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5 DECOMMISSIONING OF NUCLEAR FACILITIES

The purpose of this Section is to describe the status of and trends relative to nuclear facility decommissioning, where a nuclear facility is defined as [5.1]:

a facility and its associated land, buildings and equipment in which radioactive materials are produced, processed, used, handled, stored or disposed of on such a scale that consideration of safety is required

and decommissioning is defined as [5.1]:

administrative and technical actions taken to allow the removal of some or all of the regulatory controls from a facility (except for a repository which is closed and not decommissioned). The use of the term decommissioning implies that no further use of the facility (or part thereof) for its existing purpose is foreseen... ...For a repository, the corresponding term is closure.

Three subsections are included to elaborate on the subject area:

• Factors Complicating Decommissioning Projects,

• Recent Decommissioning Experience, and

• Agency Technical Co-operation Programme Activities Related to Decommissioning.

As many nuclear reactors will reach the end of their design lifetime in the next few decades, it is expected that decommissioning will develop into an area of increasing interest. The decommissioning status of nuclear power reactors was available on the Internet at the following URL (at time of writing):

http://www.world-nuclear.org/wgs/decom/database/database.htm

5.1 Factors Complicating Decommissioning Projects It is becoming common opinion and experience that issues complicating smooth progress in decommissioning of nuclear facilities are mostly related to planning, management and organizational issues. Lacking or inadequate technologies may play a role but they are usually not decisive in that technologies can be promptly procured in the decommissioning market at acceptable costs for most nuclear facilities. In addition, financial support may be commonly available for countries having limited resources through bilateral co-operation or assistance from the Agency and other international organizations (e.g. the PHARE and TACIS programmes of the European Union [5.2]). Third, and most importantly, inadequate technologies and insufficient funding are mostly the result of inadequate planning.

One important factor hindering timely and cost effective decommissioning is simply due to parties actively, and often successfully, lobbying against shutdown and decommissioning. Operating a facility such as a research reactor confers a prestige status in many environments. At times, old reactors, possibly operated sporadically, are not officially declared shutdown because of prestige and social aspects. It is also erroneously assumed that decommissioning will inevitably render the facility’s staff redundant and jobless. Job opportunities created by the decommissioning itself, judicious use of turnover, and re-training jobs often remain unexplored possibilities.

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One result of lack of consensus on permanent shutdown and decommissioning is the “limbo” state of several nuclear facilities. It may be legally and technically uncertain whether these facilities are shutdown or operational. In “limbo”, structural and equipment deterioration quickly occur due to insufficient care and maintenance and disregarded technical prescriptions. Restarting a facility in such a situation could be unsafe. A “limbo” state is also extremely frustrating and weighs heavily on staff morale. In such a condition, the most qualified staff may seek better job opportunities and disappear from the picture. These are the key people who would be invaluable for timely and accurate planning of decommissioning. Unfortunately, the least qualified people may remain and try to prolong the “limbo” unduly.

Another common situation is the lack of early planning for decommissioning. According to Agency recommendations [5.3], a preliminary decommissioning plan should be available at the time of a facility’s construction and commissioning. One crucial objective of this early planning is to ensure adequate funding for waste management and eventual decommissioning. The preliminary plan should be periodically updated during a reactor’s lifecycle or when there are major technological, financial or organizational changes. At permanent shutdown, ideally a final decommissioning plan should be in place. It is the unfortunate reality that this ideal pattern is not followed in practice in several countries. More often facilities reach the shutdown and decommissioning stage with little or no planning. The typical result is a prolonged idle state as described above. Developing decommissioning plans is not a matter of days. If plans are not available prior to shutdown, there will be a race against time to draft such plans and to establish the infrastructure required before key staff leave, records become irretrievable and lack of maintenance begins to erode safety margins. International experience proves that gathering a team familiar with the shutdown facility is almost impossible a few years after final shutdown.

Unfortunately, lack of early planning is often due to the misperception that decommissioning is a straight forward activity that can be undertaken with minor effort. It is encouraging that signs of greater awareness have emerged from the Agency’s observations. The disregard of decommissioning plans is coming to an end. This is clearly a cultural issue that may take time to be fully addressed.

