Search

Decommissioning programmes pose a substantial risk of failure compared to other change processes in healthcare. A better understanding of the challenges associated with change processes initiated by resource scarcity faced by healthcare managers is crucial. This study describes and compares department and unit managers' experiences during the implementation of a large-scale decommissioning programme in a Swedish region. A survey was developed and a cross-sectional study was performed, measuring 172 healthcare managers' experiences of (1) the region's leadership, (2) their own participation and (3) their own commitment and responsibility during the implementation of the decommissioning programme. Respondents were 50 department managers and 122 unit managers (93% and 58% response rate, respectively). There was a significant difference between department and unit managers in their experiences of the region's leadership and their own participation in the decommissioning programme. Unit managers were more dissatisfied with the way it developed compared to department managers. For example, unit managers reported a lower level of leadership support, incentives to participate, and that their knowledge and skills were not fully utilised. Involvement of unit managers in a more fruitful way might enhance the results of decommissioning programmes. This study highlights a key actor in this context: the unit manager. [ABSTRACT FROM AUTHOR]

Offshore wind has rapidly developed over the past three decades, with over 6000 fixed-bottom substructures installed in Europe alone as of 2022. Despite this progress, there has been limited focus on the end-of-life stages, particularly decommissioning, which is currently the default option. Sustainable offshore wind development hinges on effective decommissioning strategies for fixed-steel pile foundations. This review critically examines state-of-the-art pile-foundation-decommissioning methods recently tested in industry and academia, including partial-removal techniques like internal cutting and external cutting and full-removal approaches such as excavation and novel extraction methods. Key factors influencing decommissioning decisions, such as seabed disturbance, environmental impact, reuse potential, and cost, are discussed. Analyses reveal that current partial-removal strategies could render vast swaths of marine areas inaccessible for future development. In contrast, full removal through extraction may enable complete recycling and minimise post-decommissioning monitoring. However, significant knowledge gaps remain regarding novel extraction methods' scalability, technical feasibility, and economics. Extensive research encompassing engineering, environmental, and economic dimensions is essential to develop holistic pile-foundation-decommissioning solutions that facilitate the sustainable long-term growth of offshore wind. [ABSTRACT FROM AUTHOR]

As nuclear facilities are dismantled in decommissioning, various and large amounts of waste are generated. Even more inconveniently, they are radioactive waste due to neutron activation. Thus, the neutron capture cross-sections of nuclides targeted for decommissioning are required to evaluate the radioactivity produced. The present study selected 45Sc, 63Cu, 64Zn, 109Ag and 113In among targeted nuclides, and performed the measurements of thermal-neutron capture cross-sections by an activation method at the Kyoto University Research Reactor. The thermal-neutron capture cross-sections were derived on the basis of Westcott's convention. The present results were obtained as follows: 27.18 ± 0.28 barn for 45Sc(n,γ)46Sc, 4.34 ± 0.06 barn for 63Cu(n,γ)64Cu, 0.719 ± 0.011 barn for 64Zn(n,γ)65Zn, 4.05 ± 0.05 barn for 109Ag(n,γ)110mAg and 8.53 ± 0.27 barn for 113In(n,γ)114Inm1+m2 reactions. The results for 45Sc and 64Zn support evaluated cross-section data within the limits of uncertainties, while those for the other nuclides were slightly different from evaluated ones. The obtained results are useful not only for the evaluation of isotope production, but also for the consideration of those nuclides as flux monitors, as an alternative to Au and Co. [ABSTRACT FROM AUTHOR]

Copyright of Uranium Mining & Metallurgy is the property of Uranium Mining & Metallurgy Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper describes a method for integrating multiple dense point clouds using a shared landmark to generate a single real-scale integrated result for photogrammetry. It is difficult to integrate high-density point clouds reconstructed by photogrammetry because the scale differs with each photogrammetry. To solve this problem, this study places a QR code of known sizes, which is a shared landmark, in the reconstruction target environment and divides the reconstruction target environment based on the position of the QR code that is placed. Then, photogrammetry is performed for each divided environment to obtain each high-density point cloud. Finally, we propose a method of scaling each high-density point cloud based on the size of the QR code and aligning each high-density point cloud as a single high-point cloud by partial-to-partial registration. To verify the effectiveness of the method, this paper compares the results obtained by applying all images to photogrammetry with those obtained by the proposed method in terms of accuracy and computation time. In this verification, ideal images generated by simulation and images obtained in real environments are applied to photogrammetry. We clarify the relationship between the number of divided environments, the accuracy of the reconstruction result, and the computation time required for the reconstruction. [ABSTRACT FROM AUTHOR]

The activation level of the JAEA-Tokai tandem accelerator facility was investigated experimentally in advance of the future decommissioning. JAEA-Tokai tandem accelerator facility has a higher terminal voltage of 18 MV and a larger total floor area, Compared to other electrostatic accelerators with terminal voltage of 1 MV to 6 MV. Therefore, determination for 'where,' 'what,' and 'how many' nuclides are produced in the facility is crucial. Thermal neutrons generated by beam losses associated with accelerator operations contribute significantly to the activation of equipment and facilities. The accumulated activities of60Co and152Eu; the most considerable radionuclides at the decommissioning, can be deduced by the thermal neutron fluence rate during the accelerator operation. In this study, thermal neutron fluence measurement on the surface of the pressure vessel and concrete building was conducted with conventional methods using dosimeters and metal foil detectors as well as a new method using a portable γ-ray detector. The thermal neutron fluence in the facility during the accelerator operation ranges from 101 to 104 n/cm2/s. The sum of deduced activities of60Co and152Eu in 50 years is much lower than the clearance level of 0.1 Bq/g in all areas except in the irradiation room. [ABSTRACT FROM AUTHOR]

