[en] March 11, 2011 took place in Japan an earthquake that generated a series of tsunami waves that caused the devastation of a part of the country. Many industries were affected by this natural event and among them the nuclear power plants of Tokai, Higashi Dori, Onagawa and Fukushima Dai - ichi and Dai- ni. Many of these units were able to control with success their systems, but the big waves (14 m of height) provoked mishaps in the nuclear power plant of Fukushima Dai - ichi, designed to support waves of 5.7m of height maximum. As consequence of the accident, took place a radioactivity release of iodine-131 and cesium-137 around the north hemisphere and detecting levels of these radionuclides appearances in some environmental matrix. The Radiological Environmental Surveillance Laboratory of the Cuban Center of Radiations Protection and Hygiene from the 1985 are in charge of so much of the study of the levels of environmental radioactivity for surveillance purpose as in the framework of investigation projects related with to radiation protection of the public and the environment. As part of these work, during the months of March and April of the 2011 were monitoring several environmental samples in La Havana, to evaluated the radiological impact of the accident of the nuclear power plant of Fukushima on our country. The concentrations of iodine-131 and cesium-137 detected in the environmental samples and the comparison of these levels with the typical values of radiological background in the country are present in this paper.(Author)

[en] The Probabilistic Tsunami Hazard Analysis (PTHA) for an NPP should be required in Korea. The PTHA is a method that calculates the annual exceedance probability and height of a tsunami for a specific period, and based on the Probabilistic Seismic Hazard Analysis (PSHA). The major difference between a PSHA and PTHA are the parameters for the recurrence interval and tsunami height. Thus an analysis on the definition and determination method of these parameters is required. In this study, a basic analysis on the recurrence interval and tsunami height was performed

[en] The Fukushima Daiichi accident has clearly proven that there is a significant interaction between the nuclear units located on the same site. The international nuclear community is taking serious efforts trying to develop and reach consensus on the modalities in which the multi-unit PSA should be conducted and multi-unit safety goals should be defined. The paper presents the results obtained in the FP7 Advanced Safety Assessment Methodologies: extended PSA (ASAMPSA_E) project for the investigation regarding the use of PSA in the context of a multi-unit site. The work represents an attempt to respond to the question if in case of a site consisting of multiple nuclear installations, the traditional PSA is adequate enough to assess the risk incurred by a severe event affecting all or multiple installations on the site. The latest insights regarding the development and application of a multi-unit PSA, as the issues that require further investigations are highlighted. (authors)

[en] In this paper, remote-controlled robots, which have been used to stabilize and shut down the three troubled reactors (unit 1, 2 and 3) of the Fukushima nuclear power plant, are presented. From the press materials of NISA (nuclear and industrial safety agency), TEPCO (Tokyo electric power company) and the Yomiuri online news, we investigated the robots, which have been used for the management of severe accident of the Fukushima nuclear power plant. The military robots provided by USA, Packbot and Warrior, which are unmanned ground robots, have been sent into Unit 1 to Unit 3 to grasp the inside situation of reactor building and to record the radiation from the interior of reactors no. 1, 2, and 3. The Japanese robot, Quince, which was originally designed to be a rescue robot for disaster recovery, were modified and sent to carry out the installation of a water level gauge for the accumulated water in the basement of Unit 2. Unmanned military aerial robot, T-Hawk, provided by USA was used to check the status of rubbles around reactor building of Unit 1, 2, 3 and 4. And remote controlled construction robots made by Japan are used to clear outdoor rubbles by wireless remote control to improve working conditions

[en] The Fukushima accident brought up the issue of regulatory effectiveness in the fore. One of the causes of the accident has been attributed to the problems in effectiveness of the Japanese regulatory system. Regulatory reform is underway in Japan and in other countries many efforts have also been made to improve the effectiveness and independence of the regulatory bodies. It is important that the regulatory bodies make self-assessment of their weaknesses and strengths, to achieve the ultimate regulatory goal of assuring acceptable level of nuclear safety. In this paper an assessment has been done for the effectiveness of Indian nuclear regulatory system as implemented by the Atomic Energy Regulatory board (AERB). A number of good practices of AERB have been found and some areas have been identified where improvements are necessary

[en] The people and mass media of Korea, the closest country to Japan, showed great interest in Fukushima nuclear power plant accident. The Korean government and KINS (Korea Institute of Nuclear Safety) attempted to provide accurate information to the press through various communication actions. In this study, we conducted an in-depth analysis of the tendencies of the press according to the accident sequence and tracked the diffusion of this issue. The purpose of this study is to determine the properties of the crisis and essence of the issue. We also carry out a general evaluation and draw implications through an analysis of the communication actions of KINS

