Safe Decommissioning of Civil Nuclear Industry Sites
This WNA Position Statement presents the nuclear industry's perspective and policy on the important subject of decommissioning of civil nuclear industry sites.
Inevitably, each country and each company employs a decommissioning strategy appropriate both to the type of site to be decommissioned and also to a specific national, local and technical context. Despite such diversity, this Statement reflects a confident industry consensus that a common dedication to sound practices throughout the global nuclear industry is well established and continues to enhance an already robust record of safe and affordable decommissioning of all types of civil nuclear industry sites, from uranium mines to nuclear power reactors.
This text focuses solely on modern civil programmes that contribute to nuclear electricity generation. It does not deal with the sites from military or early civil nuclear programmes. These sites fall into the category of"legacy activities", which are generally accepted as the responsibility of national governments. It bears emphasis, however, that the decommissioning of legacy activities has also been conducted safely, and the experience gained has enhanced the process of successful decommissioning of modern civil nuclear industry sites.
Decommissioning is a normal and necessary post-operations phase. It is defined as all steps leading to the release of a nuclear site - including facilities, land, buildings and equipment - from regulatory control. These steps include the processes of decontamination and dismantling. The nuclear owner/operator is the entity responsible for all aspects of a site's decommissioning.
The two main objectives of decommissioning are to render the site permanently safe and to restore it, as far as practicable, for re-use. In pursuit of this outcome, no significant health risk may be borne by people nor may any danger be posed to the environment. After decommissioning, control of a site can reliably be reduced or even terminated without cause for concern. The nuclear industry is fully committed to the twin objectives of decommissioning: safety and restoration for re-use.
There is now a wealth of industry experience in decommissioning. Worldwide, over 100 mines, 90 power reactors, 250 research facilities and many other fuel cycle facilities have been, or are being, successfully decommissioned. Throughout the nuclear industry, this experience has been widely shared through exchange mechanisms organized by such international organizations as the IAEA (International Atomic Energy Agency), the NEA-OECD (Nuclear Energy Agency of the Organization for Economic Cooperation and Development) and the WNA. Such information exchange helps practitioners draw lessons-learned and to adapt and improve known approaches and techniques. Meanwhile, there has been a steady growth in public appreciation that nuclear sites operate safely with due care for the protection of people and the environment. This confidence is a natural consequence of comprehensive health, safety and environmental programmes that conform with regulatory frameworks. The nuclear industry recognizes that such regulatory standards are indispensable to the successful operation of all phases of civil nuclear activity, including decommissioning.
Sites undergoing decommissioning are intrinsically safer than sites in operation. This occurs because high-level radiation sources that can pose a significant hazard are, along with radioactive process materials, either removed or secured as decommissioning commences. Despite the overall decrease in radiation risk, strict attention needs to be paid to radiation safety during decontamination and dismantling activities. These activities must also be conducted carefully in terms of conventional industrial safety.
The shift from productive operations to decommissioning activities requires transitional planning. Once decommissioning begins, decontamination and dismantling become the primary activities as the site is rendered permanently safe and restored for re-use. This transformation of purpose inevitably leads to significant organizational and cultural changes. Planning is essential to help the workforce prepare for these changes, which potentially involve re-deployment or re-employment. As operations move into full-scale decommissioning, the requirement for different skills leads inevitably to a shift in workforce composition, usually involving specialized contractors. As established decommissioning practice, the nuclear industry recognizes and fulfils its responsibilities to those who have been employed at the facility being closed.
Restoring sites for re-use embodies the principle of sustainability and is a fundamental industry goal. The first benchmarks of successful decommissioning are: (1) safety and protection of the workforce, the public and the environment; and (2) restoring the site as far as practicable. The industry's even broader aim is to achieve site re-use wherever possible. A sequence that begins with safe and clean operations, passes through safe decommissioning, and culminates in effective site re-use represents the fullest possible application of the principle of sustainability.
