Fuel Management Strategies Research Articles

Study on fuel management strategy for accident-tolerant fuel on in-pile irradiation test

Within the context of the long-term development plan of batch loading of accident-tolerant fuel assemblies, an equivalent physical model of lead test assemblies is established based on the requirements of radiation testing and the applicability of analysis software. The quantitative assessment has been conducted on the impacts of parameters including zirconium alloy cladding coating and pellet additives on reactivity of fuel assembly. Concurrently, the fuel management strategy is optimized in alignment with the irradiation test objectives of ATF assemblies, leading to the creation of an evaluation process tailored for ATF assembly loading pattern. Focusing on the irradiation of the lead test assemblies into a nuclear power plant in China, three-cycle nuclear reactor loading pattern are designed, which are taking into account the economic, safety, and irradiation testing goals of the nuclear power plant. Simultaneously, the neutronic characteristics are also evaluated, quantitatively. The results show that the established equivalent physical model can effectively represent the characteristics of the lead test assemblies. The loading patterns designed based on the Optimised fuel management strategy achieve the desired goals in terms of economy, safety and radiation test requirements. The designed loading pattern evaluation process and equivalent model analysis method in this work provide guidance for the subsequent engineering design and application of irradiation testing for lead test assemblies.

Impact of in-core fuel management on the radial peaking factor in the APR-1400 with accident-tolerance fuel cladding

This study provides an in-depth examination of the initial, transition, and equilibrium cycles of the APR-1400 reactor core, focusing on reference fuel cladding and ATF cladding systems. This research highlights the importance of in-core fuel management strategies, particularly checkerboard configuration, in maintaining safe and efficient reactor operations. The radial peaking factor (RPF) is an essential parameter in evaluating the core configuration, and a study demonstrated that the RPF can be effectively controlled below the threshold of 1.85 through careful fuel reshuffling and introducing new fuel assemblies. Key findings indicate that the RPF values vary across different cycles but remain within safe limits. Specifically, the RPFs for the initial, first transition, second transition, and equilibrium cycles are 1.36, 1.21, and 1.23; 1.43, 1.38, and 1.30; 1.64, 1.44, and 1.31; and 1.29, 1.33, and 1.66, respectively, measured at the beginning, middle, and end of each cycle. These results underscore the effectiveness of the proposed fuel management strategies in maintaining a stable and safe power distribution within the reactor core. This study also underscores the potential benefits of ATF cladding materials, such as chromium-coated zirconium, which offer enhanced resistance to high-temperature oxidation, thereby improving reactor safety under normal and accident conditions. The implementation of ATFs could lead to significant improvements in safety margins, operational efficiency, and overall reactor performance. This research contributes valuable insights into optimizing in-core fuel management practices for the APR-1400 reactor. This study lays a foundation for future studies and practical applications that could further enhance the safety and efficiency of nuclear power plants. By demonstrating the advantages of ATFs and effective fuel management, this study supports the continued development and deployment of advanced nuclear technologies, promoting greater public confidence in nuclear energy as a reliable and safe power source.

Ancient Alaskan Fuel Selectivity Strategies

In ancient Alaska, people allocated wood, bone, and oil for both fuel and non-fuel purposes, which required careful management. By examining these resources through the lens of human behavioral ecology (HBE) and the principle of least effort (PLE), we can understand fuel use—especially woody fuel use—from the standpoint of selectivity, wherein ancient people considered energetic output, handling costs, and state when choosing fuel sources. At any given site, some degree of firewood selectivity, ranging from complete indifference to marked discrimination, would have been most advantageous. Accordingly, ancient Alaskans at Cape Espenberg, Gerstle River, Hungry Fox, and Walakpa would have employed different fuel management strategies tailored according to their evolving needs. Results suggest that firewood indifference was more common, and that selectivity was advantageous only at longer-term occupations where fuel was abundant. Otherwise, proximity and handling costs trumped the benefits of taxon-specific selectivity, which is a strategy meant to confer desired combustion outcomes. Detecting when and where it was beneficial for ancient Alaskans to be selective grants insight into how they categorized fuel and adapted their fuel selection behaviors to fit particular circumstances. Moreover, the restrictions imposed by finite fuel availability have general implications for settlement patterns and mobility that may help trace ancient migration routes as hunter-gatherers leap-frogged from one fuel patch to another.

