Authors:K. Varga, Z. Németh, J. Somlai, I. Varga, R. Szánthó, J. Borszéki, P. Halmos, J. Schunk, and P. Tilky
During the optimization of the AP-CITROX decontamination technology the effect of the different flow rates of the decontamination solutions on the radioactive contamination and corrosion state of stainless steel tube samples originating from steam generators of Paks NPP were studied by a pilot-plant circulation system. The results have proved that a significant increase (up to 2.89 m/s) in the flow rate of the decontamination solution in the 1-5 steps is highly recommended and in order to improve the passivity of the surfaces it should be kept as low as possible (0.5 m/s) during the passivation.
Polyvinyl acetate based strippable polymer has been developed for surface decontamination. Stainless steel, mild steel, polyvinyl
chloride and rubber have been selected as candidate materials for the radioactive decontamination studies. The ease of strippability
and homogeneity of the polymer coating has been studied using infrared spectrophotometer. Decontamination of used radioactive
respirator has been carried out and the peels obtained have been subjected to leaching and incineration studies. The infrared
spectrophotometric studies also have been counducted to study the interaction between polyvinyl acetate and ions, like cesium,
strontium and cobalt.
The composition of mixed micelles and mixed micelle — solution interfaces changes with the concentration and molar ratio of the cationic and anionic surfactants present. The micelle — solution interface includes besides the headgroups of both surfactants, the counterions of the surfactant in excess. The finding of an enhanced binding of counterions to mixed micelles may be of some practical importance in decontamination.
Authors:Ibrahim Barrak, Zoltán Baráth, Tamás Tián, Annamária Venkei, Márió Gajdács, Edit Urbán, and Anette Stájer
alone was found to be ineffective [ 23 ]; for successful surgical interventions, the contaminated implant surface must be entirely decontaminated. However, there is a lack of consensus regarding the techniques/agents to be used for decontamination [ 11
A multistage process combining photocatalytic degradation of organic complexes and complexants followed by separation of the radionuclides by ion exchange was developed and tested for the treatment of aqueous waste from chemical or electrochemical decontamination of NPP primary circuit internals. In these solutions, both the oxalic and citric acids could be quantitatively degraded within 10-12 hours of irradiation by 254 nm UV radiation in the presence of TiO2 photocatalyst. For the group radionuclides separation, a standard cation exchanger was found to be preferable to any of the set of the tested inorganic-organic composite absorbers.
Authors:G. Matuschek, H. Utschick, Ch. Namendorf, G. Bräuer, and A. Kettrup
The investigation of wastes, pollutants, contaminated soil, etc. in preparation of their thermal disposal or decontamination is related to several problems. Due to the heterogeneity of the sample materials, thermoanalytical measurements, using standard sample amounts of about 20–50 mg do not lead to reliable results. For this reason, a new thermoanalytical device for about 100 g sample amount was developed. The “Macro STA 419”, was constructed and built for simultaneous TG- and DTA-investigations with direct coupled measuring techniques for gas analysis (MS/GC-MS). The new developed device is introduced, some problems and their solutions are discussed and the function of the device is shown.
Authors:Agnés Arnaud, S. Coen, A. Jouve, M. Lelaidier, and A. Perichaud
This contribution concerns the decontamination of soils and surfaces polluted by cesium and strontium after a nuclear accident. The decontamination rate by means of an industrial polyacrylamide previously selected for its mechanical covering properties is studied. The characteristics of the polymer and its cation-exchange capacity (CEC) are specified. The chemical modification of the polymer, involving a crosslinking path and functional grafting, affords an improvement of its decontaminating properties.
Authors:G. Ucak Ozkaya, A. Besir, E. Metin, and M.Z. Durak
focused on the efficiency of vaporised EP for decontamination of cherry tomatoes inoculated with two foodborne pathogens, Salmonella Typhimurium and E. coli O157:H7. 2 Materials and methods 2.1 Bacterial strains and culture preparation Salmonella
Authors:Zoltán Németh, Bernadett Baja, Krisztián Radó, Emese Deák, Kálmán Varga, Andrea Nagy, János Schunk, and Gábor Patek
Decontamination technologies are generally developed to reduce the collective dose of the maintenance and operation personnel
at nuclear power plants (NPP). The highest efficiency (i.e., the highest decontamination factors) available without detrimental
modification of the treated surface of structural material is the most important goal in the course of the application of
a decontamination technology. At the Paks NPP the AP-CITROX procedure has been utilized for the decontamination of the primary
coolant circuit’s components (e.g., main circulating pump (MCP) and steam generators (SGs)). Our previous studies have revealed
that a ‘hybrid’ structure of the amorphous and crystalline phases was formed in the outermost surface region of the austenitic
stainless steel tubes of SGs as an undesired consequence of the industrial application of the AP-CITROX decontamination technology
during the period of 1993–2001. In this paper, we report some comparative findings on the corrosion and surface chemical effects
of the AP-CITROX procedure and the novel decontamination technology elaborated at our institution. On optimizing the operational
parameters the latter technology may become suitable for the effective decontamination of both dismountable (e.g., MCP swivel)
and separable (e.g., SGs) equipments. For this purpose experiments were performed. In this laboratory scale experiments, the
passivity, morphology and chemical compositions of the treated surfaces of tube specimens were investigated by voltammetry,
and SEM–EDX methods, respectively. The SEM–EDX results have revealed that the oxide removal is surprisingly uniform even after
2 or 3 consecutive cycles. The electrochemical studies have provided evidences that no unfavorable tendencies in the general
corrosion state of the tube samples can be detected in the course of the chemical treatments.
Authors:L. Prozorov, M. Shcheglov, V. Nikolaevsky, E. Shevtsova, and S. Korneva
The purpose of the investigations was to determine the best conditions of electrokinetic soil decontamination. Impacts of the different parameters of electric field, such as current, voltage between the electrodes and power, on the dynamics of 137Cs extraction were studied. The investigations have demonstrated the main possibilities of the electrokinetic remediation of loamy soil from radionuclide contamination.