[en] Hanford, Fernald, Savannah River, and other sites are currently reviewing technologies that can be implemented to demolish buildings in a cost-effective manner. In order to demolish a structure and, at the same time, minimize the amount of dust generated by a given technology, an evaluation must be conducted to choose the most appropriate dust suppression technology. Thus, the purpose of this research, which was conducted by the Hemispheric Center for Environmental Technology (HCET) at Florida International University (FIU), was to perform an experimental study of dust aerosol abatement (dust suppression) methods as applied to nuclear D and D. This experimental study specifically targeted the problem of dust suppression during demolition. The resulting data were used in the development of mathematical correlations that can be applied to structural demolition. In the Fiscal Year 1996 (FY96), the effectiveness of different dust suppressing agents was investigated for different types of concrete blocks. Initial tests were conducted in a broad particle size range. In Fiscal Year 1997 (FY97), additional tests were performed in the size range in which most of the particles were detected. Since particle distribution is an important parameter for predicting deposition in various compartments of the human respiratory tract, various tests were aimed at determining the particle size distribution of the airborne dust particles. The effectiveness of dust suppressing agents for particles of various size was studied. Instead of conducting experiments on various types of blocks, it was thought prudent to carry out additional tests on blocks of the same type. Several refinements were also incorporated in the test procedures and data acquisition system used in FY96

[en] During deactivation and decommissioning activities, thermal cutting tools, such as plasma torch, laser, and gasoline torch, are used to cut metals. These activities generate fumes, smoke and particulates. These airborne species of matter, called aerosols, may be inhaled if suitable respiratory protection is not used. Inhalation of the airborne metallic aerosols has been reported to cause ill health effects, such as acute respiratory syndrome and chromosome damage in lymphocytes. In the nuclear industry, metals may be contaminated with radioactive materials. Cutting these metals, as in size reduction of gloveboxes and tanks, produces high concentrations of airborne transuranic particles. Particles of the respirable size range (size < 10 microm) deposit in various compartments of the respiratory tract, the fraction and the site in the respiratory tract depending on the size of the particles. The dose delivered to the respiratory tract depends on the size distribution of the airborne particulates (aerosols) and their concentration and radioactivity/toxicity. The concentration of airborne particulate matter in an environment is dependent upon the rate of their production and the ventilation rate. Thus, measuring aerosol size distribution and generation rate is important for (1) the assessment of inhalation exposures of workers, (2) the selection of respiratory protection equipment, and (3) the design of appropriate filtration systems. Size distribution of the aerosols generated during cutting of different metals by plasma torch was measured. Cutting rates of different metals, rate of generation of respirable mass, as well as the fraction of the released kerf that become respirable were determined. This report presents results of these studies. Measurements of the particles generated during cutting of metal plates with a plasma arc torch revealed the presence of particles with mass median aerodynamic diameters of particles close to 0.2 micro

[en] This report describes a system for handling and radioassay of lead, consisting of a robot, a conveyor, and a gamma spectrometer. The report also presents a cost-benefit analysis of options: radioassay and recycling lead vs. disposal as waste

[en] Hanford, Fernald, Savannah River, and other sites are currently reviewing technologies that can be implemented to demolish buildings in a cost-effective manner. In order to demolish a structure properly and, at the same time, minimize the amount of dust generated from a given technology, an evaluation must be conducted to choose the most appropriate dust suppression technology given site-specific conditions. Thus, the purpose of this research, which was carried out at the Hemispheric Center for Environmental Technology (HCET) at Florida International University, was to conduct an experimental study of dust aerosol abatement (dust suppression) methods as applied to nuclear D and D. This experimental study targeted the problem of dust suppression during the demolition of nuclear facilities. The resulting data were employed to assist in the development of mathematical correlations that can be applied to predict dust generation during structural demolition

[en] Radioactive aerosols are generated during operations (transfer, cutting, storage and shipment of fuel) in spent fuel bays. A study has been carried out on the airborne concentration, size distribution and solubility of the aerosol, to evaluate the inhalation exposure of the workers. Personal air samplers were used for the measurement of concentration of airborne radioactivity and Andersen impactor for particle size distribution. Some of the collected sampels were followed for their solubility in lung serum simulant for a period of about 200 days. The observed concentrations of the aerosols and their activity median aerodynamic diameters (AMAD) were 418 ± 443 Bq m^-3 (βγ), 1.28 ± 1.478 Bq m^-3 (∞) and 6.79 ± 0.4μm respectively. Analysis of the samples revealed the presence of ²³⁹Pu, U, ⁹⁰Sr and ¹³⁷Cs. The clearance half-life of the aerosols was the same (155 days) for all the isotopes (U, ²³⁹Pu, ⁹⁰Sr; ¹³⁷Cs). Calculation of effective dose equivalent for the clearance half-life and for 6.79 μm AMAD aerosols was carried out using the method recommended in ICRP-30. Annual effective dose equivalent of the workers, if no respirators were worn, worked out to be 3.2 mSv (320 mrem), the contribution from alpha emitters being about 63 per cent of the total. (author). 5 refs., 2 tables

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[en] Based on the experience gained in radiation protection with the research reactors at Trombay, it has been been possible to reduce the exposure of workers. Introduction of new instruments and study of work environment have helped in early diagnosis of the deficiencies in the system status and for the identification of the sources of exposure for incorporation of remedial actions. (author)

[en] Radioactive aerosols are generated during operations (transfer, cutting, storage and shipment of fuel) in spent fuel bays. A study has been carried out on the airborne concentration, size distribution and dissolution rate of aerosols to evaluate the inhalation exposure of the workers. Personal air samplers were used for the measurement of concentration of airborne radioactivity and an Andersen impactor for the particle size distribution. The dissolution rates of some of the collected samples in lung serum simulant were followed for a period of about 200 days. Analysis of the samples revealed the presence of ²³⁹Pu, U, ⁹⁰Sr and ¹³⁷Cs. For all the radionuclides measured (²³⁹Pu, U, ⁹⁰Sr, ¹³⁷Cs) 40% of the activity dissolved rapidly (half-time 1.2d), the remainder with a half-time of 155 d. Calculation of effective dose equivalent for this dissolution half-time and for 6.8μm AMAD aerosols was carried out using the method recommended in ICRP 30 and reported in literature. The annual effective dose equivalent of the workers, if no respirators are worn, worked out to be 8.9 mSv (890 mrem), the contribution from alpha emitters being about 91% of the total. (author)

[en] Concentrations of various radioisotopes of iodine in the effluent exhaust system of Cirus have been measured. The measuring system comprises of a sampling head, a pump and a gamma spectrometer. The sampling head is similar to May-Pack and contains millipore membrane filter paper, silver-plated copper-mesh discs, activated charcoal filter paper and KI impregnated charcoal granules packed in series to measure concentration of various forms of iodines. The sampling head was modified so that it could be directly placed on a NaI or Ge-detector for on-line identification and measurement of various radioisotopes of iodine. When operated at a flow rate of 8 1 min^-1 the overall collection efficiency of the system for iodine was about 95 per cent. The collected samples were analysed in Ge-spectrometer and at 20 MWsub(Th) power concentrations of I131, I132, I133, I135 gaseous effluent of CIRUS reactor were 2.6, 34, 17 and 33 Bq m^-3 respectively which correspond to annual release rate of 1.1x10⁹, 1.5x10¹⁰, 7.3x10⁹ and 1.5x10¹⁰Bq. The measuring system has been used to test the performance of iodine removal system which was found to have removal efficiency of 92 percent for iodines. (author). 4 refs