Resource objective wildfire leveraged to restore old growth forest structure while stabilizing carbon stocks in the southwestern United States

Wildfire futures and aboveground carbon (C) dynamics associated with forest restoration programs that integrate resource objective wildfire as part of a larger treatment strategy are not well understood. Using simulation modeling, we examined alternative forest and fuel management strategies on a 237,218-ha study area within a 778,000-ha landscape that is a high priority target for federal restoration programs. We simulated two wildfire management scenarios combined with three levels of conventional forest restoration treatments over 64 years using a detailed landscape disturbance and succession model developed in prior work. We found accelerated forest restoration used in concert with resource objective wildfire was the most effective at returning old growth forest structure, while stabilizing aboveground C stocks and restoring the fire return interval to its historic range of variation. In scenarios without forest restoration, the continued practice of resource objective wildfires during shoulder fire seasons reduced summer emissions in a negative feedback loop. In the short term, scenarios without forest restoration increased live tree C, but also increased the likelihood of C loss during wildfire activity driven by extreme fire weather. We found scenarios most effective at restoring fire-excluded pine forests to their historical old growth conditions came at a short-term cost of lost C, but with the long-term benefit of substantially increasing fire-resistant live tree C. Our results inform how local decision making can best balance competing goals of sequestering C, and stabilizing C stocks in frequent-fire pine forests using the principles of local fire ecology to restore and maintain old growth forest structure.

Optimum power determination and comparison of multi-pass and OTTO fuel management schemes of HTGR-based PeLUIt reactor

A co-generation reactor based on pebble-bed High-Temperature Gas-Cooled Reactor (HTGR) has been designed. This study focuses on designing a modular nuclear reactor based on pebble bed high-temperature reactor (Electric Power and Industrial Hot Steam Plant/Pembangkit Listrik dan Uap Panas Industri, abbreviated as PeLUIt), an upgrade from Indonesia’s 10 MW Experimental Power Reactor (Reaktor Daya Eksperimen, RDE). PeLUIt is proposed as a solution for electricity and co-generation application. The 5-pass and Once-Through-Then-Out (OTTO) refueling scheme for the PeLUIt has been analyzed. PEBBED was used for equilibrium core calculations, whereas COMBINE7 was used for spectrum calculations utilizing ENDF/B-VII.0 as nuclear data. Based on the results, it can be inferred that the PeLUIt co-generation reactor analysis with an optimal power of 40 MWt is produced by increasing fuel intake into the core while retaining core geometry and fuel design. In this study, burn-up levels for each refueling scheme are also analyzed, and the value for OTTO is lower than 5-pass refueling schemes. In addition, the Depressurized Loss of Forced Cooling (DLOFC) accident scenario for both types of refueling schemes was also analyzed. The result showed that the OTTO refueling scheme has a higher safety level than the 5-pass refueling scheme.

Enhancing Performance of Hybrid Electric Vehicle using Optimized Energy Management Methodology

The fuel consumption and the fuel management strategy (PMS) of the hybrid electric vehicle are closely linked (HEV). In this study, a hybrid power management technique and an adaptive neuro-fuzzy inference (ANFIS) method are established. Artificial intelligence represents a huge improvement in electricity management across different energy sources (AI). The main energy source of the hybrid power supply is a proton exchange membrane fuel cell (PEMFC), while its electrical storage devices are a battery bank and an ultracapacitor. The hybrid electric vehicle's power management strategy (PMS) and fuel consumption are closely related (HEV). In this paper, an adaptive neuro-fuzzy inference and hybrid power management strategy (ANFIS) approach is developed. A significant advance in electricity management across multiple energy sources is artificial intelligence (AI). The proton exchange membrane fuel cell (PEMFC) serves as the primary energy source of the hybrid power supply, and the ultracapacitor and battery bank serve as its electrical storage components.

Late Paleolithic hunter-gatherers’ resilience in the face of the transformation of the vegetation landscape and climate change in the Pre-Pyrenees

