Radioactive Waste Management | Facilities & Equipment
The available installations are used to reduce the volume of accumulated waste and radioactivity is bound in containers (conditioned) by mixing e.g. ashes with cement or by embedding it in concrete. In order to preclude misunderstandings we want to point out that in the incinerator radioactivity is not being burnt up and thus annihilated for example, but is concentrated in the ashes.
These installations are an essential part of the measures that guarantee that radioactive substances do not become an environmental problem in our country. The goals are to avoid radioactive nuclides from being released to the biosphere and to prevent uncontrolled contacts of human beings. We adhere to these goals by collecting radioactive waste separately and by careful storing it after it has been suitably conditioned. During this process, radioactive nuclides are transformed into hardly soluble, scatter-resistant forms that can be stored for long periods of time.
Incinerator
Short description of flue gas cleaning
Flue gas is fed from the furnace via the flue gas pipe to three hot air filters, which are connected in parallel and equipped with 54 silicium-carbide filters with a porosity of 20 μm, and thus dedusted.
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Following this, the flue gas is led via a quench cooler to a two-step fuel-gas scrubber. In this process the flue gas is rapidly cooled down from 700°C (the temperature of the gas after the hot air filters) to about 70°C.
After that, the flue gas reaches two parallel-connected absolute filters which constitute the last step of the cleaning process and guarantee an utmost level of purity. From there the cleaned flue gas is fed to the mixing chamber and on to the 35 m high chimney.
The great technical effort that is undertaken in the cleaning process means that the restrictive emission limits stipulated by the authorities are not only easily met but are even distinctly lower than specified. At no time have the measurements taken regularly to monitor the surroundings resulted in any impairment of the environment whatsoever due to the operation of the incinerator.
- Dust filter: hot gas ceramic filters, porosity: 20 µm
- Two-step flue gas quencher
- Absolute-filter: filtration efficiency 99.99% at 0.5 μm grain size
Water treatment plant
As stipulated by the authorities all the waste water (active and inactive) arising at the Seibersdorf site has to be treated.
Inactive waste water is continually monitored by a measuring probe with a preset permissible activity gauge. When the measured activity lies below said limit the waste water gets pumped into one of our storing tanks. If the activity proves to be above the limit, the water is diverted to a tank for active water and treated as such in the following.
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Filters of the water treatment plant
Active waste water gets pumped into pre determined collecting tanks and treated by nuclide-specific precipitation. The precipitated sludge is filtered and then conditioned (drying, grouting under pressure, cement solidification). The conditioned sludge gets stored in the gantry interim storage. Finally, the cleaned water is then pumped into one of our storing basins.
Upon the Radiation Safety Department’s consent, the contents of the storage tanks are released into the environment (Leitha-Mühl-Channel). A sample taken during this process is used to determine several chemical parameters (pH, substances that may be filtered, phosphorous, CSB, BSB5 and others if deemed necessary).
At present a research project is carried out regarding the use of diaphragm-techniques (ultrafiltration) for use in waste water treatment. The goal is to reduce the application of chemical precipitants and to completely forgo additional filter materials. This would considerably reduce the amount of secondary waste generated.
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Pilot plant for membrane filtration
Workshop
Mixer for cement solidification
The mixer consists of a horizontal cylinder with blades mounted on a spindle for mixing. The mixer is driven by an electric motor with adjustable gears (46 kW) and supported by load cells which, together with weighing electronics, enable weighing directly in the apparatus.
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Mixer for cement solidification
High-pressure compactor
Waste to be pressed is put into a cartridge in the press-chamber and compacted to a so called pellet.
Experimentation hall
Cone-shaped sludge dehumidifier
By using the cone-shaped dehumidifier low viscosity up to grainy materials can be gently dried batch-wise. At present mainly sludges stemming from the water treatment plant as well as liquid waste gets treated in this way.
The facility gets filled using a filling port on the top of the lid of the dehumidifier. Afterwards the dehumidifier is evacuated and the heat transfer oil is being heated up to a certain temperature. A spiral mounted on a swivel arm constantly circulates the material assuring good heat transfer and homogeneity of the batch. The vapors then reach a pre-heated filter where fabric filters are used to reduce dust loading. The filter elements are thoroughly rinsed with nitrogen. The vapors (now free from dust) are condensed in a surface-area condenser and the condensate is then released into the sewage system. The negative pressure is created using a liquid-jet vacuum pump.