Lack of early planning for decommissioning causes a number of complications at the shutdown stage and later. In addition to inevitable delays and extra costs (e.g. for conducting obsolete operational tasks or paying the workforce for non-productive tasks) drafting a decommissioning plan from scratch is a very difficult task. For example, lack of as-built drawings may render physical and radiological characterization quite unreliable even though there is often no other way to reconstruct missing records. Subsequent decommissioning will then be subject to more unknowns than needed. Figure 5-1 provides an example of a team in charge of drafting decommissioning plans during plant operation.

Funding of decommissioning is another non-trivial issue. Except for the smaller zero- or low power reactors, decommissioning costs cannot be covered by routine operational funds. Allocating funds for decommissioning takes time and may have to compete with other national or corporate priorities. Regardless of international recommendations to establish and secure financial mechanisms for the purpose, delayed funding is often a factor hindering the progress of decommissioning.

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Planning

Team Leader

Decontamination & Dismantling

Waste Management

Costing Licensing Safety

Figure 5-1: Decommissioning-oriented Team During Plant Operation (example)

Decommissioning is a multi-disciplinary, complex process that should be conducted in an integrated manner. This includes an assessment of the tasks to be carried out and the availability of all required infrastructures. Funding is one of these. Waste management infrastructure is also essential. Waste treatment, storage and, if possible, disposal routes should be in place for all waste streams before decommissioning commences. This is often not the case, and the result is further delay or indefinite mothballing. Waste management is critical to decommissioning in various ways. The impact of regulations, or a lack thereof, cannot be overemphasized. In decommissioning waste management, regulations address, among other things, radioactive waste classification (typically based on disposal routes, see subsection 3.2) and clearance levels (see subsection 3.1). Due to large amounts of low contaminated materials/waste that derive from decommissioning, having clear regulations and clearance levels is essential for the timely and efficient management of decommissioning. As a minimum, case-by-case formulations should suffice. Experience shows that the time needed to establish or interpret clearance levels, a typical regulatory responsibility, may cause considerable delays in decommissioning.

Another infrastructure component that is often missing in reactor decommissioning is spent fuel management. For reactors where defuelling is not a routine operation, end-of-life defuelling can be on the critical path. Quite often a spent fuel management route is not immediately available. This may result in spent fuel kept at the reactor for a long time, thereby establishing a de facto dormant state.

Decommissioning oriented regulations are important for more aspects than waste management. A well defined licensing process is crucial. The application of regulations and norms that were implemented for construction and operational phases to decommissioning does not work properly and may result in a convoluted process, interpretation issues, operator versus regulator confrontation and ultimately delays and extra costs. It is encouraging that now most Member States have decommissioning regulations in force, although not always to the full extent necessary.

Another factor that is significant in decommissioning is the need for a cultural change in moving from plant operations to decommissioning. This is particularly important, for example, if a team of researchers is required to plan for and implement decommissioning of a research reactor. Cultural changes include psychological factors (“you cannot ask me to kill my reactor”), perception of downgraded professionalism (e.g. from sophisticated neutron physics to “ordinary” demolishing), re-scheduling and/or co-operating with contractors’ teams (see Table 5-1 [5.4]). It is also common that staff find it difficult to “work themselves out of a job” by performing decommissioning. Provisions should be made to find new job opportunities for individual staff members. All of these aspects are extensively dealt with in reference [5.4].

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Table 5-1: Comparison between Decommissioning and Operational Culture Requiring a Dedicated Approach

Operations Decommissioning Relying on permanent structures for the operating life of the facility

Relying on structures to assist dismantling (for temporary use)

Safety management systems based on operating nuclear facility

Safety management systems based on decommissioning tasks

Management objectives are production oriented Management objectives are project completion oriented

Routine training and refresher training Retraining staff for new activities and skills or use of specialized contractors

Permanent employment with routine objectives Visible end of employment - refocus their work objective

Established and developed regulations for operation

Changing regulatory focus

Predominant nuclear and radiological risk Reduction of nuclear and radiological risk, predominant industrial risk

Focus on functioning of systems Focus on management of material and activity inventory (e.g. for waste minimization)

Another issue in decommissioning is the uncertain role and responsibilities of parties involved. This is typical in countries not having enough experience/expertise in decommissioning. In a first-of-a-kind project, uncertainties such as unclear regulations may result in erratic approaches, sharing of responsibilities between operators and regulators or, on the contrary, over-centralization, lack of transparency and poor involvement of stakeholders. The ultimate result may be a lack of a clear policy/strategy or even disputes.