Copyright of Environmental & Social Management Journal / Revista de Gestão Social e Ambiental is the property of Environmental & Social Management Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Plug and abandonment (P&A) operations demand valuable time and resources for operational procedures and materials to establish the well barrier element. This study aims to investigate the application of a water-based fluid as a liquid well barrier element for temporary abandonment, based on estimates of its lifespan and the survival probabilities of downhole temperatures acquired through accelerated life tests. To achieve this, the water-based formulation was tested and exposed to 95, 110, 140, and 150 °C temperatures for time intervals ranging from 1 to 10 days. After the temperature exposure, the fluid properties were verified, and failure was detected by accounting for any deterioration in rheological parameters and/or a substantial increase in filtrate volume. A statistical analysis of the failure data was performed in RStudio 4.1.3 software using the Weibull Model, and the fluid average lifespans and survival probabilities were estimated for the P&A temperatures. The results obtained demonstrate that the degradation of the fluid was only observed for 140 and 150 °C temperatures. According to the results, the fluid is a promising alternative for temporary abandonment until 80 °C, with no need for monitoring once its lifetime expectation exceeds three years at this temperature. For downhole temperatures above 80 °C, the fluid is a possible alternative, however, the operation's maximum time and monitoring requirements should consider reliability metrics for each temperature. [ABSTRACT FROM AUTHOR]

In Korea, Kori Unit 1 was permanently closed in 2017 and scheduled for decommissioning. Kori Unit 1 is currently scheduled to undergo system decontamination and to be decommissioned by December 2038. Measures to properly control and remove radiological hazards must be established to go through decommissioning a nuclear power plant (NPP). Radiological characterization must precede NPP decommissioning. Radiological characterization generates a lot of data during this process. The consistency of radiological characterization data is important for systematically decommissioning NPPs. However, the data generated from radiological characterization may not be systematically managed because a database of radiological characterizations for Kori Unit 1 has not been properly established. Therefore, this study has proposed a database to be filled during radiological characterization in terms of occupational radiation exposure of personnel and decommissioning waste safety using key performance indicators presented by the International Atomic Energy Agency. From the perspective of occupational exposure, databases have been proposed for operational history investigations, decommissioning source term calculations, and investigation of the level of radiological contamination. From the perspective of the safety of decommissioning waste, databases were proposed for operational history investigation, decommissioning source term calculation, investigation of the level of radiological contamination, and investigation of radiological characteristics of decommissioning waste. [ABSTRACT FROM AUTHOR]

Thousands of offshore oil and gas platforms have been installed worldwide and are known to act as artificial reefs. Many platforms are nearing the end of their operational lives and will soon require decommissioning, but uncertainty remains about the impacts of these structures, and their removal, on the environment. Fish aggregate at platforms, but little is known about the extent of these effects in the North Sea and the causes of variability in these associations. Here, an uncrewed surface vessel (USV) was used to collect fisheries acoustic data on distributions of schooling and non-schooling fish around six oil platforms, collecting data within tens of metres of four of the surveyed platforms. In areas with more platforms, more non-schooling fish were found, and the probability of detecting fish schools was higher. Interplatform variability was found in trends in non-schooling fish density with increasing distance from platform, but the relationship was found to be strongest and most negative at the larger platforms. These findings may influence future management decisions around the decommissioning of these platforms, particularly if some structure is to be left in place to maximize the potential benefits associated with these artificial reef effects. [ABSTRACT FROM AUTHOR]

Left ventricular assist devices (LVADs) are excellent therapies for advanced heart failure patients either bridged to transplant or for lifetime use. LVADs also allow for reverse remodeling of the failing heart that is often associated with functional improvement. Indeed, growing enthusiasm exists to better understand this population of patients, whereby the LVAD is used as an adjunct to mediate myocardial recovery. When patients achieve benchmarks suggesting that they no longer need LVAD support, questions related to the discontinuation of LVAD therapy become front and center. The purpose of this review is to provide a surgical perspective on the practical and technical issues surrounding LVAD deactivation. [ABSTRACT FROM AUTHOR]

Abstract In Korea, Kori Unit 1 was permanently closed in 2017 and scheduled for decommissioning. Kori Unit 1 is currently scheduled to undergo system decontamination and to be decommissioned by December 2038. Measures to properly control and remove radiological hazards must be established to go through decommissioning a nuclear power plant (NPP). Radiological characterization must precede NPP decommissioning. Radiological characterization generates a lot of data during this process. The consistency of radiological characterization data is important for systematically decommissioning NPPs. However, the data generated from radiological characterization may not be systematically managed because a database of radiological characterizations for Kori Unit 1 has not been properly established. Therefore, this study has proposed a database to be filled during radiological characterization in terms of occupational radiation exposure of personnel and decommissioning waste safety using key performance indicators presented by the International Atomic Energy Agency. From the perspective of occupational exposure, databases have been proposed for operational history investigations, decommissioning source term calculations, and investigation of the level of radiological contamination. From the perspective of the safety of decommissioning waste, databases were proposed for operational history investigation, decommissioning source term calculation, investigation of the level of radiological contamination, and investigation of radiological characteristics of decommissioning waste.