Fundamental environmental principles - Reduce, Recover, Recycle and Re-use (the "Four Rs") - are integral to successful decommissioning. Applying these principles means minimizing contamination and recovering, recycling and reusing materials, equipment, and even waste to the fullest practical extent. Disposal is used only as a last resort. Typically, over 90% of the volume of waste generated during the decommissioning of a nuclear facility has little or no radioactive contamination, and most of the remainder has only a very low level of radioactivity. Thus, only a small percentage of waste material must be dealt with as low- or intermediate-level radioactive waste.
In developing sound end-uses for the vast majority of the materials and wastes that arise from site decommissioning, the nuclear industry acts in accordance with internationally agreed rules and procedures. These in turn are consistent with the standards governing trade in materials and goods between countries. The WNA Statement on Removal from Regulatory Control of Material Containing Radioactivity - Exemption and Clearance advocates that national authorities encourage even greater convergence toward a common set of internationally recognized rules; it argues against any attempts to move away from greater uniformity of standards and procedure.
Equally as important as the re-use of materials and waste is the re-use of land, water bodies and buildings after site decommissioning. The fact that nuclear facilities represent only a small percentage of a site's overall acreage facilitates the opportunity for site restoration and re-use. Such re-use often ranks high in public expectations.
Applying the Four Rs represents not only sound environmental practice but also creates opportunities for workforce re-deployment and local redevelopment. In commercial terms, the optimal re-use of a successfully decommissioned nuclear site may well be to build a new nuclear facility there. This option may also be optimal in a broader socio-economic sense - because it employs local skills already present and because nuclear sites usually enjoy long-standing local public support. As public appreciation of nuclear energy continues to grow, the expectation of site re-use for further nuclear operations may well become the norm.
Decommissioning requires a sound infrastructure for the management of waste and material. While the overall volume of waste is relatively small - and the nuclear industry's aim is to minimize this volume - it is essential to successful decommissioning that governments and industry have acted to ensure the existence of sufficient storage and disposal capacity for low- or intermediate-level nuclear wastes. In most countries with major nuclear programmes, storage and disposal facilities of this kind are now operational. The WNA Position Statement on Safe Management of Used Nuclear Fuel and Nuclear Waste addresses this topic. Decommissioning situations involving Used Nuclear Fuel (UNF) and other high radiation sources may require interim storage capacity if a suitable disposal site - such as a deep geological repository - is not yet available.
In the decommissioning process, the owner/operator is faced with many compliance steps and milestones. These steps begin with the submission of a decommissioning plan and an application for a decommissioning licence. Regulations apply throughout decommissioning and thereafter, and the owner/operator maintains control after decommissioning until all regulatory requirements are satisfied. At this final stage, authorities can decide to partially or fully discharge the owner/operator's responsibilities and liabilities for the decommissioned site. In the decommissioning process, it is standard practice for the owner/operator to use a quality-based management system.
While the overall cost for decommissioning is significant, it is not prohibitive or even dominant. This cost is normally planned for at an early stage and is recognized as a basic responsibility of the owner/operator. Normal industry practice is to build a decommissioning fund during the lifetime of a facility. Because decommissioning costs are relatively small compared to the lifetime value of a nuclear facility's output, the financial resources necessary for decommissioning can be accumulated through a very modest incremental addition to the price of electricity from nuclear power plants or nuclear fuel-cycle services. Accruing the resources sufficient to achieve sound decommissioning is a recognized responsibility of the site owner/operator. The systematic nature and affordability of financing for decommissioning modern civil nuclear facilities should not be confused with the entirely different situation of managing legacy activities. These involve sites from military or early civil nuclear facilities and tend to be expensive and complicated.
Building pubic confidence and trust is essential to decommissioning and requires interaction with stakeholders and a clear accounting of environmental and socio-economic impact. The process of obtaining relevant authorizations for decommissioning a nuclear site requires the owner/operator to engage stakeholders in an interactive dialogue. This engagement is not only a necessary hurdle but can be valuable in building community understanding and cooperation. In this process, each side has something to offer. The nuclear industry can build clearer public awareness of the environmental dimensions of decommissioning, while stakeholders can help the owner/operator assess the socio-economic impact of decommissioning. Properly conducted, this dialogue can produce a plan for site re-use and for local re-employment and development that enjoys strong public support.
