Nuclear and Chemical Waste Management最新文献

The analysis of lead, zinc and cadmium in Bahrain refinery sludge collected from various deposition sites at Bahrain petroleum company (BAPCO) are reported. Atomic Absorption spectrophotometric method, both flame and flameless (graphite furnace) techniques, were used for the analysis. The concentrations of lead, zinc and cadmium were found in the range, 66.1 to 14630.9 mg/kg (0.007% to 1.46%), 47.4 to 1791.1 mg/kg (0.005% to 0.17%), 0.24 to 5.40 mg/kg (0.00002% to 0.0005%), respectively. These concentrations are less than 1% as is accepted internationally. Nevertheless, these are hazardous and should be managed properly.

Laboratory studies were conducted on select physical and chemical processes for decontamination of a composite waste lubricating oil from a boiling water reactor. Physical treatments included successive filtration through 25, 8 and 1 μm filters to remove particulate matter and centrifugation to remove water. Chemical treatment consisted of mixing the oil with an aqueous solution of the chelating agent ethylenediaminetetraacetic acid (EDTA) and centrifuging the resulting emulsion. The effectiveness of the treatment processes was evaluated by measuring radionuclide concentrations in the oil following each treatment step and calculating decontamination factors.

The total activity of the oil was dominated by ⁶⁰Co, ⁵⁴Mn, and ¹³⁷Cs, although ⁵¹Cr, ⁵⁸Co, ⁵⁹Fe, and ¹³⁴Cs were also present. Filtration consistently achieved decontamination factors of approximately 200, 100, and 40 for ¹³⁷Cs, ⁵⁴Mn, and ⁶⁰Co, respectively, and reduced concentrations of the other radionuclides below their detection limits. Following filtration, centrifugation reduced ¹³⁷Cs concentrations below the detection limit and reduced ⁵⁴Mn and ⁶⁰Co concentrations by approximately 40% and 20%, respectively. Subsequent chemical treatment with EDTA reduced the ⁵⁴Mn concentration to below the detection limit and removed approximately 95% of the remaining ⁶⁰Co activity. The overall decontamination factor for successive filtration, centrifugation, and chelation was in excess of 10,000 for ⁵⁴Mn and ¹³⁷Cs and on the order of 1000 for ⁶⁰Co.

For 35 years the Nevada Test Site Complex has been contaminated by a combination of transuranic elements, fission products, and activation products. Within the nuclear detonation sites the initial radionuclide distribution depended upon the different types of nuclear tests (airburst, surface, or underground) and meteorological conditions at the time of each test. Results of this study show that the present distribution is the result of wind and water erosion, whereas site specific geomorphic features and pedogenic processes played secondary roles. The high temperatures of the detonations resulted in most of the radionuclides being incorporated into fused soil and rock materials which have very low solubilities in aqueous media. The glassy silicate contaminants vary in size, but most (91%) are greater than 0.1 mm in diameter. Therefore, the radioactivity contributed by the resuspendible (< 0.1 mm) and respirable (< 0.005 mm) particles in the soils is less than 9% of the total soil radioactivity, indicating that the site has a very low potential for off-site environmental and health hazards under natural conditions. Nevertheless, the contaminants are expected to have faster physical and chemical weathering rates than those of soil minerals because they are mostly porous glass rather than crystalline in form. From the results of the characterization studies, suggestions are made to consider pretreatment of the contaminated soils in order to reduce the volume to be removed and to maintain a stable nonerodible surface in the treated area.

The environmentally assisted cracking (EAC) behavior of cast ASTM A27 Steel was studied in simulated Hanford groundwater at temperatures of 150°C and 250°C. Fatigue-crack growth tests were employed for this purpose, and the rationale for using cyclic loadings is discussed. An example is given whereby a tentative value of a threshold stress intensity factor for EAC is derived, and an illustration is then made showing the application of the threshold to a waste repository container.

The study reported here solicited the opinions of the general public of the State of Pennsylvania and of key decision makers in environmental, civic, industry, and health groups, on various policy issues connected with the establishment of low-level radioactive waste disposal sites. Specifically, the focus was on their judgment of options designed to elicit local cooperation and their trust in various officials and agencies.

The data indicates that the general public views both compensation and power sharing options as important in promoting local cooperation. However, power sharing options are viewed as more important than incentives. The general public consistently demonstrates a preference for options which put control of the site in the hands of locals.

On the other hand, influential decision-makers, with the exception of those representing environmental advocacy organizations, tend to view compensation as more important than local power sharing. Their preferences mirror those programs currently being pursued by federal and state officials. Preferences exhibited by leaders of environmental advocacy organizations parallel those of the general public.

Furthermore, the general public demonstrates a relative lack of trust in local officials to represent their interests in siting decisions. This raises the issue of legitimacy in negotiations with local communities.