Climate change since the Last Glacial Maximum has caused both plant communities and human behaviour to adapt. Humans relied heavily on wood as fuel to sustain their daily subsistence. Thanks to efficient fuel management, they were able to persist in a challenging environment. Cova del Parco (Iberian Pre-Pyrenees) was inhabited as a settlement in different periods of the Late Pleistocene (16.4–12.7 cal kyr BP). The site has one of the most comprehensive assemblages of Magdalenian hearths, allowing several specialized and daily activity areas to be reconstructed. This study aims to provide new anthracological data regarding the transformation of the forests in the Iberian Pre-Pyrenees, as well as showing how humans adapted their behaviour as regards fuel management and the use of space around the hearths. Furthermore, we present a spatial distribution analysis of the woody taxa from Magdalenian occupations that were identified during the anthracological study. A total of 1993 charcoal fragments from Cova del Parco were identified at a taxonomic level. The anthracological results revealed the presence of 11 woody taxa, with the pine-juniper phase as a characteristic transformation of pre-forest formations in the cold climates of certain locations in the southwestern Mediterranean region. The results of our spatial analysis found that pinewood was the preferred fuel in the cave chamber, whereas juniper was most abundant in the rock shelter. However, the latest occupations revealed a shift in fuel use, with juniper becoming the primary fuel in the cave chamber. This change in behaviour is indicative of the changing needs of humans and their ability to adapt to new surroundings. It implies that strategies are contingent on context and dynamic, responding to changes in the environment. Overall, this study suggests that humans adapted to the changing environment by changing their fuel management strategies.

Initial core loading pattern optimization studies using estimation of distribution algorithm for VVER type cores

Innovative fuel management schemes based on evolutionary algorithms (EAs) now form an integral part of design and operation for nuclear reactors. In the present study, Estimation of Distribution Algorithm (EDA) has been developed for light water reactors (LWRs) and as a case study EDA has been applied to optimize the core loading pattern of VVER X2 benchmark’s initial core. EDA belongs to class of EAs where the optimization solution evolves through progress of generations and in each generation sampling of best candidates of previous generation is done. The main objectives of this study is firstly to develop and test EDA to optimize core loading pattern (LP) for VVER type cores and secondly to generate new optimized LPs having same safety features but with improved fuel utilization with respect to reference benchmark case. The most suitable values for internal parameters for EDA like population size (N), percentage best candidates (M) and weighting factor ‘α’ were evaluated for reaching a reasonable optimized solution in computationally efficient way. During this study, a number of optimized initial core loading patterns were generated, where the target parameters and safety limits are met. A comprehensive analysis for selected LPs has been carried out for full cycle and a comparison has been done for the reported safety and operational characteristics. It is observed that a few of the optimized LPs have better fuel economy than the benchmark LP.

The REBURN model: simulating system-level forest succession and wildfire dynamics

BackgroundHistorically, reburn dynamics from cultural and lightning ignitions were central to the ecology of fire in the western United States (wUS), whereby past fire effects limited future fire growth and severity. Over millennia, reburns created heterogenous patchworks of vegetation and fuels that provided avenues and impediments to the flow of future fires, and feedbacks to future fire event sizes and their severity patterns. These dynamics have been significantly altered after more than a century of settler colonization, fire exclusion, and past forest management, now compounded by rapid climatic warming. Under climate change, the area impacted by large and severe wildfires will likely increase — with further implications for self-regulating properties of affected systems. An in-depth understanding of the ecology of reburns and their influence on system-level dynamics provides a baseline for understanding current and future landscape fire-vegetation interactions.ResultsHere, we present a detailed characterization of REBURN — a geospatial modeling framework designed to simulate reburn dynamics over large areas and long time frames. We interpret fire-vegetation dynamics for a large testbed landscape in eastern Washington State, USA. The landscape is comprised of common temperate forest and nonforest vegetation types distributed along broad topo-edaphic gradients. Each pixel in a vegetation type is represented by a pathway group (PWG), which assigns a specific state-transition model (STM) based on that pixel’s biophysical setting. STMs represent daily simulated and annually summarized vegetation and fuel succession, and wildfire effects on forest and nonforest succession. Wildfire dynamics are driven by annual ignitions, fire weather and topographic conditions, and annual vegetation and fuel successional states of burned and unburned pixels.ConclusionsOur simulation study is the first to evaluate how fire exclusion and forest management altered the active fire regime of this landscape, its surface and canopy fuel patterns, forest and nonforest structural conditions, and the dynamics of forest reburning. The REBURN framework is now being used in related studies to evaluate future climate change scenarios and compare the efficacy of fire and fuel management strategies that either enable the return of active fire regimes or depend on fire suppression and wildfire effects on forest burning.

