The approach of CEZ to waste treatment is regulated by the Czech Waste Act and by the decrees issued by competent state administration authorities. CEZ regards some waste generated by the production of electricity as by-products with energy potential, and markets it.
- Waste Treatment
- The ashes
- Radioactive waste
- Waste Repository
- Additional Activities
- Waste Treatment & Manipulation
The waste produced in NPP Dukovany and NPP Temelin is transferred for a reposition, as a solid substance, or in approved containers (the acceptability conditions do not allow for any other method). The bitumination technology, implemented for liquid waste treatment in both nuclear power plants, provides for a product featuring a guaranteed long-term stability and resistance against radiation effects, highly leach-proof, and displaying around 2.5 volume reduction ratio. Solid state waste coming from the controlled zone, is sorted according to its particular properties. Such a manipulation method provides for a more conclusive specification of radionuclides contaminating the waste. A sorted-out non-active part of the waste is eliminated using conventional methods, generally applied in non-active waste management.
The solid state RAW is stored and pressed into 200 liter barrels, before the final treatment. The final treatment is applied in campaigns; barrels with prepressed contents are pressed in a heavy duty press. The pressed pieces are provided with larger barrels (overpacks of 300 to 400 liters volume) and then placed to the radioactive waste repository. The resulting volume is 6x reduced.
The ashes generated by the incineration processes in coal-fired CEZ-operated power plants may be used especially for modifying former mining landscapes, for re-cultivating purposes and also in construction layers under roads. The ingredients of ash – fly ash and slag – are used in the production of construction materials, such as cement, concrete and mortar mixtures, and masonry. Modified ash is used as construction and sealing material for landfills and is regarded as a valuable surrogate for natural clay. Industrial gypsum, generated by the process of desulphurising combustion products, is a much demanded raw material for the production of cement, plaster and plaster products, and is also used as a valuable surrogate for natural raw materials. The range of potential use of these products depends on the technology by means of which they are collected in power plants and, more importantly, on the market demand and the quality parameters of the products.
Dry withdrawal of valuable by-products and their constituents enables the producer to sell the products directly to the consumers, and the specific characteristics of the products can also be used for re-cultivating sludge beds and for shaping the relief of the landscape according to specific requirements of the particular locality. The dry withdrawal technologies also include mixing centres for the preparation of mixtures according to the formulas tailored with regard to the future purpose, for which the mixture will be used.
Changes in the treatment of valuable by-products become also evident in the records of waste outputs, which are kept in compliance Waste Act and enable CEZ to reduce the volumes of waste which is to be disposed of in return for fees or for contractual price.
In 2000 a total of approx. 3 million tons of energy-valuable by-products were utilised by CEZ, including the products left after desulphurising combustion products. The records kept by CEZ included approx. 6.5 million tons of waste. In 1993, a total of approx. 308 thousand tons of valuable by-products was utilised and the total recorded waste output amounted to approx. 7.9 mil. tons of waste. This means that over the period between 1993 and 2000 CEZ improved the utilisation of its waste by almost 28 %. E.g. the industrial gypsum, generated by the process of desulphurising combustion products in CEZ, provided secondary raw material for the production of 50 mil. m2 plaster boards before the year 1999. Valuable by-products of CEZ production are certified in order to be marketable.
The changes in the treatment of valuable by-products have also become apparent in the records of waste kept in compliance with the Waste Act, thus enabling CEZ to reduce the amount of waste which would otherwise have to be eliminated for fees or for contractual price.
The negative environmental impact of waste generated by the production of electricity and heat and also by its disposal is therefore significantly reduced.
The philosophy of nuclear waste disposal is based in internationally accepted principles of its treatment and manipulation. The health and environmental protection against negative effects of ionizing radiation, respecting the requirement of radioactive waste production minimizing, a protection of future generations against an undesired burden, as well as efforts to avoid possible health effects exceeding those, that would be acceptable at the present time, are absolutely imperative and followed by all participants of the entire process, including the CEZ, a.s., the state supervision authority, etc.
Within the process of radioactive waste treatment and manipulation, the CEZ, a.s. complies with the Act no. 18/1997 Coll., as amended later (the Atomic Act). The radioactive waste is subjected to both regulation and supervision from the side of the State Office for Nuclear Safety (SUJB). The Radioactive Waste Repository Authority (RAWRA, or SURAO in the Czech language), established as a national organization on a legal basis of the Atomic Act, is responsible for a safe storage and disposal of all the radioactive waste (RAW). Establishing RAWRA, the Czech state implemented in practice the state guarantees for a safe reposition of the radioactive waste. The RAW originator is responsible, in particular, for a provision of all the financial funds to cover the costs related with the radioactive waste treatment and manipulation (management) and its handing over in a state complying with conditions approved for its acceptance at a specific radioactive waste repository.
The primary principle of RAW disposal is its environmental separation.The waste separation, as a basis of the environmental protection, is implemented through an application of multi-barrier systems in a radioactive waste repository, where both natural and engineering (man-made) barriers are utilized, against escapes of the radioactive waste reposited, as well as against a radionuclide contamination spreading.
The natural barriers are represented by geological properties of the environment, where a RAW repository is located. Within the location selection process, criteria for a location of such facilities, as stipulated in the legislation, are rigorously evaluated. A repository may not be located in a flood-prone area or a karst region, or in regions where a repository may negatively affect subsoil or mineral water resources, etc. Desired qualities for the location include a bedrock impermeability, an adequate distance from water flows or area, an adequate distance from permanently inhabited places.
