Urban air quality in the Asian region.

Over the past decade, member states of the Regional Co-operation Agreement (RCA), an intergovernmental agreement for the East Asia and Pacific region under the auspices of the IAEA with the assistance of international organizations and financial institutions such as the World Bank and the Asian Development Bank, have started to set in place policies and legislation for air pollution abatement. To support planning and evaluate the effectiveness of control programs, data are needed that characterizes urban air quality. The focus of this measurement program describe in this report is on size segregated particulate air pollution. Such airborne particulate matter can have a significant impact on human health and urban visibility. These data provide the input to receptor models that may permit the mitigation of these impacts by identification and quantitative apportionment of the particle sources. The aim of this report is to provide an overview of the measurements of concentrations and composition of particulate air pollution in two size fractions across the participating countries. For many of the large cities in this region, the measured particulate matter concentrations are greater than air quality standards or guidelines that have been adopted in developed countries.

Study on bubble detectors used as personal neutron dosimeters.

Neutron bubble detector is so far the only personal neutron dosimeter satisfying the energy response criteria of the International Committee of Radiation Protection 60 (ICRP 60). This paper presents our studies on neutron bubble detectors including the manufacture, the relevant equipments, the basic calibrations and on-site tests for monitoring personal neutron dose. The results of calibrations show that the highest sensitivity so far manufactured by the authors reaches about 4bubbles/µSv, the correlation coefficient of dose response is 0.99, and the in-batch consistency and reproducibility are up to the ISO standards. The results of on-site test show that the in-batch consistency and between-batch consistency are within 15% relative standard uncertainty. The results are directly readable. The detectors are portable, especially suitable for on-site neutron dose monitoring in n-γ mixed radiation fields.

Study on anti-reflection of CR-39 by the nuclear track technique.

Nuclear tracks can be etched into pores in which the refractive indexes gradually increase, so that the sample surface reflects very few lights back. CR-39 samples were bombarded with sulfur ions from the Tandem Accelerator HI-13 of CIAE. Three kinds of procedures were performed in the following treatments. The reflectivity was measured for all samples, untreated and treated, within the wavelengths of visible light. The results indicated that the reflectivity of the CR-39 samples modified with the track technique and multilayer coating can be as low as 0.1%.

Radiochemical neutron-activation analysis of uncertified ultra-trace rare earth elements in two biological certified reference materials.

Radiochemical neutron activation analysis (RNAA) has been used for the determination of eight rare earth elements (La, Ce, Nd, Sm, Eu, Tb, Yb, and Lu) in two Chinese certified reference materials (CRM), GBW 08503 (wheat powder) and GBW 09101 (human hair). These determinations are important for possible certification of the above mentioned ultra-trace elements, so far not certified. A simple one-step (REE)F3 precipitation was used. Chemical yields were determined for all relevant elements by means of tracer experiments. The two CRM were also analyzed by inductively coupled plasma-mass spectrometry (ICP-MS) to compare the merits and draw-backs of these two major trace analytical techniques for these particular elements. RNAA was proven to be a reliable technique for ultra-trace analysis, especially in the certification of some ultra-trace elements.