Exclusion Area Research Articles

Radiation dose assessments for generic nuclear power plants part I: Routine operation

The main task of the site evaluation report for nuclear installation concerning nuclear safety is the protection of the public and environment from the radiological consequences of radioactive releases in both cases of normal operation and accident conditions. The atmosphere is the most important pathway to be considered in the assessment of the environmental impact of radioactive materials released from nuclear facilities. The present study is a comprehensive investigation of environmental assessments for the dose calculation model resulting from routine operation NPPs of 1000 Mw (e). The procedure consists of different parts, beginning with the manipulation of collected meteorological data such as wind speed and direction, temperature, incoming solar radiation and utilizing a set of empirical formulae for evaluating night solar radiation emitted from the ground, and then evaluating hourly stability classes and joint frequency distribution of winds by developing code. The dilution factor was evaluated using computer code (XOQDOQ code). Finally, the radiation dose assessments resulting from the routine operation of NPPs were calculated. The processes are adapted with IAEA recommendations documents, safety guides, and ICRP recommendations. The results reveal that there is no detectable value that affects the people surrounding the site nor the environmental area concerning low population zone or exclusion area.

Deer exclusion is necessary to promote post‐fire herbaceous regeneration in the understorey of a Mediterranean forest

The frequency of severe wildfires is on the rise in the Mediterranean Basin as a result of climate change and land abandonment. Recurrent wildfires may retard or impede ecosystem recovery, frequently requiring the implementation of restoration practices. In that context, a post‐fire deer exclusion experiment was conducted in a Mediterranean mixed forest ecosystem with high population densities of deer species (Fallow deer and Red deer). A deer exclusion area was established as a form of restoration intervention to promote post‐fire vegetation recovery. We surveyed plant species during the second and third springs after fire in both deer‐excluded and deer‐allowed areas in order to detect changes in the community. We analyzed the plant species composition, species diversity, and structure of herbaceous and woody plant communities. We also compared the frequency of annual and perennial herb species, functional groups, and post‐fire plant regeneration strategies. The main differences were due to differences between springs rather than of deer‐excluded and deer‐allowed plots. Deer consumed both woody and herbaceous species, favoring the assemblage of herbaceous over woody species. Deer favored the establishment of annual forbs, including unpalatable and/or exotic species, while limiting the abundance of graminoids. Observed deer impacts could have been magnified during the second spring by a drought. Our study demonstrates that deer exclusion can be an effective restoration practice for promoting post‐fire herbaceous regeneration in forests with significant densities of wild ungulates, although seasonal effects may override restoration practice effects.

Determining the depth and rate of soil movement down the soil profile using an environmental tracer: a hillslope scale assessment

Context Soil materials can be delivered to depth from both in situ and ex situ materials. Here, we examine a hillslope in an agricultural environment that has been used for cropping and cattle grazing for over 150 years and a parallel area where cattle have been excluded for approximately 20 years. The exclusion area is a shelterbelt and also provides ecological services. Aims To quantify the depth and rate of down profile soil movement using the environmental tracer 137Cs at points along a hillslope profile. Methods 137Cs concentration is measured to bedrock at regular intervals both inside and outside a fenced of ecological services area pre-drought (2015) and post-drought (2021). In Australia. 137Cs is the by-product of nuclear weapons use and testing from1945 to 1972. Therefore, this places an age constraint on any labelled soil. Key results Results show that soil materials can move down the soil profile to reach bedrock at decadal time scales. An important finding is that materials from the surface can reach depths of up to 80 cm near the hillslope crest and up to 2.2 m at the base of the hillslope. Conclusions This demonstrates a relatively rapid translocation of surface material. Implications The method provides the ability to quantify the rapid movement of soil components and demonstrates the potential for deep sequestration of soil organic carbon. The results demonstrate the potential for soil amendments and agrochemicals to be rapidly transported to depth. The findings suggest that cattle exclusion has no impact on the movement of soil materials down the profile over the 20-year exclusion period.