Efficient and secure decommissioning of nuclear facilities demands advanced technologies. In this context, gamma-ray detection and imaging are crucial in identifying radioactive hotspots and monitoring radiation levels. Our study is dedicated to developing a gamma-ray detection system tailored for integration into robotic platforms for nuclear decommissioning, offering a safe and automated solution for this intricate task and ensuring the safety of human operators by mitigating radiation exposure and streamlining hotspot localization.Our approach integrates a Compton camera based 3D reconstruction algorithm with a single Timepix3 detector. This eliminates the need for a second detector and significantly reduces system weight and cost. Additionally, combining a 3D camera with the setup enhances hotspot visualization and interpretation, rendering it an ideal solution for practical nuclear decommissioning applications.In a proof-of-concept measurement utilizing a 137Cs source, our system accurately localized and visualized the source in 3D with an angular error of 1° and estimated the activity with a 3% relative error. This promising result underscores the system's potential for deployment in real-world decommissioning settings. Future endeavors will expand the technology's applications in authentic decommissioning scenarios and optimize its integration with robotic platforms.The outcomes of our study contribute to heightened safety and accuracy for nuclear decommissioning works through the advancement of cost-effective and efficient gamma-ray detection systems.

In the calculation of DCGLs using RESRAD code, the selection of input parameter values is paramount, which is basically possible when specific measures for selecting reuse scenarios and probabilistic evaluation methods are established. When referring to the impact of the age group considered in the environmental impact assessment among the existing operations of the plant, it may also need to be applied in the decommissioning project, and there will be considerations along with site reuse scenarios and probabilistic evaluations. Therefore, the main purpose of this study is to distinguish the types of exposure affected by residual radioactivity contamination during the process of deriving DCGL to be used in the final site release stage of NPPs and to evaluate them by reasonably assigning age group parameter values. In addition, the case of entering a single value for parameter values by age group and the case of entering probabilistic distributions were compared and analyzed.

To obtain site-specific values of the Derived Concentration Guideline Levels (DCGLs) for decommissioning of KRR-1&2, the soil density and distribution coefficient values for Cs-137, a major contaminant radionuclide, were determined. The soil density was evaluated according to the test method established by the Korean Agency for Technology and Standards of the Ministry of Trade, Industry, and Energy (KATS). The distribution coefficient was evaluated using a batch test. The validity of using the evaluated soil density and distribution coefficient as site-specific values was assessed through radiation dose assessment reflecting these values. Average soil density value obtained was 1.738 g/cm3, which was within the typical range of normal soil density, 1.0–1.8 g/cm3. The average distribution coefficient value was 7,754 mL/g. Applying the maximum, average, and minimum values of the evaluated soil density and distribution coefficient showed similar radiation dose results, thus suggesting that it is reasonable to use the average values of each parameter as site-specific values. Findings of this study can help determine DCGLs that reflect the characteristics of the research reactor site.

RESRAD-ONSITE v7.2 code is used to assess the radiation effects on a farmer resident located in a hypothetical contaminated site planned for the first nuclear power plant project in Vietnam, namely Ninh Thuan 1, after decommissioning. Derived concentration guideline levels are preliminarily calculated for 17 radionuclides that are assumed to remain on a contaminated surface soil with an initial concentration of 1 pCi/g in the protected area of NPP site. For a reliable estimation, the site-specific conditions regarding the geological, hydrological, climate, and occupancy data gathered from the Feasibility Study Report (FSR) and relevant literatures for the Ninh Thuan 1 NPP site is employed as input parameters. The calculation results indicate that the peak of total exposure dose is estimated to be ca. 0.191 mSv/yr at the time of decommissioning, and then decrease over time. Furthermore, the protected site is assessed to be released at ca. 6.71 years after decommissioning under the regulation on radiation protection in Vietnam. Through this study, a radiation exposure model for residents living near the Ninh Thuan 1 NPP is preliminarily established by using the RESRAD-ONSITE code, which are expected to be useful for future implementation of the Ninh Thuan 1 NPP project in Vietnam.

A significant number of first-generation offshore wind turbines (OWTs) have either reached or are approaching the end of their operational lifespan and need to be upgraded or replaced with more modern units. In response to this concern, governments, regulatory bodies and industries have initiated the development of effective end-of-life (EOL) management strategies for offshore wind infrastructure. Lifetime extension is a relatively new concept that has recently gained significant attention within the offshore wind energy community. Extending the service lifetime of OWTs can yield many benefits, such as reduced capital cost, increased return on investment (ROI), improved overall energy output, and reduced toxic gas emissions. Nevertheless, it is important to identify and prepare for the challenges that may limit the full exploitation of the potential for OWT lifetime extension projects. The objective of this paper is to present a detailed PESTLE analysis to evaluate the various political, economic, sociological, technological, legal, and environmental challenges that must be overcome to successfully implement lifetime extension projects in the offshore wind energy sector. We propose a decision framework for extending the lifetime of OWTs, involving the degradation mechanisms and failure modes of components, remaining useful life estimation processes, safety and structural integrity assessments, economic and environmental evaluations, and the selection of lifetime extension technologies among remanufacturing, retrofitting, and reconditioning. Finally, we outline some of the opportunities that lifetime extension can offer for the wind energy industry to foster a more circular and sustainable economy in the future. [ABSTRACT FROM AUTHOR]

