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- Öberg, Tomas, 1956-
(författare)
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Brominated aromatics from waste handling and recycling processes : The Flame Retardants Project
- 1994
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Emissions of brominated aromatics from waste handling and recycling processes are discussed based on a number of investigations and measurements in waste incineration plants, steel plants and at waste landfills. Bromine in municipal waste at present levels does not seem to cause unacceptable environmental risks when treated in incineration plants with good combustion conditions and efficient flue gas cleaning. A significant increase of the bromine flow with the waste may result in an increased production of brominated aromatics. Flame retardants are important as bromine carriers, but not as specific precursor compounds. Scrap-metal re-melting processes are presently studied in an extensive test programme initiated by the industry, and a report is due in the summer of 1993. Accidental fires in waste landfills are discussed with the background of the high emissions of chlorinated aromatics. Significant emisssions of brominated aromatics can also be expected, irrespective of the bromine carrier. Precursors may play a role in this situation. (21 references).
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| 3. |
- Öberg, Tomas, 1956-
(författare)
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Chemicals in Statistics - Method Development
- 2009
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Statistics on import, manufacture, and export of chemicals can be an important information source to follow up the results of environmental policy and management decisions. In this pilot study we evaluate the use of the official trade and manufacture statistics for the purpose of screening for bioaccumulating and persistent compounds of a particular environmental relevance. An impact index to measure these properties is applied to chemical groupings in the trade statistics. Furthermore, data from the trade statistics for selected chemicals is compared to corresponding data from the Swedish Products Register, at the Swedish Chemical Agency. The results show that the level of detail in the trade statistics does not permit estimation on the impact index using a compound specific index for environmental impact. In the trade statistics, a substantial number of chemicals with different properties are often grouped with the same identifier. However, this study shows that it is possible to use the same index to identify the groups containing the most problematic chemicals. The 100 chemicals identified to rank highest with regard to the potential environmental impact index belong to several groups, but 94 of these were halogenated. The two dominating groups in the trade statistics were halogenated aromatics and hydrochlorofluorocarbons (HCFC), with 25 and 20 members, respectively. A more detailed study of the trade statistics for these high-impact groups revealed substantial deviations between data from Statistics Sweden and Swedish Chemical Agency. Anomalies and an outlier were also observed and some misclassifications discovered. The self-reported statistics thus seems to need further validation to improve their usability for chemical policy purposes. Suggestions are made for further comparisons of databases, but tracing back to primary sources may also prove necessary to ensure relevance and good quality.
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| 4. |
- Öberg, Tomas, 1956-
(författare)
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Replacement of PCBs (polychlorinated biphenyls) and HCB (hexachlorobenzene) : the Swedish experience
- 1996
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Ingår i: Alternatives to persistent organic pollutants. - Solna : Kemikalieinspektionen. - 9923050106
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The total import to Sweden of PCB between 1957-1980 has been estimated to 8,000-10,000 metric tonnes. A substantial part of the import, probably more than 50% was re-exported in goods. The use of PCB in Sweden has been restricted since 1972, and in 1978 it was decided that no new permits to use PCB in new products should be issued. Remaining part in the power sector of the industry has also been removed. Transformers or capacitors containing PCB and with a higher rating than two kilovoltamperes (reactive) may not be used after the 31st of December 1994. PCB containing transformers were never manufactured in Sweden. The problem with PCB filled transformers and contaminated transformer oils has therefore been less severe, compared to many other industrialized countries. The main chemical alternative to PCB in transformers is mineral oil with different additives. PCB was used in the manufacture of capacitors in Sweden before 1978. The use for this purpose accounted for about 80% of the import of PCB. Chemical alternatives for PCB as capacitor fluid include a multitude of chemical compounds. The capacitor fluid most frequently used today in Sweden is a mixture of methyl(phenylmethyl)benzene and methylbis(phenylmethyl)benzene. PCB was used in different building materials as a plasticiser. Chemical alternatives include chlorinated paraffins and phthalates. Chlorinated paraffins are however replaced due to environ-mental concerns, and it has also been decided to phase out the phthalates. Substantial amounts of PCB, an estimated 190-650 metric tonnes, still remain in buildings. It is obvious that measures to deal with these problems may cost many times more than the replacement already accomplished. Destruction capability and capacity are keys to a successful and final solution to the PCB problem. The destruction cost is also the major cost factor in the replacement. 17,667 metric tonnes of PCB containing waste was received by SAKAB, the Swedish hazardous waste treatment plant, between 1987-1995. This gives an idea of how much PCB wastes that have to be handled. Minor amounts of HCB (hexachlorobenzene) has been used in some parts of the Swedish industry. HCB has not been manufactured in Sweden and previous use has been replaced. Estimates of the international production are contradictory. It therefore seems premature to neglect HCB as an organic micro-pollutant of environmental concern.