Detection of goat herding impact on vegetation cover change using multi-season, multi-herd tracking and satellite imagery

The frequency and severity of Mediterranean forest fires are expected to worsen as climate change progresses, heightening the need to evaluate understory fuel management strategies as rigorously as possible. Prescribed small-ruminant foraging is considered a sustainable, cost-effective strategy, but demonstrating a link between animal presence and vegetation change is challenging. This study tested whether the effect of small-ruminant herd presence in Mediterranean woodlands can be detected by integrating remote sensing and herd tracking at the landscape scale. The daily foraging routes of seven shepherded goat herds that exploited a 100-km2 forested area of the Judean Hills, Israel, were tracked over six years using GPS (Global Positioning System) collars. Herd locations were converted to stocking rates, with units of animal-presence-days per unit area per defined time period, and mapped at a spatial resolution of 10 m. We estimated pixel-level vegetation cover change based on a time series of 63 monthly Landsat-8 images expressed as the normalized soil-adjusted vegetation index (SAVI). Spatiotemporal trend analysis assessed the magnitude and direction of change, and a random forest machine-learning algorithm estimated the relative impact on vegetation cover change of environmental factors as well as the herd-related factors of stocking rate that accrued over six years and distance to the closest corral. The last two factors were among the most influential factors determining vegetation cover change in the regional and individual-herd analyses. In some respects, the permanent herds differed in their spatial pattern of stocking rate from the mobile herds that periodically relocated their night corral throughout the year, but stocking rate scaled logarithmically for all herds individually and combined. The combination of multi-season GPS tracking, remote sensing, and machine-learning techniques, applied at a regional scale, detected herd impacts on vegetation cover trends, consistent with livestock foraging being an effective tool for fuel reduction in Mediterranean woodlands.

LEU+ loaded APR1400 using accident tolerant fuel cladding for 24-month two-batch fuel management scheme

In thiswork, a 24-month two-batch fuel management strategy for the APR1400 using LEU + has been investigated, where enrichments of 5.9 and 5.2 w/o are utilized in lieu of the conventional 4–5 w/o UO2 fuel. In addition, an Accident Tolerant Fuel (ATF) clad based on the swaging technology is applied to APR1400 fuel assemblies. In this special ATF clad design, both outer and inner SS316 layers protect the conventional zircaloy clad. Erbia (Er2O3) is introduced as a burnable absorber with two-fold goals to lower the critical boron concentration in the long-cycle LEU + loaded core as well as to handle the LEU + fuel in the existing front-end fuel facilities without renewing the license. Two types of fuel assemblies with different loading of gadolinia (Gd2O3) are considered to control both the reactivity and the core radial power distribution. The erbia burnable absorber is uniformly admixed with UO2 in all fuel pins except for the gadolinia-bearing ones. In this study, two core designs were devised with different erbia loading, and core performance and safety parameters were evaluated for each case in comparison with a core design without any burnable absorbers. The core analysis was done using the two-step method. First, cross-sections are generated by the SERPENT 2 Monte Carlo code, and the 3-D neutronic analysis is performed with an in-house multi-physics nodal code KANT.

The long-lived radionuclides radiotoxicity ranking the nuclear fuel cycle of the Belarusian NPP

Using a methodical approach to the potential biological hazard (radiotoxicity) assessment of radionuclides, computational studies and a comparative analysis of the contributions to the total radiotoxicity of long-lived fission products and actinides accumulated in the nuclear fuel cycle of the Belarusian NPP were carried out. In order to estimate correctly the 237Np isotope mass at the long-term stage of SNF management, the mathematical model of the nuclear fuel cycle of the Belarusian NPP of the code CUB was modified to take into account the transmutation chain of 241Pu, 241Am and 237Np isotopes. The initial concentrations for the main radiation-hazardous radionuclides at the time of fuel unloading from the VVER1200 reactor core are presented in the database “Radiation Characteristics of Spent Nuclear Fuel of the Belarusian NPP” developed by the authors. The database development is carried out in accordance with the recommendations of the RB-093-20 “Radiation and thermophysical characteristics of spent nuclear fuel of pressurized water power reactors and high-power channel reactors”. The main characteristics used in the nuclear fuel cycle simulation in the CUB code, such as the total mass of spent nuclear fuel (2492 tons), the number of spent fuel assemblies (5294) and the average burnup, are taken in accordance with the Spent Fuel Management Strategy of the Belarusian NPP data. It is shown that at the stage up to 100 years, the main contributors to the total radiotoxicity are the isotopes of 238Pu, 239Pu, 240Pu, 243Am, 241Pu, 241Am, 237Np, where contributions of three last of them are 0.07, 49.0 and 0.007%, respectively. But 5000 years later, the contribution of 241Am will be 0.24%, and the isotope 237Np – up to 0.1% of the total actinides radiotoxicity. The results obtained can be used to substantiate for the recovery degree requirements of 237Np, 241Pu, 241Am during the SNF of the Belarusian NPP reprocessing.

