By Michele Laraia, former IAEA Unit Leader, consultant
Michele Laraia’s series of articles are intended to start a conversation and stimulate debate. We invite you to comment or ask questions below (or send us an email) regarding this article either using your name or anonymously, and we will print some of the comments/questions in an upcoming Weekly Digital Report, as well as in the article itself. Laraia will also respond to any comments/questions from readers. Then, stay tuned next month for a new article and new debate.
THE CONTINUITY OF DECOMMISSIONING PLANNING
A three-tier structure of decommissioning planning has been promulgated by the IAEA for many years [IAEA, The Regulatory Process for the Decommissioning of Nuclear Facilities, Safety Series No. 105, IAEA, Vienna, 1990]. Typically, the decommissioning planning process is structured in three categories:
- Preliminary (a.k.a. initial) plan
- On-going plan
- Final plan
The key principle of planning for decommissioning should be continuity (a form of sustainability). Experience shows that a significant gap in planning will inevitably result in unnecessary delays (e.g. between final shutdown and the start of active decommissioning) and ultimately, extra costs. This has been the case for facilities that were shut down as the result of a political decision (e.g. a national or local referendum): inevitably the uncertainties linked to “what-to-do-now” stopped or slowed down progress in decommissioning planning. However, the three tiers of planning have different rationale and to reduce them to one seamless strategy may prove difficult.
Preliminary planning should begin when the facility is being sited, designed and constructed. The purpose of preliminary planning is to identify the resources that will be needed during future decommissioning and estimate when they will be needed. This initial planning will vary depending on the regulatory requirements, but should include at least a rough order of magnitude cost estimate, a schedule of activities, record-keeping requirements and a waste estimate by type and volume. These three items are normally initially combined into a single document due to their inter-relations.
An understanding of how decommissioning will be safely undertaken is needed to optimize the design to support decommissioning, in terms of dismantling efficiency and selection of materials or design features that will decrease radiation dose rates, facilitate equipment removal and prevent unexpected challenges to final dismantling. Early plans for decommissioning are also required to enable adequate funding arrangements for decommissioning to be put in place and to test the chosen strategy for practicability.
It should be noted that the earliest publications of the IAEA already included the notion of design features intended to facilitate eventual decommissioning [IAEA, Decommissioning of Nuclear Facilities, IAEA-179, IAEA, Vienna, 1975]. However, these provisions were viewed at the time as one-off exercise, not as part of a continuing, lifelong planning.
Following IAEA guidance, in many Member States there is now a requirement to include preliminary plans for decommissioning in the safety report prepared before operation of the facility commences. The basic objective of preliminary planning is to ensure regulators and public opinion that final decommissioning can be done in a safe, timely and cost-effective manner.
There are several reasons why the decommissioning plan should be regularly reviewed and amended during the operating life of a nuclear facility. Decommissioning or other policies may change and confirmation that the preferred decommissioning strategy remains the most appropriate will require supportive studies. Other reasons include: the confirmation that financial provisions for decommissioning are likely to suffice; to reflect the impact of significant plant modifications or events; and finally, as decommissioning approaches, to detail and finalize a “ready-for-action” plan, especially in the light of the current technological and commercial situation.
In the final few years of operation, or once the date of the final shutdown of operations is known, a decommissioning organization should be established to plan for final decommissioning. The first detailed plans need to be available before the end of operations in order to cover the period immediately following the cessation of operations: typically including fuel removal, hazard characterization and general cleanup.
It is usual for the operator of a decommissioning site to have to provide clear final plans to a regulator in order to obtain a decommissioning license or at least permission to begin active decommissioning. These plans would need to include an assessment of the safety of the intended approach. Even so, as the decommissioning work progresses problems and risks will emerge requiring modifications to those plans.
The goal of decommissioning is to reach an agreed site end state. It is important that the plan provide clarity on how this state is to be achieved. Thus, the decommissioning project must have an agreed plan to validate by sampling, surveys and other means that the required final radiological state will be achieved.
The Challenges of Decommissioning Planning
Ideally, and consistent with international positions, the decommissioning plan should be one and the same living tool paralleling and escorting the entire lifecycle of a nuclear facility from design and construction until site release (and possibly beyond in restricted release). This spans a period of 60+ years, possibly even 100 years. The plan should have enough flexibility to accommodate drastic changes to the facility’s configuration, major transitions (typically from operation to decommissioning and from decommissioning to site release and termination of the nuclear licence), idle periods and periods of intense activity. It should be able to incorporate new contents and discard redundant parts, while retaining its overall goal, i.e. to ensure safety and cost-effectiveness during and after decommissioning. One approach to keep the unity of the decommissioning plan over the plant’s lifetime is to preserve the same structure, while the degree of detail grows. In practice, however, the notion of continuity and gradual progress of the decommissioning plan is challenged by several factors, which are described in the following.