Finally, it is important that the social and environmental aspects of decommissioning on both the workforce and local communities are fully anticipated and addressed from the planning stage onwards. A recent Nuclear Energy Agency publication [5.5] addresses the issues raised and the following points are relevant:

The social and environmental issues that are of most interest to communities in the vicinity of decommissioning sites can vary considerably. Nevertheless, there are several issues that are common to a variety of nuclear facilities. Among these are health impacts of releases, both during and subsequent to the decommissioning activity. In addition to such routine releases, the risks from possible accidents, both during and after decommissioning, are also of great interest to the community. Environmental impacts of interest include effects on water quality and on wildlife, such as fish in water bodies that might receive runoff from the decommissioned site.

In many countries, legislation also requires regulatory processes to be open to the public with consultation of the public by the regulatory bodies and public hearings being held in the case of major decisions. These requirements are reinforced in certain cases by international treaties or conventions such as the Joint Convention [2.1] and the Espoo Convention (1991) [5.6], which also requires provision of information to neighbouring countries that might be affected by decommissioning activities.

In many countries it is now common practice for operators of nuclear facilities, on a voluntary basis, to maintain information centres for the public and to issue regular information bulletins

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by way of websites, publications and other means. It is also now common for regulatory bodies to publish documents describing the systems, procedures and the technical guidance they apply to regulatory decisions.

In conclusion, decommissioning of nuclear facilities requires early attention by all parties to be involved. There are no insurmountable obstacles, either technical or organizational, that cannot be overcome if due consideration is given to them in good time. As a common slogan sounds, “Failing to plan is planning to fail”.

5.2 Recent Decommissioning Experience The following reports on progress, achievements and plans at selected nuclear power plants in several countries.

5.2.1 Connecticut Yankee Decommissioning (USA)

Decommissioning progress

The decommissioning of the Connecticut Yankee (CY) nuclear power plant [5.7] in the USA was approximately 65% complete as of May 2003. The major work activity in containment was the completed clean up of the reactor cavity and transfer. Removal of the reactor pressure vessel is scheduled for late 2003. The internal demolition (removal of major components, heat exchangers, piping and cables) of the turbine building is complete. Five of seven storage tanks were demolished by May 2003.

Dry fuel storage

Connecticut Yankee and the town of Haddam, where the plant is located, signed a settlement agreement in January 2002 allowing the construction of a dry fuel cask storage facility in the location chosen by CY with negotiated conditions regarding safety and environmental monitoring. CY initiated dry fuel storage construction activities in March 2002. Forty three vertical concrete storage containers have been constructed. Site work on the storage facility is on-going. Modifications of the spent fuel pools, in preparation for fuel transfer operations, have been completed. Fuel transfer is expected to begin in the fall of 2003.

Large component removal

On 1 November 2001, the reactor pressure vessel head left the plant via a 19-axle tractor/trailer rig for the Envirocare Disposal Facility in Clive, Utah. During January 2002, the main station transformer was dismantled and in February 2002, it was transported off site via barge to Texas. All components have been removed from the primary auxiliary and waste disposal buildings.

5.2.2 Maine Yankee Decommissioning (USA)

Decommissioning progress

Decommissioning of the Maine Yankee (MY) nuclear power plant [5.7], [5.8], in the USA began in August 1997 and is scheduled to be finished in 2005. The project was about 75% complete as of May 2003. Decommissioning involves the removal of buildings and other structures and the restoration of the site to meet state and federal requirements for the cleanup of radiological and non-radiological materials. With the possible exception of some buildings or structures that could remain for reuse, the one facility left at the site in 2005 will be the Independent Spent Fuel Storage Installation (ISFSI), where MY’s spent nuclear fuel will be

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stored until the US Department of Energy removes it from the site or until another responsible, viable removal option presents itself.

Independent Spent Fuel Storage Installation

Preparations continue for moving fuel from the spent fuel pool to dry storage in the ISFSI. The internal dry run was completed in June 2002. The Nuclear Regulatory Commission’s (NRC) dry run was conducted in late July 2002. Twenty canisters of spent fuel were transferred to the ISFSI by May 2003. Transfers are expected to be completed by the spring of 2004. Moving spent nuclear fuel from wet to dry storage makes sense for several reasons:

• placing the fuel in casks readies it for transport when the time comes,

• without dry cask storage, decommissioning of the plant could not be completed, and

• dry cask storage is a passive, air cooled system that is simpler and more economical to operate then wet storage.