The safe decommissioning of civil nuclear sites is a widespread, well-demonstrated reality. The nuclear industry's strong record reflects a high degree of expertise and responsibility toward the well being of current and future generations. Accumulating experience and knowledge will serve to reinforce this already robust record of safety and achievement.
Restoring a nuclear site to the full extent practicable for re-use is fundamental to the sustainable use of resources and is the nuclear industry's guiding goal in decommissioning. Public expectations attach great weight to achieving a re-use plan that provides opportunities for workforce re-deployment and local redevelopment. The nuclear industry recognizes that a well-devised decommissioning plan can combine the fulfilment of environmental principles and of socio-economic obligations to the local community.
The nuclear industry has in recent decades successfully fulfilled its responsibilities for decommissioning its facilities and continues to meet these obligations with professional dedication and technological skill.
Additional Discussion of Safe Decommissioning Practice
DECOMMISSIONING - A NORMAL AND NECESSARY PHASE AFTER THE SAFE SHUTDOWN OF OPERATIONS
Decommissioning is a normal and necessary post-operations phase that marks the end of a site's original use. It also marks the beginning of an important new phase in which the site is rendered permanently safe and restored, to the full extent practicable, for re-use.
A site may be permanently shut down for several reasons. Among the sole or contributory factors are normal ageing/degradation; heavy refurbishment needs; and substantial changes in technologies, regulatory requirements, and markets. In the case of uranium mining sites, the cessation of a site's use often corresponds to the depletion of viable uranium ore deposits.
The UN's International Atomic Energy Agency (IAEA) defines decommissioning as "all steps leading to the release of a nuclear facility, other than a disposal facility, from regulatory control. These steps include the processes of decontamination and dismantling." The IAEA defines nuclear facility as "a civilian facility and its associated land, buildings and equipment in which radioactive material is produced, processed, used, handled or stored on such a scale that consideration of safety is required."
Decommissioning commences with the removal or securing of both high radiation sources that can represent a significant hazard and also radioactive process materials. Such sources include used nuclear fuel (UNF) in nuclear power plants (NPPs), radioactive process materials in nuclear fuel cycle facilities and NPPs, and sealed radioactive sources of various uses (e.g. for monitoring and calibration).
OVERALL GOAL OF DECOMMISSIONING AND ITS KEY ROLE IN SUSTAINABILITY
During a site's restoration for safe re-use, no significant health risk may be borne by people nor may any danger be posed to the environment. After successful decommissioning, site control can be substantially relaxed - or, in some cases, safely ended altogether.
The nuclear industry is committed to the twin objectives of decommissioning: safety and restoration. These characteristics underscore the industry's intrinsic sustainability.
Re-use can apply to various parts of the site, including land, water bodies, buildings, equipment, materials and even wastes. The nuclear industry and regulators share a responsibility to develop and implement strategies for safe and effective re-use of these valuable resources.
Re-use opens important opportunities for workforce re-deployment and local re-development. The nuclear industry accepts the obligation to pursue these goals as a high socio-economic priority.
In sum, the concept of decommissioning entails:
- Rendering a site permanently safe after the conclusion of plant operations
- Restoring the site for re-use, while maximizing the re-use of all on-site resources, including waste
- Realizing opportunities for workforce re-deployment and local redevelopment.
A WEALTH OF NUCLEAR INDUSTRY EXPERIENCE IN DECOMMISSIONING
The global nuclear industry has developed a wealth of experience in decommissioning. Decommissioning has been successfully accomplished in a variety of nuclear sites, from research facilities to large-scale industrial plants.
Worldwide, over 100 mines, 90 power reactors, 250 research facilities and many fuel cycle facilities have been safely retired from operations. Of these, many have been, or are currently being, successfully decommissioned. Much experience has been gained too from smaller-scale decommissioning projects carried out in parallel with normal operations at all types of nuclear facilities.
