Thanks to the different EC R&D framework programmes, the European Union developed the technologies, processes and procedures to deal with the end-of-life of the existing shutdown nuclear facilities.

Starting at the end of the seventies with laboratory developments, the programmes evolved to large demonstration projects (so-called pilot projects) which brought the Decommissioning and Decontamination (D&D) to a quite mature industrial activity. Since a few years now, large projects, either commercial or public funded, have been started throughout the Union and some are already completed.

The paper will focus on the realizations to date, in the whole Union, with particular attention to France, Germany, UK and Belgium. It will be shown that all kinds of nuclear facilities, from research facilities and reactor to fuel cycle plants and nuclear power plants, were involved and that experience has been acquired in almost all domains of D&D.

The information exchange and the technology share enhanced by the EC programmes have led to a development of a D&D industry in the EU able to remove nuclear facilities from the nuclear classified sites. Even in the applicant states and countries from Central and Eastern Europe, the developed technology and the experience gained in the EU have and will help to solve the problems of D&D of shut down and obsolete installations.

Improvements can still be brought to the technologies and processes used for reducing the costs, dose commitments and generated waste. Laboratories and research institutions throughout Europe are still busy in that field and are exchanging results through networks established with the EC support.

Finally, in order to disseminate the accumulated know how and improve the exchange of information within the EU, data bases have been set up and are available for the industry.

Introduction

The first question to answer should be "What is decommissioning?"

Therefore, we will use the IAEA definition of decommissioning, which states [1]:

In some national regulation, the decommissioning comprises all necessary actions needed to restore the used site for other potential uses.

The peaceful use of nuclear energy having started in the fifties, the first nuclear power plants and facilities are now reaching gradually their end-of-life. Some of them are also definitely shut down for economical reasons, as their efficiency can hardly compete with other plants.

Moreover, the old installations used by the countries with nuclear weapons programmes, are becoming redundant and are also definitely shut down. Therefore, since a bit more than 10 years, various nuclear installations are decommissioned throughout the world, and in particular in Europe.

The past European Commission Programme on Decommissioning and Decontamination

The European Commission recognized very early the need for research, development and demonstration projects in the field of decommissioning. With more than 140 nuclear power plants and almost the same number of research reactors within the Member States, it was clearly needed to be prepared to the end-of-life of these nuclear facilities.

Therefore, throughout the different EC framework programmes (see Table 1), European countries have built up a very comprehensive know-how on decommissioning and are now able to face the large scale decommissioning projects of commercial plants.

After a first period of specific R&D projects on decommissioning techniques and processes, the Union decided to start demonstration projects, so-called pilot decommissioning projects, allowing to test and demonstrate the developed techniques on a scale 1:1.

These projects, situated in different Member States, covered also almost all kind of nuclear power plants and facilities (see Table 2).

The results of these projects were made publicly available and a database system has been set up to collect and gather all interesting data from the R&D tests and from the pilot projects.

The set up of these programmes allowed also to enhance the exchange of information and data throughout the different Member States and between all kind of operators. With this large exchange, the information has been widely spread and allowed to start large projects on a sound technological basis.

The present successful experience with large scale decommissioning in Europe

Based on the accumulated experience and on the developments made in different laboratories and research centres, large scale decommissioning could proceed with the oldest nuclear installations in Europe. This includes nuclear power plants from different sizes and types, and fuel reprocessing plants or former nuclear military facilities.

To exemplify this experience, some important data will be given for 4 countries already active in the decommissioning process, and also involved in the pilot projects supported by the Commission, i.e. France, Germany, the United Kingdom and Belgium.

This does not preclude that practical decommissioning is also gained in other Member States like Italy, the Netherlands, Sweden, Spain, ...

The present experience in France

The 2 main operators having gained important experience in decommissioning are the utility EDF and the French CEA.

Other operators have also either started decommissioning or carried out the necessary studies, but will not be listed hereafter.

EDF experience - Deconstruction of the EDF UNGG type

EDF operates nowadays a nuclear network consisting of 58 PWR units; it is however with the Uranium Natural Graphite Gas (UNGG, i.e. Gas Cooled Reactor) that EDF started its nuclear electricity production.

