Waste disposal for nuclear power plants. A technologically solved challenge

Transcription

1 Waste disposal for nuclear power plants A technologically solved challenge

2 This brochure provides information about disposal of the residual materials and waste accumulating in German nuclear power plants. The images, tables and graphics contained in the brochure may be used in preparing lectures concerning the disposal of nuclear power plants. For this purpose, the representations can be downloaded at: Please make reference to the source when using the information.

3 Overview of topics Page Foreword 4 1 Nuclear power plants and their corresponding disposal facilities in Germany 6 2 Radioactive materials from nuclear power plants 7 3 Classification of radioactive waste 8 4 Fuel assembly disposal 9 Reprocessing 10 Direct final disposal 11 Transport and interim storage of fuel assemblies 12 Conditioning and final disposal of spent fuel assemblies 14 5 Recyclable and non-recyclable radioactive materials 15 Residual materials and waste management concept 15 Release 16 Recycling of metals by melting 17 Radioactive waste 18 Annual operational waste volume from nuclear power plants in Germany 19 Optimised treatment methods for solid and liquid radioactive waste from nuclear power plants 19 Volume reduction of radioactive waste 19 Incineration facility for radioactive waste 20 High-pressure compaction of solid radioactive waste 21 In-drum drying for solidifying liquid radioactive waste 22 Examples of packaging of radioactive waste 23 Transport of radioactive materials 24 Interim storage 24 6 Decommissioning and dismantling of nuclear power plants 25 7 Quality assurance 27 Waste treatment with methods qualified by the BfS (Federal Office for Radiation Protection) 27 Waste package documentation 28 Waste Flow Tracking and Documentation System (AVK) 28 8 Final disposal 29 Responsible institutions in final disposal of radioactive waste in Germany 29 Structure of a repository for radioactive waste in a salt formation 31 9 Final disposal sites and pits 32 Development of final disposal 32 Asse 33 Morsleben 33 Konrad 34 Gorleben 35 Glossary 36 List of illustrations 40 Further websites 41 Imprint 43

4 Fig. 1 Energy mix of Germany s electricity supply between 1960 and Renewables* *Hydro power, wind energy, biomass, photovoltaics, domestic waste and geothermics; practically only hydro power prior to Oil and natural gas Share of electricity generation in % Lignite Hard coal Nuclear power Old and new Former West German States Federal States Foreword For 40 years now, nuclear power has been making an important contribution to a safe, economical and environment-friendly power supply of the industrial nation of Germany. On occasions, the share of nuclear energy amounted to more than 30 %. During this period, radioactive waste have accumulated during operation of the nuclear power plants, the disposal of which this brochure intends to describe. Amendment of the German Atomic Energy Act 1) in 2011 in the wake of the natural and reactor disaster in Japan has substantially transformed the situation of nuclear power in Germany: for eight plants, the authorisation for continued electricity production has been forced to immediatly expire. Restricted electricity generation quotas and concrete decommissioning dates have been assigned to the nine remaining nuclear power plants. Subsequently, the last three German nuclear power plants will be withdrawn from the grid at the end of After assigning a modified use to nuclear power with these new framework conditions, it is to be expected in the future that the political endeavours for final disposal of radioactive waste as a duty of the German Federation will increase. These include the conversion and commissioning of the approved Konrad repository for non-heat-generating radioactive waste and the rapid further exploration of the Gorleben salt dome so that a statement about the possible suitability for a repository for heat-generating radioactive waste can be made. Since some time will elapse until the repository is commissioned, the nuclear power plants have developed and are applying treatment methods for the waste. The aim is, in addition to manufacture repository-compatible and conditioned waste packages, a reduction of the volumes of waste. Interim storage facilities exist and the transports are long-established practice. The radioactive waste are disposed of according to the «polluter pays» principle: those who generate radioactive waste must bear all the disposal costs. This also applies to final disposal of the radioactive waste. Although the German Federation is responsible for this, the costs are nevertheless immediately passed on to the waste producers. 1) words printed in italics are explained in further detail in the glossary (from p. 36 onwards)

5 Fig. 2 Energy mix of Germany s electricity supply from % 23 % 5 Oil and natural gas 16 % Nuclear power Lignite 23 % Hard coal Hydro power and other renewables 19 % During the residual life spans of the nuclear power plants, further radioactive waste will accumulate. The same applies to decommissioning of the plants. Radioactive residual materials also arise however during the use of radioactive materials in medicine, research and industry. During their disposal, i.e. in all stages of treatment, interim storage, transport and final disposal, protection of man and the environment takes utmost priority. Consequently, radioactive materials must be dealt with such that impermissible radionuclide concentrations in the biosphere are ruled out. Tried and trusted methods, facilities and containers have been available for this purpose for many years now. To name a few examples: - Reprocessing of spent fuel was already developed almost 50 years ago and has been industrial practice in Europe since the 1980 s. - Storage casks for spent fuel assemblies have been authorised and are in use since the early 1980 s. - Central interim storage facilities for high-level waste (HLW) from reprocessing and spent fuel assemblies have existed since the early 1980 s; decentralised storage facilities at the power plant sites have been in operation since 2007 at the latest. - Treatment methods for radioactive waste have existed since the first nuclear power plants were commissioned; they have been continuously adapted to the changing requirements of interim storage and final disposal. - The decommissioning of nuclear power plants has been common practice for more than 20 years now; three plants have already been completely decommissioned. - The Konrad repository for low and intermediate-level waste (LLW and ILW) is approved and is currently being extended. - Solely implementation of the disposal stage, i.e. final disposal of heat-generating waste, has not yet been performed by the German Federation. Nevertheless, the necessary technologies have been available for many years. In this brochure «Disposal of nuclear power plants in Germany: a technologically solved challenge», the methods for conditioning, interim storage and final disposal of spent fuel assemblies and radioactive waste in addition to the political background and the legal framework are illustrated in pictorial and text form. It is intended to make a contribution to objective information and an open dialogue.

