Ocean current data obtained by Acoustic Doppler Current Profiler across the Tsugaru Strait (Joint research)

Kawamura, Hideyuki; Hirose, Naoki*; Nakayama, Tomoharu*; Ito, Toshimichi

JAEA-Data/Code 2021-004, 34 Pages, 2021/05

JAEA-Data-Code-2021-004.pdf:3.72MB

The Japan Atomic Energy Agency measured the ocean current across the Tsugaru Strait using an Acoustic Doppler Current Profiler attached on a ferryboat from October 1999 to January 2008. The characteristics of the ocean current in the Tsugaru Strait must be understood for predicting oceanic dispersion of radioactive materials released from nuclear facilities around the strait. Furthermore, it is critical to elucidate the mechanism of the Tsugaru Warm Current from an oceanography viewpoint. The dataset obtained in this investigation consists of daily ocean current data files that record the components of the current speed in the east-west and north-south directions from the surface layer to the bottom layer. The dataset stores 2,211 daily ocean current data files, despite some data periods missing from October 1999 to January 2008. In this study, information on the dataset is described for users to analyze the dataset properly for their purposes. Section 1 provides the background and purpose of the ocean current measurement, Section 2 explains the methodology of measurement using an Acoustic Doppler Current Profiler, and Section 3 explains the record format of the daily ocean current data files and data acquisition rate and presents analysis results. Finally, Section 4 concludes this study.

ITER project; Status of procurement activities in domestic agency of Japan and application of HIP technology

Takatsu, Hideyuki; Enoeda, Mikio; Suzuki, Satoshi; Hirose, Takanori; Koizumi, Norikiyo; Takahashi, Koji

Proceedings of International Conference on Hot Isostatic Pressing (HIP '11), p.35 - 40, 2011/04

ITER is a mega-science fusion project, under an international collaboration of seven Members, to construct, operate, exploit and decommission a tokamak-type experimental reactor at Cadarache site with a mission to demonstrate the scientific and technological feasibility. The ITER Project started technical activities in 2007 and is now in a serious construction phase. Domestic Agencies of the seven member countries are in the process of manufacturing long lead-time components. Some of the ITER components apply HIP technology in manufacturing processes in view of a number of potential advantages. In this paper, examples and status of application of HIP technology by the Domestic Agency of Japan are overviewed.

Simulation of concentrations of anthropogenic radionuclides in the Japan Sea

Kawamura, Hideyuki; Ito, Toshimichi; Kobayashi, Takuya; Otosaka, Shigeyoshi; Hirose, Naoki*; Togawa, Orihiko

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 4 Pages, 2010/10

This study aims to demonstrate many findings in the Japan Sea expeditions by Japan Atomic Energy Agency between 1997 and 2002 making use of an ocean general circulation model. A numerical experiment is performed between 1945 and 2000 with deposition at the sea surface by global fallout as main source of anthropogenic radionuclides. The concentrations of Sr and Cs in the surface layer are approximately in the range of 1.0-1.5 Bq/m and 2.0-2.5 Bq/m and they exponentially decrease with depth from the sea surface to the sea bottom. Total amounts of Sr and Cs in the seawater of the Japan Sea are estimated to be about 1.34 PBq (1 PBq = 10 Bq) and 2.02 PBq in the numerical experiment, which demonstrates observational estimations in the Japan Sea expeditions. Time series of the total amounts show that they attain the maximums of 4.86 PBq for Sr and 7.33 PBq for Cs in 1964.

Sequential forecasting of the surface and subsurface conditions in the Japan Sea

Hirose, Naoki*; Kawamura, Hideyuki; Lee, H. J.*; Yoon, J.-H.*

Journal of Oceanography, 63(3), p.467 - 481, 2007/06

https://doi.org/10.1007/s10872-007-0042-5

This study estimates and forecasts a realistic change of the Japan Sea by assimilating satellite measurements into an eddy-resolving circulation model. Suboptimal but feasible assimilation schemes of approximate filtering and nudging play essential roles in a system. The sequential updates of error covariance significantly outperforms the asymptotic covariance due to irregular sampling patterns from multiple altimeter satellites. The best estimate shows an average rms difference of 1.2 C only to the radiometer data, and also explain about half of sea level variances measured by the microwave observation. It is demonstrated that a forecast persistency strongly depends on variable, depth, and location.