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- Müller, Christina, et al.
(författare)
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Strategy for verification and demonstration of the sealing process for canisters for spent fuel
- 2004
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Electron beam welding and friction stir welding are the two processes now being considered for sealing copper canisters with Sweden’s radioactive waste. This report outlines a strategy for verification and demonstration of the encapsulation process which here is considered to consist of the sealing of the canister by welding followed by quality control of the weld by non-destructive testing. Statistical methodology provides a firm basis for modern quality technology and design of experiments has been successful part of it. Factorial and fractional factorial designs can be used to evaluate main process factors and their interactions. Response surface methodology with multilevel designs enables further optimisation. Empirical polynomial models can through Taylor series expansions approximate the true underlying relationships sufficiently well. The fitting of response measurements is based on ordinary least squares regression or generalised linear methods. Unusual events, like failures in the lid welds, are best described with extreme value statistics and the extreme value paradigm give a rationale for extrapolation. Models based on block maxima (the generalised extreme value distribution) and peaks over threshold (the generalised Pareto distribution) are considered. Experiences from other fields of the materials sciences suggest that both of these approaches are useful. The initial verification experiments of the two welding technologies considered are suggested to proceed by experimental plans that can be accomplished with only four complete lid welds each. Similar experimental arrangements can be used to evaluate process "robustness" and optimisation of the process window. Two series of twenty demonstration trials each, mimicking assembly-line production, are suggested as a final evaluation before the selection of welding technology. This demonstration is also expected to provide a data base suitable for a baseline estimate of future performance. This estimate can then be used for the safety assessment. In order to provide data for the analysis of welds it is required to use well defined methods for the investigation of the weld integrity. As the total length of the welds produced during the verification and demonstration exceeds 140 m and these needs to be examined with a reasonable resolution non destructive methods (NDT) with high data acquisition rates are required. Destructive methods like metallographic sectioning and examination or tensile testing can be used only to provide complementary information as the acquisition of these data are labour-intensive and time consuming. As the analysis is relying on the reliability of the NDT it is required to have a strategy for the determination of this. Three different ways to investigate the reliability of NDT signals are described. The performance demonstration, the parameter approach and the Integral Approach: ROC – Receiver Operating Characteristic and its relation to POD (probability of detection). The first step of a performance demonstration is to define the essential technical parameters of the system. The ROC and POD methods are appropriate tools to provide a clear measure of integral performance of the system though it has to be paid by high effort in test series with realistic test samples. With POD the user can learn about the detection capability whereas the ROC gives more information about the system’s capability to distinguish between signal and noise. The modular approaches open the door to a promising technique – more efficient and with the capability also to optimize the system. The data evaluation methods chosen to be applied for this assessment is the quantitative POD (Probability of Detection) method according to MIL-STD 1823 /section B4/. The (1-POD) curve will provide the probability of missing a defect as function of defect size which can be used as input for probabilistic risk assessment. Finally, a hypothetical calculation example Appendix 2 is provided to illustrate the fitting of data and extrapolation using the extreme value models.
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