6 Fig. 3 Nuclear power plants and their corresponding disposal facilities in Germany 3 1 Nuclear power plants and their corresponding disposal facilities in Germany In Germany, 9 commercial nuclear power plants with a gross design rating of some 12,700 MW were in operation under load at 8 sites at the end of 2011, including 7 pressurised water reactors (PWR s) and 2 boiling water reactors (BWR s). A total of 19 power and prototype reactors have now been shut down and are currently in different phases of decommissioning. The Niederaichbach nuclear power plant, the Kahl superheated steam reactor and the Kahl experimental nuclear power plant have been completely decommissioned; the former power plant sites have returned to «green meadows». With the resolution of the German Lower House on nuclear phase-out in summer 2011, the authorisation for operation under load is expiring for eight plants. Even before use of nuclear power for electricity generation was begun in 1962 with commissioning of the Kahl experimental nuclear power plant (VAK), key decisions concerning disposal of the radioactive materials accumulating during power plant operation were made: As early as between 1967 and 1978, radioactive waste were placed in storage in the Asse pit and between 1981 and 1998 in the Morsleben repository. The Konrad pit is approved as a repository site and is currently being extended into a repository. The Gorleben salt dome is being explored at present. Until the repositories are commissioned, radioactive waste are being stored at the power plant sites or in central interim storage facilities. Until 2005, spent fuel assemblies were taken to France or Great Britain for reprocessing following a decay time in the fuel pool of the nuclear power plants. The reusable materials separated in the process are recycled in German nuclear power plants; the waste arising are returned to Germany according to contract and undergo interim storage until a suitable repository is available. The spent fuel assemblies undergo interim storage in decentralised storage facilities at the nuclear power plant sites. Treatment of the operational waste is performed at the power plant sites or in central facilities. The waste treatment plants of the research centres in Karlsruhe and Jülich are also available for this purpose.

7 Fig. 4 Differentiation of the radioactive residual materials Radioactive residual materials from nuclear power plants Waste Operational waste For conventional use, recycling or removal of released materials 7 Spent fuel assemblies - high-level radioactive - heat-generating Other radioactive materials - intermediate or low-level radioactive - non-heat-generating Decommissioning waste Other radioactive materials - intermediate or low-level radioactive - non-heat-generating 2 Radioactive residual materials from nuclear power plants During operation and decommissioning of nuclear power plants, radioactive residual materials occur which, as stipulated by the legislator, are to be harmlessly recycled or disposed of in a controlled way, i.e. handed over to a Federal repository. Materials, the activity inventory of which - following decontamination if necessary - may demonstrably result in negligible radiation exposure of the population may be conventionally used, recycled or removed if the competent authority issues a corresponding release. They subsequently no longer fall under the term «radioactive materials» and are no longer subject to monitoring under the German Atomic Energy Act. Radioactive residual materials that can not be released are to be regarded as radioactive waste and must be disposed of. Since the manner of disposal essentially depends on the physical, particularly radiological characteristics, spent fuel assemblies (irradiated fuel elements) and intermediate and low-level radioactive operational or decommissioning waste are considered separately here.

8 Fig. 5 Classification of radioactive waste Radioactivity Waste designation Examples of waste Final disposal Bq / m 3 Distribution of total volume of waste high-level intermediatelevel heat-generating waste waste with negligible heat generation Fission products from reprocessing Conditioned fuel assemblies Core components e.g. Gorleben repository 5 % of the volume of waste with 99 % of the radioactivity low-level Waste from reprocessing Operational waste from nuclear power plants Waste from decommissioning Konrad repository 95 % of the volume of waste with 1 % of the radioactivity 3 Classification of radioactive waste Radioactive waste are described according to international practice based on their radioactivity (measured in Bq per m 3 of the waste) as low-level (LLW), intermediate-level (ILW) or high-level waste (HLW). The radioactive inventory and the heat arising during radioactive decay are of significance for considerations relating to safety analysis regarding final disposal in Germany. Consequently, the radioactive waste submitted for final disposal are divided into those with negligible heat generation and into heat-generating waste: - Waste with negligible heat generation involve above all waste from operation of the nuclear power plants and their decommissioning. They will be placed in storage in the future in the already approved Konrad repository. - The heat-generating waste principally include the high-level radioactive fission products from reprocessing and spent fuel assemblies. A separate repository, e.g. in Gorleben (rock salt) is to be set up for the latter.