6 units, for which EDF assumes the exclusive responsibility, were constructed at the sites of CHINON, SAINT-LAURENT and BUGEY. They were all successively and definitely shut down for economic reasons and are, for the moment all in a different stage, being dismantled according to the dismantling processus in force in EDF. This processus depends on the national regulations and the deconstruction strategy adopted by the company. It consists in carrying out, after the final shut down, a partial dismantling in order to reach quickly the stage of a Basic Nuclear Installation for Storage ("Installation Nucléaire de Base d'Entreposage - INB-E) and to defer, after a waiting period of about 25 to 50 years to decay the radioactivity, the complete dismantling of the installation.

The most important information about the operating period of these installations is given in Table 3 below.

The intended partial dismantling stage corresponds to IAEA stage 2. However, at the Chinon A1 unit, the presence of the metallic sphere protecting the reactor and the auxiliary systems allowed to limit the partial dismantling to the equipments outside the sphere and those susceptible to be flooded in the lower part of the sphere.

This sphere facilitates the preservation of the materials and their supervision; moreover, it has been transformed in a museum, open for the public since 1986.

For units Chinon A2 and A3 having a different conception (there is no reactor containment), a more expanded partial dismantling was retained. Some modifications were necessary to assure the containment of the whole installation in 5 volumes (3 for A3), one for the reactor and one for each of the 4 heat exchanger buildings (2 for A3). All the other circuits and equipments were dismantled and stored in specific packages, placed on the floor of the exchanger buildings or in the empty space surrounding the reactor.

Units Chinon A1 and A2 are presently in INB-E stage while, for unit Chinon A3, the partial dismantling works are being achieved.

For the 3 other installations (Saint-Laurent A1 et A2 and Bugey 1), where the activities for shutting them definitely down are still going on, the retained approach is similar to the one carried out at Chinon A2 and A3. Here it is even more easy due to the integrated conception of the reactor of which all the components are gathered in one single large-sized containment (reactor caisson) in pre-stressed concrete.

The storage installation is essentially meant for the carefully confined reactor caissons.

All the loops and equipment components in the vicinity of these caissons or located in the other nuclear buildings of the installation will be dismantled.

The INB-E stage at Saint-Laurent A1 and A2 should be reached in 2004 and at Bugey 1 in 2002.

The know-how, acquired during these first operations, especially in the case of Chinon A2 and A3, led to important works, and permitted:

• to see the importance of prelimary preparation and studies; this was especially the case for the radiological characterization and inventory;
• and to confort EDF in its fully deferred dismantling strategy from the viewpoint of the difficulties concerning the evacuation of the generated waste.

CEA experience - The decommissioning project for the Brennilis nuclear power plant

Although the CEA has accumulated D&D experience in all kinds of fuel, laboratories and research facilities, one of its main present tasks concerns the EL 4 decommissioning project at the site of Brennilis in the French Brittany.

In September 1997, the CEA and EDF started decommissioning work on Brennilis Nuclear Power Plant, which has been closed for 12 years. Except for the reactor building, which is to be fitted out pending final dismantling, all the buildings on the site are dismantled and demolished.

This is the first time that such an operation has taken place in France.

• General characteristics of the EL 4 facility
  

  The EL 4 facility was built in the early 1960s in the Monts d'Arrée region of Brittany, by a lake with an existing dam. Its capacity was not great (electrical 73 MW, thermal 250 MW) as it was designed to check, on an industrial scale, the feasibility of a French series of power reactors using heavy water as the moderator and pressurised carbon dioxide as the coolant.

  EL 4 first went critical at the end of 1966, and the plant was connected to the EDF grid in July 1967. However, following the first oil crisis, the government authorities chose to adopt light water technology (56 reactors currently operating) to rapidly increase the number of nuclear power plants in France. Therefore, EL 4 remained the only heavy water reactor in France.

  After several adjustments, the reactor operated for over fifteen years with a highly satisfactory availability factor, until its final shutdown in 1985 for economic reasons.

  From the beginning, this experimental plant project was jointly managed by the CEA (designers of the heavy water series) and EDF (in charge of generating and distributing electricity). They will continue to co-operate throughout decommissioning.