Globally, aging offshore oil and gas (O&G) platforms face resource depletion, and regulations often demand platform removal through decommissioning. In the North Sea, >€90 billion will be needed for decommissioning by 2060. However, the influence of O&G platforms on fish communities is poorly understood. This challenges predictions of possible fisheries scenarios associated with different decommissioning options. Here, we examined the role that North Sea platforms played on fish communities. We explored patterns of fish abundance and body size variation along transects from O&G platforms comparing catch per unit effort data. Fish abundance was positively associated with O&G platforms. Atlantic cod, plaice, saithe, and mackerel were most abundant near platforms. Similarly, larger Atlantic cod were near the O&G platforms. Our study provided information for decision‐making regarding platform decommissioning scenarios by evidencing O&G platform habitat provisioning for various commercial fish species. [ABSTRACT FROM AUTHOR]

There is currently a rising interest in reusing and repurposing offshore facilities through decommissioning; however, major challenges arise, such as size, weight, sea depth, planned use, and location. This article aims to discuss the philosophy that needs to be adopted for field redevelopment, particularly when existing platforms must be preserved and integrated into new greenfield facilities. The article also discusses the concept of weight shedding during the decommissioning of offshore facilities to either extend the life of existing platforms or provide clear space for new equipment to be installed by removing unnecessary components and structures. The above aspects of decommissioning are investigated through the redevelopment of a case study of a mature offshore oil field located in shallow water. The study indicated that weight shedding presents a favourable method for decommissioning offshore installations and can effectively lower expenses, minimise environmental consequences, and optimise the use of resources. [ABSTRACT FROM AUTHOR]

This study aims to evaluate how the operational procedure adopted for pellet placement and the exposure to subsurface conditions influence the mechanical integrity of bentonite plugs used as barrier elements in the abandonment of petroleum wells. To this end, the plugs were formed by hydrating the pellets directly in water, simulating the onshore procedure, while the offshore plugs were obtained from pellets hydrated in deionized water after immersion in diesel or olefin, which are suggested as displacement fluids. The plugs obtained were tested by compression and adhesion tests. These mechanical tests were also carried out for specimens obtained from plugs exposed to four formulations of synthetic formation waters. The results obtained demonstrated that, in the offshore procedure, the previous contact with olefin may adversely affects the mechanical stability of bentonite plugs, while plugs formed from pellets immersed in diesel presented satisfactory mechanical properties. However, the contact with formation water evidenced that the onshore plug presents superior resistance than the offshore plug previously immersed in diesel. The highly successful performance of the onshore plug was attested by the maintenance of the compressive strength, which exhibited a maximum reduction of 13%, even after exposure to the most saline formation waters. [ABSTRACT FROM AUTHOR]

Decommissioning is inevitable for each nuclear facility and, lately, it has become one of the most topical issues. Several decontamination methods have been successfully applied worldwide; however, variations in operating chemistry and/or different composition of the construction materials play a very important role and can cause unexpected problems. The experiments aim at dissolving the most resistant chemical present in corrosion layers, chromium (III) oxide, using redox chemistry and further test the found redox system on stainless steels and its model corrosion products. It was found out that persulfate solution in diluted sulfuric acid supported by Ag+ ions can efficiently dissolve Cr2O3 and selected substrates at temperature as low as 50 °C. [ABSTRACT FROM AUTHOR]

Purpose: Historical French fleet of Nuclear Power Plants (NPP) is near end-of-life, with 14 NPPs planned to begin decommissioning by 2035. Despite decade-old calls for more research regarding these activities' environmental impact, very few if any studies were conducted since. Due to the French fleet high-degree of standardization, a prospective investigation regarding the Fessenheim NPP—first large-scale plant to be decommissioned in France, starting 2026—is conducted to identify results of interest beyond this case study. Methods: A life cycle assessment is realized, following ISO 14040/44, with a functional unit defined as "the decommissioning of the Fessenheim NPP." The system boundaries encompass four unit-processes: dismantling of electromechanical equipment, clean-up of the structures, demolition of plant buildings, and transport of conventional and radioactive waste (RW). This last unit-process is investigated separately to make a clear comparison of conventional and radioactive waste. Pre-decommissioning activities, soil rehabilitation, and RW final storage are excluded. Primary data were obtained from the decommissioning public report of EDF (Electricity of France), with scaling based on the literature and third-party reports/documents. Background processes were modeled with the ecoinvent 3.8 database. Environmental impacts are estimated using the CML-IA baseline methodology to allow comparison with previous works based on CML2001. Results and discussion: The "Metal cutting" sub-process is found to be the major contributor to environmental impacts during dismantling, clean-up, and demolition, results varying from 62.6 to 99.5% depending on the impact category. A sensitivity analysis explores the effect of variation in shares of thermal and mechanical cutting. It demonstrates the huge potential of impact reduction for the total system under study if thermal cutting use is limited as much as possible. Despite representing only 5% of the total mass of waste, RW scores 1.8–6.6 times higher than conventional waste during transport, due to much higher distances to cover and specific conditioning. Previous explorations of results transferability are found to be methodologically uncertain, and the NPP total power installed is evaluated as an unpromising transferability factor. Conclusions: Decommissioning of nuclear power plants is still in need of thorough studies based on exhaustive and transparent datasets. Until then, state-of-the-art prospective assessments and transferability of LCA results to future studies are severely limited. Restraint in use of oxy-acetylene cutting is nevertheless highly recommended. French unique policy regarding very low-level waste needs further consideration, and decentralized storage sites are a promising research lead. [ABSTRACT FROM AUTHOR]