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DehumidifierMeasuring hall
Low-level measurement facility
Due to the decommissioning of the ASTRA reactor as well as other facilities from 45 years of R&D about 80 - 100 t of contaminated materials or materials suspected to be contaminated are accrued every year from 2003 to 2015 at the Seibersdorf site. The treatment and conditioning of this waste would generate about 200 to 250 200-l-barrels per year. According to Austria’s radiation safety laws, NES is tasked with the collection of a repository charge for each barrel and to transfer this this money on to the Federal Government. At the moment this charge stands at € 9,422 per 200-l-barrel. This means that NES can achieve significant cost reductions by implementing measures to minimize waste. Since 2003, NES has therefore carried out release measurements of slightly radioactive materials like concrete and soil, for example, by using a modern, automatic measurement facility called RADOS RTM640Inc (see picture on the right). Thus, low-level materials can be disposed of as inactive waste as long as the activities measured are below the legally stipulated release thresholds.
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Release measurement facility Waste assay system
The waste assay system consists of a Tomographic Gamma Scanner System (TGS) from Canberra, Connecticut/USA that combines High Resolution Gamma Spectrometry (HRGS) for net full energy peak determination, with three-dimensional single photon emission images. Three-dimensional transmission and emission images are generated by scanning the object with three degrees of freedom (rotation, translation and elevation).
The TGS uses high purity germanium detection (HPGe) and low spatial resolution transmission and emission imaging to obtain improved measurement accuracy over non-imaging gamma-ray techniques. The material to be examined is thought to be divided into a number of vertical and radial volume elements. The activity is quantified in each of these voxels (“volume pixels”) using matrix correction techniques based on the activity content and matrix properties of each voxel.
The TGS system consists of the following components:
- Collimated, coaxial p-type HPGe detector mounted on a vertical detector lift assembly. The collimator is an automated variable collimating aperture made of tungsten (12.7 - 60 mm diameter).
- Digital Signal Processor (DSP), a reference pulser as well as an Accuspec B acquisition interface board providing a full featured Multi-Channel Analyzer.
- A highly collimated 60Co transmission source (9.25 GBq nominal activity) with tungsten shutter and lead storage shield atop a vertical lift assembly.
- Drum rotator and translation assembly and conveyor system for automated measurement of up to six 200 l drums.
Radiation safety and protection
For these activities the following measuring devices are available:
- Personal dosimeters
- A large number of contamination and dose-rate monitors
- Personal contamination monitors
- Aerosol monitors
For the measurement and analysis of resulting routine samples the following systems for activity measurements are available:
- Total activity (alpha and beta) measuring station
- Gamma-spectrometry measuring system
Laboratories
In the laboratories, various tests required when handling radioactive waste are carried out. The laboratories are designed to perform all sorts of radio chemical analyses, including monitoring and development of processes.
The radiochemical analyses are carried out on samples originating from the NA department (like waste, water, contaminated material of any sort). The samples are analyzed by using alpha- and gamma-spectrometry as well as LSC. For alpha-spectrometry and LSC, in particular, it is necessary to pre-treat the samples chemically and to separate radio nuclides. Besides wet chemical methods, other techniques are used for these purposes. Among them are: liquid-liquid extraction, ion exchange chromatography and extraction chromatography.
- X-Ray fluorescence spectrometer PANalytical PW 2404
- Ion chromatography Dionex ICS 2000 and ICS 3000 DP
- Carbon-sulfur analyzer ELTRA CS 500
- Photometer Lange ISIS 9000
- Flash point measuring apparatus Pensky Martens
- Combustion Calorimeter IKA C4000 (calorific value determination)
- Further equipment for chemical analysis (pH-meter, conductivity measurement etc.)
- Press for testing concrete stability TONIPACT 3000
- Cupboard for material testing Köttermann 2224 (conditioning cabinet)
- Supersonic testing equipment Steinkamp BP V (non-destructive strength test)
- Stamping volumeter JEL STAV 2003 (for determination of the bulk density)
- Equipment for sieve analysis FRITSCH analysette 3 PRO (particle size distribution)
- Liquid Scintillation Counter WALLAC QUANTULUS 1220
- Alphaspectrometer Canberra Alpha Analyst
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X-Ray fluorescence spectrometer
In order to carry out the many different radioanalytical methods for radiation protection, additional equipment for laboratory analyses is available, as for example:
- Alpha/Beta gross counting systems
- X-ray spectroscopy systems
- Alpha spectroscopy systems
- Liquid scintillation counter
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Gammaspec laboratoryAs for non-destructive techniques our equipment includes
- Drum scanning
- Drum tomography
(see also the section on 
waste assay system.)
Furthermore, we analyze sections of terrain, buildings or waste by using
- In Situ gamma spectromentry (ISOCS-System)
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ISOCS