This professional experience has been widely shared among nuclear practitioners worldwide through conferences, seminars and workshops. These meetings continue to be held under the auspices of international organizations such as the IAEA, the NEA-OECD and the WNA.
Accumulated and shared experience in decommissioning constitutes a knowledge bank of tested techniques, proven standards, and best practices. This knowledge provides a strong foundation for an industry professionalism that helps to build trust among stakeholders in the decommissioning process.
Experience at each facility itself is also important when the time for decommissioning arrives. Many of the good practices that are essential for safe operations and public confidence during the production phase of a nuclear facility are also a prerequisite for efficient decommissioning. These include complete record-keeping on operations, materials, and maintenance; preservation of drawings of facility design and modifications; thorough surveys of contamination and prompt decontamination; and meticulous accounts of any leakages and spills.
The many types of nuclear sites and facilities and a great diversity of national, local and technical contexts have resulted in a variety of approaches to decommissioning.
For facilities at the front end of the nuclear fuel cycle (e.g. conversion, enrichment and fuel manufacturing facilities), the challenges arise from naturally occurring radioactivity and chemical hazards. For sites at the back end (e.g. reprocessing facilities), the risks are increased by the presence of high-level sources of artificial radioactivity and direct irradiation. At all of these sites, decommissioning begins with the removal or securing of high-level sources that can represent a significant hazard and also radioactive process materials. Examples of high-level sources are front-end fissile material and back-end used nuclear fuel. Facilities are then decontaminated by thorough rinsing and cleaning, and finally dismantled. In the process, contaminated materials and wastes are sorted and removed.
At nuclear power plants (NPPs), the initial phase - removal of used nuclear fuel, decontamination and sealing - is followed by a deactivation period. This delay facilitates subsequent steps when high-level radioactivity in certain process equipment will have decayed significantly. Within the industry there is debate as to whether this deactivation period is necessary. Some organizations prefer to proceed through the decommissioning process soon after the cessation of power generation, while others prefer postponement while radioactive decay reduces radioactivity levels and thereby facilitates decontamination and dismantling activities. In the latter procedure, the facility is placed under surveillance during the interim phase with the highest radioactive locations sealed and monitored. A third approach, used in the USA for NPPs, consists in sealing and putting the facility under surveillance for a longer period of time until radioactive decay decreases radioactivity to an inherently safe level that permits termination of the site licence. Among these NPP decommissioning options, the choice depends on specific circumstances, particularly the site's planned end-use and the destination of used nuclear fuel.
At uranium mines, the decommissioning of mills poses challenges similar to those at other front-end facilities. Due to their large volumes and low radioactive levels, uranium tailings that result from conventional (mechanical) mining usually remain on site. Decommissioning work includes improving the long-term containment of tailings basins; placing a cover on top of tailings to reduce both water infiltration and the emission of radon gas; and collecting, treating and monitoring water discharges from tailings basins and mines (Tailings themselves are not a decommissioning waste as they result from mining operations.). For mining operations using in-situ leaching (ISL), the decommissioning process centres on the recovery of injection well pipes and process wastes, and on the restoration of underground water quality through treatment and monitoring.
For both NPPs and nuclear fuel cycle facilities, the final decommissioning steps are the restoration of the site's landscape and long-term monitoring and institutional control. Restoration work for an NPP involves a relatively small area as compared to a uranium mine, where a much wider swath of terrain has been disturbed.
All decommissioning approaches employ flexibility and adaptability in pursuing the essential objectives of safety and restoration.
Decommissioning work employs a myriad of proven techniques and technologies. These include:
- Measuring and monitoring, which have become steadily more sophisticated over the years
- Decontamination by applying chemical, mechanical, electrical or mixed processes to metal, concrete and other materials
- Dismantling - for example, by mechanical or thermal cutting
- Remote control of manipulators and robots
- Treatment and conditioning of wastes and effluents.
Some of the techniques and technologies employed by the nuclear industry are used in decommissioning conventional industrial facilities. Each technique and technology involves a variety of available tools and equipment. The decision of which to employ will always take into account safety and the goal of minimizing any additional generation of wastes.