The detection of ionising radiation in materials from the decommissioning of a dicalcium phosphate plant meant that this whole operation had to be overhauled in terms of radiological protection and safety. Thus, an operations plan was drawn up that included: initial training for all workers involved, measurements of dose rates and a set of analyses by gamma and alpha spectrometry. Samples of "dry sludge" and debris were analysed for the identification and quantification of the radionuclides present, samples of workers' urine were analysed for the detection of any internal contamination, samples of washing water and air filters were analysed for the detection and control of any radioactive atmospheric contamination. In addition, individual dosimeters were distributed to workers. The extent of contamination was identified and the areas where higher values were detected were properly marked. From the results obtained (radiation dose rates and activity concentrations), it was possible to establish categories and separate the contaminated materials according to their physical characteristics. After the plant decommissioning, the resulting waste with dose rates higher than the effective dose limits for the public was packed in big bags. These bags were divided in 3 groups according to the external radiation dose rates at contact. This segregation allowed the competent authority to release a significant number of big bags from regulatory control. The remaining big bags are stored in two metal containers subject to regular radiological monitoring. The objective of this work is the presentation of a factual article where the methodology implemented to deal with this situation, which had never occurred in Portugal, is described, having only the Portuguese legislation as a reference.

In accordance with the fundamentals of state policy in the field of ensuring nuclear and radiation safety, State Corporation «Rosatom» carries out the remediation of JSC “AECC” nuclear legacy sites. The article presents the results of environmental impact assessment carried out in 2021-2023 in the vicinity of sublimation waste storage facilities that are being decommissioned. Health physics studies involved ambient dose rate measurements, sampling (soil, groundwater) and analysis of radiological and non radiological environmental pollutants. The external gamma dose rate, as well as content of natural and artificial radionuclides in soil, don’t exceed background levels. While uranium presence in groundwater is found to be 10 times and higher then background level. The data obtained indicate that the accumulated wastes of sludge sumps (bottom sediments, pulp) сome into contact with natural water. Flooded storage facilities form a plume of contamination spreading out in the direction of groundwater flow. Given the current situation optimization of the existing environmental monitoring programs in the JSC “AECC” health protection zone is recommended and reference levels of uranium proposed.

Accomplishing the retrieval of fuel debris from Fukushima Daiichi Nuclear Power Plant (1F) Unit 3 (1F3) requires an understanding of its distribution. In this study, we performed real-scale corium spreading and sedimentation behavior analyses using Lagrangian moving particle hydrodynamics and large eddy simulation methods. These methods allowed us to calculate the spreading of corium with various shear viscosities under water conditions and to propose the best estimation for the fuel debris distribution in 1F3. To minimize uncertainties arising from unknown boundary conditions, we investigated relevant parameters through literature review. Our analyses showed that highly viscous corium tends to pile up within the pedestal region under strong convective vapor and boiling heat transfer, while low-viscosity corium spreads to the outside of the pedestal regions regardless of cooling efficiency. We identified three cooling modes based on initial shear viscosity and cooling efficiency and predicted the fuel debris distribution in 1F3 by comparing our results to those of the Tokyo Electric Power Company (TEPCO) and Organisation for Economic Co-operation and Development/Nuclear Energy Agency (OECD/NEA) Benchmark Study of the Accident at the Fukushima Daiichi Nuclear Power Station (BSAF) project. The distribution estimation of highly viscous corium derived from oxidic corium is consistent with the three-dimensional reconstructed image by TEPCO and the calculated results by the OECD/NEA BSAF project. [ABSTRACT FROM AUTHOR]

This paper presents a case study of using Scan-to-BIM technology for evaluating the quantity and cost of a nuclear power plant during the decommissioning process. The study proposes a process for applying Scan-to-BIM in the dismantling stage and develops a BIM-based VPL (Visual Programming Language) to acquire accurate as-is databases that are crucial for nuclear power plants handling radioactive materials. The proposed process and system were applied to K-1 NPP (Nuclear Power Plant), the first nuclear power plant in Korea, and the results were compared to those obtained using the conventional method. The study found that errors in quantity evaluation using the conventional method ranged from around 10% to over 10 times, and were attributed to various causes such as outdated as-is drawings and limitations in expressing information in drawings. By using the Scan-to-BIM process and system, errors in quantity evaluation were significantly reduced, and the conventional method was found to have underestimated the dismantling cost by 20%. The findings of this study provide important insights for the efficient and accurate decommissioning of nuclear power plants, and demonstrate the effectiveness of the proposed method and system for evaluating the quantity and cost of a nuclear power plant during the decommissioning process. [ABSTRACT FROM AUTHOR]

