Paks Nuclear Power Plant is the largest radioactive waste producer in Hungary. During the operation of the nuclear power plant, a fraction of the radioactive isotopes produced by nuclear reaction in the reactor can get into the coolant. A part of these isotopes, such as tritium and noble gases are discharged into the environment. The aerosols and volatile components, such as iodine, are collected with filters, while the contaminants being present in the water are absorbed by ion exchange resins.
Other low level wastes (working clothes, gloves, etc.) may be generated during routine maintenance work. These wastes are solid and liquid wastes, may include ion exchange resins, and contaminated oil. The small volume of waste produced by the Interim Spent Fuel Store is treated together with the wastes of power plant origin.
Liquid radioactive wastes
Waste waters containing chemical agents and radioactive isotopes are generated from various sources within the controlled zone of the nuclear power plant. These water solutions, with low solid content (3-5 g/dm3), contain all dissolved chemical agents, which are used for the purpose of setting the water regime of the primary system, the regeneration of the water purifiers, the fine control of the reactor power and for decontamination purposes.
Following a chemical treatment, the collected waste waters are evaporated to a concentrate with app. 200 g/dm3 “boric acid content”. During the operation of the power plant, a total volume of 5346 m3 evaporation concentrate was produced up to 1 January 2008, with 255 m3 of which in 2007.
A volume of 975 m3 evaporation residues, containing alpha radiants, were produced during the period from the incident in April 2003 to 1 January 2008, which are stored in special tanks, separately from the other concentrates. The annual volume of evaporation concentrates expected to be generated at the present rate of production is 250 m3/year, which will result in 7400 m3 evaporation residues during the design service life of 30 years.
Ion exchange resins have been stored in two tanks. The total volume of spent resins produced during the operation up to 1 January 2008 was 150 m3. The annual volume of spent resins expected to be generated at the present rate of production is 5 m3/year, which, including the final discharge of ion exchange columns, will result in 335 m3 waste resin during the 30-year design service life.
Considering the planned modification of the spent resin tanks, it is expected that the available storage (870 m3) will be sufficient for the accommodation of wastes produced during the design service life and the extended service life of the power plant.
The decontamination solutions used during the recovery from the consequences of the incident at Unit 2 were collected into two tanks. A volume of 220 m3 decontamination solution was generated during the recovery work, up to the 1st of January 2008.
Based on the estimated annual volume of liquid waste for the 30-year design service life, the total volume of conditioned liquid wastes to be disposed is app. 18000 m3. The volume to be disposed of will be significantly reduced with the use of the Liquid Waste Processing System after putting into operation. This is expected to take place in 2010. If this happens, the disposal of only a smaller volume of 7300 m3 conditioned liquid waste will need to be provided.
Solid radioactive wastes
The presently applied practice for processing the solid wastes is as follows:
- The separation of compactible and non-compactible wastes is carried out basically as early as the time of collecting the wastes; non-compactible waste is very rarely loaded into plastic bags. The wastes collected into bags include various used parts, structural components, insulation materials, contaminated tools, etc. which, due to their dimensions or weight, can not be loaded into plastic bag.
- The volume reduction of compactible wastes, to a reduction factor of 5 on average, is performed by use of a 500 kN compactor. It is concluded on the basis of the so far obtained experience, that 80 to 85% of the solid radioactive wastes is compactible.
- The radioactive sludge, removed from the equipment used for the collection, chemical treatment, settling and ad-interim storage of primary water leakages are solidified by the addition of diatomaceous earth in a ratio of 1:1. From March 2007, the solidification was carried out by settling the sludge and by the subsequent removal of liquid content with a wet vacuum cleaner of industrial design, rather than soaking by diatomaceous earth.
The solid wastes, including aerosol filters and solidified sludge, are all loaded into 200 l special metal drums (with plastic coat inside). Some half of the of the waste is plastic, and may consist some textile, heat insulation material, wood, metal, rubber, glass and paper as well.
As of 1 January 2008, solid LILW were stored in 8333 drums, in interim storage locations in the plant site. Considering the present rate of generation, the annual quantity of waste is expected to be 850 off 200 l drums. For the 30-year design lifetime of the power plant, the total volume of solid wastes to be disposed is 2900 m3 as estimated on the basis of the annual volume.
In case of the successful operation of the Liquid Waste Processing System (FHFT), the disposal of only a significantly lower volume of solidified liquid wastes will need to be provided.
Large volume of radioactive waste of decommissioning origin will be generated in the case of Paks Nuclear Power Plant only.
Only a small volume of radioactive waste will be produced during the initial phase of the decommissioning and dismantling, e.g. from the removal of fuel assemblies from the core and from the flushing of the reactor cooling loops. For the wastes arising from the dismantling of the reactor, preparations will be needed for the storage phase, in accordance with applied practice.
This period may be several decade long, to allow for the decay of short lived isotopes to a significant degree during this time. Even so, a much larger volume of LILW is expected to originate from the decommissioning and dismantling than from the operation. The volume, after conditioning, of LILW generated during decommissioning will be, as calculated, as much as 17 900 m3. The estimated gross volume of HLW to be disposed of in a deep geological repository is 410 m3.