[en] The 7. conference on nuclear science and technology was held on 1-2 December 1998 in Bangkok. This conference contain papers on non-power applications of nuclear technology in medicine, agriculture and industry. These application include irradiation of food for disinfestation; tram technologies used in diagnosis and therapy and radiation chemistry important to industrial processes. Some technologies which evolved from the development of nuclear power industry are also discussed

[en] One of the disadvantages of conventional X-ray radiography is its inability to magnify image; and thus, fine details of millimeter-size specimens may not be resolved. To overcome this disadvantage, a microfocus X-ray source is needed; and at present, it can only be generated by activating atoms of a metal target using electron microbeam from an expensive electron microscope (EM). The technique is known as X-ray microscopy. This research work is aimed to modify the electron gun section of a cathode ray tube as an economical microfocus soft X-ray source in a vacuum chamber. When the electron beam has an energy in a range of 0-20 keV and a current in order of 10 nA. The beam is focused on to a thin film gold target, a L_α characteristic X-ray with an energy of 9.71 keV is generated. The X-ray projection mechanism can be adjusted to magnify an image by 2-50 times. To benchmark the modified X-ray microscopy system for its spatial resolution and image quality, X-ray micrographs were taken on the 80 μm of copper wire and small fish (GUPPY - Poecillia reticulata) using the modified electron gun and compared with those taken using and electron source from a conventional EM, JEOL-JSM-T220. Testing conditions of both systems were configured to operate at a 20 kV accelerating voltage and a setting of target to specimen distance and a target to film distance for *2 and *5 of magnification, respectively. The exposure time was set to be 60 min using an X-ray film type Agfa STRUCTURIX D7. The image quality obtained from both systems was found to have comparable degree of sharpness at *2 magnification. While, at *5 magnification shown the unsharpness of X-ray image from the modified system, due to a limitation of spot size of electron beam which is controlled by electrostatic focusing lens

[en] This research was aimed to study the effects of groundwater and acid rain upon the mobility of radionuclides (Cs-134 and Co-60) in contaminated top soil. Clay soil was homogeneously packed in columns with dimension φ.12.5 cm. * 50 cm.. At the top 5 cm. of the columns, soil contaminated with radionuclides was added with the same consistency. Column were kept standing for 4 months in an artificial water table kept at 3 cm. from the bottom. During this period artificial acid rain with pH3, 4.5 and 6 was applied weekly at the top. Soil samples were taken every 30 days for examination of total and extracable radioactivity. It was shown that with the aide of the rain radionuclide movement down the profile was greater, with Co-60 > Cs-134. However acidity of the rain shown no effect on their movement

[en] Chromatographic packed-soil Column was used to study the relative mobility and distribution of endosulfan in soil. With water saturated flow and gravity, Phrabat soil (PakChong Series) showed much more relative mobility and distribution than Rangsit soil (Rangsit Series). This was agreed with soil permeability of the two soils with were 0.34 and 9.16 mm/hr for Rangsit soil and Phrabat soil, respectively. This result was in agreeable with the adsorption coefficient (k_d) of the two soils which was higher in Rangsit soil compared to Phrabat soil. The distribution of endosulfan was found mostly in the top 10 cm of soil. As expected distribution to deeper extend was observed in Phrabat soil

[en] The radioactive decontamination of equipments and handling tools, the objective of which is to reduce the exposure dose to reach the radiation safety limit for workers. The decontaminated equipments and tools can be reused for economical benefit. In this experiment, decontamination of Be-reflector handling tools from Japan Material Testing Reacor (JMTR) was performed by electropolishing method. The experiment was conducted in a 10 litre plastic container filled with 5 litre acid electrolyte using stainless steel plate (SUS 304) as cathode and Be-reflector handling tool as anode. The current applied was DC 200 Volt, 12 Ampere. The density of current was about 109 mA.cm.^-2 The experiment's results were as follows, the optimal time for redox reaction was 30 minutes, the decontamination efficiency was about 98% and the surface activity after decontamination was less than 3.7 Bq.cm^-2 inwhich was within the contamination limit for material reused

[en] Carbon-14 was analysed by direct absorption of carbon dioxide on the mixture of organic amine compound and scintillation cocktail then counted by low level liquid scintillation counter. This method can be applied for radiocarbon dating. In this study, the effects of carbon dioxide absorption, and counting efficiency were investigated using various commercial available cocktail. It was found that permafluor V and Ready Gel showed the highest carbon dioxide absorption whereas the Permafluor V showed the highest counting efficiency

[en] The uranium isotope, i.e., uranium-238, uranium-235 and uranium-234 in sediments have been analysed using Uranium-232 as tracer. The samples were digested in conc. nitric acid, conc. hydrochloric acid and conc. hydrofluoric acid, respectively. Uranium were then extracted into TBP in CCl₄ back extracting by dilute HCl. Then uranium was separated by electrodeposition and subsequent α-radiation of each isotopes were measured by α-spectrometry. Chemical yield of the electrodeposition was found to be 99.02%. The accuracy and precision were checked by using Standard reference material IAEA-300 and SRM-4350. The average deviation coefficient is about 4.05%

[en] Monte Carlo Simulation was used to simulate the multiple scattering and the flux attenuation of penetrating fast neutrons in a solid cylindrical sample of single nuclei. The sample-size effect and the source related background effect are the aim of this investigation. The simulation used actual dimension and geometry of a tritium target-sample-detector. Results of simulation will be shown in comparison with the experimental results on a Double Differential Neutron Emission Cross Section of Bismuth (²⁰⁹Bi) at 14 MeV neutron

[en] The sterilization dose setting by ISO 11137 method 1 was conducted for natural rubber examination gloves provided by a local factory. The suitable sterilization dose for an average product bioburden falls between 20 - 25 kilogray. Maximum dose of 25 or 50 kilogray results in no changes of tensile s and elongation at break. Samples of examination glove were irradiated using various doses between 10 - 50 kilogray. Analysis of soluble protein content using modified Lowry method was carried out and the results revealed that irradiation did not affect the decrement of soluble protein content in this case. However, thin film samples were prepared in laboratory and treated in the same procedure. The results were also the same. The results did not show any correlation. Two factors are possibly presumed : un consistency of samples and the irradiation of finished products could not affect those soluble proteins in rubber gloves

[en] The strippable paint, one of the adhesion method, is to decontaminate solid surface of materials or/and a large area. Two kinds of specimen planchet, SUS 304 stainless steel and polycarbonate plastic, contaminated with radioactive ¹³⁷Cs were studied under various conditions. It included surface bottom types, the flat and convex concentric circle type, normal condition at room temperature and overheat condition (∼80 degree celsius). This method used coating paints which contains some elements to have a reaction with radioactive materials selectively. ALARA-Decon clear, Rempack-X200 clear, JD-P5-Mrs.Coat and Pro-Blue-color guard were selected to use as the coating paints. The contaminated surface was coated by the strippable paint under the optimum time, followed by peeling the paint seal. The Rempack-X200 showed the best result, the highest decontamination efficiency which are about 99-100% for all conditions of specimens. The JD-P5 and ALARA-Decon showed good results, which are 98-99% decontamination efficiency for the normal condition set of specimens and about 94-97% for the overheat set of specimens. They can decontaminate polycarbonate specimens better than stainless steel specimens. The Pro-Blue-color guard showed the lowest decontamination efficiency of which 60% for polycarbonate specimens at normal condition and 40%, 30% for stainless steel specimens at normal and overheat conditions respectively. There was no effects of surface bottom types significantly