration of both transmutation efficiency and fuel cycle parameters.

Experimental studies of power distribution in LEU-fuel of the IVG.1M reactor

For the past ten years, the IVG.1M research reactor has been converted from high-enriched uranium (HEU) fuel to low-enriched uranium (LEU) fuel. Currently, the final stages of the IVG.M reactor conversion, including physical and energy start-ups, are underway. As part of the physical start-up, one of the objectives was to conduct physical studies on the power distribution across the radius and height of the fuel assemblies in water-cooled technological channels. Studies were carried out using the activation gamma-spectrometric method based on correspondence between energy release and measured gamma-radiation activity of fission or activation products. The ENREDI program was used to determine the detailed relative power distribution over radial cross section of fuel assembly. During these experimental studies, relative power distribution along the height and radial cross section of the IVG.1M fuel assembly, as well as power peaking factors were obtained. These studies will make it possible to evaluate the changes in the IVG.1M reactor fuel power profile after the fuel enrichment reduction, and to verify the accuracy of neutronic simulations.

Steady-state analysis of ROSTOV-2 benchmark problem using SERPENT-2 and PARCS codes

Recently, a new benchmark problem has been introduced by the OECD/NEA on the Rostov-2 reactor to address the verification and validation of novel High-Fidelity Multi-Physics tools. In line with the first phase of this benchmark, the current research was dedicated to the steady state reactor physics analysis, using “traditional multi-physics” codes for further and future comparisons. A set of homogenized two-group cross-section libraries were developed using SERPENT-2 Monte Carlo code. Some sophisticated techniques have been employed for detailed consideration of radial as well as axial reflectors, spacer grids and assembly discontinuity factor evaluation. Since PARCS code requires the group constants in PMAXS format, the generated libraries were re-formatted using the GenPMAXS interface. The PMAXS library verification, as well as the steady state analysis have been conducted in three operational states of the reactor using PARCS nodal diffusion code, independent SERPENT-2 Monte Carlo simulation and some available reference data. A set of criticality calculations have been conducted to evaluate the total reactivity worth of different control rod groups, the group #10 integral reactivity curve, fuel temperature coefficient and the critical boron concentration in Hot Zero Power (HZP) and Hot Full Power (HFP) states. The maximum reactivity difference between PARCS and SERPENT-2 simulations was less than 100 pcm in all criticality calculations. In HFP state, the relative power distribution in radial and axial directions were calculated and compared. The maximum Power Peaking Factors (PPFs) and the location of the “hot assembly” from PARCS and SERPENT-2 are in good agreement with each other. Finally, the burn-up calculation was conducted with PARCS code to evaluate neutronic parameters at some specific burn-up values. The calculated reactor physics parameters including the critical boron concentration, the power peaking factors, the power and burn-up distributions at the Beginning of Experiment (BOE) were consistent with available reference data.

Relative power and interpersonal trust.

Because trust is essential in the development and maintenance of well-functioning relationships, scholars across numerous scientific disciplines have sought to determine what causes people to trust others. Power dynamics are known to predict trust, but research on the relationship between power and trust is inconclusive, with mixed results and without systematic consideration of how the relative power distribution within dyadic relationships may influence trust in those relationships. Building on interdependence theory, we propose that both individuals in an unequal-power dyad trust each other less than individuals in an equal-power dyad because unequal-power dyads heighten the perception of a conflict of interest. We demonstrate the effect of relative power on interpersonal trust across eight main studies and 16 supplemental studies (including 12 preregistered studies; total N = 10,531), and we test the mechanism with measurement-of-mediation and moderation-of-process approaches. We confirm that the effect of power on interpersonal trust occurs only with relative power (an interpersonal manifestation of power), not with felt power (an intrapersonal manifestation). Finally, we show that the effect of relative power on interpersonal trust via conflict of interest is attenuated in the presence of intergroup competition, a theoretically motivated moderator with practical implications. Overall, the present research clarifies the relationship between relative power and interpersonal trust, suggests that high- and low-power individuals may share similar psychological experiences within the context of unequal-power relationships, and highlights the importance of considering the context in which power dynamics occur. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Nükleer Reaktörlerde Nanoparçacık Olarak Kalsiyum Karbonat Kullanımının Araştırılması