Evaluating the Efficacy of Targeted Cattle Grazing for Fuel Break Creation and Maintenance

Invasive and highly flammable annual grasses continue to alter wildfire regimes across rangelands of the western United States. These hazardous fuels have contributed to the increasing prevalence of western megafires in recent decades. It is clear that existing rangeland fuel management strategies are challenged to keep pace with this growing threat. Targeted livestock grazing, however, might serve as a novel and effective fuels management tool that could be wielded at a scale commensurate with the annual grass–wildfire problem. Unfortunately, this practice has lacked a rigorous scientific foundation to support broad-scale application and decision making. We evaluated the efficacy of targeted beef cattle grazing, applied during the spring, for reducing herbaceous fuel heights, loads, and continuity while maintaining ecosystem health in fuel breaks strategically positioned between invaded, fire-prone landscapes and wildland-urban interface, greater sage-grouse (Centrocercus urophasianus) habitat, and other critical resources threatened by wildfire damage. Our broad-scale experiment was conducted during 2017–2021 as three replicate research projects distributed across the northern Great Basin of Idaho, Nevada, and Oregon. We found targeted grazing in spring reduced total herbaceous and cheatgrass fuel heights and, in some cases, total 1-h and cheatgrass fuels loads and fuel continuity, while producing no consistent adverse effects or trends in ecosystem health within the fuel break treatments relative to nominally grazed controls. One targeted grazed fuel break in this research successfully intercepted three wildfires in 4 yr conserving sage-grouse habitat downwind. Although additional research is required, these findings suggest targeted grazing provides an effective means of reducing fine fuels while avoiding adverse ecosystem impacts. Some expected outcomes from the use of this tool would be improved wildland firefighting safety and efficacy, reduced wildfire size, and enhanced protection of human lives, property, and critical natural and cultural resources within the broad scope of annual grass-wildfire problem.

Stakeholder perceptions of wildfire management strategies as nature-based solutions in two Iberian biosphere reserves

Increased large and high-intensity wildfires cause large socioeconomic and ecological impacts, which demand improved landscape management approaches in which both ecological and societal dimensions are integrated. Engaging society in fire management requires a better understanding of stakeholder perceptions of wildfires and landscape management. We analyze stakeholder perceptions about wildfire-landscape interactions in abandoned rural landscapes of southern Europe, and how fire and the land should be managed to reduce wildfire hazard and ensure the long-term supply of ecosystem services in these fire-prone regions. To do so, a structured online questionnaire was sent to the stakeholders of two transboundary biosphere reserves in Spain-Portugal. Our analysis also questioned to what extent fuel management strategies can be considered nature-based solutions (NbS) using the IUCN standard. Overall, stakeholders state that fire should be managed and support fire prevention in lieu of fire suppression policies. Rural abandonment is perceived as the main cause of large wildfires, with high-intensity fires impacting the study regions more than in the recent past, a trend which they expect to continue in the future in the absence of management. All the suggested fuel management strategies, except chemical treatments, were accepted by the stakeholders who perceive more positive than negative effects of fuel management on forest ecosystem services. Transboundary coordination was rated as inadequate or even nonexistent. We did not find differences among stakeholder sectors and biosphere reserves, indicating that in the study area, there is a general agreement on perceptions about wildfire and associated impacts at the landscape level. Finally, we showed that promoting agricultural and livestock uses, modifying forest species composition to increase fire resistance, and introducing large herbivores have the potential to become effective NbS in the regions. This study represents a first-step analysis representing a base for future co-design and implementation of NbS to improve fuel management, contributing to the understanding of the stakeholder support for their application in addressing the socioeconomic challenges in high fire-risk areas.