This paper describes a three-dimensional (3D) modeling method for sequentially and spatially understanding situations in unknown environments from an image sequence acquired from a camera. The proposed method chronologically divides the image sequence into sub-image sequences by the number of images, generates local 3D models from the sub-image sequences by the Structure from Motion and Multi-View Stereo (SfM–MVS), and integrates the models. Images in each sub-image sequence partially overlap with previous and subsequent sub-image sequences. The local 3D models are integrated into a 3D model using transformation parameters computed from camera trajectories estimated by the SfM–MVS. In our experiment, we quantitatively compared the quality of integrated models with a 3D model generated from all images in a batch and the computational time to obtain these models using three real data sets acquired from a camera. Consequently, the proposed method can generate a quality integrated model that is compared with a 3D model using all images in a batch by the SfM–MVS and reduce the computational time. [ABSTRACT FROM AUTHOR]

Currently, over 100 nuclear power units globally have been in operation for more than 40 years. Hindered by the limitations of computer technology at the time, these nuclear facilities lack detailed electronic drawings. Activities such as equipment replacement and process circuit system modifications during operation result in discrepancies between paper drawings and actual conditions. Given the complexity and irreversibility of nuclear facility decommissioning activities, virtual simulation technology is often employed before the decommissioning process begins to assist in designing and validating decommissioning plans. Consequently, the creation of high-precision 3D models is crucial for subsequent decommissioning designs. Through innovatively utilizing laser-scanning 3D model reconstruction technology in the reconstruction of the model of China's first heavy water research reactor undergoing decommissioning, this paper provides an overview of the process of laser-scanning 3D model reconstruction and its application in reconstructing the heavy water research reactor model. Using a 3D laser scanner, four decommissioning areas of the heavy water research reactor, including the reactor building, secondary water pump room, ventilation center, and low-level radioactive wastewater storage tank area, were subjected to 3D laser scanning. The acquired point cloud data from 572 scanning stations were processed using point cloud processing software for denoising, stitching, and triangulation. The triangulated model was then imported into modeling software for 3D reconstruction, ultimately establishing a digitalized model of the heavy water research reactor suitable for subsequent decommissioning simulation and design. [ABSTRACT FROM AUTHOR]

The article aims to propose a social impact assessment model that can help operators in the oil and gas exploration and production sector to evaluate the social impacts in the onshore and offshore dimensions of the decommissioning of subsea oil and gas production systems. Based on the technical characteristics of the operation, the literature review and the workshops held with interested parties, the conceptual model was developed. The model includes 2 dimensions: (i) onshore, which encompasses impacts on logistics and infrastructure and onshore employability, and (ii) offshore, which involves external context, restrictions on artisanal fishing, restrictions on tourist activities and offshore employability. The impacts in both dimensions result from the operationalization of decommissioning. The contribution of this study is to propose a social impact assessment model that takes into account the onshore and offshore dimensions of the offshore-based decommissioning process of submarine systems and to propose future research. The proposed model can support decision-making by companies and governments in the process of decommissioning submarine systems and can also help other types of offshore installations. [ABSTRACT FROM AUTHOR]

During the Fukushima Daiichi Nuclear Power Plant (1F) accident, volatile radioactive fission products (FPs) such as Cs-137 were released, which significantly influenced mid- to long-term decommissioning strategies. A substantial amount of the remaining cesium in the pressure vessel may have deposited onto the 304 stainless steel (SS304) steam separators and dryers. This deposited cesium presents a safety hazard during 1F's decommissioning, as it can generate radioactive dust and complicate waste storage. However, the cohesive and adhesive strengths of CsOH-chemisorbed oxide scales, crucial for understanding the release of cesium-bearing particles from SS304 surfaces, remain undefined. In this study, we explore how CsOH chemisorption affects the cohesive and adhesive strengths between oxide scales and SS304 substrates using a scratch tester. Our tests revealed that cracks formed at approximately the same load, but the overall cohesive strength of the oxide scales decreased following CsOH chemisorption. Furthermore, the transition from cracks to bulk separation occurred more rapidly in CsOH-chemisorbed SS304 substrates, especially those with lower silicon content. Finally, we found that adhesive failure could not be achieved even at 70 N, suggesting that the deposited cesium cannot be completely removed from SS304 during the decommissioning of 1F. [ABSTRACT FROM AUTHOR]

Since 2016, the Bureau of Safety and Environmental Enforcement (BSEE) has collected decommissioning expenditure data from operators in the deepwater US Gulf of Mexico, defined as water depth greater than 122 m, to estimate the decommissioning liability of leases. BSEE uses both statistical tools and work decomposition methods to estimate the decommissioning cost of all active wells, structures, and pipelines on deepwater leases. The purpose of this paper is to evaluate BSEE cost estimates in the deepwater US Gulf of Mexico across four decommissioning stages and to infer unit cost statistics and cost functions in the region. Fixed platforms in 250–500 m water depth are expected to cost between $10 and $80 million to decommission, spars about $55 million, ship-shape floaters around $30 million, and tension leg platforms and their smaller (mini) versions between $18 and $25 million. The deepwater decommissioning market value is estimated at $24.3 billion circa 2022. [ABSTRACT FROM AUTHOR]