• Decommissioning of the site in three stages
  

  The decommissioning of the Monts d'Arrée site is a planned operation, set to be carried out in stages corresponding to the three stages of decommissioning as defined by the IAEA:

  • Stage 1, or "monitored closure", was achieved after final shutdown operations were completed at the end of 1992, following the removal of all the spent fuel from the site.

  • Stage 2, or "partial or conditional release": at the Brennilis plant, following the decree 96-978 of 31 October 1996, Stage 2 work commenced: a contract was awarded to a contractor group and to some specialized companies, to dismantle all the equipment and systems in the nuclear buildings (except the reactor building), clean up the walls of the rooms and, after systematic monitoring, demolish the buildings.

    In the reactor building, only the heavy water systems contaminated with tritium and the old electrical systems are to be dismantled in Stage 2. Pending the final dismantling of the building, certain operations are being carried out: reinforcing of the reactor containment, installation of new alarm and protection devices, renovation of the electrical system and the ventilation (which is to be fitted with a air-drying system to prevent corrosion of the metal structures).

    Over a hundred people are involved in these operations and conventional techniques are being used (sawing and cutting with traditional mechanical tools, disassembly and demolition with jack hammers). However, precautions must be taken when using these techniques in a nuclear environment.

  • Stage 3, or "full and unconditional release": the CEA and EDF carried out a feasibility study of the alternative scenarios which were less time-intensive than the reference scenario which set final dismantling after a period of 50 years to allow the radioactivity of the core to decrease.

The experience in Germany

The production of nuclear electricity started in Germany with the experimental nuclear plant in Kahl (VAK). This plant with an electrical output of 15 MW was the basis for the nuclear industry, which came to an output of 24.000 MW in 1988 and 1989 with the start-up of three KONVOI plants. This is adequate to 34 % of the total electricity production in Germany.

Since then no more nuclear plants were constructed or went into operation. At the moment there are 19 nuclear power plants at 14 sites in operation. Another 16 (Table 4) are finally shut down or are under dismantling already.

• Planning and costs of a dismantling
  

  Therefore the German utilites follow the strategy that a nuclear power plant has to be removed from the site completely after its life time. The radioactive material has to be disposed finally if a decontamination and a free reuse is not possible.

  These measures are payed with money that has been collected during the operation of a plant. The decision for the amount of this money is based on detailed studies.

  Two reference projects have been investigated in these studies as there are the nuclear power plant Biblis A (1204 MW) as an example for a pressurized water reactor and Brunsbüttel (805 MW) as an example for a boiling water reactor.

  The study deals with the dismantling of all materials out of the controlled area and includes the buildings as well. These are normally the reactor and auxiliary building and in case of a boiling water reactor the turbine hall too.

  First of all the studies characterized the site with respect to the components, materials, design and radioactive inventory. Taking into account the possible nuclear waste management and the situation of final waste disposal, the results of the study were certain procedures for dismantling, treatment and packaging linked with the necessary expenditure of time, man power and tools.

  This led to detailed descriptions of the whole procedure down to single working steps. The result of this planning is, that the dismantling costs are nearly independent of the type of the plant, PWR or BWR, and the decommissioning option.

  In both cases the costs are in the range of 10 % of the actual costs to build a new plant. This is for example 700 Mio DM (about 358 Mio€) for the dismantling of a 1300 MW plant, referring to 1994.

  This corresponds to 1 % of the price for one kWh, respectively 0.0025 DM/kWh (0.00128 €/kWh).

  This study is accepted by the authorities and the independent experts and is updated periodically. Experiences out of actual projects and changes in the waste management are taken into consideration. Meanwhile each nuclear power plant has its own study which considers the special conditions and allows to calculate the dismantling costs. The update is done annually.

• Decommissioning options
  

  As known, the International Atomic Energy Agency (IAEA) has defined three phases of decommissioning:

  • Stage 1: shutdown of the plant; opening systems blocked and sealed
  • Stage 2: safe enclosure; partial dismantling of systems; time of enclosure
  • Stage 3: dismantling of all radioactive parts and removing them from the site; cleaning of the buildings for unrestricted reuse of the site; "green meadow"

  In Germany the decommissioning is slightly different from these steps.