A Consequence-Informed Licensing Path Selection for the Design of Physical Protection Systems at Commercial Nuclear Power Facilities

The survivability of the domestic nuclear power industry depends on the cost-competitiveness of safe and secure nuclear power generation. Advanced reactor design concepts aim to have increased safety margins over traditional large light water reactors (LWRs). With increased safety margins comes the potential for a corresponding decrease in off-site risk to the general public from a hypothetical release of radioactivity due to sabotage or theft. Without sacrificing safety or security, advanced reactor designers may be able to achieve operational cost improvements over current LWRs in part by designing less burdensome physical protection systems (PPSs) and by replacing on-site response forces with off-site response forces. To accommodate these developments, the U.S. Nuclear Regulatory Commission is drafting new rulemakings for physical security when licensing through the current frameworks in 10 CFR 50 or 10 CFR 52 along with drafting an entirely new licensing framework: 10 CFR 53. A novel technology-inclusive consequence-informed methodology for the selection of the optimal licensing path for the design of PPSs at advanced fixed-site commercial nuclear power facilities is presented herein. This methodology proposes integrating security considerations at the beginning of a reactor facility design effort to streamline the licensing process. Off-site total effective dose equivalents at the exclusion area and low population zone boundaries were identified as the key metrics when determining a design’s most appropriate licensing path that in turn affects the design requirements placed upon the PPS. Given these metrics, source-term generation of potential adversary-induced physics-based sabotage actions utilizing severe accident modeling software and off-site plume dispersal modeling were identified as appropriate for determining siting constraints, potential target sets for hypothetical sabotage events, and their subsequent off-site dose consequences. The methodology proposes using the consequence results from the sabotage modeling, in combination with desired cost-saving PPS characteristics, to help inform the licensing path selection. Once a licensing path is chosen, the methodology utilizes the Design and Evaluation Process Outline to evaluate an effective PPS following the licensing requirements placed on the facility. This paper also presents examples of hypothetical commercial nuclear power facilities with varying consequence levels and demonstrations of how to select the optimal licensing pathways for each.

ORCA: A Tool for Radiological Consequences for Accidental Releases

Evaluating atmospheric dispersion and radiological doses in the vicinity of buildings is required for small modular reactors (SMRs) because of the reduced size of their exclusion area boundary. The current Canadian nuclear industry tool for these calculations implements the methodology defined in CSA Standard N288.2-M91, which was written to support large Canada Deuterium Uranium (CANDU) nuclear reactors as opposed to SMRs. The ORCA (On/offsite Radiological Consequences of Accidents) code has been developed to address this technical concern in addition to evaluating atmospheric dispersion and doses in the far field. The code calculates worker and public doses following an airborne release of radioactive material into the atmosphere under postulated accident conditions at a nuclear facility. The current paper presents the key assumptions and methods utilized in ORCA and discusses qualification of the software to the requirements of CSA Standard N286.7-16. The new model is applicable to SMRs and existing reactor designs and reduces conservatisms in the near field (i.e., <1 km from the source) relative to the methods in CSA N288.2-M91.

Radiological consequence assessment from long term station blackout nuclear accident on Buyende nuclear power plant of Uganda

Uganda’s energy policy of 2023 and Vision 2040 plans to address the country’s electricity shortage by introducing nuclear power of 24,000 MW capacity by 2040. The pioneer nuclear power plants with a generation capacity of 8,400 MW will be built in Buyende District. This study focused on assessing the radiological consequences of potential nuclear accident on any of the four technologies of APR1400, VVER1200, HPR1000, and APR1000. Evaluation of acute and chronic radiation effects from a long-term station blackout accident using RASCAL and GENII codes identified the order of minimum health risks to the public as APR100, HPR1000, VVER1200, and APR1400 if single units are constructed. The total effective dose equivalents and thyroid doses at the exclusion area boundary and emergency protection zone were within the regulatory limits of 250 mSv and 3,000 mSv, respectively for all the reactor technologies.

