[en] The criteria for shallow ground disposal of radioactive wastes as developed by Nuclear Regulatory Comission-US and International Atomic Energy Agency are discussed. Emphasis has been given to: elaboration of various basic components of a national strategy for radioactive waste disposal; development of technical requirements; environmental standards, consensus among scientific community and public confidence. Aspects of site selection, evaluation/characterization and site suitability are dealt with. Some results of characterization of a site for temporary storage of low level solid radioactive wastes in Instituto de Pesquisas Energeticas e Nucleares - IPEN - CNEN/Sao Paulo are described. The methods used for hydrological characterization include use of artificial tritium for unsaturated zone and radioactive tracers like I - 131, Cr⁵¹Cl₃, Cr⁵¹EDTA, Br⁸² for the saturated zone. (Author)

[en] Experimental and theoretical investigations of two different types of pipe riser clamps used to support the vertical runs of pipes in nuclear and fossil power plants are reported

[en] The results of the study of bituminization of simulated radwaste - spennt ion-exchange resins, borate evaporator/concentrates and animal ashes, are presented and discussed. Distilled and oxidizer bitumen were used. Characterization of the crude material and simulated wastes-bitumen mixtures of varying weigt composition (30, 40, 50, 60% by weight of dry waste material) was carried out. The asphaltene and parafin contents in the bitumens were also determined. Some additives and were used with an aim to improve the characteristcs of solidified wastes. For leaching studies, granular ion-exchange resins were with Cs - 134 and mixtures of resin-bitumen were prepared. The leaching studies were executed using the IAEA recommendation and the ISO method. A conventional screw-extruder, common in plastic industry, was used determine operational parameters and process difficulties. Mixtures of resin-bitumen and evaporator concentrate-bitumen obtained from differents operational conditions were characterized. (Author)

[en] A conductivity probe and a temperature probe have been developed for in-situ measurements in various hydrological field studies. The conductivity probe has platinum electrodes and is powered with two 12 volt batteries. The sensing element of the temperature probe consists of a resistor of high coefficient of temperature. Response of the conductivity probe is measured in a milliampere mater while the resistance of the thermistor is read by a digital meter. The values of conductivity and temperature are derived from respective calibration. The probes are prototype and their range of measurement can be improved depending upon the requirement of the field problem. (Author)

[en] To study radionuclide leaching from bitumen waste forms, many samples of bitumen mixed with ion-exchange resin labelled with ¹³⁴Cs were prepared. The resins used in the tests were nuclear grade mixed cationic/anionic bead resins. Different bittumen types were assayed: two destilled and to oxidized bitumens. Laboratory to scale samples, with surface/volume ratio (S/V) = 1, were molded to 5 cm diameter and 10 cm height. The composition of the mixtures were: 30, 40, 50 and 60% by weight of dried resin with bitumen. The leachant was deionized water with a leachant volume to sample surface rario of about 8 cm. Leached fractions were collected according to the recommendation of ISO method, with complete exchange of leachant beckers after each sampling. The volume collected for analysis was one liter. Marinelli were used for counting in a Ge(Li) detector. Up to now, results of 250 days have been accumulated. Samples prepared with distilled bitumen have shown a diffusion coefficient of the order of 10^-14 cm²/sec and those prepared with oxidized bitumen yielded a diffusion coefficient of the order of 10^-12 cm²/sec. Mathematical models of transport phenomena applied to cylindrical geometry were employed to fit experimental data. (Author)

[en] A system for incinerating the combustible solid and liquid radioactive wastes was developed in order to achieve higher mass and volume reduction of the wastes generated at IPEN-CNEN/SP or received from other institutions. The radioactive wastes for incineration are: animal carcasses, ion-exchange resins, contaminated lubricant oils, cellulosic materials, plastics, etc. The optimization of the process was achieved by considering the following factors: selection of better construction and insulating material; dimensions; modular design of combustion chambers to increase burning capacity in future; applicability for various types of wastes; choise of gas cleaning system. The off-gas system utilizes dry treatment. The operation is designed to function with a negative pressure. (Author)

[en] The method of determining flow and drection of ground water by using radioactive tracers in ground water borings is described. Various parameters controlling the measurements are discussed in detail. Application of the method in studying a variety of geohydrological problems, in view of the hydrological evaluation of the waste disposal site at IPEN, is indicated. Comparison of the method with conventional pumping tests is made. (I.C.R.)

[en] The criteria for shallow ground disposal of radioactive wastes as developed by Nuclear Regulatory Commission-US and International Atomic Energy Agency are discussed. Emphasis has been given to: elaboration of various basic components of a national Strategy for radioactive waste disposal; development of technical requirements; environmental standards, consensus among scientific community and public confidence. Aspects of site selection, evaluation/characterization and site suitability are dealt with. Some results of characterization of a site for tempory storage of low level solid radioactive wastes in Instituto de Pesquisas Energeticas e Nucleares-IPEN-CNEN/Sao Paulo are described. The methods used for hydrological characterization include use of artificial tritium for unsaturated zone and radioactive tracers like I-131, Cr⁵¹ Cl₃, Cr⁵¹ EDTA, Br⁸² for the saturated zone. (Author)

No abstract available

[en] A brief description of the tested concepts, for determination of environmental capacity and impact by critical path analysis technique and of dose limitation/optmization for radioactive releases is made. These concepts/methodologies are being applied in the environment of IPEN. The aquatic environment of IPEN is dealt with in detal with a view to evaluate the possible critical paths, its capacity, and present and future radiological impacts. (Author)