  The main difference with the IAEA steps is the so called "post operation phase". During this phase the licence for operation is still valid. This licence covers the removal of all operational waste like, nuclear fuel, filter resins and other media. The costs for that are not included in the calculation of the decommissioning studies.

  The decommissioning options of the German utilities are:

  • immediate dismantling
  • deferred dismantling of the plant after 30 years.

  Both options have specific advantages and disadvantages (see Table 5). The decision for one option is done under the responsibility of the owner respectively the operator. It is done considering the special situation of each single site knowing that the money for this work has been collected before, and is available.

  Important criteria are e.g. characterization of the site, personnel situation, availability of a final storage for radioactive waste and a future use of the site.

  Table 5. The factors that need to be considered for the immediate dismantling respect the deferred dismantling

  Reasons for direct dismantling	Reasons for later dismantling
  Financing is available	Financing is not available now
  Costs are predictable (near term)	Lower radwaste volume
  Experienced operating staff available	Lowest collective dose
  Minimizes impact to local economy	Benefits from other projects
  Aspects of the licensing procedure	No final storage available
  Earlier site reuse possible
  Positive public perception (today)
  Permits earlier termination of responsibility

  In Germany the so called "dismantling licence" is something in between the steps 1 and 2 of the IAEA scale. It differs case by case and may include the dismantling of radioactive systems too.

  The "safe enclosure" as it is known in Germany requires special measures to prevent un-allowed access and an obligatory control of the function of the "safe enclosure". The necessary effort for that is much higher than it is considered in international studies. In addition to that the total dismantling includes the demolishing of the buildings too.

• Experiences in decommissioning
  

  All 16 nuclear power plants in Germany which are on the way to dismantling have been shut down unplanned. Only the NPP of Kahl has been shut down as planned after 25 years of successful operation.

  The NPP in Lingen (KWL) is a BWR and had an electrical power of 252 MW. Its time of operation was between 1968 and 1977. The operator decided to do the safe enclosure with partial dismantling. The safe enclosure is planned to be 25 years. The main reason for this decision was that final storage for radioactive waste was not available.

  The unit A in Gundremmingen is a BWR with an electrical power of 250 MW. It was in operation between 1966 and 1977. The operator decided to dismantle the components and systems which were no longer required immediately and to keep the building as workshops for the future. One of the main reasons for this decision was to prove that the preventive financial requirements were calculated correctly.

  The well known argument for the safe enclosure to use the effect of decay of 60Co is correct with respect to the physical aspects, but with the work in Gundremmingen it could be shown, that this advantage can be more than compensated by means of sensible measures of radiation protection.

  From the point of view of radiation protection it is more convenient to dismantle a facility immediately and as long as the experienced staff is on the site, then to wait for 100 years, as it is also discussed in Germany.

The Greifswald Site

At the Greifswald site (KGR), there are in total 8 reactor units of the Russian pressurized water reactor type VVER 440. Units 1-4 are of the model 230 and units 5-8 of the more recent model 213. There are also a wet storage for spent fuel, a warm workshop and additional buildings for the treatment and storage of radioactive waste.

After the reunification of the German States, the 4 operating units of the Greifswald Nuclear Power Plant were shut down, the trial operation of unit 5 and all construction work for units 6-8 were stopped. Investigations in view of the reconstruction of some units showed no acceptable economical solution.

Finally, in 1990 the decision was taken to decommission units 1-4, followed by the same decision for unit 5 in 1991.

The licence for the decommissioning of the overall plant and for the dismantling of plant parts was issued on 30 June 1995. The dismantling works in the turbine hall units 1-5 and in the controlled area of unit 5 have started in October 1995.

The present status of the project is as follows : Non-contaminated and contaminated plant parts in the controlled area of unit 2 and 5 and in the turbine hall of units 1-5 are being dismantled, packed and stored on site or in hall 7 of the ISN.

Totally, approximately 20 000 Mg plant parts have already been dismantled (status 10/99).

The reactors of the units 1-4 (approximately 2 000 Mg) must be remotely dismantled due to their high activity. The preparation of the documents for execution, the manufacturing and mounting including commissioning are finalized since the beginning of 1998. The execution of model dismantling at non-activated reactor components has been started in June 1999. After the transport and installation of the equipment, the remote dismantling in unit 1 and 2 will start at the beginning of the year 2000.