A risk-averse solution for the prescribed burning problem

Hazard reduction is a complex task involving important efforts to prevent and mitigate the consequences of disasters. Many countries around the world have experienced devastating wildfires in recent decades and risk reduction strategies are now more important than ever. Reducing contiguous areas of high fuel load through prescribed burning is a fuel management strategy for reducing wildfire hazard. Unfortunately, this has an impact on the habitat of fauna and thus constrains a prescribed burning schedule which is also subject to uncertainty. To address this problem a mathematical programming model is proposed for scheduling prescribed burns on treatment units on a landscape over a planning horizon. The model takes into account the uncertainty related to the conditions for performing the scheduled prescribed burns as well as several criteria related to the safety and quality of the habitat. This multiobjective stochastic problem is modelled from a risk-averse perspective whose aim is to minimize the worst achievement of the criteria on the different scenarios considered. This model is applied to a real case study in Andalusia (Spain) comparing the solutions achieved with the risk-neutral solution provided by the simple weighted aggregated average. The results obtained show that our proposed approach outperforms the risk-neutral solution in worst cases without a significant loss of quality in the global set of scenarios.

Experimental investigation on operating light-duty diesel engine using ethanol–gasoline blends in a homogeneous charge compression ignition combustion mode

The advanced diesel combustion mode of homogeneous charge compression ignition (HCCI) provides simultaneous lessening of soot and oxides of nitrogen (NOx) emissions. However, HCCI operations with low volatility and high reactivity diesel fuel require energy-intensive vaporizers and suffer from a restricted operating load range. In this work, high volatility, and low reactivity ethanol–gasoline blends were utilized as fuels in a port fuel injected light-duty diesel engine operated in HCCI mode to address this limitation. To study the effect of adding ethanol to the test fuels, its content was progressively increased from 10% to 60% by simultaneously reducing the gasoline content. 6% of an ignition improver, 2-ethylhexyl nitrate (2-EHN), was added to test fuels to attain stable HCCI combustion in the test engine at lower engine loads. A combined experimental and statistical approach was followed to characterize the HCCI engine combustion, performance and emissions. The impact of independent operating factors of ethanol–gasoline fuel blend composition and engine load on the various response parameters was estimated using multi-regression models developed based on the response surface method (RSM). The optimization of engine parameters was performed using the desirability approach of RSM to maximize performance and minimize emissions. The engine operating load range was extended from 23% (1.22 bar BMEP) to 86% (4.63 bar BMEP) with ethanol–gasoline–2-EHN-fuelled HCCI, which was a substantial improvement over the achievable load range only up to 38% (2.02 bar BMEP) with diesel-fuelled HCCI. All the multi-regression models developed were statistically significant at a 95% confidence level. The results showed that the indicated thermal efficiency improved, and soot and NOx emissions reduced with increased ethanol content in the test fuels. The test engine showed optimal working conditions when operated using 49% ethanol in the test fuels at 75% engine load. To benchmark the HCCI engine performance under optimal operating conditions, it was compared with conventional diesel combustion at 75% engine load. The NOx and soot emissions decreased by 76% and 98%, respectively, while indicated thermal efficiency increased by 20% for HCCI than conventional mode. The optimal fuel reactivity was determined at various engine loads by using the model equation developed for combustion phasing. According to the findings of this study, the fuel management strategy of using ethanol and gasoline blends is a viable method to enhance the performance and emission metrics of HCCI engines.

Assessing the effects of alternative fuel treatments to reduce wildfire exposure

Effective landscape-scale fuel management strategies are essential for reducing wildfire risk in Mediterranean fire-prone areas. In this study, the minimum travel time (MTT) fire-spread algorithm as implemented in FlamMap was applied to assess the potential of alternative fuel treatments for lowering wildfire losses in a 5,740-ha study area in eastern Sardinia, Italy. Twenty-seven wildfires at 10-m resolution were simulated considering three wind speeds (15, 18, and 21 km h−1) to compare fuel treatments: no treatment (NT), irrigated agroforestry areas with shrub clearing (T1), prescribed fire in eucalyptus stands (T2), and irrigated grasslands (T3). The simulations replicated a recent large wildfire that occurred in the study area (Orrì wildfire, 2019) and considered the weather and fuel moisture conditions associated with this event. The average wildfire exposure outputs (burned area, probability of burning, conditional flame length, potential crown fire occurrence, and surfaces withflame lengths above 2.5 m) decreased after fuel treatments, compared to no treatment. T1 was the most effective strategy in mitigating wildfire hazards and provided the most significant performance for several wildfire exposure indicators. Treating only 0.5% of the study area (~ 30 ha) resulted in a decrease in all wildfire exposure metrics to ~ 10% within the study area. In addition, the total surface characterized by high flame length (average > 2.5 m) was the lowest in the T1 treatment. This study can help land and fire managers optimize fuel treatment opportunities and wildfire risk mitigation strategies in Mediterranean areas.

