Search Results

You are looking at 1 - 5 of 5 items for :

  • Author or Editor: T. Aono x
  • Chemistry and Chemical Engineering x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract  

Seawater samples were collected from the East China Sea continental shelf and analyzed for 239+240Pu activities. The vertical profiles of 239+240Pu had a similarity for all three stations in the East China Sea. 239+240Pu concentrations were low in the surface layer (3-4 mBq/m3) and increased gradually with depth to become high in the near-bottom layer (7-10 mBq/m3). 239+240Pu concentrations in seawater and the concentrations of suspended particles showed almost the same vertical profiles in the East China Sea continental shelf. The maximum value of 239+240Pu found in the near-bottom layer may be due to the contribution of Pu-rich suspended particles.

Restricted access

Abstract  

Seawater samples were collected from the Yamato Basin and the Tsushima Basin in the Japan Sea and analyzed for their239+240Pu and137Cs concentrations. The concentration of239+240Pu was 7.4 mBq/m3 in the surface water and increased with depth to a maximum value of 38.6 mBq/m3 at 500 m at the Yamato Basin station. The subsurface maximum may be produced by scavenging of239+240Pu in surface water and release of239+240Pu from settling particles. The239+240Pu inventories in the water column were 86.6 and 85.2 Bq/m2 at the two basin stations, suggesting that 90% of239+240Pu delivered to the Japan Sea is still present in the water column.

Restricted access

Abstract  

A technique to determine concentrations of 32P, 33P and 7Be in dissolved and particulate forms, in the upper ocean was developed. By using a large volume in situ filtration and concentration system (LV-FiCS), several tons of seawater at different depths were filtered concurrently through two kinds of filters. The dissolved radionuclides were concentrated onto adsorbents in the LV-FiCS. The radionuclides obtained were further purified by precipitation and ion-exchange chromatography, and quantified by gamma-spectrometry and ultra-low level liquid scintillation counter measurements. The technique was used with good results in a coastal area of Ibaraki, Japan.

Restricted access

Summary  

From the viewpoint of environmental radioactivity monitoring, the determination of uranium and its isotope ratio is important for identifying and assessing the environmental impact of any unexpected release from nuclear facilities. In this work, a survey was conducted to determine 238U concentrations and 235U/238U atom ratios in coastal waters off Rokkasho Village, Aomori, Japan, where several uranium-related nuclear facilities have been operating since 1992, and a newly constructed nuclear fuel reprocessing plant is scheduled to be commissioned in 2006. Seawater samples were analyzed directly after a 10-fold dilution using isotope dilution sector-field ICP-MS. Based on the results, we concluded that there is no observable uranium contamination in the investigated sites. In addition, for the first time, a correlation between uranium concentration and salinity was established in coastal waters using the SF-ICP-MS technique.

Restricted access

Abstract  

An analytical method for the determination of 239Pu and 240Pu in marine particle samples by sector field high-resolution ICP-MS was developed. The method was applied for large and small particle samples (particle diameter: >70 μm and 1–70 μm, respectively, collected with a large volume in situ filtration and concentration system at different depths in the water column off Rokkaho, Japan, where the spent nuclear fuel reprocessing plant of Japan Nuclear Fuel Ltd. has started test operation since March 2006.

Restricted access