Handling and disposal of unwanted radioactive material.

"May 1988."

Nature and genesis of clay minerals of the Rustler Formation in the vicinity of the Waste Isolation Pilot Plant in Souteastern New Mexico

Detailed mineralogical studies of the matrix and fracture-fill materials of a large number of samples from the Rustler Formation have been carried out using x-ray diffraction, high-resolution transmission electron microscopy, electron microprobe analysis, x-ray fluorescence, and atomic absorption spectrophotometry. These analyses indicate the presence of four clay minerals: interstratified chlorite/saponite, illite, chlorite, and serpentine. Corrensite (regularly stratified chlorite/saponite) is the dominant clay mineral in samples from the Culebra dolomite and two shale layers of the lower unnamed member of the Rustler Formation. Within other layers of the Rustler Formation, disordered mixed chlorite/saponite is usually the most abundant clay mineral. Studies of the morphology and composition of clay crystallites suggest that the corrensite was formed by the alteration of detrital dioctahedral smectite in magnesium-rich pore fluids during early diagenesis of the Rustler Formation. This study provides initial estimates of the abundance and nature of the clay minerals in the Culebra dolomite in the vicinity of the Waste Isolation Pilot Plant.

Iodide Retention by Modified Kaolinite in the Context of Safe Disposal of High Level Nuclear Waste

Bentonite clay is identified as potential buffer in deep geological repositories (DGR) that store high level radioactive wastes (HLW) as the expansive clay satisfies the expected mechanical and physicochemical functions of the buffer material. In the deep geological disposal of HLW, iodine-129 is one of the significant nuclides, attributable to its long half-life (half life 1⁄4 1:7 × 107 years). However, the negative charge on the basal surface of bentonite particles precludes retention of iodide anions. To render the bentonite effective in retaining hazardous iodide species in DGR, improvement of the anion retention capacity of bentonite becomes imperative. The iodide retention capac-ity of bentonite is improved by admixing 10 and 20% Ag-kaolinite (Ag-K) with bentonite (B) on a dry mass basis. The present study produced Ag-kaolinite by heating silver nitrate-kaolinite mixes at 400°C. Marginal release of iodide retained by Ag-kaolinite occurred under extreme acidic (pH 1⁄4 2:5) and alkaline (pH 1⁄4 12:5) conditions. The swell pressure and iodide etention results of the B-Ag-K specimens bring out that mixing Ag-K with bentonite does not chemically modify the expansive clay; the mixing is physical in nature and Ag-K presence only contributes to iodide retention of the admixture. DOI: 10.1061/(ASCE)HZ.2153-5515.0000121. © 2012 American Society of Civil Engineers.

Effects of the Cessation of Sewage Sludge Dumping at the 12-Mile Site: Proceedings of the 12-Mile Dumpsite Symposium, Ocean Place Hilton Hotel, Long Branch, New Jersey, 18-19 June 1991

This study owes its inception to the wisdom and experience of the staff of the Northeast Fisheries Science Center who, after several decades of surveys in the New York Bight, recognized a unique opportunity to capitalize on the decision to stop ocean dumping of sewage sludge and designed an innovative field study to evaluate effects on living marine resources and their habitats. For decades ocean dumping was viewed as a cheap and effective means for disposal of wastes generated by urbanized coastal areas. Even after the 12-mile site was closed, sewage sludge continued to be dumped at Deepwater Dumpsite 106. The 6-mile site off the NewJersey coast is still used as a dumpsite for dredged material from New York Harbor areas. Discussions continue on the propriety of using the deep ocean spaces for disposal of a variety of material including low level radioactive wastes. Consequently, managers are still faced with critical decisions in this area. It is to be hoped that the results from the 12-mile study will provide the necessary information on which these managers can evaluate future risks associated with ocean waste disposal. (PDF file contains 270 pages.)

Biologische Veränderungen im Versenkungsgebiet für schwach radioaktive Abfälle im Iberischen Tiefseebecken?

From 1979 to 2000, the site for the dumping of low-level radioactive wastes and an unaffected site in the North-east Atlantic were investigated to determine the biomass data of the benthopelagic nekton and the benthic organisms. The investigation shall demonstrate the influence on the biocoenosis of the so-called "artificial reef effect", caused by dumped waste drums. For sampling benthopelagic and benthic organisms, we used a modified Agassiz trawl, called the Deep-sea Closing Net. With the exception of the “Amperima event” in 1996 – a unique occurrence of a large number of sea-cucumbers – there was no change in the composition of benthopelagic and benthic organisms through the years. The biomass of the benthopelagic nekton was characterized by Macrouridae(rat-tailed fishes) and the main tax on of the benthos was Actiniaria (sea-anemones).