With the present acquired experience, it can be stated that the decommissioning and dismantling of the Russian VVER type reactors do not pose specific problems when compared with the Western PWRs. However, the size of the project and the resulting mass flow is huge. In order to achieve a safe and cost effective project, it is necessary that all stakeholders, i.e. EWN, authority and authorized experts, achieve a positive co-operation.

The project has proceeded very well: major licences and agreement on licensing strategy are obtained, fuel elements have been evacuated, disposal of radioactive waste is running on schedule and a sophisticated data base system has been built up.

The experience in the United Kingdom

The United Kingdom based its nuclear power production mostly on Gas cooled reactors (Magnox type and AGR type). The main decommissioning operation and experience are thus coming from these types of reactors (see Table 6).

In parallel, important decommissioning operations are also carried out on non-reactor nuclear facilities.

Table 7 gives details of decommissioning currently being undertaken by the United Kingdom Atomic Energy Authority (UKAEA) at their sites at Winfrith, Harwell, Windscale and Dounreay. At Dounreay, UKAEA's largest site, operations have now ceased and a 50 year programme has commenced to decommission all the site plants, including pilot power plants. Other examples of decommissioning occur at the BNFL site at Sellafield, and include a Separation Plant, Plutonium recovery plant, a Caesium extraction plant, Silo Sludge retrieval and various other smaller projects.

Most of the decommissioning of reactors follow the strategy of safe-store, the safe enclosure being reached either promptly after shut-down (e.g. in Trawsfynnyd) or after a deferment of about 35 years (like Berkeley and Hunterston).

The main incentive to select the "safestore' and "deferred dismantling" strategy for the gas-cooled reactors is based on the reduction of dose rate with time, the main radiating isotope (60Co) decreasing naturally up to a factor 10,000 after about 100 years.

The WAGR (see next figure), being selected as European pilot project during the 3rd framework programme (see §3 above) is also considered as UK's demonstration project in nuclear reactor decommissioning. Its ultimate objective is to demonstrate the decommissioning of industrial scale power reactors. In the six year programme to dismantle the reactor core and pressure vessel, the Remote Dismantling Machine and Waste Route have been commissioned and are now being used to remove, package and encapsulate intermediate level waste in concrete boxes for storage in a purpose built ILW Waste store.

Figure 1. The WAGR project: Removal of the heat exchangers

• Overall decommissioning strategies in the United Kingdom
  

  For the purpose of the development of decommissioning strategies and plans nuclear facilities in the UK can, in general terms, be segregated into two categories: Reactor and Non-Reactor Facilities.

  After defuelling, the principal radio-nuclides present in reactors are of a relatively short half-life such that there is some benefit from radioactive decay over time. In addition the radioactivity post defuelling is in the form of activated materials in the reactor core region which can be contained relatively easily.

  In non-reactor facilities, the radioactivity is present as contamination rather than activation with radio-nuclides, which are, in general, of a long half-life so there is little benefit to be gained by allowing time for decay. The facility design, construction, and condition of facilities can have a determining effect on strategies for their decommissioning. The radioactivity in reactors is not usually very mobile and is contained within a massive bio-shield whereas in the non-reactor facilities the radioactivity tends to be potentially more mobile and the facility containment life, without major work, is shorter.

  Non-reactor facilities include:

  • fuel conversion, fabrication and enrichment plants;
  • irradiated fuel reprocessing plants;
  • post irradiation handling facilities and other laboratories;
  • waste processing facilities.

  There are many such facilities in the UK. Prime examples include the BNFL uranium fuel fabrication facilities at Springfields, Preston, and the irradiated fuel reprocessing and waste-processing complex at Sellafield.

  In the UK there are a number of reactors with power levels above 1 MWth, which will fit into the general reactor strategy. These include:

  • Carbon Dioxide cooled Magnox (26 on eleven sites) and Advanced Gas Reactors (15 on eight sites);
  • Air cooled reactors (3 on two sites);
  • Light water cooled reactors (2 on one site);
  • Liquid metal cooled (fast) reactors (3 on two sites);
  • Heavy water cooled materials testing reactors (3 on two sites).

