National Nuclear Energy Commission

About: National Nuclear Energy Commission is a government organization based out in Rio de Janeiro, Brazil. It is known for research contribution in the topics: Dosimetry & Laser. The organization has 3816 authors who have published 4694 publications receiving 59951 citations.

Instrumental method for the determination of trace elements in water samples by neutron activation analysis

Abstract: Thermal neutron activation analysis and a large-volume high-resolution Ge(Li) gammaray spectrometer, connected on-line to a DEC PDP 8/L computer, have been used to measure the concentrations of Na, Sc, Cr, Fe, Co, Ni, Zn, As, Se, Br, Rb, Ag, Sb, Cs, W and Hg in some Italian subsurface water samples. The instrumental method requires neither a chemical separation technique nor a pre- or post-concentration of the trace elements to be detected. As a consequence, this method eliminates many inherent errors associated with chemical determinations. The technique is sensitive, precise and particularly suitable for routine analysis of many trace elements at both natural and pollution levels in water samples. The interferences due to fast neutron (n, p) and (n, α) reactions are not appreciable, with the only exception of the54Fe(n, p)54Mn and58Ni(n, p)58Co reactions. Losses of volatile, elements, e. g. As, Br and Hg, during irradiation proved to be negligible.

Radiological Risk Assessment by Convergence Methodology Model in RDD Scenarios

Abstract: A radiological dispersal device (RDD) is a simple weapon capable of causing human harm, environmental contamination, disruption, area denial, and economic cost. It can affect small, large, or long areas depending on atmospheric stability. The risk of developing a radio-induced cancer depends on exposure, and an effective response depends upon available timely guidance. This article proposes and demonstrates a convergence of three different capabilities to assess risk and support rapid safe resource efficient response. The three capabilities that are integrated are Hotspot for dispersion, RERF for epidemiological risk, and RESRAD-RDD for response guidance. The combined methodology supports decisions on risk reduction and resource allocation through work schedules, the designation and composition of response teams, and siting for operations. In the illustrative RDD scenario, the contamination area for sheltering, evacuation, and long-term public concern was greatest for calm atmospheric conditions, whilst close-quarter responders faced highest dose rates for neutral atmospheric conditions. Generally, the risks to women responders were found to be significantly greater than for men, and the risks to 20-year-old responders were three times that of their 60-year-old counterparts for similar exposure.

Assessment of organic and inorganic contaminants in sediments of an urban tropical eutrophic reservoir.

Abstract: Although the Ibirite reservoir (an urban tropical eutrophic reservoir) has been the recipient of the discharge of a large volume of raw urban sewage, the key cause of ecosystem degradation has been historically solely attributed to the discharge of effluents from an oil refinery. This fact motivated an investigation to unravel the compositions of contaminants in the sediments to evaluate their distributions, possible sources, and potential impacts on sediment–water quality. The concentrations of polycyclic aromatic and aliphatic hydrocarbons and of metals and metalloids were, in general, significantly lower than some selected polluted sites used for comparison. Calculated distribution indexes showed that the hydrocarbon sources were petrogenic, pyrogenic, and biogenic. Only a few PAHs exceeded the threshold effects level (TEL) guideline. Industrial activities are the presumed sources of metals and metalloids except for copper, which is from copper sulfate used as algaecide in the reservoir. The bioavailable concentrations of some metal and metalloid exceeded the TEL–PEL guidelines. The acid volatile sulfide concentration was greater than that of the simultaneously extracted metals in the clayey–silty reservoir sediments, whereas the opposite result was observed for the sandy sediments of the tributaries. The sediment interstitial water toxic units were >1 for metals, thus indicating that metals are potentially toxic to the benthos. Considering the data set generated in this study, it can be concluded that the degradation of Ibirite reservoir and its tributaries cannot be solely attributed to the input of hydrocarbons, but predominantly to the discharge of raw urban sewage and effluents from other industrial sources.