Radioaktives Cäsium im Fisch der Barentssee weiterhin abnehmend

A decrease of 137Cs concentration in cod flesh from Barents Sea is shown by six years random sampling. This reduction runs parallel to reduced emissions from the nuclear fuel reprocessing plant Sellafield (Great Britain). It must be emphasized that even the highest values from 1992 are lower than comparable ones from the North Sea and from the Baltic. Although there is no increase of the radiation dose on people by consuming these fishes further monitoring should not be stopped. Potential risk arises from radioactive wastes of the russian nuclear navy in their coastal area. Obviously a safe storage seams almost too expensive.

Assessment of siltation rate and sediment transport in Bombay harbour based on Cesium-137 distribution

Low level aqueous radioactive wastes from the nuclear complex at Trombay are discharged into the Bombay harbour. Of the 6 principal radionuclides comprising the discharge, cesium-137 is most predominantly taken up by silt from the sea water. Isoactivity contours show that activity levels just off the point of discharge, and further south to Pir Pau, were between 50 and 100 pCi/g. Activity in the main channel of the harbour remained below 10 pCi/g, while further north (below the Thane Creek bridge) it was around 20 pCi/g. Activity in the top 6 cm of a core off Trombay naval jetty was <5 pCi/g, reaching a maximum of 178 pCi/g at 14cm below the surface. Thereafter, it tapered off to 5 pCi/g down to a metre.

Modelling of the natural chlorine cycling in a coniferous stand: implications for chlorine-36 behaviour in a contaminated forest environment

Considered as one of the most available radionuclide in soileplant system, 36Cl is of potential concern for long-term management of radioactive wastes, due to its high mobility and its long half-life. To evaluate the risk of dispersion and accumulation of 36Cl in the biosphere as a consequence of a potential contamination, there is a need for an appropriate understanding of the chlorine cycling dynamics in the ecosystems. To date, a small number of studies have investigated the chlorine transfer in the ecosystem including the transformation of chloride to organic chlorine but, to our knowledge, none have modelled this cycle. In this study, a model involving inorganic as well as organic pools in soils has been developed and parameterised to describe the biogeochemical fate of chlorine in a pine forest. The model has been evaluated for stable chlorine by performing a range of sensitivity analyses and by comparing the simulated to the observed values. Finally a range of contamination scenarios, which differ in terms of external supply, exposure time and source, has been simulated to estimate the possible accumulation of 36Cl within the different compartments of the coniferous stand. The sensitivity study supports the relevancy of the model and its compartments, and has highlighted the chlorine transfers affecting the most the residence time of chlorine in the stand. Compared to observations, the model simulates realistic values for the chlorine content within the different forest compartments. For both atmospheric and underground contamination scenarios most of the chlorine can be found in its organic form in the soil. However, in case of an underground source, about two times less chlorine accumulates in the system and proportionally more chlorine leaves the system through drainage than through volatilisation.

The licensing of a laboratory for manipulating radionuclides in Brazil

Radionuclides take a major role in guidelines of environmental agencies/national organizations of countries worldwide. In Brazil, CNEN-Comissão Nacional de Energia Nuclear is responsible for managing all subjects related to nuclear energy in the country. Thus, laboratories employing radionuclides for the development of their activities must submit a Radioprotection Plan to CNEN in order to get an operation license. Such plan must indicate that the laboratory is exempt of risks to the people involved and designed to fit all related environmental aspects. This was the case of LABIDRO-Hydrochemical and Isotopes Laboratory that belongs to IGCE-Geosciences and Exact Sciences Institute from UNESP - the University of the State of São Paulo Júlio de Mesquita Filho, located at Rio Claro city, São Paulo State, Brazil. The total monthly activity of the radionuclides utilized during the laboratorial activities held at LABIDRO corresponds to 0.01 μCi. This paper describes all information provided by LABIDRO in order to get the CNEN license. The LABIDRO plan also showed the expected radioactive waste released when the experiments take place and CNEN decided that it fits the guidelines established by Brazilian legislation. Therefore, LABIDRO received its license for utilizing radionuclides, which is valid until September 2016. © 2013 WIT Press.

Estudo comparativo da evolução da legislação internacional e brasileira sobre repositórios geológicos de rejeitos radioativos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)