9 Fig. 6 Ways of disposal for fuel assemblies in Germany 9 4 Fuel assembly disposal Up to 1994, reprocessing of fuel assemblies was the politically desired and only permissible way of disposal. After the failure of German reprocessing, plants in France and Great Britain were used. The main stages are as follows: - Decay storage of the fuel assemblies in the fuel pools of the nuclear power plants - Transport to France or Great Britain - Reprocessing of the fuel assemblies and recovery of the recyclable uranium and plutonium - Repository-compatible conditioning, i.e. isolation and packing of the fuel assemblies in disposal casks (POLLUX ) - Return of the conditioned waste to Germany for interim storage - Final disposal in deep geological formations - Manufacture of new uranium- or mixed-oxide fuel assemblies On amendment of the German Atomic Energy Act in 1994, the way of disposal of direct final disposal was legally equated with reprocessing. Since mid-2005, delivery of irradiated fuel assemblies to reprocessing plants has been impermissible according to the newly amended German Atomic Energy Act. Today, spent fuel elements are disposed of via the route of direct final disposal. The individual stages are as follows: - Decay storage of the fuel assemblies in the fuel pools of the nuclear power plants - Packing in casks and storage containers - Dry interim storage in the central storage facilities in Gorleben and Ahaus in addition to newly created storage facilities at the nuclear power plant sites - Repository-compatible conditioning of the fuel assemblies - Final disposal in deep geological formations, for example in rock salt

10 Fig. 7 Fuel assembly disposal: reprocessing / statistics for a PWR per year of operation Reprocessing Reprocessing of spent fuel assemblies was in the past the politically desired and only permissible way of disposal. For this purpose, long-term contracts were concluded with the reprocessing plants in France and Great Britain. Under these contracts, 6,100 t of fuel assemblies are or will be reprocessed. As a result of the amendment of the German Atomic Energy Act, the incoming transport of fuel assemblies for reprocessing has no longer been permissible since mid Nuclear fuel introduced up to that time can also however be subsequently reprocessed. The complete recovery of the radioactive materials separated during the reprocessing in France and Great Britain for recycling or final disposal is agreed in the reprocessing contracts and is secured by state treaties. For reprocessing, the fuel assemblies are initially mechanically crushed in shielded cells. The fuel contained in the fuel rods fragments is chemically dissolved. During several process stages, the recyclable fuel elements (uranium and plutonium) are separated from the waste (fission products and actinides) and cleaned. Separated plutonium and uranium are recycled. The plutonium is processed together with depleted or natural uranium to form mixedoxide fuel assemblies and is redeployed in the reactor. Around 86 % of the plutonium separated and remaining to be separated in the future has now already been recycled. The uranium is either enriched again or mixed with already existing enriched material to form new fuel assemblies. The utilisation of both material flows is presented every year to the supervisory authorities of the Federal States. The heat-generating liquid waste separated during the dissolution process are uniformly incorporated in a glass mass, cast in a stainless steel canister and sealed with a lid. The remaining cladding and fuel assembly structural components are compacted and likewise packed in stainless steel canisters. The stainless steel canisters for vitrified or compacted waste are of the same dimensions (gross volume 180 litres). Transport and interim storage are performed in casks, for example of the CASTOR type. The reprocessing waste from a PWR operating year correspond to the volume of one to two of these casks and consist of approximately one third of HLW and approximately two thirds of ILW. The reprocessing waste packed transport and storage casks are repatriated to Germany where they remain in interim storage until final disposal. Approximately 130 casks are required for the complete recovery of all vitrified HLW from reprocessing in France and Great Britain. Recovery from France has already been completed to a great extent and should be finished by around Completion of recovery of vitrified HLW from Great Britain could be accomplished around The interim storage capacities in the Gorleben and Ahaus

11 Fig. 8 Fuel assembly disposal: direct final disposal; statistics for a PWR per year of operation 11 transport cask storage facilities suffice for recovery of all waste from reprocessing. This is presented before the supervisory authorities of the Federal States by the energy supply companies each year in proof of precautionary measures for disposal of radioactive waste according to the German Atomic Energy Act. The return of the vitrified glass canisters to Germany is preceded by a multistage assent procedure in which the quality assurance organisation of the operator of the reprocessing plant, the competent French and British state controlling bodies and the German authorities responsible for the interim storage and final disposal of radioactive materials are involved with their independent experts. The entire transport cycle is also predetermined in a master work sequence concept and is released at the behest of the competent authorities following appraisal by an independent expert. Direct final disposal Since mid-2005, the German Atomic Energy Act has stipulated direct final disposal as the only way of disposalfor the spent fuel assemblies. In this case, the spent fuel assemblies are treated after their use for electricity generation as waste and not, as during reprocessing, as recyclable material. The fuel assemblies remain as a rule in the fuel pool of the nuclear power plant for many years. The residual activity and temperature of the fuel assemblies is reduced in this manner. They are subsequently transferred to transport and storage casks, e.g. of the CASTOR type and conveyed to an interim storage facility at the nuclear power plant site. Storage facilities have been set up and in operation at all nuclear power plant sites since During the 1990 s, a few fuel assembly casks were also transported to the central storage facility originally created for this purpose in Gorleben and Ahaus. During interim storage, the fuel assemblies cool down such that they can subsequently be finally disposed of. According to the current state of the art, fuel assemblies should be unloaded from the transport and storage casks after interim storage in a conditioning facility. The fuel rods are subsequently withdrawn from the fuel assemblies and packed in disposal casks, for example of the P OLLUX type. In this form, they can finally be disposed of. Other cask and repository concepts are under development as alternatives. These among other aspects pursue the aim of being able to store reprocessing waste and spent fuel assemblies underground using the same technology.