Reactor Pressure Vessel Removal

Reactor vessel removal work was a major activity, which is now complete. Nozzle cutting was completed in July 2002. The reactor lift (598 tons) into the shipping container was completed successfully in August 2002 (see Figure 5-2). On 6 May 2003, the reactor vessel was shipped by barge from the MY site to the Barnwell disposal facility in South Carolina.

Greater than Class C (GTCC) waste (this is a USA waste class, see subsection 3.2)

GTCC waste (unsuitable for near-surface disposal, according to US regulations, see Figure 3-2) is irradiated stainless steel that was removed from the reactor vessel. For disposal purposes, GTCC waste is treated like spent fuel and will be stored at the ISFSI in four casks. The last of the GTCC casks was recently transferred to the ISFSI.

Site reuse

As part of a 1999 Federal Energy Regulatory Commission settlement agreement, MY will donate the Eaton Farm plus a surrounding 200 acres (~80 hectares) to a non-profit entity for conservation and environmental education purposes. The State of Maine recently completed a radiological survey of Eaton Farm that found the property to be radiologically clean. The State’s survey confirmed the results of previous survey work done by MY and the NRC.

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Figure 5-2: Maine Yankee Reactor Vessel Removal

5.2.3 San Onofre Decommissioning (USA)

San Onofre Unit 1 (SONGS 1) began active decommissioning in 1998 [5.7]. SONGS 1 was first physically separated from the adjacent operating Units 2 and 3, followed by system and building removal to provide space for dry cask storage of spent Unit 1 fuel. Dry cask storage is needed to decommission the SONGS 1 spent fuel pool, radwaste and cooling systems. A reactor vessel internal (RVI) segmentation project to remove high dose components from the reactor vessel was undertaken and successfully completed. This activity was conducted to create a reactor vessel LLW (this is a USA waste class, see subsection 3.2) package that would be acceptable to the Barnwell, South Carolina, LLW disposal facility. Additional SONGS 1 decommissioning activities are scheduled to continue into 2008.

The RVI project was the most challenging decommissioning activity to date and is considered the highest risk in terms of industrial safety, personal exposure and the generation of secondary waste for SONGS 1 decommissioning. Contaminated materials inside the reactor vessel, considered GTCC waste, were removed from the Reactor Vessel and placed in the reactor cavity. The materials were then segmented under water using abrasive water jet cutting and metal disintegrating machining. Resultant pieces of GTCC waste were then packaged into modified fuel containers for long term storage at the ISFSI. An underwater filtration and secondary waste handling system was designed to capture activated cutting residues, to maintain water clarity for cutting and to maintain dose levels to meet SONGS’ ALARA (as low as reasonably achievable) standards.

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Design was completed and concrete poured for the ISFSI pad for the dry storage of all SONGS 1 spent fuel stored in the SONGS 1, 2 and 3 spent fuel pools. The SONGS 1 GTCC waste is temporarily stored in the SONGS 1 spent fuel transfer pool and will be moved to the ISFSI at a later date. Transnuclear, Inc. designed the horizontal storage modules (HSM) and dry canister design for use in the SONGS high seismic, coastal and marine environment. The SONGS 1 storage facility will house 19 HSMs (2 HSMs will store GTCC waste, 17 HSMs will each hold a canister filled with 24 fuel assemblies).

5.2.4 Vandellós-I Decommissioning (Spain)

Vandellós-I, in Spain, was a 497 MW gas graphite type nuclear power plant. Its construction began in 1967 and it started operation in 1972. In 1989 a fire in the turbine house led to the final shutdown of the reactor. Trusteeship for the site was transferred from the utility, Hispano-Francesa de Energía Nuclear S.A. (HIFRENSA), to the Spanish waste management agency ENRESA in February 1998. Since then, the main decommissioning activities of Vandellós-I have been undertaken, such as post operational clean out, the conditioning of spent fuel and the treatment of operational wastes, including the graphite components from fuel elements [5.9].