Soil and plant attributes under grazing exclusion in semi-steppic semi-arid rangelands, Iran

The aim of this study was to investigate the effect of exclusion (20 years) on the attributes of soil and vegetation in northwest of Iran. Three sites in grazed and three sites in exclusion areas were selected. At each site, three 100 m transects were established for sampling purposes. Soil attributes, including electrical conductivity, pH, calcium carbonate, organic carbon, nitrogen, phosphorus, potassium, clay, silt, calcium, magnesium, and bicarbonate were measured in the lab. Additionally, the primary and secondary attributes of vegetation including density, canopy cover, aboveground net primary production (ANPP) of plant functional types (PFTs), diversity, richness and evenness indices were recorded. The findings of our study indicate that the exclusion site exhibited significantly higher levels of soil organic carbon (1.91%), total nitrogen (0.95%), available phosphorus (1.75 ppm), and soluble potassium (163.52 ppm) compared to the grazed site. However, no significant differences were observed in other soil characteristics between the two sites. Density, canopy cover percentage, ANPP of PFTs (p < .01), diversity (1.92), and richness index (9.64), were higher in the exclusion area (p < .05), while, evenness showed no significant difference. The total species density and canopy cover within the exclusion area were also found to be higher than in grazed areas. Results suggest that exclusion in semi-arid semi-steppes plays an important role in rangeland management.

Dose analysis of nearby residents and workers due to the emission accident of gaseous radioactive material at the spent resin mixture treatment facility

The dose from a possible accident at a microwave-based spent resin mixture treatment facility that was to be installed and operated at the Wolsong nuclear power plant was analyzed to evaluate the radiological safety prior to its installation and operation. The dose to which workers and nearby residents are likely to be exposed was calculated based on the atmospheric dispersion and deposition factors using the XOQDOQ code. The highest atmospheric dispersion factors were 1.349E-05 s/m3 (workers) and 1.534E-06 s/m3 (residents). The highest doses due to emissions from the mock-up tank before operation were 1.91E-06 mSv (workers) and 1.78E-07 mSv (residents). Even after 3 h of operation, emissions from the mock-up tank had the greatest impact ranging from 4.63E-08 to 1.24E-06 mSv (workers) and 2.74E-10 to 1.16E-07 mSv (residents), respectively. The doses were 7.09E-09–4.55E-07 mSv and 4.18E-11–4.25E-08 mSv at 4–5 h of operation, and the maximum doses after operation reached 5.69E-07 mSv and 5.31E-08 mSv for the workers and residents, respectively.Even at the exclusion area boundary (EAB), 4.76E-08–9.51E-07 mSv (annual dose:9.52E-05–1.90E-03 mSv/y) was below the dose limit of the EAB, and the safety of the facility installation inside the NPP was confirmed.

Modeling and coverage analysis of heterogeneous sub-6GHz-millimeter wave networks

The joint adoption of sub-6GHz and millimeter wave (mmWave) technology can prevent the blind spots of coverage, enabling comprehensive coverage while realizing high-speed communication rate. According to the sensitivity of mmWave, base stations should be more densely deployed, which is not well described by existing Poisson hole process (PHP) and the Poisson point process (PPP) models. This paper establishes a sub-6GHz and mmWave hybrid heterogeneous cellular network based on the modified Poisson hole process (MPHP). In our proposed model, the sub-6GHz base stations follow the PPP, and the mmWave base stations (MBSs) follow MPHP distribution. The expressions of the coverage probability are derived by using the interference calculation method of integrating the nearest sector exclusion area. Our theoretical analysis has been verified through simulation results, suggesting that the increase in the cell radius decreases the coverage probability of signal-to-interference-plus-noise ratio (SINR), whereas the increase in the sector parameter has the opposite effect. The variation of sub-6GHz base stations (SBSs) density imposes more significant impact than the MBSs on the SINR coverage probability. In addition, the decrease in MBSs density will reduce the average bandwidth allocated to the user equipment (UE), thus reducing the rate coverage probability.