  There are a number of small low and zero energy reactors where the decommissioning strategy can be different from the above, usually because the radioactivity is at a much lower level so there is no benefit from decay.

The experience in Belgium

Although Belgium is a relatively small country within Europe, the share of nuclear produced electricity is the second one, just after France, with more than 50 % being generated by Nuclear Power Plants.

Since the end of the eighties, two main decommissioning projects have been started: a PWR power plant and a reprocessing plant. Belgium had thus also accumulated experience in decommissioning through 2 main projects: BR3 and Eurochemic.

BR3 was the first pressurized water reactor, designed by Westinghouse, exported outside the USA. It is a small power plant with a limited power output of 10.5 MWe. The reactor has been shut down in 1987 and was selected by the EC in 1989 as one of the four european pilot decommissioning projects.

It is also used as test case and demonstration project in nuclear power plant decommissioning, and allows to test and to compare various techniques and procedures for the execution of this type of operation.

The decommissioning project started in 1989. In 1991, a Full System Decontamination of the primary loop reduced the dose rate in the vicinity of the primary loop by a factor 10. The same year, a first high active internal, the 5.4 t thermal shield was dismantled underwater by 3 different dismantling techniques, the EDM cutting, the milling cutter and the plasma arc torch. Mechanical cutting, essentially milling cutter and band saw, were selected for the further dismantling of the two sets of internals; the original Westinghouse internals ("33 years decay") and the Vulcain internals ("7 years decay").

This allowed to compare deferred dismantling with immediate dismantling. No significant radiological, technical or economical profit was gained by dismantling the old internals because due to the still high dose rate of 2 to 3 Sv/h at mid plane, remote underwater cutting is still required. The next important step is the cutting of the 28 t Reactor Pressure Vessel. All the preparatory work is finished and the real cutting operations have now started by the removal of the insulation shroud. Dismantling of some contaminated circuits was also performed using mostly hands on cutting techniques. Minimizing the amount of radioactive waste and free release of the dismantled materials have always been the main objectives. Recycling of slightly radioactive metallic materials could be performed thanks to an agreement with a nuclear foundry. For concrete, an R&D programme has been started to recycle radioactive concrete in the radioactive waste conditioning sector. Progress was also made on the establishment of free release limits and procedures and on the development of decontamination techniques for metals and concrete.

The Eurochemic reprocessing facility at Dessel in Belgium was constructed from 1960 to 1966. From 1966 to 1974, a consortium of 13 OECD countries reprocessed 180 t of natural and low-enriched and 30 t of high-enriched uranium fuels in this demonstration plant.

After shutdown, the plant was decontaminated to keep it in safe standby conditions at reasonable cost. Radiation in the cells was decreased to average levels below 0.2 mSv/h.

In 1984, Belgoprocess took over the activities on site. In 1986 it was decided to stop processing in Belgium and to decommission facilities built for that purpose.

From 1987 to 1990, two storage buildings for uranyl nitrate, plutonium dioxide and spent solvents were emptied and decontaminated as a pilot project to prove the feasibility of decommissioning up to restoring green field conditions, to check techniques and costs and to train personnel. Remaining building structures were monitored for unconditional release, withdrawn from the controlled area, demolished and disposed of as industrial waste.

In 1991, Belgoprocess started decommissioning of the main process building on an industrial scale. It is a rectangular construction of about 80 m long, 27 m wide and 30 m high. Basic inventories are:

• building volume : 56,000 m3;
• concrete volume : 12,500 m3;
• concrete surface : 55,000 m3;
• metal structures : 1,500 Mg.

The core of the building comprises a large block of 40 main cells, containing the chemical process equipment. Access areas and service corridors are located on 7 floor levels.

About 106 cell structures have to be dismantled. Some cells have contamination levels up to 125 Bq/cm2 (beta) and 200 Bq/cm2 (alpha). Some hot spots give gamma dose rates of several mSv/h.

