Abstract: The present invention provides a boiling water-type nuclear power plant comprising: a passive safety system having depressurization valves and a gravity driven core cooling system as an emergency core cooling system; a passive containment vessel cooling system in which reactor steam released in the containment vessel is cooled by a heat exchanger in a cooling water pool installed in the upper portion of the containment vessel; and a containment vessel flooding system which injects cooling water into a dry well of the containment vessel on an accident; wherein a containment vessel spray cooling system for injecting cooling water into the containment vessel via a pump is further added as a safety system.

Abstract: The present invention provides a boiling water reactor nuclear power plant in which a reactor core support plate, upper grid plate, and a reactor core consisting of fuel assemblies supported by these plates are provided in the inner base portion of a nuclear reactor pressure vessel. Control rod guide tubes and a reactor core shroud are positioned over the upper grid plate, and a control rod drive mechanism is provided further above same, whereby the control rods can be inserted from above the reactor core, and natural circulation of cooling water inside the reactor can be achieved by means of a chimney effect of the control rod guide tubes. According to the above structure, there can be provided a compact and economical nuclear power plant.

Abstract: The present invention is to provide a reactor core that allows a nuclear plant to continuously operate for a long term period, for example 15 years or longer, without requiring any fuel exchange, reduces the duration and number of maintenance steps involved in regular plant inspections, markedly improves plant availability and economic efficiency, and is effective in terms of nuclear nonproliferation.

Abstract: The present invention provides an optical waveguide device having a bottom cladding layer, a core and a top cladding layer, wherein a first submerge-preventing silica-based layer is further provided over the bottom cladding layer and under the core, and the first submerge-preventing silica-based layer is doped with at least one dopant and the first submerge-preventing silica-based layer is higher in softening temperature than the top cladding layer.

Abstract: Disclosed is an electrophotographic photoreceptor comprising a substrate and provided thereon, a photosensitive layer comprising a charge generation material, a triarylamine charge transport material, and a compound represented by Formula 1: ##STR1## wherein R.sub.1 represents a secondary or tertiary alkyl group; R.sub.2 represents a halogen atom, an alkyl group, an aryl group or an alkoxyl group; n represents an integer of 0 to 3, and Ar represents an aryl group.