Narrow Results

Ashes generated in the incinerator for radioactive waste at the Kaya Memorial Takizawa Laboratory was analyzed using the PIXE system established at the Nishina Memorial Cyclotron Center. An easy method of sample preparation of ash powder for the PIXE is described. Many elements in the ash sample were detected. The PIXE used in this study is shown to be a very valuable method for analyzing the ash.

Each concentration of specific elements in water extracted from the ash produced by an incinerator used for radioactive waste at the Kaya Memorial Takizawa Laboratory was simultaneously determined using PIXE established at the Nishina Memorial Cyclotron Center. Each concentration of the elements extracted from the ash depends on the pH of the water. The PIXE used in this study was shown to be a very valuable analytical method for environmental analysis.

Medical waste management is of great importance due to its impact on both the public health and the environment. This chapter addresses issues related to medical waste management including: characterization and classification of medical waste, handling, segregation, transportation, labeling, treatment, and disposal. The health and environmental hazards are also included along with the required training of the public and the personnel involved in medical waste management.

Solubilization, precipitation, sorption, and uptake of metal cations by microorganisms justifies the use of fungi in the removal of superficial radionuclide deposits from brickwork and (corroded) metal elements of dismantled nuclear power facilities and accidental spills on a dry way. The citrate and oxalate releasing ascomycete, Aspergillus niger, the oxalate producing brown-rot basidiomycete, Fomitopsis pinicola and several wood- and soil-inhabiting basidiomycetes were tested for their ability to acquire, and translocate uranium and to reduce the weight of metal plates by the expected production of carboxylic acids. Metals and plates of Portland cement were also exposed to solutions of carboxylic and mineral acids to substantiate the results. The nature of the watersoluble and -insoluble reaction products was not determined. The recalcitrant uranium was taken up and translocated through 100-mm long hyphal systems. In addition, all fungal mycelia were able to reduce the weight of the pure or alloyed metals, Fe > Zn > Cu, CuZn > AlMgSi > Cr significantly when added as plates to liquid and solid fungal substrates for 50 to 180 d. The dominating fungal carboxylic acids, malonic > citric, malic > oxalic in realistic solutions of 1 g L⁻¹ were able to reduce the weight of Fe > Ni > Zn > Cu > Al disks upon the formation of soluble and insoluble compounds. The mineral acids, H₂SO₄ > HNO₃ > HCl in solutions with a comparable initial pH transformed Fe > Ni >> Al primarily to insoluble precipitates. Plates of Portland cement increased their dry weight in the solutions of carboxylic acids apparently by the incorporation of the acids’ carbon whereas the mineral acids reduced the dry weight of the samples. Calcium was solubilized by all acids but oxalate. It is concluded that trace metals such as U spread in entire fungal networks which can thus serve as repositories of critical nuclides. In addition, fungal carboxylic acids dissolve (potentially contaminated and corroded) metal surface layers in the μm range by the formation of soluble and insoluble compounds most of the latter can be brushed off. Further tests comprise the placement of plastic-net stabilized lignocellulose mats overgrown with trace metal accumulator fungi on dry structured surfaces contaminated by critical nuclides and the subsequent ashing of the mats by air filtering. Respective in-situ tests with contaminated construction elements are inevitable to confirm economy and efficacy of microbial versus acid- and surfactant-based cleaning procedures.

In this chapter, a brief introduction is presented to radioactive pollution and its management. Both natural and artificial sources of radiation are discussed with special attention to the relative importance of each source. In addition, radioactive isotope applications in tracing, radiography, insect control, food preservation, medical diagnoses, therapy, sterilization, and power generation are briefly described. Sources of radioactive pollution are identified including nuclear weapon tests, nuclear accidents, routine effluent release into the environment, and radioactive waste. Radioactive pollution prevention measures are presented including: treaties, regulations and standards, and technical methods to control pollution. The risk-informed regulatory process is briefly described, along with the technical methods to control radioactive wastes via site selection criteria, design of radioactive waste disposal facilities, and performance assessment.