12 Fig. 9 Underwater loading of a CASTOR cask Transport and interim storage of fuel assemblies Before their final disposal in deep geological formations, spent fuel assemblies must undergo interim storage for a number of years to allow the decay heat (heat generated by residual activity) to adequately subside. Consequently, special transport and storage casks have been developed for dry interim storage of the fuel assemblies. The casks employed today, e.g. of the CASTOR type, with a wall thickness of approx. 40 cm, weight up to 120 t and have a double lid system. They ensure shielding of the radiation of the fuel assemblies with simultaneous outward heat dissipation. The double lid system consisting of a primary and secondary lid guarantees safe long-term inclusion and allows continuous monitoring of the tightness of the casks. Officially tested repair concepts exist in the unlikely event that leakage of one of the lids should occur. The casks must undergo an extensive authorisation and licensing procedure under traffic law. They comply with the international regulations. Even a crash by a rapid flying military aircraft on a cask was simulated by a ballistic test. It was shown that even this highly unlikely event with extremely high stresses on the cask does not result in any failure of the sealed containment. The fuel assemblies are loaded into the cask in the fuel pool of the nuclear power plant. The filled cask is drained, dried, tested for tightness and handled according to the requirements in terms of hazardous goods and storage regulations. The central interim storage facilities in Ahaus and Gorleben were put into service in the early 1990 s as interim storage facilities for spent fuel assemblies and recovered waste from reprocessing. Predominately casks containing vitrified HLW from reprocessing are stored in the Gorleben interim storage facility. The Ahaus interim storage facility is to primarily receive conditioned ILW likewise derived from reprocessing in the future. Since discontinuation of the transports for reprocessing in 2005, additional storage capacities for spent fuel assemblies were required in addition to the existing central storage facilities. Hence, on-site interim storage facilities were set up at all operational nuclear power plants. The last of the 12 on-site interim storage facilities entered service in The operating licences of all interim storage facilities are limited to 40 years. It is therefore possible to dispense with transports of fuel assembly casks from the power plants to the central interim storage facilities until further notice.

13 Fig. 10 Interim storage of CASTOR casks 13 The following principles apply to storage of fuel assemblies in casks: - The fuel assemblies are inside sealed and accident-proofed casks. - The casks guarantee safe inclusion of the contents, radiation shielding, heat dissipation and criticality safety. - In conjunction with the storage, the casks ensure compliance with all legal requirements concerning radiation protection of the environment (dose values according to the radiation protection ordinance). In the loading area, the delivered casks are lifted off the transport vehicle using the hall crane and are transferred to the handling or maintenance area. In the latter, the pressure switch for cask monitoring is installed, the protection plate is applied and radiological measurements and leakage tests are performed on the cask, if this has not already been done during handling after loading. The cask is set down at its storage location using the hall crane and is subsequently connected to the monitoring system. The heat emanating from the fuel assemblies is mainly dissipated with the hall air by natural convection. The interim storage facilities consist of reinforce concrete halls and in one case of two disposal tunnels in an adjacent former quarry. The capacities range between 80 and 192 cask storage locations.

14 Fig. 11 Gorleben pilot conditioning facility (PKA); external view of the dismantling cell with manipulators Conditioning and final disposal of the spent fuel assemblies During the 1980 s and 1990 s, a reference concept for conditioning and final disposal of fuel assemblies was developed by the State and industry. This makes provision for the following stages: A pilot conditioning facility (Pilot-Konditionierungsanlage, PKA) was created for conditioning spent fuel assemblies and put into service non-«radioactively». The individual working stages and working procedures were tested and demonstrated with inactive fuel assemblies. In doing so, the fuel rods are mechanically withdrawn from the fuel assembly frame and placed «side by side» in disposal casks without any further treatment. The structural components of the fuel assemblies undergo high pressure compaction and are packed and disposed of in the cask as also used for other metallic waste from operation or decommissioning of the nuclear power plants. The compact packaging of the fuel rods and the high pressure compaction of the structural components reduce the volume to be disposed of. In order to simplify handling in the repository, small containers were also developed which are suitable for vertical borehole emplacement in conjunction with the vitrified HLW. In this case also, technical feasibility and reliability of the storage system has already been demonstrated in above-ground handling trials. In the PKA waste from reprocessing can also be transferred from the interim storage casks to transfer casks for conveying to the r epository. The POLLUX was developed as a disposal cask for the fuel rods from around 10 PWR or around 30 BWR fuel assemblies, to be stored horizontally in the tunnels of the repository. Handling of the cask in shaft and tunnel transport in addition to during emplacement was tested and demonstrated in above-ground trials in original sizes and dimensions. Fig. 12 Gorleben pilot conditioning facility (PKA); internal view of the dismantling cell