Decommissioning involves the removal and decontamination of equipment from each cell, the decontamination of cell walls, ceilings and floors, the dismantling of the ventilation system, followed by a complete monitoring in view of unrestricted release of the remaining structures. Most of the work is done by hands-on operations under protective clothing tailored to each task. Some tool automation and automatic positioning systems are successfully applied.

Information exchange enhanced by the EC

The European Commission gave the opportunity to enhance the information exchange and collaboration between different operators and Member States through the different projects performed during the preceding framework programme.

Moreover, some specific tools and systems were set up in order to improve the exchange of information, the dissemination of the collected results and the collaboration between the laboratories, research centres, operators, etc.

Among the different actions taken (like the organization of specific conferences, workshop, training courses, etc.) two main actions were performed and are presently available:

• the set up of a European database on decommissioning tools, dose and cost (EC-DB Tool and EC-DB Cost);
• the set up of an internet website, presenting the main results and activities in the field of decommissioning (the present website: http://www.eu-decom.be)

Return of experience and future needs

The various projects running in Europe since more than 10 years now have brought a lot of information and return of experience. Among them, one can mention:

• The better estimate of the cost of decommissioning based on the actual experience.
• The development of tools and procedures for minimizing the dose, the generated waste and the costs.
• Whatever should be the selected strategy, it is always better not to wait too long after shutdown to start the dismantling activities: indeed, the knowledge of the plants disappears quickly and the needed equipment rapidly degrades and can give problems if waited too long.
• For Light Water Reactors (LWR), the presence of pools and water allows to dismantle quite easily the highly active components of the reactor in a safe manner, using water as radiological shielding medium.
• No significant improvements in the dose commitments and in the waste amount can be expected from a deferment of about 30 years. A longer period is needed to reach significant dose and waste volume reduction.

Moreover, through the exchange of information and the collection of technical and cost data in a European database, the return of experience built up till now is available for future decommissioning operations.

On the other hand, the decommissioning activity being foreseen to increase dramatically within the next 10-20 years, there is further need for collaboration between the different actors, through networking and exchange of experience. The training of staff and operators of future decommissioning is also a very important topic and should be organized at European level, in order to take profit of the accumulated experience and know-how.

Also, as small improvements in the technology can lead to important savings regarding the huge amount of installations to be decommissioned in the future, there is still need for further research and development in techniques and processes allowing to minimize the generated waste, the dose uptake and the costs. Therefore, co-ordinated Research and Technological Developments, with support of the European Commission, can still improve the competitivity of the European industry and minimize the impact of these activities on the environment.

Conclusions

With the different projects running or already achieved, it has been shown that the European Union has acquired a very broad experience in decommissioning. Although the management of the decommissioning waste has not been developed in this paper, it is obvious that the management and handling of the materials and waste generated by the D&D is also an important part of the European experience so far.

European-wide collaboration has been enhanced by the Commission and allowed the different Member States to dispose of up-to-date technology and return of experience in the field of decommissioning. Research and developments can still be important in order to further optimize and reduce the generated waste and the associated cost and to improve the safety and impact on the environment.

With the experience already acquired to date, it has been demonstrated that the nuclear industry is prepared to manage the end-of-life of its installations. It is probably one of the few industries that has shown so much concern about the end-of-life of its installations and has acquired experience and know-how to be able to have clean industrial sites after operation.

References

1. IAEA Safety Series n°105, The regulatory process for the decommissioning of nuclear facilities, 1990.
2. The decommissioning project for Brennilis nuclear power plant, P. Reynard, CEA, 1999.
3. The WAGR project, T. Benest, UKAEA, 1999.
4. Decommissioning in Germany, U. Priesmeyer, KGB, 1999.
5. Decommissioning and dismantling of the Greifswald Nuclear Power Plant, Energiewerke Nord GmbH, 1999.
6. International Conference SFEN Dismantling of Nuclear Facilities, Experience and Developments from the Decommissioning of the BR3 Nuclear Power Plant and the former Eurochemic, Reprocessing Plant in Belgium, V. Massaut, L. Teunckens, Avignon 15-18 March 1998, ref. 052/98-03.
7. UKAEA Decommissioning projects by Site and Plant (Draft), J. Williams, T. Benest (UKAEA), 1999.

Author

© 2001-2008 European Communities. All Rights Reserved. Disclaimer.