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[en] Tohoku Electric Power Company promotes development of various power sources to provide a stable supply of electricity in the future, and nuclear power takes a leading part. In August 1989, construction of Onagawa nuclear power plant Unit No. 2 (825MW) was started, following Unit No. 1 (524MW) which went on line in 1984 as Tohoku Electric's first nuclear power plant unit. Unit No. 2 began commercial operation in July 1995 through satisfactory construction work such as RPV hydraulic test in March 1994, fuel loading in October 1994, and various startup tests in each power stage. The design and construction of Unit No. 2 reflect construction and operation experience gained from Unit No. 1, and the latest technology, including that of the LWR Improvement and Standardization Program, was adopted to enhance facility reliability, improve operation and maintenance performance, and reduce worker dosage. Features of the facility, construction techniques, and a description of preoperation of Onagawa nuclear power plant Unit No. 2 are described in this paper. (author)
[en] Aso is a large caldera volcano in Kyushu, Japan. Several dikes, which cut the Pre-Aso volcanic rocks, are exposed in the southwestern region of the caldera (Ono and Watanabe, 1985). The dikes, trending NE-SW and N-S, are composed of pyroxene andesite and hornblende andesite. Systematic relation between the rocks type and direction of the dikes in not observed. In this study, K-Ar ages have been determined on these dike rocks. The ages of dike rocks range from ca. 0.8 to 0.5 Ma, being consistent with the ages of the Pre-Aso volcanic rocks at the caldera wall. There are no significant relations between the ages and the rock type. Except for one sample with weak alteration, the diskes trending NE-SW are older than those of N-S, suggesting a change of direction of the maximum pressure axis of regional stress in the volcanism. (author)
[en] The Tohoku Electric Power Company is currently building unit No. 1 nuclear power station in Higashidori village, Aomori prefecture, with commercial operation scheduled to start July 2005. The Unit 1 is a BWR with the output of 1,100 MWe. Features of unit No. 1 are adoption of Improved Mark I type PCV and discharge the warmed seawater below the water surface system. Some of the characteristic construction approaches are (1) Adoption of hybrid all-weather construction method, (2) Use of a tower crane to carry large blocks, (3) Production of steel frames and beams as a unit, (4) Use of a slope face for steep slope excavation, (5) Adoption of a package type control panel system (PCPS) double floor structure. We are also conducting 'Clean Plant Activities', keeping the working environment, piping, and equipment very clean. This contributes greatly to reduce the lower radiation exposure for workers after starting the commercial operation. (author)
[en] Two volcaniclastic deposits - a debris-avalanche deposit(NgDA) and a lahar deposit (NgL) were discovered along the Nigorikawa River on the western slope of Aso central cones, southwestern Japan. The Nigorikawa debris-avalanche deposit, having a maximum thickness > 3 m, contains numerous plastically deformed debris-avalanche blocks (< 3.7 m) of volcanic ash and soil layers in a poorly-sorted silty to clay matrix. The Nigorikawa lahar deposit contains many subangular to subrounded lithic clasts (< 0.7 m) and shows clast-supported and matrix-rich depositional structures. We obtained a 14C age of 2.230±70 years BP from a wood fragment in NgDa, which corresponds to 400-100 cal BC (2σ). The date is consistent with the age of cultural remains (the Yayoi period: 300 BC-300 AD) underlying the debris-avalanche deposit. We obtained a 14C age of 4,100±60 years BP (2880-2480 cal BC) from a wood fragment in NgL. These 14C ages indicate that major volcaniclastic flows have inundated the Nigorikawa River multiple items in the past 4,000 years. Although the source and cause of the volcaniclastic flows remain unsolved, this discovery provides important information about volcanic hazards in the western part of Aso central cones. (author)
[en] Highlights: ► tRNAs are tranlocated into the nucleus in heat-induced HeLa cells. ► tRNAs form the unique granules in the nucleus. ► tRNA ganules overlap with nuclear stress granules. -- Abstract: The stress response, which can trigger various physiological phenomena, is important for living organisms. For instance, a number of stress-induced granules such as P-body and stress granule have been identified. These granules are formed in the cytoplasm under stress conditions and are associated with translational inhibition and mRNA decay. In the nucleus, there is a focus named nuclear stress body (nSB) that distinguishes these structures from cytoplasmic stress granules. Many splicing factors and long non-coding RNA species localize in nSBs as a result of stress. Indeed, tRNAs respond to several kinds of stress such as heat, oxidation or starvation. Although nuclear accumulation of tRNAs occurs in starved Saccharomyces cerevisiae, this phenomenon is not found in mammalian cells. We observed that initiator tRNAMet (Meti) is actively translocated into the nucleus of human cells under heat stress. During this study, we identified unique granules of Meti that overlapped with nSBs. Similarly, elongator tRNAMet was translocated into the nucleus and formed granules during heat stress. Formation of tRNA granules is closely related to the translocation ratio. Then, all tRNAs may form the specific granules.