15 15 5 Recyclable and non-recyclable radioactive materials Residual materials and waste management concept A series of framework conditions applies for dealing with radioactive residual materials, derived from legal regulations, operational action guidelines or the requirements of interim storage and final disposal: Waste prevention: accumulation of radioactive waste should already be avoided at the source. To this end, no unnecessary packaging materials should be introduced into the radiation-controlled area, films for masking or covering should be recycled and contamination of plant sections, tools or operating material should be prevented. Release: the release of materials for conventional waste disposal or for recycling, either restricted, for example in nuclear facilities, or unrestricted for free use also serves to avoid radioactive waste. Volume reduction: it serves above all for optimum utilisation of existing interim storage capacities and reduction in transports. For this purpose, the waste are conditioned, i.e. burnt or compressed for example. Conditioning: its purpose is to transform the waste into a form compatible with interim storage facilities and repositories by treatment and/or packing. The requirement of the repository is that the waste must be solidified (for example concreted), must not contain any free water to allow exclusion of decomposability and fermentability and be delivered in authorised packaging. Interim storage: until transfer to a repository, the waste undergo interim storage at the nuclear power plant sites or in central facilities. Final disposal: the waste are separated from the biosphere by final disposal in deep geological formations. Waste tracking: the flow of the radioactive waste from their emergence to transfer to the repository is tracked. The Waste Flow Tracking and Documentation System (AVK: Abfallfluss-Verfolgungs- und Produkt-Kontrollsystem) serves for this purpose. It documents all the necessary information concerning the quantity, whereabouts, processing status and packing of the waste.

16 Fig. 13 Way of disposal for radioactive residual materials from radiation-controlled areas Radioactive residual materials accruing in the radiation-controlled area Decay storage Separate collection according to material type and activity inventory Direct reuse or recycling in the nuclear field possible and economically viable? YES Reuse or recycling in the nuclear field Decontamination measures or buffer storage are to be verified and/or implemented if necessary NO Release according to 29 StrlSchV (radiation protection ordinance) possible, economically viable? YES Release - Unrestricted release - Release for disposal - Release of scrap metal for recycling - Release of buildings for demolition - Release in the individual case procedure NO Radioaktiver Abfall Radioactive waste Conditioning Interim storage and final disposal Release Release is performed by an administrative act of the competent authorities according to the radiation protection ordinance. Materials with a low level of radioactivity can be released if they may only result in an effective dose of up to 10 microsieverts per calendar year for individual members of the population. The authorities may consider this fulfilled if the release values stipulated in the radiation protection ordinance are complied with, i.e. 1/10 of the natural radiation exposure (ø 2.1 millisieverts per year in Germany) is not exceeded. In individual cases, proof that the protection target is reached for a stipulated release path may be provided by a separate procedure.

17 Fig. 14 Controlled recycling of metals 17 Recycling of metals by melting During operation of nuclear facilities and their decommissioning, contaminated piping, valves, heat exchangers, containers and steel components of the most diverse types arise which if necessary following prior decontamination are melted down and reprocessed into products for nuclear facilities. Thus, disposal casks or shielding are manufactured from recycled material. Up to 2009, contaminated plant components were processed in this way to make new products (approx cast components) with a total weight of 19,000 t in the form of cast iron containers, shielding components, crane weights etc. and redeployed in nuclear facilities. Only the non-recyclable products arising from the melting process (e.g. slag, filters) are disposed of as radioactive waste, amounting to approx. 1% by weight of the material originally used.

18 Fig. 15 Typical operational waste for a nuclear power plant with a PWR, by way of example annual raw waste of a 1300 MW plant and radioactivity spectrum Radioactivity Bq / m m 3 2 m 3 2 m 3 18 m 3 1 m m 3 Bead resins Filter cartridge inserts Metal components Evaporator concentrates Filter concentrates and sludges Solid waste m 3 Bead resins m 3 Oils Radioactive waste The annual amount of operational raw waste is around 200 m 3 on average for a nuclear power plant with a PWR and around 280 m 3 for a BWR. The difference lies in the fact that in a BWR, the primary steam directly drives the turbine and therefore contamination in larger plant sections is to be expected. The principal PWR waste flows include for example: Ion exchange resins (bead resins): They are mainly used in the systems such as coolant purification, fuel pool cleaning and coolant preparation. Their task is to chemically or physically bind dissolved fission products released by defect fuel rods in addition to corrosion products from the reactor circuit. The subsequent conditioning of the resins is based in principle on dehydration; they are ultimately stored as solid matter in the waste container. Filter cartridge inserts: filter cartridge inserts used downstream from the ion exchangers serve to filter out solids such as abraded resin and radioactive corrosion products that are not retained on the ion exchange resins. The spent filter cartridge inserts undergo high pressure compaction and are packed in waste containers. Evaporator concentrates: these are the residues from the evaporation facility of the waste water treatment system. The concentrates are discontinuously drained with a solid content of approx. 15 to 20 % into concentrate containers where they are dehydrated and already packed as solids in waste containers. Filter concentrates: the filter concentrates include the blow-downs from mechanical filters in the purification systems. They consist of the filtered-out materials and the filter media used. The subsequent drying of the filter concentrates allows interim storage as solids in waste containers. Solid waste: solid waste arising from general nuclear power plant operation are composed of combustible waste, e.g. paper, clothing, plastics and non-combustible waste, such as scrap metal, rubble and mineral insulating material. The non-combustible waste undergo high pressure compaction in metal cartridges and are collected as in containers as compacted pellets. Oils: lubricants and oils from the entire radiation-controlled areas are generally uncontaminated or only low contaminated. They can therefore often be released for conventional disposal. Metal components: these essentially involve high-level radioactive components, mostly from the core region (e.g. control rods).