[en] In literature quite a lot of data is available on uptake of radioactive caesium in mushrooms. There is less available on the evolution of concentration in fruitbodies after several years and on 'outbound' transfer of radiocaesium from fruitbodies to their direct environment, i.e. dilution according to cooking techniques. The recent event at Fukushima has put the question of radionuclides in food, and the following exposure of consumers, high on the agenda. The purpose of this paper is twofold: (1) in order to investigate the variation in time of caesium uptake by fungi, analyses of the same species having grown on the same spot at different intervals during the last 25 years have been performed and (2) in terms of radiation protection the most important thing is the activity taken in by the consumer and not the contamination of raw products. Preparation can have a great impact on activity concentration. Various species of mushrooms frequently eaten have been sampled in Europe and contaminated areas in Japan. Different preparation techniques that can break the walls of the hyphae (drying, deepfreezing etc.) have been applied as well as different treatments: boiling or macerating in water with salt, in acid and basic media. The pH of different media was adjusted and measured. The samples and the medium were analysed separately in gamma spectrometry. (author)

[en] As the progression of Fukushima accident is worsened by the runaway reaction at a high temperature above 1200 .deg. C, it is essential to ensure the stabilities of coating layers on conventional Zr-based alloys during normal operations as well as severe accident conditions. This is because the failures of coating layer result in galvanic corrosion phenomenon by potential difference between coating layer and Zr alloy. Also, it is possible to damage the coating layer during handling and manufacturing process by contacting structural components of a fuel assembly. So, adhesion strength is one of the key factors determining the reliability of the coating layer on conventional Zr-based alloy. In this study, two kinds of Cr-coated Zr-based claddings were prepared using arc ion plating (AIP) and direct laser (DL) coating methods. The objective is to evaluate the scratch deformation behaviors of each coating layers on Zr alloys. Large area spallation below normal load of about 15 N appeared to be the predominant mode of failure in the AIP coating during scratch test. However, no tensile crack were found in entire stroke length. In DL coating, small plastic deformation and grooving behavior are more dominant scratching results. It was observed that the change of the slope of the COF curve did not coincide with the failure of coating layer

[en] UGVs are appealing for Urban Search and Rescue (USAR) and Modern military Operations in Urban Terrain (MOUT). They can also be useful for nuclear emergency situation for similar reasons, thus some of UGVs are utilized for various purposes in Fukushima NPPs in Japan. But current UGVs are far from commonplace because they have shown a noticeable lack of reliability in real field conditions. Therefore, in order to use UGVs for nuclear emergency situations there are two important problems to be solved: One is development of reliable UGVs and another is a proper method to evaluate reliability of those developed UGVs correctly. This paper presents a Bayesian Network (BN) based UGV reliability assessment model which covers the whole development life-cycle of a UGV. It models faults insertion and elimination process during a development phase, and then integrates all development phases to get the final number of faults. The checklist method is used to gather the input data for the BN model. The objective of this paper is to present the quantitative reliability assessment method that will be applied to various UGVs for remote-response in nuclear emergency situations

[en] The fail safety design is referred to as an inherently safe design concept where the failure of an SSC (System, Structure or Component) leads directly to a safe condition. Usually the fail safe design has been devised based on the design basis accident (DBAs), because the nuclear safety has been assured by securing the capability to safely cope with DBAs. Currently regards have been paid to the DEC (Design Extension Condition) as an extended design consideration. Hence additional attention should be paid to the concept of the fail safe design in order to consider the DEC, accordingly. In this study, a case chosen from the Fukushima accident is studied to discuss the issue associated with the fail safe design in terms of DBA and DEC standpoints. For the fail safe design to be based both on the DBA and the DEC, a Mode Changeable Fail Safe Design (MCFSD) is proposed in this study. Additional discussions on what is needed for the MCFSD to be applied in the nuclear safety are addressed as well. One of the lessons learnt from the Fukushima accident should include considerations on the fail-safe design in a changing regulatory framework. Currently the design extension condition (DEC) including severe accidents should be considered during designing and licensing NPPs. Hence concepts on the fail safe design need to be changed to be based on not only the DBA but also the DEC. In this study, a case on a fail-safe design chosen from the Fukushima accident is studied to discuss the issue associated with the fail safe design in terms of DBA and DEC conditions. For the fail safe design to be based both on the DBA and the DEC, a Mode Changeable Fail Safe Design (MCFSD) is proposed in this study. Additional discussions on what is needed for the MCFSD to be applied in the nuclear safety are addressed as well