The Diverging Focus of the Decommissioning Plans
It should be appreciated that timing and circumstances dictate a different focus of the decommissioning plan. Typically a preliminary plan drafted at the plant’s design and construction stage mainly serves a prescribed policy (i.e. the feasibility of decommissioning), rather than a technical aim. As a Statement of Intentions, it addresses provisions that will materialize only after many years (mostly the funding). Decommissioning-oriented approaches taken at this stage will have a significant impact, but at a much later time. The technical detail at this stage is minimal, since nobody can predict with any certainty what the radiological conditions will be after the plant will be operating for a number of years.
A 60+year leap to the inception of active decommissioning will show quite a different picture. Here decommissioning is a concrete reality and the plan will dictate tasks to the tiniest detail. At that point in time costs will no longer be remote estimates, and each cent will count. Decommissioning is a multi-disciplinary science, and all aspects are interrelated: a change to one aspect at this stage will at once reflect on all others. Therefore the final decommissioning plan will not be allowed (as it was instead possible for the preliminary plan) to disregard any technical, administrative or financial details. Decisions will have to be finalized on each detail of the plan (while providing enough flexibility for changes in the course of the works).
One or Two Decommissioning Plans?
In the light of their different focus, how is the final plan linked to the preliminary plan? How and when will preliminary evolve to final? In other words, will a final plan be a continuation and refinement of the initial plan, or are these in fact two totally different plans? Has the preliminary plan any relevance to the final plan? Should not we use a different terminology for the preliminary plan (e.g. Statement of Intentions for Future Decommissioning)? What will be the role and contents of the “ongoing” plan?
The recognition that some information is superfluous in a preliminary decommissioning plan has prompted some regulators to promulgate separate guidance on preliminary or final decommissioning plans. One example of this approach is Canada [CANADIAN NUCLEAR SAFETY COMMISSION, Decommissioning Planning for Licensed Activities, Regulatory Guide G-219, 2000 http://nuclearsafety.gc.ca/pubs_catalogue/uploads/G219_e.pdf ]. The Swedish regulators has also indicated different contents for the preliminary or the detailed decommissioning plan in [SWEDISH RADIATION SAFETY AUTHORITY, The Swedish Radiation Safety Authority’s Regulations on Planning before and during Decommissioning of Nuclear Facilities, SSMFS: 2008:19 https://www.stralsakerhetsmyndigheten.se/Global/Publikationer/Forfattning/Engelska/SSMFS-2008-19E.pdf ].
About the Author:
Michele Laraia is a chemical engineer by background. An Italian citizen, he gained his first degree at the University of Rome in 1973. In 1975, he received a post-graduate degree as nuclear engineer. From 1975 to 1991, he worked at Italy’s Regulatory Body (ENEA/DISP), firstly in the capacity of reviewer of radioactive waste management systems, and since 1982 as licensing manager of decommissioning projects. During the 1982-1991 period, under his management seven small research reactors and other nuclear fuel cycle facilities were totally dismantled in Italy and their sites returned to other uses. In other plants, modifications to license conditions were implemented in preparation to decommissioning.
From July 1991 to 2011, Laraia worked at the International Atomic Energy Agency, Waste Technology Section, as Unit Leader responsible for decontamination and decommissioning of nuclear installations, closeout of uranium mining and milling sites, and environmental restoration. The objectives of the work were to provide advice to Member States on the planning and implementation of adequate methodologies and technologies for decommissioning of nuclear and radiological installations and site remediation, to collect and disseminate information on good practices for safe and cost-effective decommissioning, and to provide direct assistance (through the Technical Co-operation Programme) to Member States in the implementation of their programes and establishment of the required infrastructure for decommissioning and site remediation, and to strengthen their technical capabilities. His tasks included the drafting of technical publications, organization of international conferences and seminars, and the management of technical cooperation projects with developing countries, either on a national or regional scale. Some 50 technical reports and other documents for dissemination to the international community were prepared by Laraia as the Scientific Secretary, and another few dozen coordinated with him. His publications (journals, conference proceedings) amount to over 100. Over 30 less-developed countries received direct IAEA assistance with Laraia in the role of leading Technical Officer.
Laraia retired from the IAEA in 2011. Since then, he has offered consulting services in nuclear decommissioning including lecturing, training, reviewing decommissioning plans, and drafting of worldwide overviews and topical reports for a number of national/international organizations.