Abstract: Aims We assessed the beta diversity of macroinvertebrates associated with aquatic macrophytes in a dam-regulated river floodplain. We tested two hypotheses: (1) macroinvertebrates associated with aquatic macrophytes have higher beta diversity (higher turnover and nestedness components) in the downstream areas closer to the São Francisco River compared to upstream sites; (2) closer lakes share a higher similarity of aquatic macroinvertebrates, disregarding their position relative to the dam. Methods We sampled four lakes, including two upstream (L1- natural and L2- regulated by a Small Hydropower Dam - SHD) and two downstream (L3, L4, unregulated) by the SHD. Results We corroborated our first hypothesis because we found a higher turnover of macroinvertebrates associated with aquatic macrophytes close to the São Francisco River (L4 downstream), where higher non-native mollusk species richness occurs, while we found higher nestedness upstream and downstream of the SHD (L1, L2, L3). We corroborated our second hypothesis, as closer lakes are more similar than distant lakes. Finally, these differences were consistent between lakes for emergent, floating leaf, and submerged aquatic macrophytes. Conclusions Aquatic macrophytes are essential habitats for macroinvertebrates in the Pandeiros River basin, with higher beta diversity in the lake closer to the São Francisco River.

Abstract A model of the evolution of the onshore wind turbine blade mass installed in Denmark is proposed described by a Weibull distribution, and the age of the blades is estimated from decommissioning data to t50%,onshore = 29 years when half of the blade mass of an installation year has been decommissioned. This is considerably longer than the 20 year design lifetime of onshore turbines, which is often assumed to be an estimate of the End‐of‐Life of turbine blades. Thus, blade waste predictions using the simple assumption may predict that installed blade masses are entering recycling processes about 9 years sooner that what is observed in Denmark. The blade mass for decommissioning in Denmark is estimated to peak at 2000 and 5000 ton/year in 2028 and 2045 using the Weibull model.

The calculation and visualization of the dose field in the decommissioning of nuclear facilities is one of the important functions of the decommissioning virtual simulation system. The dose field simulation tools can provide radiation field distribution and play an important role in determining the decommissioning plan and protecting personnel during the engineering implementation process. This article investigates the development of dose field calculation and visualization in the reactor decommissioning virtual simulation systems. A preliminary technology plan suitable for the development of the decommissioning dose field calculation and visualization display programs of the first Heavy Water Research Reactor (HWRR) in China is proposed. The applicability of the selected scheme is analyzed. The functional requirement and development direction of the HWRR reactor decommissioning dose field tool are preliminarily determined. Furthermore, the reactor vessel of HWRR reactor is modeled, the dose field distribution is calculated and visualized based on the preliminary decommissioning code. This research can provide technical support for the development of the decommissioning simulation system for the first HWRR reactor in China.

Offshore wind has rapidly developed over the past three decades, with over 6000 fixed-bottom substructures installed in Europe alone as of 2022. Despite this progress, there has been limited focus on the end-of-life stages, particularly decommissioning, which is currently the default option. Sustainable offshore wind development hinges on effective decommissioning strategies for fixed-steel pile foundations. This review critically examines state-of-the-art pile-foundation-decommissioning methods recently tested in industry and academia, including partial-removal techniques like internal cutting and external cutting and full-removal approaches such as excavation and novel extraction methods. Key factors influencing decommissioning decisions, such as seabed disturbance, environmental impact, reuse potential, and cost, are discussed. Analyses reveal that current partial-removal strategies could render vast swaths of marine areas inaccessible for future development. In contrast, full removal through extraction may enable complete recycling and minimise post-decommissioning monitoring. However, significant knowledge gaps remain regarding novel extraction methods’ scalability, technical feasibility, and economics. Extensive research encompassing engineering, environmental, and economic dimensions is essential to develop holistic pile-foundation-decommissioning solutions that facilitate the sustainable long-term growth of offshore wind.

It is observed that the number of onshore wind farms that reach the end of their service life is continually increasing. The decision-making process that defines the future of the farm is a challenge for the owners. This systematic review aimed to identify which factors influence the decision-making process at the end-of-life cycle of onshore wind farms. In accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol, a research strategy was developed and used the Scopus, Web of Science and EMBASE databases. Initially, 2767 articles were identified, but, after double-blind screening, 26 articles were analyzed in full. The scarcity of studies on this topic and little elucidation are limitations of this review. The results include (i) a systematization of six options for decision making, (ii) thirteen factors influencing the decision-making process associated with categories of external factors (logistics and infrastructure aspects, regulatory aspects and public policies, national energy guidelines, the technological development of the sector); and internal factors (economic/financial, operational and environmental aspects). It is concluded that most of the publications consist of simulations and theoretical studies highlighting a bottleneck in experiences and feasible data to support decisions at the end of service life. It is highlighted that most of the studies showed that partial decommissioning with partial repowering, as well as total decommissioning, were the most feasible options for the end-of-life cycle, with aspects related to public policies and regulatory aspects, as well as environmental, operational and economic/financial aspects, being the most influential, especially due to the wake effect, operation and maintenance costs (OPEX) and the protection of guarantees and incentives for operation in a new operating cycle. [ABSTRACT FROM AUTHOR]

