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[en] The IAEA Coordinated Research Programmes (CRPs) on the behaviour of spent fuel and storage facility components during long term storage were initiated in 1981 under various titles. The first programme was designated BEFAST-I (BEhaviour of spent Fuel Assemblies in STorage), followed by BEFAST-II in 1986 and BEFAST-III in 1991. Follow-on CRPs were called SPAR-I to -III (Spent fuel Performance Assessment and Research), respectively. Overall, 20 countries and one international organization participated in one or more of the CRPs. During the CRPs, the participating countries contributed their R&D results on fundamental questions regarding spent fuel storage. The overall objectives of the CRPs were to develop a technical knowledge base on long term storage of commercial power reactor spent fuel through evaluation of operating experience and research by participating Member States, and to extrapolate predictions of spent fuel behaviour over long periods of time. A final report for each stage of the CRPs was prepared and published as an IAEA Technical Document (TECDOC). Towards the end of the BEFAST-III project, it became apparent that the R&D component of the project was decreasing steadily; more emphasis was being placed on the operation and implementation of storage technology. However, the storage technology (particularly dry storage) was undergoing a rapid evolution: new fuel and material design changes were coming on stream and target discharge burnup were steadily increasing; in addition, storage durations were predicted to be much longer than anticipated. Because of all these changes, a subsequent project was proposed to address the impact of these new parameters on long-term storage and to determine their consequences on subsequent operations, especially handling and transportation. The paper describes the research objectives and a selection of the findings related to spent fuel and storage system performance of the BEFAST and SPAR activities from 1981 until today. (author)
[en] The United States Department of Energy (DOE) is beginning to lay the groundwork for implementing interim storage of spent nuclear fuel (SNF) as recommended by the Blue Ribbon Commission on America’s Nuclear Future (BRC). These plans include activities to: 1) establish one or more Interim Storage Facilities (ISF) using consent-based siting; and 2) prepare for large-scale transport of SNF. The BRC’s report to the Secretary of Energy was published on January 26, 2012. The Administration’s Strategy for the Management and Disposal of Used Nuclear Fuel and High-Level Radioactive Waste was released on 11 January 2013. The Strategy includes a phased, adaptive, and consent-based approach to siting and implementing a comprehensive management and disposal system. As part of a series of ongoing foundational activities the DOE has completed initial studies to more fully develop and document a suite of generic design alternatives for an away from reactor interim storage facility focused on the receipt and storage of SNF in welded canisters. Concepts developed include: 1) The currently deployed and U.S. licensed above grade vertical and horizontal storage systems associated with each canister design; 2) A standardized storage over pack; 3) Below grade cylindrical vertical storage cavity and closure lid that provides radiation shielding and structural protection during storage; and 4) Vault System above and below grade. This paper will review some of the design concepts developed. The paper draws upon material produced by Chicago Bride and Iron for the United States Department of Energy. (author)
[en] An Execution Strategy Analysis (ESA) capability and tool is being developed to evaluate alternative execution strategies for future deployment of a consolidated Interim Storage Facility (ISF) using a consent-based siting process per the Administration’s Strategy for the Management and Disposal of Used Nuclear Fuel and High-Level Radioactive Waste (Strategy). Application of an ESA approach not only leverages on but also goes beyond traditional project analysis tools. The ESA tool allows for on-going performance assessment of the evolving project execution plan that takes into account significant assumptions, risks, and uncertainties throughout the project lifecycle. The ESA process and tool are used to support the development of plans, budgets, and alternative execution/ implementation strategies for meeting the goals in the Strategy. The paper describes the process by which the ESA capability and tool are continuing to be developed and addresses the value of applying such a process in implementing a long-term strategy for managing used nuclear fuel (UNF) and High Level Radioactive Waste (HLW). (author)
[en] Dry storage was originally designed to cool down and reduce the radioactive levels from spent nuclear fuel (SNF), so that reprocessing and recovery of valuable fission products can start and as alternative technology to wet storage after the required cooling time of SNF at reactor pools. Current existing dry storage facilities are designed for several decades of operation and, among other dry storage systems, concrete casks and vaults have demonstrated to be credible solutions for long term storage of SNF. Extending currently licensed storage periods will require licensees and certificate of compliance holders to renew and extend their initial license term. Thus, as part of the revised ageing management programmes, the licensees need to address the potential degradation mechanisms of concrete casks, as well as consider the use of different inspection techniques to detect these mechanisms in order to monitor cask performance throughout this extended period. There are four different dry storage system designs employing concrete: (1) Bolted lid cask employing shielding materials in the cask wall. In some bolted lid designs, concrete is included in the cask wall; (2) Steel canisters inside concrete overpacks (horizontal design); (3) Steel canisters inside concrete overpacks (vertical design). There are two variants of the vertical design: (a) Concrete overpacks exposed to the atmosphere. The exposed concrete surfaces of the concrete cask are coated with a commercial-grade sealant to provide protection to the cask surfaces during current and long term storage operations; (b) Concrete overpacks with an outer steel liner; (4) Concrete vaults. This type of storage system uses metal canisters in all-metal silos located inside concrete vaults. Only types (2), (3)(a) and (3)(b) are considered in this chapter.