New results from the DANSS experiment

We present new results from the DANSS experiment on the searches for sterile neutrinos. They are based on approximately 5 million inverse beta decay events collected at 10.9, 11.9 and 12.9[Formula: see text]m from the reactor core of the 3.1[Formula: see text]GW Kalinin Nuclear Power Plant in Russia. We do not see any statistically significant sign for the [Formula: see text] oscillations. The exclusion area in the [Formula: see text], [Formula: see text] parameter space goes up to [Formula: see text] in the most sensitive region. Plans for DANSS upgrade are presented. This upgrade should allow DANSS to test Neutrino-4 claim of observation of sterile neutrinos.

Automated Prediction of Bacterial Exclusion Areas on SEM Images of Graphene-Polymer Composites.

To counter the rising threat of bacterial infections in the post-antibiotic age, intensive efforts are invested in engineering new materials with antibacterial properties. The key bottleneck in this initiative is the speed of evaluation of the antibacterial potential of new materials. To overcome this, we developed an automated pipeline for the prediction of antibacterial potential based on scanning electron microscopy images of engineered surfaces. We developed polymer composites containing graphite-oriented nanoplatelets (GNPs). The key property that the algorithm needs to consider is the density of sharp exposed edges of GNPs that kill bacteria on contact. The surface area of these sharp exposed edges of GNPs, accessible to bacteria, needs to be inferior to the diameter of a typical bacterial cell. To test this assumption, we prepared several composites with variable distribution of exposed edges of GNP. For each of them, the percentage of bacterial exclusion area was predicted by our algorithm and validated experimentally by measuring the loss of viability of the opportunistic pathogen Staphylococcus epidermidis. We observed a remarkable linear correlation between predicted bacterial exclusion area and measured loss of viability (R2 = 0.95). The algorithm parameters we used are not generally applicable to any antibacterial surface. For each surface, key mechanistic parameters must be defined for successful prediction.

Analysis of Onshore Wind Exclusion Area on Regional Setback Distances in Local Government Ordinance

Analysis of Onshore Wind Exclusion Area on Regional Setback Distances in Local Government Ordinance

Axion-like dark matter detection using Stern–Gerlach interferometer

Quantum sensors based on the superposition of neutral atoms are promising for sensing the nature of dark matter (DM). In this study, we utilize the Stern–Gerlach (SG) interferometer configuration to seek a novel method for the detection of axion-like particles (ALPs). Using an SG interferometer, we create a spatial quantum superposition of neutral atoms such as ^{3}He and ^{87}Rb. It is shown that the interaction of ALPs with this superposition induces a relative phase between superposed quantum components. We use the quantum Boltzmann equation (QBE) to introduce a first-principles analysis that describes the temporal evolution of the sensing system. The QBE approach employs quantum field theory (QFT) to highlight the role of the quantum nature of the interactions with the quantum systems. The resulting exclusion area demonstrates that our scheme allows for the exclusion of a range of ALP mass in the range 10^{-10}le m_{a}le 10^{2},textrm{eV} and ALP-atom coupling constant in the range 10^{-13}le g_{ae}le 10^{0}.

Comparative Analysis of Emergency Planning Zone and Control Room Habitability for Potential Nuclear Reactor Deployment in Ghana.

Following the recent surge in harnessing clean energy sources to fast-track carbon neutrality, renewable and nuclear energies have been the best-rated sources of clean energy. Even though renewable energy presents an almost insignificant risk to public health and the environment, they are insufficient to support the growing demand for the high energy required for industrialization. Despite the competitive potential of nuclear energy to meet these demands, public concerns about its safety have significantly hindered its mass deployment in developing countries. Therefore, one of the primary considerations in commissioning a nuclear power plant is the establishment of emergency planning zones based on the reactor type and other siting criteria. Based on Ghana’s reactor type assessment (RTA), four reactor designs were considered in this study which are APR1400, HPR1000, VVER1200, and Nuscale Power Module. Using the NRC’s SNAP/RADTRAD and RASCAL codes, this research sought to investigate radionuclide doses released at the Exclusion Area Boundary (EAB), Low Population Zone (LPZ), Control room (CR), and the 16 km recommended public safe zone during Fuel handling Accidents (FHA), Rod Ejection Accident (REA), and Long-Term Station Blackout (LTSBO). The results revealed that reactors’ power contributed to the source term activities and offsite consequences during REA and LTSBO, while FHA was predominantly affected by the number of fuel assemblies and a fraction of damaged fuel. Additionally, the accidents considered in this study followed a similar trend of impact in decreasing order of reactor power and the number of fuel assemblies; APR1400 < VVER1200 < HPR1000 < Nuscale. Nevertheless, all the doses were within regulatory limits.