In this study, calcium carbonate (CaCO3) was considered as nanoparticle. In the first part of the study, half-value layer (HVL) and mean free path (MFP) values, which are radiation shielding parameters, were investigated in determined energy ranges by Phy-X open access software. At increasing energy levels, the HVL value reached approximately 10 cm, while the MFP value reached approximately 17 cm. In the second part of the study, the reactor core geometry was modeled with the MCNP code and then the relative power distribution values were determined. COBRA code input was prepared with the determined relative power distribution values and thermal analyzes were made. These analyzes were performed for three different nanoparticle ratios. As a result of the analysis, the temperature value at the end of the channel was 613 K when only water was used as a coolant, while the temperature value at the end of the channel was 611.19 K when 0.03% nanoparticles were used. Although the coolant temperature increased with the nanoparticle ratio, it was observed that the temperature decreased when only water was used.

Novel ion imaging concept based on time-of-flight measurements with low gain avalanche detectors

Treatment planning in ion beam therapy requires accurate knowledge of the relative stopping power (RSP) distribution within the patient. Currently, RSP maps are obtained via conventional x-ray computed tomography (CT) by converting the measured attenuation coefficients of photons into RSP values for ions. Alternatively, to avoid conversion errors that are inherent to this method, ion computed tomography (iCT) can be used since it allows determining the RSP directly. In typical iCT systems, which usually consist of a tracking system and a separate residual energy detector, the RSP is obtained by measuring the particle trajectory and the corresponding water equivalent path length (WEPL) of single ions travelling through the patient. In this work, we explore a novel iCT approach which does not require a residual energy detector. Instead, the WEPL is estimated indirectly by determining the change in time of flight (TOF) due to the energy loss along the ion’s path. For this purpose, we have created a Geant4 model of a TOF-iCT system based on low gain avalanche detectors (LGADs), which are fast 4D-tracking detectors that can measure the time of arrival and position of individual particles with high spatial and time precision. To assess the performance of this TOF-iCT concept, we determined the RSP resolution and accuracy for different system settings using the Catphan® CTP404 sensitometry phantom. Within the set of investigated system parameters, the lower limit of the RSP accuracy was found at 0.91%, demonstrating the proof-of-principle of this novel TOF-iCT concept. The main advantage of using this approach is that it could potentially facilitate clinical integration due to its compact design, which, however, requires experimental verification and an improvement of the current WEPL calibration procedure.

The effect of back optic zone diameter on relative corneal refractive power distribution and corneal higher-order aberrations in orthokeratology

PurposeTo compare axial elongation, relative corneal refractive power (RCRP) distribution within the pupillary diameter, and corneal higher-order aberrations (HOAs) in myopic children wearing orthokeratology (ortho-k) lenses with different back optic zone diameters (BOZD). MethodsChildren aged 8–11 years were fitted with 5.0 or 6.2 mm-BOZD ortho-k lenses (groups A and B, respectively). Axial length (AL) and corneal topography were measured at baseline and during the annual visit. RCRP and corneal HOAs were compared between the two groups after one-year treatment. Multivariate linear regression analysis was performed to determine the association between AL elongation and RCRP parameters, corneal HOAs, and other variables between the groups. ResultsAfter one-year treatment, axial elongation was slower in group A than in group B, with a difference of 0.15 mm. Children in group A showed smaller treatment zone size, smaller 3/4X value (describing the distance from the apex RCRP profile rising to its three-quarter-peak level), greater RCRP sum value within the pupillary area, and higher increases in corneal total HOAs and horizontal coma (Z31). AL elongation was significantly correlated with baseline age, baseline spherical equivalent refraction (SER), treatment zone size, and 3/4X value. ConclusionsOrtho-k lenses designed with smaller BOZD increased myopia control efficacy, induced a steeper distribution of the RCRP profile within the pupillary diameter, and induced greater increases in corneal total HOAs and horizontal coma (Z31). Lens-induced RCRP profile within pupillary diameter, rising to its three-quarter-peak level at a smaller distance, may show a better myopia control effect.