19 Fig. 16 Optimised treatment methods for solid and liquid radioactive waste from nuclear power plants Type of waste Solid waste Liquid waste Raw waste Metal components, rubble, etc. Metal components, insulation, etc. Paper, plastics, fabrics, etc. Oil Sludges Evaporator concentrate Filter concentrate Ion exchange resins 19 Conditioning Incineration Drying, dehydration, cementing Compacting Waste products Solid waste Compacted pellet Salt block, granulate, powder, cement block Repository cask e.g. container e.g. container, cast iron container Annual operational waste volume from nuclear power plants in Germany Approximately 3,900 m 3 of raw waste per year currently accumulate in the German nuclear power plants. As a result of the treatment and conditioning methods applied today, the total volume of conditioned operational waste for final disposal is substantially reduced and amounts in total for all the efficient German nuclear power plants to a final disposal volume of only approx. 800 m 3 /year. Optimised treatment methods for solid and liquid radioactive waste from nuclear power plants It is endeavoured as a matter of principle to reduce the volume during waste conditioning. This aim is achieved through the conditioning and packing methods available and under further development. The volumes of ash from incineration amount in the most favourable case to only approx. 1/50th of the raw waste volumes. They can be further reduced by a factor of 2 with the aid of a high-pressure compactor. The volume reduction results in a corresponding increase in the specific activity. In the case of compressible raw waste, a volume reduction by a factor of 2 to 5 can be achieved. The high-pressure compacted waste must finally be packed in repository-compatible form. The transport and storage limit values for the dose rate are complied with through the selection of the cask shielding, e.g. steel or concrete container. Volume reduction of radioactive waste Example: combustible and compressible waste from nuclear power plants. Typical raw waste from a nuclear power plant include combustible and compressible waste. These waste are delivered in drums or containers in case of external conditioning. The raw waste are mainly sorted into combustible and non-combustible materials. Subsequent sorting is performed at the conditioner s premises if necessary. Fig. 17 Waste treatment methods for volume reduction

20 Fig. 18 Annual waste volume from operation of the German nuclear power plants Last revised 2010 Incineration facility for radioactive waste The aim of incineration is to substantially reduce the volume of the combustible waste such as plastics, fabrics, wood and paper, which are radioactively contaminated, in compliance with the emission control requirements. The radioactivity contained in the raw waste is quantitatively transferred to the incineration residues (ash and filter dusts) which are disposed of as radioactive waste. The volume reduction factor during incineration of the waste is approx. 50. The remaining mineral materials (ashes and filter dusts) are no longer decomposable and fermentable and can consequently be stored in the long term. Fig. 19 Loading an incineration furnace Fig. 20 Flow diagram of an incineration facility for radioactive waste

21 Fig. 21 FAKIR hydraulic super compactor 21 High-pressure compaction of solid radioactive waste For high-pressure compaction, the waste are introduced into cartridges or pressing drums and are compacted with a pressing force of up to 2,000 t. Moist waste are dried in order to avoid free fluids > 1 % and gas formation, e.g. as a result of corrosion. During this treatment, the waste are processed into dimensionally stable compacted pellets. Compacted pellets are subsequently placed in 200-litre drums or repository containers. Fig. 22 Compacted pellet following high-pressure compaction

22 Fig. 23 PETRA mobile drying facility In-drum drying for solidifying liquid radioactive waste Drying processes are used for volume-reducing conditioning of liquid radioactive waste such as ion exchange resins, evaporator concentrates or sludges. A possible method is in-drum drying. The final product of this process is a solid waste product (solid matter) which can undergo long-term storage in waste containers. Depending on its design, a facility for in-drum drying can be operated on a stationary or mobile basis. The liquid waste stored in collecting tanks are drawn off using a pump and fed into the reservoir. The concentrate can be chemically treated in the reservoir. The heat required for drying is supplied to the waste container by means of a heating system. The steam (vapour) arising during evaporation is piped to the condenser. The distillate accumulating is supplied to the waste water collection system. The system is operated at negative pressure in order to lower the boiling point.

23 Fig. 24 MOSAIK cask Fig. 25 Repository container 23 Examples of packaging of radioactive waste The packaging guarantees safe handling of the waste during the necessary loading activities and transports in addition to during their interim storage and final disposal. Suitable types of packaging are available for the various waste types, customised in their design to the specific characteristics of the waste. The cask spectrum ranges from 200-litre steel sheet drums to heavy cast iron containers for safe shielding from the radioactive radiation. All the packaging types used have undergone specific tests and licencing procedures both for transport and storage. Fig litre drum on activity measuring system

