اسد باباخانی

Most of automatic ultrasonic testing (AUT) systems are unable of testing of the two ends of parts so that usually 10 cm of pipe-ends remain untested. The main reason for this limitation is the geometry of the probe holder with respect to the part during the test. When several probes are positioned in different directions inside a probe holder, the waves emitted by all probes cannot enter the part from its edge. This is a serious challenge even in manual UT: a probe cannot test the very beginning area of a pipe or part in the same direction of its scanning direction. One solution for this obstacle is application of the full immersion method. However, in testing of relatively big parts, this reduces the overall testing speed of AUT. This article presents the experience of authors in developing a simpler and faster contact-based immersion technique that efficiently tackles the issue.

Released radioactive materials from a nuclear power plant due to an accident can be transported to far regions by wind. Some models are available to predict the dispersion. This article reports some parts of the results of a research in which using one of the models, named HYSPLIT, to predict the dispersion of some isotopes of iodine and cesium released from ten nuclear power plant to the atmosphere. These power plants are located in 20-50o N & 25-75o E. The results show that a severe accident in each of the power plants potentially are able to contaminate Iran. In nuclear emergency preparedness and response plan, source of hazards should not only be limited to Bushehr Nuclear Power Plants, but also all the nuclear power plants located in the region should be considered. The results can be used to optimize site locations for early warning monitoring stations for radioactive materials.

In this research work, the biological effect of local green algae on adsorption of 226Ra concentration in 5 samples of hot spring̕ s water of Ramsar city has been investigated. To increase the cellular adsorption capacity of green algae it was first treated by one molar solution of NaCl for omission of obtrusive ions. The radioactivity of 226Ra in the samples was measured using HPGe spectrometry system. The amount of algae used for each sample was 3 gr/lit. The obtained results show that the maximum adsorption occurs in radium concentration of 30 Bq/lit and equilibrium time of 4 hours. When the amount of radium increases, absorbent being saturated and then the adsorbtion rate of radium in water̕ s samples decreases. Due to the effect of temperature on adsorption, so all of the adsorption processes have been performed in 20° C using magnetic mixer which controls the temperatures of the samples.

Fukushima Dai-ichi nuclear power plant accident in Japan seriously questioned the worldwide presumed trust about the safety of existing nuclear power plants. Neither the advanced facilities nor the existing emergency response preparedness could hamper the rapid expansion of the accident, resulting in the world's most severe nuclear crisis after the Chernobyl accident. This paper presents a chronologic study of the accident and the responses to it in order to recognize the main phases of the crisis management in Fukushima. The study reveals that out of the total five recognized phases, the three first ones have mainly gone through by inevitable reactions, situation assessments, and data gathering for a comprehensive response planning. Investigating the influence of each phase on expansion of the accident is indeed of vital importance for effective planning for responding to similar accidents. Deficiency of preventive measures leading to the occurrence of the accident and incompetence of the Japanese nuclear safety infrastructure in hindering the rapid expansion of the crisis, are also discussed. Following a root cause analysis, the paper concludes with proposals for preventing similar accidents and shortening the duration of the first phases of the aftermaths.