To date, the procurement of the necessary equipment and materials and the preparatory activities (modifications and assembly of installations, infrastructures, etc.) have been completed. Work is being completed on the disassembly of the conventional components and active parts, as well as on implementation of the waste and materials management plan.

These activities extended to the conclusion of the partial dismantling interventions and were essentially completed at the end of 2002. Completion is expected near the end of the first half of 2003. During this stage, the reactor shroud was confined, demolition and backfilling operations were performed, and the facility was prepared for the latency period.

A major task was the total static isolation of the reactor pressure vessel, where 1 700 penetrations were cut, seal-welded and inspected. Polyurethane foam was also used as an insulation agent and various forms of physical protection were installed.

The leak tightness of the vessel was tested by subjecting the vessel to a slight over-pressure of the order of 0.5 kg/cm2 and evaluating the leakage over a period of time. The results were satisfactory, about 18% of the acceptance criteria. Figure 5-3 provides an aerial view of the Vandellós site showing its status as of early June 2003.

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Figure 5-3: Vandellós Status as of June 2003

Following partial dismantling there will be a waiting period. Although not yet defined, this period is estimated at about 25 years. It will be followed by total dismantling of the remaining parts of the plant. This will leave the site completely free for subsequent, unrestricted use.

On completion of the latency period, around the year 2027, the last level of dismantling will begin. This will imply the total release of the site and its return to the owner, HIFRENSA.

5.2.5 Windscale Pile Decommissioning (UK)

The Windscale Pile One reactor was shut down in 1957 when a fire damaged a large portion of the core. Its sister reactor, Pile 2, was also shut down following the fire. Both Piles have been kept in safe care and maintenance since 1957. In 1993, the United Kingdom Atomic Energy Authority (UKAEA) programme to decommission the Piles began with the Phase 1 work of removing sludge and fuel debris from the air and water ducts and to seal the ducts from the Piles. This project was successfully completed in 1999.

In September 1997, a contract was awarded to a British Nuclear Fuels Limited (BNFL) led consortium to remove the core of the reactor and to condition and package the wastes. The technical proposal involved robotic arms to dismantle the core structure and the use of argon to ensure a fire-free environment during decommissioning.

In 1999, a major technical review was started to evaluate the robustness of the solution proposed and to consider other options for decommissioning Pile 1. This technical review is still on-going.

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The remaining damaged spent fuel in Pile 1 is estimated to total 15 metric tonnes. Pile One internal dismantling is seen by international decommissioning experts as second only to the task faced in dealing with the Chernobyl-4 internals, destroyed in the 1986 explosion and fire in the Ukraine. The Chernobyl-4 inventory is around 120 metric tonnes.

5.2.6 Treatment of Waste Sodium from the Prototype Fast Reactor, Dounreay (UK)

A major technological challenge in the decommissioning the 250-MW Prototype Fast Reactor (PFR) at the former Dounreay fast breeder and reprocessing complex in Scotland is associated with the 1 500 metric tons of flammable, liquid metal sodium [2] that have to be removed and treated [5.10].

A sodium disposal plant started work in August 2002 to remove radioactive contamination and to convert the sodium to a salt that can be discharged safely to sea. As of April 2003, the plant had processed 120 tons of sodium (35 tons from the secondary circuit, 27 tons from the primary circuit, and 58 tons from storage [5.11]).

The disposal plant is situated in the former PFR turbine hall. The sodium is reacted with aqueous sodium hydroxide which, following neutralization with hydrochloric acid, produces salt water. It is intended to treat all of the bulk sodium from the PFR over the next two years.

The process has not been carried out previously on such a scale. A particular feature of note is an ion exchange plant to remove cesium from the sodium before it is discharged to sea.

In a recent development, the first neutron shield rod was completely removed from the reactor vessel, to enable a drilling machine to be fitted. The machine will be lowered into the reactor vessel at a later date to drill a hole through the internal lower structure, to allow sodium to drain into the lower area of the vessel for eventual removal.

Following the removal of the bulk sodium, traces will still coat the pipes of the reactor cooling circuits and exist in small pools throughout the system. A process known as “water vapour nitrogen” is being developed to remove all such residual traces. A decommissioning test centre was officially opened by the UK Energy Minister in August 2002.