Long-Term Response of Fuel to Mechanical Mastication in South-Eastern Australia

Mechanical mastication is a fuel management strategy that modifies vegetation structure to reduce the impact of wildfire. Although past research has quantified immediate changes to fuel post-mastication, few studies consider longer-term fuel trajectories and climatic drivers of this change. Our study sought to quantify changes to fuel loads and structure over time following mastication and as a function of landscape aridity. Measurements were made at 63 sites in Victoria, Australia. All sites had been masticated within the previous 9 years to remove over-abundant shrubs and small trees. We used generalised additive models to explore trends over time and along an aridity gradient. Surface fuel loads were highest immediately post-mastication and in the most arid sites. The surface fine fuel load declined over time, whereas the surface coarse fuel load remained high; these trends occurred irrespective of landscape aridity. Standing fuel (understorey and midstorey vegetation) regenerated consistently, but shrub cover was still substantially low at 9 years post-mastication. Fire managers need to consider the trade-off between a persistently higher surface coarse fuel load and reduced shrub cover to evaluate the efficacy of mastication for fuel management. Coarse fuel may increase soil heating and smoke emissions, but less shrub cover will likely moderate fire behaviour.

Contrasting the efficiency of landscape versus community protection fuel treatment strategies to reduce wildfire exposure and risk

We examined the financial efficiency and effectiveness of landscape versus community protection fuel treatments to reduce structure exposure and loss to wildfire on a large fire-prone area of central Idaho (USA). The study area contained 63,707 structures distributed in 20 rural communities and resorts, encompassing 13,804 km2. We used simulation modeling to estimate expected structure loss based on burn probability and characteristics of the home ignition zone. We then designed three fuel management strategies that targeted treatments to: 1) the surrounding areas predicted to be the source of exposure to communities from large fires, 2) the home ignition zone, and 3) a combination of the landscape and home ignition zone. We evaluated each treatment scenario in terms of exposure and expected structure loss compared to a no-treatment scenario. The potential revenue from wood products was estimated for each scenario to assess the cost-efficiency. We found that the combined landscape and home ignition zone treatment scenario which treated 5.7% of the study area resulted in the highest overall reduction in predicted exposure (47.5%, 100 structures yr−1) and predicted loss (69.1%, 57 structures yr−1). Home ignition zone treatments provided the best predicted economic and per area treated performance where exposure and loss were reduced by one structure by treating 89 and 111 ha per year, respectively, with an annual cost of $33,645 and $73,672. Revenue from thinning was the highest for landscape fuel treatments and covered 16% of the required investment. This work highlighted economic and risk tradeoffs associated with alternative fuel treatment strategies to protect developed areas from large wildland fires.

Investigations on load range extension of a homogeneous charge compression ignited light-duty diesel engine operated with diisopropyl ether and gasoline blends

A major obstacle for commercial implementation of homogeneous charge compression ignition (HCCI) combustion mode is a narrow operating load range. Several thermal and fuel management strategies have been investigated so far to address the shortcomings of HCCI, among which fuel management strategies are generally more effective. The present study intends to utilize high volatile, optimum reactivity fuel to extend the operating load range of a light-duty diesel engine operated in HCCI mode. Experiments are conducted at the rated engine speed, and varying load conditions. The tested fuels include blends of gasoline and diisopropyl ether and the additive 2-ethyl hexyl nitrate (2-EHN). Diisopropyl ether is a low reactivity, and high volatile renewable fuel that has the potential to replace crude oil derived gasoline. In the fuel blends, the proportion of diisopropyl ether is increased from 10% to 60% by volume with a corresponding decrease in gasoline proportion. The results obtained are compared with diesel HCCI considered as the reference. The engine can operate only up to 38% of rated load (2.02 bar brake mean effective pressure) in diesel HCCI mode, which is increased up to 58% of rated load (3.08 bar brake mean effective pressure) with diisopropyl ether-gasoline-2-EHN fuel blends. An improvement in indicated thermal efficiency is observed upon increasing the diisopropyl ether content in the tested fuel blends. The oxides of nitrogen and smoke emissions are low in HCCI with all the fuel blends, while the unburned hydrocarbon and carbon monoxide emissions increase compared to diesel HCCI. Overall, the present research shows that diisopropyl ether is a potential fuel to achieve desired performance and emission targets in an HCCI engine.