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Advances and Innovations in Nuclear Decommissioning

By: , Posted on: July 14, 2017

Nuclear decommissioning has been a mature industry (and a mature science) for at least 10–15 years. The cessation of major R&D programs (national, e.g., under the aegis of the US Department of Energy, and international, e.g., by the European Commission) around the year 2000 ideally signaled a general understanding that the basic decommissioning technology was available worldwide. Since then, technological efforts have aimed at optimizing methods and techniques, but no major breakthroughs have emerged. As of today, it is commonly accepted that the industry can effectively deal with almost all cases of nuclear decommissioning, with exceptions remaining for large facilities that had been affected by severe accidents resulting in exceedingly high contamination and irradiation levels. Other difficult-to-decommission facilities include those that were built at the beginning of the nuclear era, when design and operation criteria were much less stringent than they are today. And yet, the experience being gained from the decommissioning of Fukushima, especially from the wide use of robots and other remotely operated technology, can influence the decommissioning strategies more than currently appears to do: it is not unthinkable that in the not-too-far future a fleet of robots will do a high portion of decommissioning work instead of humans. But for this to happen (a real breakthrough, indeed!), robotics costs should become more affordable and robots should become more versatile. A full chapter has been given in this book to explain the decommissioning process after a severe accident.

As mentioned above, to do justice to technological progress, decommissioning is a mature industry. Therefore a few years ago I was tasked with editing of Laraia1, which was a consolidated summary of all decommissioning aspects that prevailed at that time. Decommissioning is multifaceted (or multidisciplinary): Laraia1 dealt with such aspects as assessment of decommissioning strategies, safety and radiation protection, decontamination and dismantling, waste management, planning, redevelopment of decommissioned sites, and international experiences. Laraia1 was intended for those embarking in nuclear decommissioning as newcomers or upgrading their skills to a new field. It provided comprehensive knowledge of decommissioning as standalone science. To this end, the book maintains its usefulness to date.

Six years have not passed in vain. It was already evident in 2011—when the book was completed—that decommissioning should have not been examined only from the angle of technology. For example, there were chapters in Laraia1 about stakeholder involvement and the organization and management of decommissioning projects. The “soft side” of decommissioning had already come to light; but, as that book provided a summary of the basic knowledge of the time, it gave more emphasis to the consolidated aspects of decommissioning and less emphasis to the emerging aspects. It is assumed that the large pool of decommissioning experts at work today, including a network of companies and independent consultants specializing in decommissioning as a whole and in specific aspects of it—vendors, suppliers, and all those who make decommissioning an international “market”—need to familiarize themselves with aspects that were not deemed essential in 2012. Laraia1 maintains its role of providing background information and guidance and should be usefully read or consulted as a precursor to this book.

Therefore the chapters that follow, while being a follow-up to Laraia1 as far as general progress is concerned, and more and more experience and feedback is being gained, cast light also on new areas.

Click here to read the Introduction for a limited time on ScienceDirect.

In regard to advances, this book expands on emerging technologies. As said above, while no major technological breakthroughs are expected in the near future, a continual flow of advances contributes to making decommissioning a safer and more cost-effective technology. If one refers to the automobile industry, it can be stated that car manufacturing has been a mature industry for at least 50 years, yet more recent advances like the anti-lock braking system have significantly improved the safety of driving. Likewise the growing use of lasers as cutting or decontamination tools has greatly added to the accuracy and efficiency of decommissioning.

Another chapter deals with new international recommendations in safety and radiation protection and their application to decommissioning. In this regard the key milestone can be attributed to the 2014 publication of the new edition of the Basic Safety Standards (BSS), sponsored by the IAEA and a number of other international organizations. In the field of decommissioning, it is expected that the BSS will contribute to achieve harmonization of national approaches to decommissioning, especially as far as clearance criteria are concerned.

To provide examples of growing experience, this book addresses the post-2012 decommissioning of nuclear power plants worldwide, and a chapter that did not exist in Laraia1 discusses the decommissioning of research reactors. The sheer number of research reactors that have reached the end of their service lives and are planning for and implementing decommissioning worldwide (at least 100 reactors), and the diversity and uniqueness of research reactor features make them an ideal target for a dedicated chapter.

Experience has shown that decommissioning (i.e., dismantling) and environmental remediation projects on the same site are both aimed at reducing hazards and/or achieving a common end state for the facility and its site. Therefore, decommissioning and remediation should be ideally viewed in conjunction since they require the integration and optimization of infrastructure (i.e., human, scientific, and financial resources). The integrated management of decommissioning and remediation is expected to more consistently achieve the site end objectives and require less post-decommissioning remediation work and more manageable institutional control. A dedicated chapter of this book provides some examples and scenarios in which decommissioning and remediation projects developed in an integrated fashion should produce successful outcomes.

As said initially in this preface, the period that elapsed since the publication of Laraia [1] has seen the appearance of new lines of thought, as well as innovations. In other words, there are aspects of decommissioning that were not given adequate attention in the past and these are more important now because other more traditional issues have been solved.