The engineering barriers consist of the repository structure itself, a waste placement in the repository, and, e.g., a container or a matrix designed to incorporate and keep the waste. The low and medium active waste repository structure in NPP Dukovany (URAO), which is designed for a reposition of radioactive waste from nuclear power plants of the Czech Republic, consists of a system of ground level concrete chambers separated by a few insulation layers. The insulation protects the chamber contents escape into the ambient environment.
The repository safety represents the principle requirement in relation to the environment and health protection of the population group concerned. It is ensured by the repository structure design and by operation methods following predetermined regimes and conditions. The repository safety is verified, additionally, through a system of control mechanisms. Subject to a decision of SUJB, concerning an approval of Safety Operation Limitations and Conditions, the maximum (radio)activity that may be placed in the repository is limited. The limitation brings practical consequences concerning the safety, particularly in the distant future, when not even an incidental intrusion into the repository area may cause a significant health problems. At present, the safety is verified by repository monitoring results, a consistent adherence to operation limitations and conditions, maintenance of acceptability conditions from the side of the waste originator, and their uncompromising verification when waste is handed over to Radioactive Waste Repository Authority.
The repository inside of NPP Dukovany, with its used storage space of 55 0003, divided into 112 chambers, is capable of containing radioactive waste from the both Czech nuclear power plants' operation, together with the waste originating from their decommissioning. The waste recycling, which in the period of the nuclear power plant operation is limited to, e.g., metallic waste from equipment revisions, PE sheets, waste water regeneration inside of the controlled zone, shall gain more importance in the time of a facility decommissioning. Materials, after decontamination and inspection, returned to the environment shall be capable of being used again, e.g. metal scrap, concrete, etc.
The spent nuclear fuel and highly active waste in general have a common denominator, i.e. a very long period throughout which they maintain their dangerous properties. In cases of their disposal, additionally, the principle of their separation from the environment applies. In respect of the requirement ensuring a long-term separation from various effects (human activity, climatic effects), all the projects of future repositories, as well as repositories of hazardous waste containing plutonium from defense armament programs, newly introduced into operation in New Mexico (USA), are located in deep-seated geological formations hundreds of meters underground.
A commencement of such a deep-seated repository operation in the Czech Republic conditions is envisaged for the year 2065, approximately. Until the time, the spent nuclear fuel shall be safely deposited in containers.
The financial means allocated to fund all the costs related to all the radioactive waste and spent nuclear fuel disposal are paid, in accordance with the Atomic Act, by nuclear facility operators, to a nuclear account, to which the CEZ, a.s. is the most significant contributor. The nuclear account provides for a financing of activities of RAWRA (SURAO), which in accord with its mission ensures a reposition of radioactive waste, as well as a preparation for future construction and operation of such a spent fuel repository.
The Utilization of Secondary Raw Materials
The solid waste from burning coal has so far been water-sluiced or pneumatically transported from power stations to nearby sludge beds, and its impact on the surrounding environment was minimalized by technical means.
The implementation of desulphurization, however, introduces a new structure of solid waste. The wet limestone washing method produces industrial gypsum as a by-product. The fluidized-bed boiler technology produces a solid lime-siliceous mixture. When appropriately mixed with ash and lime, these wastes produce a stabilized compound. Multiple tests have shown that the compound is harmless to the environment. It is, therefore, used to reclaim the former ash deposit sites, and to restore the landscape to its original appearance. The changes in waste disposal concern all of CEZ’s fossil power stations. The stations are altering their water systems at the same time.
Ash and industrial gypsum are beginning to be utilized as secondary raw materials. The Mělník Power Station has installed new equipment to produce Rhenipal, an ash-based material that stabilizes sludges from sewage treatment stations. Industrial gypsum, the purity of which is guaranteed by the high standards of desulphurization equipment, is utilized to make sheets of drywall for the building industry. One of the companies producing the drywall is Knauf Počerady, s. s r. o., a joint venture of CEZ and Knauf, whose products are successful on the Czech market and abroad. Industrial gypsum from the Prunéřov Power Station is processed by Gaprom, a joint venture of CEZ and ProMineral, a subsidiary of the German RWE AG. It is used for the production of Alpha-binders, mainly for construction purposes. In the future, Gaprom should also process industrial gypsum from the Tušimice Power Station.
Rigips, a subsidiary of British Gypsum Industries Ltd., will make drywall products from the Mělník Power Station’s industrial gypsum.
Support for Renewable Sources
In the past few years, CEZ’s activities in the field of renewable sources have focused mainly on the utilization of wind energy, photovoltaic conversion of solar energy, and the burning of biomass.
Furthermore, studies are being conducted on new technologies of energy accumulation and conversion.
Additional Business Activities
CEZ also participates significantly in Energotrans, a company supplying the capital Prague with heat from the nearby Mělník Power Station. The company also participates in a number of companies providing services for power utilities.
|The overall view of the Počerady Power Station with the Knauf works||Industrial gypsum from the Prunéřov Power Station is used for the production of Alpha-binders||The pipeline supplying heat from the Mělník I Power Station to Prague|
Waste Treatment & Manipulation
The CEZ, a.s., within the process of waste treatment and manipulation, complies with all the relevant legislation applicable in the Czech Republic and respects decisions of national and public administration authorities. The main energy products of CEZ, a. s. are both electricity and heat produced; the energy by-product is the waste subsequent to their production. Most of the by-product the CEZ, a.s. transfers for utilization in other, certified, products or utilize it within the company. Thus, waste development is prevented and its quantity limited, in compliance with legal regulatory requirements. The scope of utilization of energy production by-products outside of CEZ, a.s. is mostly limited by the demand.