Feasibility study of a proton CT system based on 4D-tracking and residual energy determination via time-of-flight

Objective. For dose calculations in ion beam therapy, it is vital to accurately determine the relative stopping power (RSP) distribution within the treatment volume. A suitable imaging modality to achieve the required RSP accuracy is proton computed tomography (pCT), which usually uses a tracking system and a separate residual energy (or range) detector to directly measure the RSP distribution. This work investigates the potential of a novel pCT system based on a single detector technology, namely low gain avalanche detectors (LGADs). LGADs are fast 4D-tracking detectors, which can be used to simultaneously measure the particle position and time with precise timing and spatial resolution. In contrast to standard pCT systems, the residual energy is determined via a time-of-flight (TOF) measurement between different 4D-tracking stations. Approach. To show the potential of using 4D-tracking for proton imaging, we studied and optimized the design parameters for a realistic TOF-pCT system using Monte Carlo simulations. We calculated the RSP accuracy and RSP resolution inside the inserts of the CTP404 phantom and compared the results to a simulation of an ideal pCT system. Main results. After introducing a dedicated calibration procedure for the TOF calorimeter, RSP accuracies less than 0.6% could be achieved. We also identified the design parameters with the strongest impact on the RSP resolution and proposed a strategy to further improve the image quality. Significance. This comprehensive study of the most important design aspects for a novel TOF-pCT system could help guide future hardware developments and, once implemented, improve the quality of treatment planning in ion beam therapy.

Neutronic and fuel cycle performance of VVER-1000 for dual cooled annular fuel with coated burnable poison

The feasibility of the dual cooled annular fuel rod with coated burnable absorber in the hexagonal assembly of the VVER-1000 reactor was studied. The models consist of a 4.5% enriched dual cooled UO2 fuel rod with a coating of Gd2O3, Er2O3, PaO2, AmO2, and ZrB2 as the burnable absorber. Designed models along with the reference designs were simulated in lattice physics code Dragon and Monte Carlo code OpenMC. Burnup analysis was conducted for 1620 EFPD. The multiplication factor, as well as reactivity, was determined for fuel burnup. Improvement in the multiplication factor and reactivity is observed for dual cooled annular fuel with coated burnable poison. Designed models also showed a significant increase in thermal fission reaction rate compared to the reference design. Linear reactivity model (LRM) was used to calculate cycle burnup, discharge burnup, and cycle length for three and four batch refueling schemes. No degradation is observed in fuel cycle performance using dual cooled annular fuel with coated burnable absorber except for the model of gadolinium. The other absorbers showed better results than gadolinium in both neutronic and fuel cycle performance. PaO2 used model showed the most promising result among them. The value of k-infinity was found to be 1.27089 at BOL and the cycle burnup was around 15 MWD/kg. Also, no cycle length penalty was observed for PaO2. Burnup-dependent atomic concentration was studied. A lower concentration of fission product poison was also noticed in designed models. The analysis of relative pin power distribution and energy-dependent neutron flux is also included in this study.

Investigation of UO2 fuel efficiency for ABV small modular reactor

ABSTRACT In recent years, small modular reactors have received considerable attention in various countries due to having some capabilities such as small dimensions. The ABV reactor is a small modular reactor with a power of 45 MWth. For this reactor, various applications such as use as a desalination plant, source of electrical and thermal energy, etc. have been considered. In this reactor, an unconventional metal fuel called silumin with 16.5% enrichment and a cycle length of 3000 days has been used. The main purpose of this research is to investigate the performance of conventional UO2 fuel while maintaining the initial cycle length as the main fuel of ABV reactor. To achieve this purpose, the performance of UO2 fuel with enriches of 8%, 10%, 12%, 14%, and 16% with different percentages of Gd2O3 has been investigated. To perform the calculations, the RELAP5 thermohydraulic code and the PARCS neutronic code have been coupled by using a Parallel Virtual Machine, and the reactor core quantities included: effective multiplication factor, relative power distribution, feedback coefficients, plutonium and uranium isotope concentrations, axial and radial temperature distribution of fuel rod, heat flux and DNBR have been calculated and is within an acceptable range for this design.