PROTECTING PEOPLE AND THE ENVIRONMENT
Public opinion has come increasingly to appreciate that nuclear sites operate safely with due care for the protection of people and the environment. This confidence derives in part from rigorous industry adherence to the standards embodied in health, safety and environmental protection programmes.
Such standards continue to apply during decommissioning. When decommissioning begins - and high-level radiation sources and radioactive process materials are removed or secured - a site becomes intrinsically safer for both people and the environment. Nonetheless, health, safety and environmental standards continue to be observed as the owner/operator pursues two aims:
- Maintaining a high level of safety and protection during decommissioning
- Achieving a permanently high level of safety and protection after decommissioning.
Decommissioning activities differ markedly from the previous operation of a facility. A fundamental difference is that decontamination and dismantling require closer contact with contaminated equipment, materials and wastes. Inevitably, the new tasks at hand represent a significant change in the workplace, often requiring new workers with different skills and experience. Even then, specific training may be needed for the decommissioning workforce to acquire the skills necessary for rendering a particular site permanently safe and restoring it for re-use.
Throughout a site's decommissioning, public authorities monitor the owner/operator's compliance with health, safety and environmental protection requirements. Once decommissioning is completed, acceptance must be obtained from key stakeholders - including local authorities and the general public - that these requirements have been fully met. This acceptance is a prerequisite to gaining official agreement that control over the site can be safely reduced or ended.
SITE RE-USE IS FUNDAMENTAL TO THE SUSTAINABLE USE OF RESOURCES
While the initial benchmark of sound decommissioning is the application of rigorous standards of health, safety and environmental protection, the ultimate aim is to restore the site for re-use to the fullest extent practicable.
The environmental principles known at the "Four Rs" - Reduce, Recover, Recycle, and Re-use - provide the guide to this goal. "Reduce" means taking all steps possible to minimize the generation of waste. Buildings, equipment and materials that are highly contaminated will generally need to be decontaminated and dismantled, and in some cases disposed of after treatment and conditioning. But land, water bodies and many buildings that emerge from successful decommissioning will be available for re-use. Moreover, some 90% of the waste volume generated during decommissioning is, for practical purposes, uncontaminated and may easily lend itself to recycling.
Public expectations attach high value to site re-use because of the potential for workforce re-deployment and local redevelopment. Commercially, the best re-use of a successfully decommissioned site may well be the construction of a new nuclear facility in its place; and this option may also be congruent with national needs and local aspirations. From a national perspective in many countries, nuclear power is gaining increasing policy support as a reliable source of affordable, cleanly generated electricity. And from a local perspective, the replacement option draws upon skilled labour already available and is also likely to enjoy the public acceptance that is common to communities familiar with nuclear power.
Uniformity in regulatory standards facilitates predictability, planning, and efficiency in all areas of nuclear industry practice, including the decommissioning process. There is thus an increasing effort internationally to develop agreed universal standards that will lend consistency and coherence to national regulatory regimes. Recently the IAEA adopted international standards on the removal from regulatory control of materials containing trace levels of radioactivity; these standards were particularly designed to govern the use or disposal of bulk quantities of such materials as may occur during decommissioning. These standards - and similar IAEA standards for land and water bodies at decommissioned sites - are milestones in regularizing the process of achieving safe and efficient re-use of decommissioned nuclear facilities.
MOST DECOMMISSIONING WASTES ARE UNCONTAMINATED OR OF A VERY LOW RADIOACTIVE LEVEL
The concept of decommissioning suggests an enormous task of decontamination, requiring the dismantling or destruction of many buildings and much equipment and requiring the disposal of a correspondingly large volume of radioactive waste. In fact, over 90% of the total volume of waste generated during decommissioning is non-radioactive and uncontaminated, and most of the remainder has only a very low radioactive level. Thus, only a small percentage of the overall wastes generated during decommissioning requires treatment, conditioning and disposal due to radioactivity.
