In Korea, additional regulatory requirements are increasing due to the full-scale decommissioning of nuclear power plants following the permanent shutdown of Kori Unit 1 and Wolseong Unit 1. Accordingly, it is necessary to preemptively expand the scope of physical protection regulations from design, construction, and operation stage to back-end nuclear fuel cycle such as cessation of operation and decommissioning. According to Article 2, Paragraph 24 of the Nuclear Safety Act, the decommissioning of nuclear facilities is defined as all activities to exclude them from the application of the Nuclear Safety Act by permanently suspending the operation of nuclear facilities, demolishing the facilities and sites, or removing radioactive contamination. In other words, it refers to a series of technologies or activities to safely and efficiently dismantle nuclear power plant and remove radioactive contamination and restore them to their original state after permanently shut down of nuclear power plant. Security changes during decommissioning and decontamination since removing fuel from the reactor alters the plant’s safety status, some of the systems or components considered as vital equipment during plant operation will no longer be needed. The vital areas may be reduced as fewer buildings, equipment and systems need to be protected, which means access controls, surveillance and so on can be reduced. And also, decommissioning will probably require more workers than operation would, although this might not be the case at all times. From a security point of view, this might require more personnel or additional access points. Changing operating require changed security measures, to ensure that the required security level will be maintained while at the same time work proceeds efficiently. Once all of the fuel is removed from the plant, radiological release risk is much lower. The lower risk requires a lower level of security measures. Even during the removal of nuclear material and contaminated equipment from nuclear facilities, lower level of security measures should meet regulatory requirements based on a graded approach. Therefore, this study intends to examine the responsibilities and obligations of regulatory authorities, regulator, and nuclear operators in terms of protection after permanent shutdown and decommissioning.

The IAEA states that in the event of sabotage, nuclear material and equipment in quantities that can cause high radiological consequences (HRC), as well as the minimum systems and devices necessary to prevent HRC, must be located within one or more vital areas. Accordingly, in Article 2 of the ACT ON PHYSICAL PROTECTION AND RADIOLOGICAL EMERGENCY, the definition of the vital area is specified, and a nuclear facility operator submits a draft to the Nuclear Safety and Security Commission to establish vital areas and must obtain approval from Nuclear Safety and Security Commission. Since the spent fuel pool and new fuel storage area are areas where nuclear material is used and stored, they can be candidates for vital areas as direct targets of sabotage. The spent fuel pool is a wet spent fuel storage facility currently operated by most power plants in Korea to cool and store spent nuclear fuel. Considering the HRC against sabotage, it is necessary to review whether sepnt fuel pool needs to establish a vital area. In addition, depending on the status of plant operation during the spent fuel management cycle, the operation status of safety systems to mitigate accidents and power system change, so vital areas in fuel handling building (including spent fuel pool) also need to be adjusted flexibly. This study compares the results of the review on whether the essential consideration factors are reflected in the identification of essential safety systems and devices to minimize HRC caused by sabotage in the spent fuel storage system with the procedure for identifying the vital area in nuclear power plants. It was reviewed from the following viewpoints: Necessity to identify necessary devices to minimize the radiation effects against sabotage on the spent fuel pool, Review of necessary elements when identifying vital areas to minimize the radiation effects of spent fuel pool against sabotage, Necessity to adjust vital areas according to the spent fuel management cycle. The main assumptions used in the analysis of the vital area of the power plant need to be equally reflected when identifying vital areas in spent fuel pool. And, the results of this study are for the purpose of minimizing the radiological consequences against sabotage on the spent fuel storage system including the spent fuel pool and used to establish regulatory standards in the spent fuel storage stage.

In this study, we report a general method for preparation of a one-dimensional (1D) arrangement of Au nanoparticles on single-walled carbon nanotubes (SWNTs) using biologically programmed peptides as structure-guiding 1D templates. The peptides were designed by the combination of glutamic acid (E), glycine (G), and phenylalanine (F) amino acids; peptides efficiently debundled and exfoliated the SWNTs for stability of the dispersion and guided the growth of the array of Au nanoparticles in a controllable manner. Moreover, we demonstrated the superior ability of 1D nanohybrids as flexible, transparent, and conducting materials. The highly stable dispersion of 1D nanohybrids in aqueous solution enabled the fabrication of flexible, transparent, and conductive nanohybrid films using vacuum filtration, resulting in good optical and electrical properties.

NGC 1333 is a nearby star forming region, and IRAS 4A and IRAS 4BI are low-mass Class 0 protostars. IRAS 4A is a protobinary system. The NGC 1333 IRAS 4 region was observed in the 22 GHz water maser with a high resolution (0.08") using the Very Large Array. Two groups of masers were detected: one near A2 and the other near BI. Most of the masers associated with A2 are located very close (< 100 AU) to the radio continuum source. They may be associated with the circumstellar disk. Since no maser was detected near AI, the A2 disk is relatively more active than the Al disk. Most of the masers in the BI region are distributed along a straight line, and they are probably related with the outflow. As in many other water maser sources, the IRAS 4 water masers seem to trace selectively either the disk or the outflow. Considering the outflow lifetimes, the disk-outflow dichotomy is probably unrelated with the evolutionary stage of protostars. A possible explanation may be that both the outflow-maser and the disk-maser are rare phenomena and that detecting both kinds of maser around a single protostar may be even rarer.

We observed CO J = 2 → 1 and J = 3 → 2 lines toward several star formation regions with extremely high velocity (EHV) outflows: W3 IRS5, W28 A2, GL2591, S140, and Cepheus A. The full width of the wings are 90-235 km s-1. Some wings show clear break of slope in the line profile implying that the nature of the EHV outflow is different from that of the high velocity outflow. We suggest that the EHV CO wing emission is tracing CO molecules in the stellar wind or jet which drives the high velocity outflow.