Oil spill simulation in the Japan Sea

Kawamura, Hideyuki; Kobayashi, Takuya; Hirose, Naoki*; Ito, Toshimichi; Togawa, Orihiko

WIT Transactions on Ecology and the Environment, Vol.88, p.273 - 278, 2006/00

An assessment system of marine environment in the Japan Sea is being constructed in the Japan Atomic Energy Agency. It is composed of an ocean general circulation model (RIAMOM), a particle random-walk model (SEA-GEARN) and a radiation dose assessment model (COLDOS). This study aims to confirm a validity of the assessment system by reproducing a movement of spilled oil at an incident of Russian tanker Nakhodka, in January 1997. Realistic reproduction of ocean conditions is a significant factor for accurate simulations of the movement of spilled oil. In this study, one of data assimilation techniques, an approximate Kalman filter, was introduced by combining RIAMOM with sea level measurements of satellite data. The assimilated results were in good agreement with observed oceanic phenomena both qualitatively and quantitatively. Using the calculated ocean currents, simulations of behaviour of spilled oil was performed with SEA-GEARN. The tanker was ruptured in a storm about 100 km north of the Oki Islands in Shimane Prefecture, Japan, on January 2, 1997. Most of oil spread over off Hyogo, Kyoto, Fukui and Ishikawa Prefecture, meanwhile a part of it reached a coast of Niigata Prefecture detouring around Noto Peninsula by January 21, 1997. The most important feature in these regions is considered to be a branch of the Tsushima Warm Current (TWC). Owing to a variability of TWC, ocean eddy activities and a sea surface wind, the spilled oil dispersed widely in space. On the other hand, the strong northeastward component of TWC was likely to drive the spilled oil to Niigata Prefecture. A number of experiments with different parameters and situations showed that the assimilated daily ocean currents with wind drift gave the best effect on simulation for the movement of spilled oil.

Benchmark experiments of thermal neutron and capture -ray distributions in concrete using Cf

Asano, Yoshihiro; Sugita, Takeshi*; Hirose, Hideyuki; Suzaki,Takenori

Nuclear Science and Engineering, 151(2), p.251 - 259, 2005/10

https://doi.org/10.13182/NSE05-A2544

no abstracts in English

Annual report of STACY operation in FY. 2000; Experiments on neutron-interacting systems with two slab-shaped core tanks and 10% enriched uranyl nitrate solution, 2 (Contract research)

Onodera, Seiji; Hirose, Hideyuki; Izawa, Kazuhiko; Tanino, Shuichi; Kaminaga, Jota*; Sakuraba, Koichi; Miyauchi, Masakatsu; Tonoike, Kotaro; Miyoshi, Yoshinori; Yanagisawa, Hiroshi; et al.

JAERI-Tech 2001-057, 54 Pages, 2001/09

JAERI-Tech-2001-057.pdf:4.28MB

no abstracts in English

Annual report of STACY operation in F.Y. 1998, 2; 800mm-diameter cylindrical core10% enriched uranyl nitrate solution (Contract research)

Onodera, Seiji; Sono, Hiroki; Hirose, Hideyuki; Tanino, Shuichi; Nagasawa, Makoto*; Murakami, Kiyonobu; Sakuraba, Koichi; Miyauchi, Masakatsu; Yamane, Yuichi; Ono, Akio

JAERI-Tech 2000-013, p.57 - 0, 2000/03

JAERI-Tech-2000-013.pdf:2.43MB

no abstracts in English

Construction of STACY(Static Experiment Critical Facility)

Murakami, Kiyonobu; ; Hirose, Hideyuki; ; *; *; Sakuraba, Koichi; ; ; *; et al.

JAERI-Tech 98-033, 70 Pages, 1998/08

JAERI-Tech-98-033.pdf:2.25MB

no abstracts in English

Improvement of fuel sampling device for STACY and TRACY

Hirose, Hideyuki; Sakuraba, Koichi; ; ; *; *; ; ; ; Miyauchi, Masakatsu; et al.

JAERI-Tech 98-015, 52 Pages, 1998/05

JAERI-Tech-98-015.pdf:1.68MB

no abstracts in English