Because some wastes will be generated, decommissioning requires a sound infrastructure and system for waste management. Only with such a system can the owner/operator plan a sequence of activities by which waste and other materials are optimally managed, taking into account costs, risks and benefits. These activities include pre-sorting and collection; control, characterization and sorting; pre-treatment and preconditioning; treatment and conditioning; handling; storage and disposal. Sorting is especially important, as costs depend on waste and material concentrations, quantities, forms and types and on the resulting destinations for storage and disposal.
For much of the wastes and material, disposal routes or "4Rs streams" have been established, though more can still be done to develop these routes and enhance their efficiency. For the lower volumes of intermediate level wastes, the common practice is disposal or storage as an interim measure. For very low-level radioactive material and wastes, countries currently vary in their practices for exemption and clearance, with some countries permitting unrestricted recycling and re-use. As in other aspects of regulatory practice, this area will benefit from the development and adoption of international standards.
OWNER/OPERATOR RESPONSIBILITIES DURING DECOMMISSIONING AND BEYOND
The owner/operator's responsibility for all aspects of a nuclear facility continues through every phase of the site's decommissioning. Having submitted a decommissioning plan and obtained a decommissioning license, the owner/operator must complete decommissioning in compliance with all license requirements and other applicable regulatory requirements. Even when decommissioning work is satisfactorily completed, the owner/operator remains responsible for the site until formally discharged of this obligation by relevant authorities.
In meeting these responsibilities, owner/operators customarily use a quality-based management system in all phases of decommissioning. Such systems use the well-established PDCC steps of professional management - Plan, Do, Check, Correct - to meet all regulatory requirements at every stage of decommissioning.
A COMPREHENSIVE REGULATORY FRAMEWORK
In all countries, decommissioning is subject to a comprehensive regulatory framework. The initial step - the owner/operator's submission for a license - usually triggers a sequence of evaluations and peer reviews to establish clearly what steps will be necessary to comply with the standards and requirements of relevant authorities. In this process, it is standard practice for the owner/operator to prepare a well-documented supporting case and for the relevant authorities to convene public hearings to facilitate the presentation of all stakeholder views. This interaction will sometimes produce an amendment in the decommissioning plan and the license application.
Once a licence has been issued, regulatory oversight continues until the decommissioning process has reached the stage of long-term monitoring and institutional control. At this final stage, authorities can decide to discharge the owner/operator, fully or partially, from further responsibility and liability for the decommissioned site.
THE FUNDING OF DECOMMISSIONING
The overall cost for decommissioning is significant, although low in comparison with the lifetime productive output of the facility being closed. Financing for this cost is customarily planned at an early stage of the facility's life and is recognized as a responsibility of the site owner/operator. Common industry practice is to build a decommissioning fund during the life of a facility by integrating an incremental cost into the price of electricity from nuclear power plants and of the services rendered by fuel cycle facilities. The systematic accumulation and affordability of decommissioning costs for modern civil nuclear facilities is not to be confused with the management of legacy activities - involving military and early civil nuclear facilities - which tend to be expensive and complicated.
Today, for all nuclear facilities, standard international practice includes the preparation of a decommissioning plan at an early stage, often even before the start-up of operations. During a facility's operational life, this plan is regularly updated.
The modality by which an owner/operator fulfils the responsibility of accumulating decommissioning funds varies according to national policy. The owner/operator can either: (1) contribute into an external fund controlled by authorities; or (2) make allocations within organizational accounts in compliance with generally accepted accounting principles (GAAP) under the oversight of independent auditors or authorities.
ENVIRONMENTAL AND SOCIO-ECONOMIC IMPACT AND STAKEHOLDER INVOLVEMENT
In many countries, before the formal application for a decommissioning licence, a preliminary process occurs aimed at assessing the environmental and socio-economic impact. The result is called an Environmental Impact Statement (EIS). Generally, this process includes public hearings where stakeholders have ample opportunity to influence the conduct of a decommissioning project.
In anticipation of this formal process, the owner/operator often takes the initiative by seeking stakeholder input from the outset of planning. This is efficient from the owner/operator's perspective, and also serves to enhance public trust, confidence, and acceptance. Once decommissioning begins, this interaction usually continues through public meetings, workshops, and debriefings.