24 Fig. 27 Loading of MOSAIK -casks Transport of radioactive materials Radioactive materials are considered as hazardous goods according to international and domestic legal regulations and are subject to the pertinent provisions under traffic law and the German Atomic Energy Act during transportation on public or publicly accessible highways. Suitable types of packaging are available for all radioactive materials for transportation. The packaging depends on the characteristics, the activity inventory and the type of the radionuclides of the materials to be transported. The hazardous materials ordinances stipulate the requirements that the packaging has to fulfil. The casks are equipped with a shock absorber for transport - if required. Interim storage In Germany and other countries, radioactive waste undergo interim storage above-ground following appropriate conditioning. This allows flexible organisation of disposal from emergence of the waste to their final disposal. The following are available for this purpose for the nuclear power plant waste: - internal storage capacities at the nuclear power plant sites - external interim storage facilities: Gorleben, Mitterteich, Ahaus They were essentially created at the instigation of the nuclear power plant-operating companies. These facilities are designed for storage of all types of radioactive waste from nuclear power plant operation and decommissioning. Fig. 28 Storage of concrete shielding for disposal

25 Fig. 29 Decommissioned nuclear power plants in Germany 25 6 Decommissioning and dismantling of nuclear power plants Unlike industrial facilities, nuclear power plants are decommissioned at the end of their technical and economic lifespan, which implies that the plant has to be dismantled. Already before commissioning of a nuclear power plant, the requirement existed in Germany to conceptually prove the latter s ability to be dismantled and decommisssioned. Furthermore, the obligation exists under the German Atomic Energy Act to harmlessly recycle radioactive waste or dispose of it in a controlled way. This indirectly induces among the operators the requirement under commercial law to make financial provision for the decommissioning of their plants by forming provisions. Consequently, the German nuclear power plant operators already dealt at an early stage with the question of decommissioing of their nuclear power plants in planning terms and developed a decommissioning concept with which both technical feasibility is proven and the costs are determined. The concept is updated at regular intervals in order to take account of modified framework conditions in addition to the state of the art and obtain current cost estimations for the formation of provisions. In doing so, the section of the nuclear power plant containing the main radioactive components is transformed into a safe state free of fuel assemblies and other radioactive media. This area is subsequently effectively sealed until decommissioning. A large number of successfully implemented technologies are available for dismantling itself, both for decontamination and disassembly and for the disposal of the materials accumulating. In Germany, 19 nuclear power plants and prototype plants of the first construction generation, mainly those with a small and moderate output, had already been dismantled by the end of Among these, three - the Niederaichbach nuclear power plant, the Kahl superheated steam reactor and the Kahl experimental nuclear power plant - have now been completely dismantled. With the resolution of the German Lower House on nuclear phase-out in summer 2011, the authorisation for operation under load is expiring for a further eight plants. Decommissioning can begin directly after granting of the decommissioning licence. Alternatively, the plant can be transformed into a so-called «safe enclosure» for a limited period (e.g. 30 years) before being subsequently dismantled.

26 Fig. 30 Distribution of the accrued masses during decommissioning of the radiation-controlled area of a PWR (indications in t) Total mass of the radiation-controlled area (PWR reference power plant) 156, For final disposal Concrete and reinforcement Plant components For free recycling 143,000 9,800 For harmless recycling Radioactive waste (concrete/reinforcement) Material for harmless recycling Waste for conventional disposal 13, , For dumping For final disposal For final disposal Radioactive waste (plant components) Radioactive waste (secondary waste, e.g. from decontamination) During dismantling of the nuclear section (radiation-controlled area) of a large nuclear power plant with a PWR, around 143,000 t of concrete structures accumulate with reference to the total mass of 156,500 t, which can be almost completely conventionally recycled following removal of any surface contamination. Only approximately 600 t of the concrete requires final disposal as radioactive waste. Since the waste accumulating during decommissioning of the nuclear power plants are similar to the radioactive waste arising during nuclear power plant operation, the same conditioning methods are by an large used during their treatment. The mechanical installations - essentially piping and components - including the entire steel construction (e.g. platforms and mountings) form a mass of around 13,500 t in the radiation-controlled area of a PWR. Among these materials, only around 3,000 t require transfer to a repository as radioactive primary waste and around 500 t as radioactive secondary waste (incl. from decontamination). The remaining 9,800 t can likewise be directly released or recycled after decontamination or melting down. Clearance is given for conventional disposal for approx. 700 t. Hence, with reference to the total mass of the radiation-controlled area, only a good 2 % need to be conveyed to a repository as radioactive waste. The repository container volume from the decommissioning of all energy supply company nuclear power plants (both, those already in decommissioning and those currently in operation) is expected to amount to approx. 115,000 m 3, i.e. all the dismantling waste to be disposed of would fit into a cube 50 m square. Fig. 31 Transport of a steam generator out of the Stade nuclear power plant for recycling

27 Fig. 32 Treatment of radioactive waste with work sequence plans concerning interim storage and final disposal Preparation for conditioning Supervisory authority Work sequence plans application to Preliminary testing Procedure qualification Work sequence plans release BfS Responsibility Waste producer Representative Expert BfS/supervisory authority 27 Accompanying control Representative Expert Conditioning Documentation Waste producer Test report Representative Expert Interim storage/ final disposal Release BfS/supervisory authority Interim storage facility Repository Interim storage/ final disposal 7 Quality assurance Quality assurance acquires particular importance during conditioning of radioactive waste from nuclear power plants. The measures involved are based in this case on the following main tenets: - Waste treatment with methods qualified by the Federal Office for Radiation Protection (BfS) - Waste package documentation - Waste Flow Tracking and Documentation System (AVK) Waste treatment with methods qualified by the BfS Before the conditioning work may begin, the work sequence plans are studied and assessed by independent experts. The BfS and the competent supervisory authority approve the work sequence plans based on these studies. The waste conditioning is performed according to established treatment stages, with an accompanying control - generally by the experts of the respective conditioning facility commissioned by the supervisory authorities - being performed. All waste and treatment data are documented during the conditioning work. A provision of the radiation protection ordinance is that conditioning of radioactive waste for the purpose of final disposal be performed using methods qualified by the BfS. Full account was taken of this requirement with introduction of work sequence plans and likewise in individual cases by campaign-independent procedure qualifications. For product control with work sequence plans, all relevant working and testing stages are listed that must be followed up to interim storage and final disposal of the waste.

