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Radionuclides Migration in the Japan Sea

#2886


Distribution of Artificial Radionuclides and Winter Convection in the Japan Sea

Tech Area / Field

  • ENV-WPC/Water Pollution and Control/Environment
  • ENV-MIN/Monitoring and Instrumentation/Environment

Status
8 Project completed

Registration date
12.09.2003

Completion date
15.08.2008

Senior Project Manager
Yakusheva A A

Leading Institute
Far Eastern Regional Hydrometeorological Research Institute, Russia, Primorsky reg., Vladivostok

Supporting institutes

  • MIFI, Russia, Moscow

Collaborators

  • Kyushu University / Research Institute for Applied Mechanics, Japan, Fukuoka\nJapan Atomic Energy Agency, Japan, Ibaraki

Project summary

The goal of the project is to study radionuclide distribution and winter convection in the Japan Sea. The main sources of radionuclides in the Japan Sea are as follows:
1. Global atmospheric fallout.
2. Input with river runoff.
3. Discharge from Russian navy facilities situated in Peter the Great area and further transport by currents.
4. Seepage from containers with radioactive wastes disposed to the Japan Sea bottom.

Since 2000/2001 winter, the intensification of bottom water formation has been observed in the Japan Sea. The main areas where these new bottom waters can be formed are the northern part of the Japan Sea (Tatarsky Strait) and the area to the south from Peter the Great Bay. Therefore, radionuclides from the navy facilities in Peter the Great Bay as well as from containers disposed of in 1966-1993 can be transported to the surface layer and consumed by plankton and fish, including edible ones.

The situation at the navy facilities in Peter the Great Bay is worsening. The dismantling of decommissioned nuclear submarines is far behind schedule and the capacity of existing storages of nuclear wastes is catastrophically not enough. This problem has been discussed recently at the international conference “Ecological Problems of Nuclear Submarine Utilization and the Development of Nuclear Energy Sources in the Region” (Vlapostok, September 2002).

As for the liquid and solid radioactive wastes dumped in the Japan Sea, their total activity is about 70 curies (including one tanker, two reactors with nuclear fuel and 41 containers). Taking into account that disposal had taken place from 1966 till 1993, the possibility of leakage of radionuclides from the corroded containers is very high. Due to winter convection, the “ventilation” of the whole water column from the surface to the bottom is taking place and therefore radionuclides from the bottom layer can be transported to the surface and included into the food chain (consumed by biota and then by humans). This is the real threat for the population of the countries surrounding the Japan Sea. In some expeditions carried out by FERHRI specialists in collaboration with Japanese scientists (JAERI) in summer, elevated activities of 239, 240Pu were detected at the surface. The possible reason of these elevated activities might be winter convection. To proof this hypothesis it’s necessary to carry out detailed observations in winter.

It is suggested to implement observations in the central part of the Japan Sea (to the south from Peter the Great Bay, in the area of radionuclide waste dumping) and in the northern part of the Japan Sea, i.e. in the areas of possible winter convection. Expeditions will be carried out in winter (March) during three years because the severity of winters (and, therefore, possibility of winter convection) can differ from year to year. The program of the expeditions will include seawater and bottom sediment sampling in the Japan Sea. Special samplers will be used to take water samples. Sediment samples will be taken by grab sampler “Ocean-50”. For radioactivity measurements, surface layer (about 3 cm) and subsurface layer of bottom sediments will be used. Samples will be preserved or processed as required before analysis in shore laboratories.

After the expeditions, detailed measurements of radionuclide activities in seawater and bottom sediment samples will be performed in shore laboratories as well as analysis of oceanographic data. The time needed for analysis, data interpretation and report preparation after the expedition is about 8 months. As a result of this study, the distribution of artificial radionuclides in the Japan Sea in winter will be revealed depending on intensity of winter convection.


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