[en] In the normal operation of the Thai Research Reactor located inside office of Atomic Energy for Peace, trivial quantities in volume and activity of low-level liquid waste are discharged to the fresh-water system under authorization. It is the purpose of this report to estimate the doses to members of the public from the releases to the surface water environment. Environmental monitoring program is carefully conducted to measure the activity of radionuclides in the pathways to man. The only potential pathway contributing to the radiation dose by the local members in the vicinity or OAEP is the consumption of fresh-water plant, swamp cabbage, white stem Ipomoca reptans. The calculated committed effective dose to members of the public who are likely to receive maximum dose are 0.11 μSv. The result shows that normal operation of the research reactor insignificantly contributes to the annual effective dose equivalent limit for the public recommended by the International Commission on Radiological Protection (1991), that is, 1 mSv y^-1

[en] An universal interfacing card has been developed for data communications between the NIM system and 16 bit IBM personal computer, XT/AT, to improve performance of the measuring system. It can be applied for both data analyzing and nucleonic controlling system, using a package program which is designed for supporting the user. The universal interfacing card can transfer the BCD counting data from a scaler with six digit capacity and receive a signal level from 8 modules of ratemeter with multiplexing system. Each channel can accept the signal of 0 to 100 mV with an error of less than +₃.6% full scale. The card can be generated 0 to 10 V low level discriminator scanning signal with resolution of 10 mV and linearity 0.998. Besides, it can control eight sets of external devices through the signal obtained by comparing the result from the ratemeter with that from the reference point

[en] The determination of iron and manganese in soil samples of soy-bean fields from Maehia Research Station, Chiang Mai were studied. Soil samples were collected before cropping and after harvesting, and neutron activation analysis was applied to determine the total amounts of iron and manganese in soil samples by the measurements of gamma radiation from radioisotope decays of Fe-59 and Mn-56 at energies of 1099 and 846 keV, respectively. The amounts of iron and manganese were found to be in the ranges of 1.04-1.32% and 0.049-0.068%, respectively. The contents of water-soluble iron and manganese from soil samples determined spectrophotochemically were found to be in the ranges of 15.7-19.6 and 0.39-1.33 μg/g, respectively

[en] Commercial packages of fragrant rice, 50 kg each, were used to determine the efficiency of an industrial gamma irradiator, Model JS-8900. The maximum product throughput was 6,300 kg in 1 hr 27.12 min with the overall average absorbed dose in the product carrier of 1.0 kGy. Fragrant rice irradiated at 0, 0.5, 0.9 and 1.1 kGy were used for sensory acceptability evaluation. The panel accepted the color, the taste and the texture of steamed-fragrant rice, regardless of radiation doses. In addition, the odor and the color of raw-fragrant rice irradiated at 0.9 and 1.1 kGy were accepted

[en] The radioactive tracer technique was used to determine residence time of natural gas in Mercury Removal Unit with on-going process operation at Gas Separation Plant Petroleum Authority of Thailand, Muang District, Rayong Province. These 3 units were connected in parallel. The radioactive tracer used was krypton-85. It was found that the mean residence time of those three units were 31.74, 30.08 and 30.31 seconds

[en] The project on the Industrial Application of Isotopes and Radiation was carried out under the Regional Co-operative Agreement (RCA) for Research, Development and Training related to Nuclear Science and Technology in Asia and the Pacific 1982 to 1991. The project was underpinned by UNDP funding and supplemented by extra-budgetary financing mostly from Japan, Australia and IAEA but with some contributions from India and China. There were also major inputs from the 'in kind' contributions made by the participating Member States. Altogether some US$ 14.3 million have been identified as the total contribution to the support of the activities over these ten years

[en] Analyses for concentrations of iron, niobium and tantalum in valuable ores by X-ray fluorescence analysis (XRF) method, characteristic X-rays of Fe was interfered by the escape peak of Nb from HPGe(LEPS) detector. To solve this problem, normalizations of Nb spectra with the computer program were used. The result analyzed for Fe, Nb and Ta concentration in the sample, compared to those with the neutron activation analysis (NAA) method, the corresponding errors about 5% were obtained satisfactorily. This method of XRF can be applied efficiently instead of NAA method during the reactor shut-down for a long period

[en] Interest in zirconium as a structural material for nuclear reactors has led to a research for cheaper, more convenient ways of opening up Thai zirconium ores. The most abundant domestic zirconium ore is zircon. Caustic soda was found to be effective in decomposing this ore. The content of zirconium oxide and hafnium oxide in Thai zircon were found to be 65.57+-0.18% and 1.43% respectively by X-ray fluorescence spectrometer. By using a caustic to zircon sand weight ratio of 3:2 and a furnace temperature of 550⁰C for 45 min, the zircon sand was decomposed without previous grinding. It was found that 98.62+-0.23% of the Thai zircon reacted to form water-soluble sodium silicates and water-insoluble sodium zirconates. The contents of zirconium and hafnium oxide in the zirconia sample determined by neutron activation technique were 92.14+-1.86% and 2.53+-0.30% respectively. Quality test of the zirconium crystals done by X-ray diffraction technique found that most of the zirconia crystal structure were monoclinic, some tetragonal form was also present

[en] Environmental pollution problems such as the green-house effect by increase of CO₂, acid rain caused by flue gases, and contamination of chemicals and pesticides in foods and water, have become serious in the world with the rapid development of industry and agriculture. To solve some of these problems, radiation treatment has being applied for the removal of the contaminants from flue gases and waste water from industrial plants. On the other hand, the contribution of radiation biology for these environmental pollution problems is not direct but it has contributed indirectly in many fields. This paper describes the contributions of radiation biology for environment in the following two topics: 1) control of insects and microorganisms, and 2) application of radiation for agricultural wastes

[en] The radioactive wastes after treatment must be kept in a suitable waste form for further storage and/or ultimate disposal. Cementation is one of the suitable methods for conditioning of such waste because of its simple, cheap and good quality of products. The basic properties of radioactive waste form particular significance regarding an evaluation of performance in the disposal environment include: leachability, radiation resistance, thermal properties and other mechanical properties, especially the compressive strength. In this study, the compressive strength of conditioned waste products of various simulated waste compositions are tested. As according to the recommendation for safe handling during transportation and disposal of cemented radioactive wastes, the minimum compressive strength requirement is 150 kg/cm³. The proper percentage compositions of the cemented wastes founded in this work are 12.18-15.25, 20.77 and 19.05-54.14 for the spent resin, sludge and inorganic absorbers respectively