Abstract: A device for supplementing structural integrity of a spent nuclear fuel assembly during handling is provided. The spent nuclear fuel assembly includes spacer grids for supporting fuel rods, guide tubes, and top and bottom nozzles for supporting upper and lower ends of the guide tubes. The device includes a housing, a rod member and fixing members. The housing includes a plurality of free end portions, stopper protrusions formed at an end of each of the free end portions, a first male thread formed on an outer surface, and a female thread formed on an inner surface. The rod member includes a pressurization protrusion at one end and a second male thread for engaging with the female thread of the housing. The fixing members are configured engage with the first male thread to secure the device to the top nozzle of the spent nuclear fuel assembly.

Abstract: The present invention relates to a voltage source converter based DC connection method and a control method for implementing a system for maintaining respective different frequencies (multi-frequencies) by reflecting load quality levels of respective microgrids when multiple stand-alone microgrids are connected to each other in which voltage source converters (VSCs) installed at connection points of the microgrids for effectively controlling respective microgrids having different frequency control ranges present an effective control method based on a concept using normalizing frequencies of unit microgrids to be similarly applied in an islanded operation mode of multiple grid-connected microgrids as well as multiple stand-alone microgrids to avoid the same frequency criterion and enable an economic operation to which the load power quality level of the microgrid is reflected, thereby minimizing a transient to stably operate a microgrid system.

Abstract: The present invention relates to a voltage source converter based DC connection method and a control method for implementing a system for maintaining respective different frequencies (multi-frequencies) by reflecting load quality levels of respective microgrids when multiple stand-alone microgrids are connected to each other in which voltage source converters (VSCs) installed at connection points of the microgrids for effectively controlling respective microgrids having different frequency control ranges present an effective control method based on a concept using normalizing frequencies of unit microgrids to be similarly applied in an islanded operation mode of multiple grid-connected microgrids as well as multiple stand-alone microgrids to avoid the same frequency criterion and enable an economic operation to which the load power quality level of the microgrid is reflected, thereby minimizing a transient to stably operate a microgrid system.