Identification of atmospheric pollutants control mechanisms during co-combustion of coal and non-toxic wastes

Doctoral dissertation for Ph.D. degree in Sustainable Chemistry

Federal action plan for research and monitoring related to at-sea disposal of low-level radioactive wastes : FY 1986 to FY 1990

Mode of access: Internet.

¿Impact from road transport of radioactive wastes in Spain?

Transports of radioactive wastes in Spain are becoming issues of renewed interest, due to the increased mobility of these materials which can be expected after the building and operation of the planned central repository for this country in a near future. Such types of residues will be mainly of the medium and high activity classes and have raised concerns on the safety of the operations, the radiological protection of the individuals, the compliance with the legal regulations and their environmental consequences of all kind. In this study, relevant information for the assessment of radiological risk of road transport were taken into account, as the sources and destination of the radioactive transports, the amount of traveling to be done, the preferred routes and populations affected, the characterization of the residues and containers, their corresponding testing, etc. These data were supplied by different organizations fully related with these activities, like the nuclear power stations, the companies in charge of radioactive transports, the enterprises for inspection and control of the activities, etc., as well as the government institutions which are responsible for the selection and location of the storage facility and other decisions on the nuclear policies of the country. Thus, we have developed a program for computing the data in such a form that by entering the radiation levels at one meter of the transport loads and by choosing a particular displacement, the computer application is capable to calculate the corresponding radiological effects, like the global estimated impact, its relevance to the population in general or on those people living and driving near the main road routes, the doses received by the most exposed individuals (e.g. the workers for loading or driving the vehicle), or the probability of detrimental on the human health. The results of this work could be of help for a better understanding and management of these activities and their related impacts; at the same time that the generated reports of the computer application are considered of particular interest as innovative and complementary information to the current legal documentation, which is basically required for transporting radioactive wastes in the country, according with the international safety rules (like IAEA and ADR).Though main studies are still in progress, as the definite location for the Spanish storage facility has not been decided yet, preliminary results with the existing transports of residues of medium activity indicate that the radiological impact is very low in conventional operations. Nevertheless, the management of these transports is complex and laborious, making it convenient to progress further in the analysis and quantification of this kind of events, which constitutes one of the main objectives of the present study for the radioactive road mobility in Spain.

Long-term management of liquid high-level radioactive wastes stored at the Western New York Nuclear Service Center, West Valley : final Environmental Impact Statement.

"June 1982."

Radioactive wastes

Cover title.

Improvements needed in the land disposal of radioactive wastes : a problem of centuries : report to the Congress /

Cover title.

Radionuclide concentrations in raw and purified phosphoric acids from Brazil and their processing wastes: implications for radiation exposures

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Study of the interactions of Neptunium with humic substances and the clay mineral montmorillonite by direct and non direct speciation methods

For the safety assessment of radioactive waste, the possibility of radionuclide migration has to be considered. Since Np (and also Th due to the long-lived 232-Th) will be responsible for the greatest amount of radioactivity one million years after discharge from the reactor, its (im)-mobilization in the geosphere is of great importance. Furthermore, the chemistry of Np(V) is quite similar (but not identical) to the chemistry of Pu(V). Three species of neptunium may be found in the near field of the waste disposal, but pentavalent neptunium is the most abundant species under a wide range of natural conditions. Within this work, the interaction of Np(V) with the clay mineral montmorillonite and melanodins (as model substances for humic acids) was studied. The sorption of neptunium onto gibbsite, a model clay for montmorillonite, was also investigated. The sorption of neptunium onto γ-alumina and montmorillonite was studied in a parallel doctoral work by S. Dierking. Neptunium is only found in ultra trace amounts in the environment. Therefore, sensitive and specific methods are needed for its determination. The sorption was determined by γ spectroscopy and LSC for the whole concentration range studied. In addition the combination of these techniques with ultrafiltration allowed the study of Np(V) complexation with melanoidins. Regrettably, the available speciation methods (e.g. CE-ICP-MS and EXAFS) are not capable to detect the environmentally relevant neptunium concentrations. Therefore, a combination of batch experiments and speciation analyses was performed. Further, the preparation of hybrid clay-based materials (HCM) montmorillonitemelanoidins for sorption studies was achieved. The formation of hybrid materials begins in the interlayers of the montmorillonite, and then the organic material spreads over the surface of the mineral. The sorption of Np onto HCM was studied at the environmentally relevant concentrations and the results obtained were compared with those predicted by the linear additive model by Samadfam. The sorption of neptunium onto gibbsite was studied in batch experiments and the sorption maximum determined at pH~8.5. The sorption isotherm pointed to the presence of strong and weak sorption sites in gibbsite. The Np speciation was studied by using EXAFS, which showed that the sorbed species was Np(V). The influence of M42 type melanodins on the sorption of Np(V) onto montmorillonite was also investigated at pH 7. The sorption of the melanoidins was affected by the order in which the components were added and by ionic strength. The sorption of Np was affected by ionic strength, pointing to outer sphere sorption, whereas the presence of increasing amounts of melanoidins had little influence on Np sorption.