Knowledge of platform ecology is necessary to best inform decommissioning practice. Remotely operated vehicle (ROV) video is often collected during standard industry operations and may provide insight into the marine life associating with offshore platforms, however, the utility of this video for ecological assessments remains unclear. Archival ROV video surveys at the Wandoo oil platforms on Australia's North West Shelf was evaluated for its utility, with only 4.9% of imagery usable for standardised ecological studies. Based on the subset of usable ROV video, the influence of depth and structural complexity on attributes of the fish assemblage on the Wandoo oil platforms was examined. Vertical ROV transects on three vertical shafts on the Wandoo platforms were stratified into 10 m depth strata from 0 to 50 m, with 111 fish taxa from 25 families identified and counted across all depth strata. At both platforms, taxonomic richness and abundance was significantly highest in shallow regions and declined with depth. Small reef fish were predominantly associated with structurally complex habitat in shallow regions (<22 m), whilst large demersal species dominated below 32 m. Future decommissioning policy in Australia should consider the vertical fish distributions and the importance of shallow sections of platforms. Finally, the dearth of usable video was due to the haphazard method of collection and it is recommended that future surveys should be conducted according to scientific standards to ensure greater utility of the video for both industry use and scientific research. [ABSTRACT FROM AUTHOR]

In the decommissioning of the Fukushima Daiichi Nuclear Power Station, radiation dose calculations necessitate a 3D model of the workspace are performed to determine suitable measures for reducing exposure. However, the construction of a 3D model from a 3D point cloud is a costly endeavor. To separate the geometrical shape regions on 3D point cloud, we are developing a structure discrimination method using 3D and 2D deep learning to contribute to the advancement of 3D modeling automation technology. In this paper, we present a method for transferring and fusing labels to handle 2D prediction labels in 3D space. We propose an exhaustive label fusion method designed for plant facilities with intricate structures. Through evaluation on a mock-up plant dataset, we confirmed the method's effective performance. [ABSTRACT FROM AUTHOR]

After the nuclear accidents of Chernobyl and Fukushima, several countries concerned with nuclear energy production set up robotic accident intervention groups with the aim to intervene in place of humans in hostile environments with high levels of contamination or irradiation. It is the case of France. The operational feedback of such robotic groups may be of interest for teams performing decommissioning on nuclear facilities. In this aim, a comparative analysis of robotic intervention contexts was undertaken between training contexts and a real operating situation. This allowed us to confirm determinants of performance already identified in the literature and highlighted new determinants of performance for intervention in nuclear environments. [ABSTRACT FROM AUTHOR]

The most challenging task in the decommissioning of the Fukushima Daiichi Nuclear Power Station is to retrieve molten and solidified fuel debris, including in reactor internals. The International Research Institute for Nuclear Decommissioning (IRID) has developed various robots that can investigate the interior of a primary containment vessel (PCV) to clarify where fuel debris has accumulated and how it has formed. The scenarios of each unit caused by the accident are different; therefore, IRID has developed robots to satisfy the requirements of each unit. The robots can be categorized into three types: non-submersible robots driving through air, submersible robots swimming underwater, and investigation robots with arms that can extend to enter the PCV. This review focuses on the technological development of robots based on their functionality. Most of the robotic technology is acquired and utilized based on the results of subsidy projects for countermeasures for decommissioning and contaminated water granted by the Japanese government. [ABSTRACT FROM AUTHOR]

During the decommissioning activities, a movie was shot inside the reactor building during the investigation of the primary containment vessel by applying photogrammetry, which is one of the methods for three-dimensional (3D) reconstruction from images, to the images from this movie, it is feasible to perform 3D reconstruction of the environment around the primary containment vessel. However, the images from this movie may not be suitable for 3D reconstruction because they were shot remotely by robots owing to limited illumination, high-dose environments, etc. Moreover, photogrammetry has the disadvantage of easily changing 3D reconstruction results by simply changing the shooting conditions. Therefore, this study investigated the accuracy of the 3D reconstruction results obtained by photogrammetry with changes in the camera angle of view under shooting conditions. In particular, we adopted 3D computer graphics software to simulate shooting target objects for 3D reconstruction in a dark environment while illuminating them with light for application in decommissioning activities. The experimental results obtained by applying artificial images generated by simulation to the photogrammetry method showed that more accurate 3D reconstruction results can be obtained when the camera angle of view is neither too wide nor too narrow when the target objects are shot and surrounded. However, the results showed that the accuracy of the obtained results is low during linear trajectory shooting when the camera angle of view is wide. [ABSTRACT FROM AUTHOR]

A model of the evolution of the onshore wind turbine blade mass installed in Denmark is proposed described by a Weibull distribution, and the age of the blades is estimated from decommissioning data to t50%,onshore = 29 years when half of the blade mass of an installation year has been decommissioned. This is considerably longer than the 20 year design lifetime of onshore turbines, which is often assumed to be an estimate of the End‐of‐Life of turbine blades. Thus, blade waste predictions using the simple assumption may predict that installed blade masses are entering recycling processes about 9 years sooner that what is observed in Denmark. The blade mass for decommissioning in Denmark is estimated to peak at 2000 and 5000 ton/year in 2028 and 2045 using the Weibull model. [ABSTRACT FROM AUTHOR]