[en] Degraded landscapes adjacent to gold tailing storage facilities (TSFs) typically suffer from loss of ecosystem function as a result of seepage pollution. Restoration of these areas has become a primary concern in the fields of environmental science and management within recent decades. To assess the extent of land degradation, detailed monitoring of pollution took place over a period of 4 years on farmland adjacent to a gold TSF in South Africa. The Landscape Function Analysis (LFA) monitoring procedure was developed by David Tongway for the Australian rangelands, and has been utilised in this investigation to assess the impact of seepage pollution on the soil within the aforementioned farmland area. This paper indicated that the LFA procedure could not accurately present landscape stability and ecosystem functionality at the seepage-polluted sites within the short monitoring period presented in this study. It was established that no adverse effects on the natural vegetation were apparent, other than encroachment by Seriphium plumosum, which affected the grazing quality of the area but contributed significantly to the LFA values.
[en] Research activities on steel corrosion in concrete at ZAG started more than a decade ago, with the main focus on developing monitoring systems that would be capable of following the evolution of corrosion processes under various conditions. It should be mentioned that these activities were not oriented specifically at issues of dry SNF storage, but they opened new possibilities for monitoring the evolution of corrosion damage in SNF/HLW dry storage facilities.
[en] Civil engineers analyze, plan, and design Portland cement reinforced concrete structural components and structural systems. Durability considerably concerns civil engineers who prepares specifications for concrete service life. The service life of a reinforced concrete is determined by its design, construction, ageing and maintenance during use. The prediction of the deteriorative influences that could cause degradation of concrete in the environment it is exposed is an important task. Durability of cementitious materials mostly depends on the possibilities of penetration of hazardous ions into the porous material with water as medium, and pore connectivity, the fraction of total porosity that is connected, exerts an important control on preferential flow into cementitious materials. This work presents results of quantitative evaluation of pore connectivity of graphene-based cement nanocomposite. Three mortar mixtures were prepared with different graphene addition. A geometric modeling considering pore with cylindrical shape was applied in order to evaluate the pore network connectivity. The results showed pore structure connectivity depends on graphene addition percent. The goal of this research is to provide technical requirements related to the production the Brazilian radioactive waste repository. (author)
[en] Efficient spent fuel management (SFM) requires an evaluation of the potential interface issues among phases of the nuclear fuel life cycle including: process and equipment compatibility; policy considerations; and different positions of the many stakeholders that influence management options and decisions. Because many issues affect multiple stakeholders and may require long lead times to resolve, it is important to identify interface issues early and solve them in a timely manner. Opportunities are lost if interfaces are not identified and addressed in the early stages of each of the back-end of fuel cycle (BEFC) phases. The objective of this paper is to suggest a process for systematically identifying and evaluating the potential interface issues in SFM, and to recommend effective management based on the experience of Member States before losing timely resolution opportunities. The principles presented in this paper emphasize the importance of systematically identifying and managing interface issues within the BEFC. Because of the complexity of the issues and interfaces, a process is provided to help ensure exact identification of applicable interface issues and consideration of the associated issues and opportunities. Of the conclusions drawn; the most important are: assuring compatibility of schedules, equipment, and acceptance criteria are key to solve interface issues; Interface issue will take on increasing importance as storage periods are extended and countries plan consolidation into regional or centralized dry storage facilities, particularly if inspections and/or repackaging are needed to prepare fuels for long-term storage; additional pro-active efforts are needed from every participating organization in the BEFC to ensure early attention to public acceptance. Accurate information must be provided in a user friendly format. (author)
[en] The report “Managing Aging Effects on Dry Cask Storage Systems for Extended Long-Term Storage and Transportation of Used Fuel, Rev. 2” is a key reference in the U.S. Nuclear Energy Institute’s (NEI’s) “Industry Guidance for Operations-Based Aging Management”. The guidance in NEI 14-03, Rev. 0 was submitted for endorsement by the U.S. Nuclear Regulatory Commission (NRC) in September 2014, while the NRC is updating its own guidance document in the “Standard Review Plan for Renewal of Used Fuel Dry Cask Storage System License and Certificate of Compliance”, NUREG-1927. The main features of the aging management report are highlighted, along with a brief discussion of guidance documents from industry and NRC, as well as the aging management needs for a Pilot Interim Storage Facility and beyond. The latter is of interest as the used fuel may need to be stored and transported multiple times before final disposal at a mined repository or geological disposal facility. (author)