To begin with, the cultural changes taking place in an organization transitioning from operations to decommissioning require attention. The cultural issues of a decommissioning project (e.g., workers’ backgrounds, sense of ownership, or team spirit), though contributing to a considerable portion of all decommissioning-related incidents and near-misses, have yet to be thoroughly reviewed, and it time that this experience is discussed; therefore, a chapter is devoted to this in this book. Culture includes people and human factors. The goal of the chapter on decommissioning culture is to provide information regarding cultural issues, their impacts on activities, and anticipated challenges due to culture.

Given the long timescales of decommissioning projects (100 years or more, especially if early and detailed planning is included), the preservation of well-understood information and its transfer to subsequent generations and responsible organizations are vital elements of the decommissioning industry. Future players will need to know enough about contaminated facilities and sites so that they are aware of the remaining hazards and make risk-informed decisions concerning the safety, security, and ultimate redevelopment of the site. The information must be preserved in a form that can be retrieved, understood, and usable over a long period of time.

A dedicated chapter stresses the fact that the planning and implementation of decommissioning generates a considerable amount of information, which can be incorporated in records, and in the tacit knowledge accumulated by those directly involved in these activities. So far the decommissioning community has instead focused on the technological aspects of record preservation (e.g., longevity). While these studies remain important, there have been only a few examples where the conceptual issues of an integrated and comprehensive (i.e., open to all stakeholders) knowledge management system have been addressed.

Another chapter of this book is given to the financial aspects of decommissioning. On one hand, there are projects where the very fact that several players are ready to bid for a contract implies that there must be a “real cost” of decommissioning; on the other hand, diverging, escalating costs of decommissioning projects are often quoted as evidence of the uncertainties still looming on this topic. Decommissioning cost estimations can vary considerably both within and across countries, even for similar facilities. These differences may have good technical reasons but make the process of reviewing estimates difficult and the estimates themselves vulnerable to criticism. Therefore, the recent publication of the International Structure for Decommissioning Costing (ISDC) of Nuclear Installations by the OECD Nuclear Energy Agency (NEA), the International Atomic Energy Agency (IAEA), and the European Commission (EC) intended to propose an internationally-accepted, standard structure of decommissioning cost items either directly for the production of cost estimates or for purposes of comparison. This and other innovations in the financial field of decommissioning are discussed in the pages that follow.

Another chapter deals with unexpected events and findings during the decommissioning of nuclear facilities, and the lessons learned from those events. They have often been referred to as “unknowns”; however, many of the problems encountered during decommissioning were well known, but they simply were not given enough attention. In some other cases, the problem may not have been ever encountered by the decommissioning team, prompting the sudden development of new tools and procedures with inevitable delays and extra costs. In this chapter, examples of actions, decisions, or omissions are given and some analysis has been performed to identify the underlying causes that may lead to unexpected difficulties during decommissioning. The chapter evaluates the need for, and implications of, using lessons learned to prepare for possible occurrences; it also discusses how to mitigate the impacts of any such occurrences.

In a dedicated chapter of Laraia1 the term “stakeholders” had been used mostly to designate the local communities. This is not the case for a “follow-up” chapter in this book, where non-local categories of the populace and various public interests are also addressed. Stakeholders addressed in this book are not just those living in the vicinity of the nuclear installation under decommissioning. In fact, impacts from a large project can be felt in distant countries (e.g., in financial terms or in image). It is therefore essential for those responsible for a decommissioning project to identify all possible stakeholders at the onset of a project and to start a dialogue with no unnecessary delay.

Finally, a new trend has emerged in recent years. Previously it was de facto assumed that the (radiological) end state of a decommissioned site should be unrestricted release (greenfield). Likewise, it was assumed that materials resulting from decommissioning should be either released as nonradioactive for unrestricted release or disposed of as radioactive waste. Experience has shown that less expensive, intermediate options are possible; the site itself could be subject to restricted release (brownfield) or the materials and waste arising from decommissioning could be released in a predetermined condition or for predefined uses. Another chapter of this book deals with these innovations.

The target groups of this book are decision-makers, plant operators, contractors, waste managers, and regulators involved in planning, management, authorization, and execution of decommissioning activities. The report is particularly relevant for those responsible for nuclear facilities approaching the end of their foreseen lifetime. The report should also be of interest for the designers and builders of new nuclear installations: to date it is a general requirement that the design and construction of nuclear installations should include full consideration of eventual decommissioning. It is assumed that the readers will have basic knowledge of such disciplines as nuclear physics, radiation protection, and waste management.

This book is based on presenting, discussing, and exchanging information on international experience, lessons learned (not leaving out mishaps and near-misses), issues, and challenges in planning for and implementing the decommissioning of nuclear installations. Special focus is given to international (especially IAEA’s) positions, recommendations, and guidelines inherent to all aspects of decommissioning. As a practical means to ensuring success, the book is imbued with a sense of realism. To this end, wide use is made of case studies, facts-of-life and anecdotal evidence. As decommissioning is a multidisciplinary process, an integrated approach is pursued and single aspects are considered from multiple angles.

Reference: 1. M. Laraia (Ed.), Nuclear Decommissioning: Planning, Execution and International Experience, 978-0-85709-115-4, Woodhead, Cambridge (2012)

You can read the Introduction for a limited time on ScienceDirect.

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