Restoration of a declining foundation plant species: Testing the roles of competitor suppression, fire reintroduction and herbivore exclusion

Abstract Maintaining ecosystem processes within patches of remnant vegetation is critical to minimising biodiversity loss in agricultural landscapes. Foundation species—habitat‐forming organisms that interact with many other species—are therefore a priority for conservation and restoration in farming areas. Triodia spp. grasses are foundation species of arid and semi‐arid Australia that largely depend on fire for recruitment, but fire is suppressed or excluded in many agricultural areas. We tested the effectiveness of controlled burns and competitor removal (exotic and native grasses), both in isolation and combined, on recruitment rates of Triodia scariosa in remnant vegetation using a before‐after, control‐impact study across 126 plots. A subset of plots were located in an herbivore exclusion area inside a reserve. There was no recruitment of T. scariosa 1 year after burning, regardless of treatment or control, and the burns killed all existing plants. However, T. scariosa germinated by 2 years post‐burn, with the greatest recruitment in sites where both burning and grass removal were applied. Two years after burning, T. scariosa abundance (adults and recruits) remained low outside reserves, but returned to original levels in reserves and in areas where large herbivores were excluded. Synthesis and applications. Despite failing to increase overall abundance, we show that restoration of a foundation plant species in degraded, agricultural landscapes can be achieved through a combination of fire reintroduction and competitor suppression. Germination trials from soil samples suggest a depleted seed bank limited recruitment rates, and therefore emphasise the importance of carefully timing restoration actions to overcome recruitment bottlenecks.

Application and Optimization of Algorithms for Pressure Wave Evaluation Based on Measurement Data

Leakages can occur in a district heating network, resulting in high economical damage. The propagating pressure wave resulting from large, spontaneous leakages reaches sensors at different locations in the network. This leads to pressure drops registered at each sensor at a different point in time. The time differences help to localize the leakage. Different algorithms are presented and applied in this paper to estimate the pressure drop time points based on non-uniform, time-discrete sensor signals. Five of the nine algorithms are self-developed with, e.g., parts of linear regression, whereas the other four algorithms have already been described in the literature, such as change-point detection. In this paper, several recorded events were investigated, and the algorithms were applied to real measurement data. After detection, leakage localization was performed to determine the affected exclusion area. A performance criterion was used as a measure to compare the algorithms. For practical application, the best-performing algorithm was identified. Furthermore, the events were classified according to how well they could be evaluated.

Efficient Global Optimization of Non-Differentiable, Symmetric Objectives for Multi Camera Placement

We propose a novel iterative method for optimally placing and orienting multiple cameras in a 3D scene. Sample applications include improving the accuracy of 3D reconstruction, maximizing the covered area for surveillance, or improving the coverage in multi-viewpoint pedestrian tracking. Our algorithm is based on a block-coordinate ascent combined with a surrogate function and an exclusion area technique. This allows to flexibly handle difficult objective functions that are often expensive and quantized or non-differentiable. The solver is globally convergent and easily parallelizable. We show how to accelerate the optimization by exploiting special properties of the objective function, such as symmetry. Additionally, we discuss the trade-off between non-optimal stationary points and the cost reduction when optimizing the viewpoints consecutively.