Core calculations for small modular reactor during burnup cycle

ABSTRACT Nuclear, modular water (AVB) reactor is a small modular reactor with special capabilities and it can be used as a source of energy for various applications. In this research, the core calculations of this reactor have been performed during the burnup cycle with deterministic and Monte Carlo approaches by the computational codes WIMSD, PARCS, and MCNPX. Due to the temperature and pressure limits for coolant in this reactor, the PMAXS generator and the developed PARCS code, PARCS-MOD, have been used in a deterministic approach. Quantities include the effective multiplication factor, the relative power distribution, the fuel, and moderator temperature distribution, reactivity feedbacks, and concentrations of some isotopes during the cycle are calculated. In addition, to comparing the results of the two approaches, some general results were compared with the results published in the documents, which we see an acceptable difference in this regard. The maximum value of for states BOC, MOC and EOC are −1.39, −1.85, and −1.87 (pcm.K−1), respectively. The relative difference between the calculated relative power is less than 2.6%. The relative difference between the coolant average temperature and the fuel average temperature calculated with the reference values is 0.21%, and 0.14%, respectively. The maximum axial coolant density is 650 (kg.m−3). Also in this research, the dead time of the ABV reactor has been calculated which is zero.

Validation results of the BIPR-8A code, the new module of the software package KASKAD

Abstract The BIPR-8A executable module is a main component of the BIPR 2007 code. This module is intended for three-dimensional coarse mesh calculation of the VVER reactor cores. This paper presents the results of validation of the BIPR-8A executable module. Validation is based on comparison of the calculated results with the operating data of power plants with the VVER-440, VVER-1000 and VVER-1200 reactors, and with the results of calculations obtained by using Monte Carlo codes. The results of comparison of the following values at HZP (hot zero power) power level and operational power level are presented: critical concentration of boric acid, temperature reactivity coefficient, efficiency of the control rods system, relative power distribution of fuel assemblies and 3D power distribution, effective multiplication factor.

Design of a Four-Branch Optical Power Splitter Based on Gallium-Nitride Using Rectangular Waveguide Coupling for Telecommunication Links

This paper reports design of a simple four-branch optical power splitter using five parallel rectangular waveguides coupling in a gallium-nitride (GaN) semiconductor/sapphire for telecommunication links. The optimisation was conducted using the 3D FD-BPM method for long wavelength optical communication. The result shows that, at propagation length of 925 μm, the optical power input was successfully split into four uniform output beams, each with 24% of total input power. It is also shown that the relative output power distribution is almost stable through the C-band range. At the operating wavelength of 1.55 μm, the proposed power splitter has an excess loss lower than 0.2 dB. This study demonstrates the opportunity to develop optical interconnections from UV-Visible to near IR wavelengths.

Neonatal Monosodium Glutamate Administration Disrupts Place Learning and Alters Hippocampal–Prefrontal Learning-Related Theta Activity in the Adult Rat

Neonatal treatment with monosodium glutamate causes profound deficits in place learning and memory in adult rats evaluated in the Morris maze. Theta activity has been related to hippocampal learning, and increased high-frequency theta activity occurs through efficient place learning training in the Morris maze. We wondered whether the place learning deficits observed in adult rats that had been neonatally treated with monosodium glutamate (MSG), were related to altered theta patterns in the hippocampus and prelimbic cortex, which were recorded during place learning training in the Morris maze. The MSG-treated group had a profound deficit in place learning ability, with a marginal reduction in escape latencies during the final days of training. Learning-related changes were observed in the relative power distribution in control and MSG-treated groups in the hippocampal EEG, but not in the prelimbic cortex. Increased prefrontal and reduced hippocampal absolute power that appeared principally during the final days of training, and reduced coherence between regions throughout the training (4–12 Hz), were observed in the MSG-treated rats, thereby suggesting a misfunction of the circuits rather than a hyperexcitable general state. In conclusion, neonatal administration of MSG, which caused a profound deficit in place learning at the adult age, also altered the theta pattern both in the hippocampus and prelimbic cortex.