Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Ogawa, Tatsuhiko; Morev, M. N.*; Kosako, Toshiso*
Transactions of the American Nuclear Society, 109(2, Part 2), p.1253 - 1255, 2013/11
Depth distributions of radioactive fragments in a thick lead target exposed to 400 MeV/u carbon ions were measured to obtain isotopic production cross-sections of 
Pb(
C,x)X (X=
Sc, 
V, 
Mn, 
Co, 
Co, 
Fe, 
Se, 
Rb, 
Sr, 
Sn, 
Te, 
Xe, 
Ba, 
Ce, 
Pm, 
Pm, 
Gd, 
Eu, 
Gd, 
Hf and 
Hf) reactions as excitation functions. The obtained fragment distributions were converted to excitation functions of fragmentation cross-sections by the modified stacked-foil method. This conversion procedure was validated by comparing the obtained data with the available thin target experimental data. The obtained cross-sections were in good agreement with the previously published results. Comparison of the obtained cross-sections and the simulation by PHITS showed that PHITS underestimates fragments lighter than 90 amu by factor of about 10 whereas the fragments heavier than 110 amu were predicted within a factor of 3. Energy and mass dependences of the obtained cross-sections give insight into the reaction mechanism and will be useful for radiation transport code benchmarking. Furthermore, this study clarified that excitation functions of fragmentation reactions induced by heavy ions can be obtained by applying the method adopted in this study.
Satoh, Daiki; Kojima, Kensuke; Oizumi, Akito; Matsuda, Norihiro; Iwamoto, Hiroki; Kugo, Teruhiko; Sakamoto, Yukio*; Endo, Akira; Okajima, Shigeaki
Transactions of the American Nuclear Society, 109(1), p.1261 - 1263, 2013/11
A computer software, named CDE (Calculation system for Decontamination Effect), has been developed to support planning the decontamination. CDE is programed with VBA (Visual Basic for Applications), and runs on Microsoft Excel with a user friendly graphical interface. It calculates dose rate distributions in a target area before and after the decontamination from a radioactivity distribution and DF (Decontamination Factor), which is a ratio of original radioactivity to remaining one after the decontamination. DRRF (Dose Rate Reduction Factor) is also derived to express the decontamination effect. All the calculation results are visualized on an image of the target area with color map. Owing to its quick calculation speed, CDE is able to investigate the decontamination effect in various cases for a short period. This is very useful to establish a rational decontamination plan before an action.
Cs distribution on territory of FukushimaKitamura, Akihiro; Yamaguchi, Masaaki; Oda, Yoshihiro; Kurikami, Hiroshi; Onishi, Yasuo*
Transactions of the American Nuclear Society, 109(1), p.153 - 155, 2013/11
Long term Cs transport and its future distribution on the territory of Fukushima were predicted based on the USLE and the GIS. By modeling the soil erosion, transport, and deposition, we simulated the future distributions of air dose rates of Cs in mSv/h for 2, 6 and 21 years after the accident. The predictions made by METI were compared with the present results. The predictions of relatively high air dose rate areas were consistently matched between the two models over time. However, our model seemed to predict the decreasing rate of the Cs concentration with time to be slightly less than that of METI prediction. Some portions of the results obtained in the present study were used to provide influxes of sediments and Cs as boundary conditions and lateral inflows for the hydraulic river model.
Cs transport in the Ukedo River of FukushimaKurikami, Hiroshi; Kitamura, Akihiro; Yamaguchi, Masaaki; Onishi, Yasuo*
Transactions of the American Nuclear Society, 109(1), p.149 - 152, 2013/11
We applied the TOMAM model to the Ukedo River as a preliminary analysis to roughly understand what was important for cesium migration. The main lessons were as follows: Cesium migrates mainly in high river discharge conditions. Migration in a dissolved form is important in low river discharge conditions, while suspended sediments, especially silt and clay, are main carriers of cesium in high discharge conditions. Bed contamination is mainly reflected by sediment erosion and deposition instead of direct sorption in the riverbed.