Beneficial effects of livestock exclusion on tree regeneration, understory plant diversity, and soil properties in semiarid forests in Iran

AbstractZagros forests in western Iran have been impacted by severe fuelwood removal, traditional agricultural systems, non‐timber products removal, and livestock grazing. These conditions have led to the forest area diminishing from 10 to 6 million hectares over the last six decades. This study was conducted to understand the consequences of livestock exclusion on understory plant diversity, forest tree regeneration, and soil physicochemical properties in semiarid forests. We selected four neighbouring areas, including those subject to livestock exclusion and to grazing, in the Zagros oak forests of Iran. Ten randomized sampling plots (400 m2) were established, and all plant species were recorded in each area. A soil physicochemical analysis indicated a significant improvement in soil nitrogen, phosphorous, potassium, and organic matter in the livestock exclusion area compared to the grazing area. The Shannon–Wiener diversity and species richness was also significantly higher in the livestock exclusion areas compared to the grazed. Grazing tolerant species like Poa bulbosa were abundant in grazing areas, while palatable and nitrogen‐fixing species disappeared. The tree regeneration rate was significantly higher in the exclusion areas compared to the grazing areas, and its values were 0.079 and 0.006 per square metre in the exclusion and grazing areas, respectively. The results of the present study provided evidence that exclusion had a significant effect on improving soil chemical properties, understory plant diversity index, and sapling regeneration. However, the regeneration rates were still low, and therefore, livestock exclusion alone may not be enough to promote forest restoration. Therefore, to better understand plant diversity and tree regeneration in the Zagros forests, livestock exclusion and other factors such as soil seed bank and socio‐economic status of people should be considered.

Leakage Localization in District Heating Networks Based on Real Network and Measurement Data

Fast localization of leakages in district heating networks is a demanding yet important task for network operation. Every leakage results in a loss of medium thus of energy. In case of small leakages, the medium lost can be replenished to maintain network operation. However, if the loss of medium is too large, it may be inevitable to shut down network operation. This can be prevented by separating the damaged network part using exclusion areas. For this, the leakage must be assigned to the correct exclusion area as fast and accurately as possible. This is a major challenge for current district heating networks without existing or with leakage localization systems delivering results too slow, so that other methods of leakage detection and localization are needed here. In a joint research project, three model- and data-based approaches are developed to localize leakages in real time. These are based on operating data which are typically measured for operational needs such as pressure or flow rate. The first approach evaluates the pressure wave which traverses the network at speed of sound when a leakage occurs. The second, purely data-driven approach uses machine learning models to localize leakages. The training phase of this approach is based on a large number of simulated leakages using a network model. The last approach uses the same network model to numerically compute the network state and localize leakages depending on available measurement data. In previous publications these approaches are evaluated using simulated measurement data with encouraging results. In this paper the work is continued and carried out to measurement data of a real district heating network. It is shown that each method is individually applicable to localize leakages under real conditions and provides plausible results. This encourages further development for using synergies which may deliver even better results.

Effects on carrion consumption in a mammalian scavenger community when dominant species are excluded

Carrion is a valuable resource exploited not only by obligate scavengers but also by a wide variety of facultative scavengers. These species provide several important ecosystem services which can suffer if the scavenger community composition is altered, thus reducing the ecosystem provided. We studied the response of the Mediterranean facultative scavenger community to the exclusion of larger scavenger species (red fox Vulpes vulpes, European badger Meles meles, and wild boar Sus scrofa) using an exclusion fence permeable to small scavenger species (mainly Egyptian mongoose Herpestes ichneumon, common genet Genetta genetta, and stone marten Martes foina). The exclusion of dominant facultative scavengers led to a significant reduction in the amount of carrion consumed and an increase in carrion available for smaller species and decomposers, over a longer period of time. Although carrion consumption by the non-excluded species increased inside the exclusion area relative to the control area, it was insufficient to compensate for the carrion not eaten by the dominant scavengers. Of the small scavenger species, only the Egyptian mongoose significantly increased its carrion consumption in the exclusion area, and was the main beneficiary of the exclusion of dominant facultative scavengers. Therefore, altering the facultative scavenger community in Mediterranean woodlands can reduce the efficiency of small carcass removal and benefit other opportunistic species, such as the Egyptian mongoose, by increasing the carrion available to them. This interaction could have substantial implications for disease transmission, nutrient cycling, and ecosystem function.