28 Fig. 33 Waste Flow Tracking and Documentation System (AVK: Abfallfluss-Verfolgungs- und Produkt-Kontrollsystem) collage Waste package documentation The data collected during conditioning are included in the waste package documentation. These data are supplemented with analysis data. Following an internal quality control, the package documentation is verified and audited by independent experts. The verified documentation forms the basis for the delivery to the interim storage facility or repository. The Waste Flow Tracking and Documentation System forms an important basis. Waste Flow Tracking and Documentation System, AVK The regulatory guideline on the control of residual radioactive material and radioactive waste (waste control guideline) of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU)requires that the quantity, whereabouts, processing status and packaging of the waste can be traceably determined with regard to safe interim storage and final disposal by documentation of all disposal stages (conditioning, transportation and interim storage). The radiation protection ordinance prescribes that an electronic system accepted by the BfS be used for this purpose. aspects an overview of the flow of the nuclear power plant waste with information about the container type, activity inventory and transport data. The waste producers are organised in the so-called AVK association and use a central system administration and user support in addition to a central body which performs with its own software the function of superordinate data control, archiving and analysis in the sense of self-monitoring by the operators. Since 1995, the suitability of the AVK system has been regularly appraised with regard to the official requirements by an independent expert. In the form of this system, the waste producers (energy supply companies), conditioners and operators of interim storage facilities have at their disposal a practice-proven electronic documentation system for radioactive waste recognised by the authorities which allows uninterrupted tracking of the waste from their origin to their transfer to a Federal repository. In order to fulfil this requirement, the German nuclear power plant operators, the conditioning facilities and the external interim storage facilities have been implementing the AVK in a data network since mid The AVK system provides its users among other

29 Fig. 34 Responsible institutions in final disposal of radioactive waste in Germany RSK/SSK/ESK consultancy BMU Administrative and technical supervision BMWi Administrative and technical supervision BMU Federal Ministry for the Environment, Nature Conservation and Nuclear Safety RSK Reactor safety commission Federal State authorities planning approval Bergämter Planning approvals BfS Responsible for construction and operation, applicant DBE Constructor and operator BGR SSK Radiation protection commission ESK Disposal commission BMWi Federal Ministry of Economics and Technology 29 Konrad repository Necessary expenditure Ordinance on Advance Payments for the Establishment of Federal Facilities for Safe Custody and Final Storage for Radioactive Waste Waste producer Gorleben project BfS Federal Office for Radiation Protection BGR Federal Institute for Geosciences and Natural Resources DBE Deutsche Gesellschaft zum Bau und Betrieb von Endlagern für Abfallstoffe mbh 8 Final disposal Responsible institutions in final disposal of radioactive waste in Germany According to the German Atomic Energy Act, it is the German Federation s responsibility to set up facilities for securing and final disposal of radioactive waste. The Federal Office for Radiation Protection (BfS) is responsible for planning, constructing, operating and decommission the facilities. It is subject with regard to nuclear safety and radiation protection to the technical directions of the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety (BMU), which is advised among other by the Disposal Commission (ESK), the Reactor Safety Commission (RSK) and the Radiation Protection Commission (SSK). For practical fulfilment of its duties, the BfS generally commissions as a third part the Deutsche Gesellschaft zum Bau und Betrieb von Endlagern für Abfallstoffe mbh (DBE). The geoscientific expertise is contributed by the Federal Institute for Geosciences and Natural Resources (BGR). Research and development concerning final disposal has been or is conducted by the Helmholtz Centre in Munich, the Karlsruhe Institute of Technology and the Jülich research centre in addition to various universities and other institutes. This work is financed and organised by the Federal Ministry of Economics and Technology (BMWi), formerly also by the Federal Ministry of Education and Research (BMBF) and insofar as site-specific, by the BfS. Construction and operation of a repository require planning approval. The supreme Federal State authorities appointed by the Federal State government involved are responsible for this. In the case of the planning approval procedure for the Konrad repository, this was the Ministry for the Environment, Energy and Climate Protection of Lower Saxony (NMU). Anyone who possesses radioactive waste is obliged according to the German Atomic Energy Act to hand these over to a German Federal facility. For as long as no repository is available, the waste must undergo interim storage. This is either the task of the operator of nuclear facilities or of the Federal States for deliverers from medicine, industry and research (Federal State collection facilities). Financing of the necessary expenditure for exploration, approval procedures and construction of the repository is provided by the waste producers according to the «Ordinance on Advance Payments for the Establishment of Federal Facilities for Safe Custody and Final Storage for Radioactive Waste». The current costs of repository operation and repository decommissioning are likewise borne by the waste producers.