Kitamura, Akihiro; Machida, Masahiko; Sato, Haruo; Nakayama, Shinichi; Yui, Mikazu
Transactions of the American Nuclear Society, 109(1), p.156 - 157, 2013/11
Computational modeling and simulating team of Fukushima Environmental Safety Center, Japan Atomic Energy Agency has been started to develop a number of mathematical models of radioactive contaminants on the land and rivers, lakes, and estuaries in Fukushima, as well as the basic studies of adsorption/absorption mechanism of Cs and soils. These predictions will be utilized for the dose assessment from the environmental contamination and the proposal of countermeasures to dispersion of contaminant. In this presentation we describe the outline of our current activities.
Yamashita, Shinichiro; Osaka, Masahiko
Transactions of the American Nuclear Society, 109(1), p.140 - 142, 2013/11
The decommissioning work of Fukushima Dai-ichi Nuclear Power Plant (1F-NPP) is intensively being promoted according to the Mid-and-long Term Roadmap towards the Decommissioning of 1F-NPP units 1-4. Many research and development works are underway in order to ensure the progress of the decommissioning work. One of the R&D programs relates to the removal of fuel assemblies (FAs) from the spent fuel pool (SFP), in which the seawater was injected as an emergency counter-measure for fuel cooling during the accident. For the anticipation of the long term integrity of irradiated FA structural materials that experienced a diluted seawater exposure part of a fundamental research plan was described to support the estimation of the long-term possible influences of corrosive factors on the component materials of FAs. In this study, whether or not acceleration of corrosion occurred was investigated by the immersion test under constant potential for SUS304L and Zircaloy-4.
-ray analysis using spallation neutrons at J-PARCToh, Yosuke; Ebihara, Mitsuru*; Harada, Hideo
Transactions of the American Nuclear Society, 109(1), p.116 - 117, 2013/11
no abstracts in English
Okuda, Eiji; Ito, Chikara; Takamatsu, Misao; Ashida, Takashi; Ito, Hideaki; Nagai, Akinori
no journal, ,
In the experimental fast reactor Joyo, it was confirmed that the top of the irradiation test Sub-Assembly (S/A) of "MARICO-2" (material testing rig with temperature control) had bent onto the in-vessel storage rack (IVS) as an obstacle and had damaged the Upper Core Structure (UCS). This incident necessitates the replacement of the UCS and the retrieval of MARICO-2 S/A for Joyo re-start. Along with four stages involving jack-up and retrieval of the existing damaged UCS (ed-UCS), retrieval of the MARICO-2 S/A, and installation of the new UCS (n-UCS) in the restoration work plan, current conditions at Joyo are being carefully investigated, and the results are applied to the designs of special handling equipment, which is being manufactured and scheduled for operation in 2014.
Ito, Chikara; Nishimura, Akihiko; Oba, Hironori; Wakaida, Ikuo; Naito, Hiroyuki; Sugiyama, Akira; Chiyatani, Keiji
no journal, ,
no abstracts in English
spectrometry of low-volatile FPs for accountancy of special nuclear material in molten core material of Fukushima Daiichi Nuclear Power Plant; Numerical simulation of leakage -ray from molten core materials in hypothetical canisterSagara, Hiroshi*; Shiba, Tomooki*; Tomikawa, Hirofumi; Ishimi, Akihiro; Hori, Keiichiro; Saito, Masaki*
no journal, ,
For the nuclear material accountancy of molten core material in Fukushima Daiichi Unit 1, 2 and 3 (1F1, 1F2 and 1F3), feasibility studies of variety of technologies are being performed. As one of the technologies, feasibility study of passive spectroscopy of low-volatile FPs for nuclear material accountancy in molten core material has been performed with reviewing TMI-2 experience, and the correlation of actinides and FPs inventory in core of 1F1, 1F2 and 1F3, considering the sensitivity of axial neutron spectrum, void, burnup, enrichment distribution unique to BWR fuel, and also leakage -ray from molten core materials sphere model. In the present paper, numerical simulation of leakage -ray from molten core materials in hypothetical canister is dealt for determination of radioactivity of low-volatile high-energy emission FPs, which could be utilized for nuclear material quantity estimation.
Okumura, Masahiko; Nakamura, Hiroki; Machida, Masahiko
no journal, ,
no abstracts in English