The work associated with the task is giving several Scottish Highlands companies experience and opportunities to build their presence in the growing marketplace for nuclear decommissioning services in the U.K. They were gaining skills and benefiting from alliances with some of the leading companies in Britain and Europe.

5.2.7 Research Reactor Decommissioning at Risoe National Laboratory (Denmark)

The Danish government is to commence decommissioning of the three research reactors at its Risoe National Laboratory [5.12].

None of the units is still operating. The largest, the 10 MW DR3, was permanently shut in October 2000, the others earlier. The government now hopes that the reactors can be decommissioned and the site brought to green field status within 11 years. Previous estimates 2 It is worth noting that the Agency has a task on “Radioactive sodium waste treatment and conditioning”. A

consultants’ meeting was held May 2003 to finalize a report that is expected to be issued in late 2003. The report will provide a comprehensive overview of radioactive sodium management worldwide.

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that it could take as long as 50 years before the site could be returned to green field have been revised because it is now perceived that the work can be accelerated using more advanced technology.

In parallel, Denmark will be trying to find a site for disposal of low- and medium level radioactive waste (these are Danish waste classes, see subsection 3.2) from Risoe, as well as one for about 250 kilograms of high level waste.

5.3 Agency Technical Co-operation Programme Activities Related to Decommissioning

The Agency has Technical Co-operation (TC) projects in the area of nuclear facility decommissioning. Information can be found on the TC Department’s web site (http://www-tc.iaea.org/tcweb). At time of writing, NPP decommissioning projects were active for the Ignalina Unit 1 reactor in Lithuania (TC project LIT/4/002) and the Bohunice A-1 reactor in the Slovak Republic (TC project SLR/4/008). The Agency’s role is complementary to the activities of the European Bank for Reconstruction and Development (ERDB) and is intended to upgrade resources and capabilities of recipient countries. Training of local parties is an essential component of the Agency’s assistance. In addition, the Agency provides specialized assistance, such as remote operations and robotics in the A-1 project. Other TC projects include assistance in the drafting of decommissioning plans for research reactors in Latvia, in Romania and in Serbia and Montenegro.

References for Section 5

5.1 International Atomic Energy Agency, On Line Safety Glossary, http://www.iaea.org/ns/CoordiNet/safetypubs/iaeaglossary/glossaryhomepage.htm.

5.2 Web-based information about PHARE and TACIS nuclear safety programmes http://europa.eu.int/comm/external_relations/nuclear_safety/intro/phare_tacis_implementation.htm.

5.3 International Atomic Energy Agency, “Decommissioning of Nuclear Power Plants and Research Reactors”, Safety Guide No. WS-G-2.1, IAEA, Vienna, 1999.

5.4 International Atomic Energy Agency, “Management and Organization in Decommissioning of Large Nuclear Facilities”, Technical Report Series No. 399, IAEA, Vienna, 2000.

5.5 Nuclear Energy Agency, “The Decommissioning and Dismantling of Nuclear Facilities, Status, Approaches and Challenges” NEA, 2002. http://www.nea.fr/html/rwm/reports/2002/3714-decommissioning.pdf.

5.6 Web-based information about the “Convention on Environmental Impact Assessment in a Transboundary Context” (Espoo, 1991). http://www.unece.org/env/eia/welcome.html.

5.7 American Nuclear Society, Newsletter, Decontamination, Decommissioning and Reutilization Division, May 2002 http://ddrd.ans.org/newsletters/May_2002.pdf. http://ddrd.ans.org/newsletters/Oct_2002.pdf http://ddrd.ans.org/newsletters/May_2003.pdf

5.8 Maine Yankee web site, www.maineyankee.com (as of 29 May 2003).

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5.9 Santiago, J.L., Vidaechea, S., “Recent Developments in D&D of Nuclear Facilities in Spain, Int. Conf. On Radioactive Waste Management and Environmental Restoration”, Bruges, Belgium 30 Sep. – 4 Oct. 2001, ASME 2001.

5.10 Nucleonics Week, “Liquid sodium proves a challenge in PFR decommissioning project”, August 29, 2002.

5.11 UKAEA, Dounreay Bulletin (as of 29 May 2003) http://www.ukaea.org.uk/dounreay/bulletin41.htm

5.12 Nucleonics Week, “Danes begin decommissioning of Risoe Laboratory Reactors”, August 29, 2002.

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