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IAEA-SM-354/257P XA9951503 MONITORING OF RADIOACTIVE CONTAMINATION OF THE FAR EASTERN OF

V.V. CHELIYKANOV Russian Federal Service for Hydrometeorology and Monitoring of the Natural Environment (Roshydromet), Moscow, Russia

The system of the natural environment radioactive contamination monitoring started to operate in 60s-70s as a part of hydrometeorological service. The purpose was to assess the wide spread radioactive contamination caused by as nuclear tests conducted in the former USSR and abroad, as an operation of the nuclear cycle enterprises. Monitoring of marine environment radioctive contamination had an important place in this system and was conducted by Roshydromet practically in the all of the seas washing the territory of Russia and also in other of the World which are under influence of the global and different local sources of radioactive contamination. First of all in the Far Eastern Russian waters observations were arranged on ^Sr content in the near shore coastal waters using the existing hydrometeorological stations. These observations were carried out by SPA "Typhoon" in cooperation with the regional departments of Roshydromet in the Sea, in the coastal waters of the North-West (coastal waters of the )and in the Sea of . Due to these observations we are able now to trace the dynamics of ^Sr content in the Far Eastern waters from the middle of 60s. Now the concentration of ^Sr in waters of the points of monitoring is about 2-4 Bq/m3. In addition to observations on the stationary monitoring points a special investigations of radioactive contamination of the Far Eastern seas were carried out periodically using Roshydromet research vessels. Besides investigations in the seas washing the territory of Russia, investigations of radioactive contamination in other Pacific Ocean areas were conducted during such a spesific surveys. The first such survey was undertaken in 1962 in the North-West Pacific, including the Japan Sea. The content of ^Sr in the surface Japan Sea waters that time was about 20 Bq/m [ 1 ]. In 1974, for example, the survey of the North Pacific Ocean radioactive contamination was undertaken (from the Japan Sea till Columbia River mouth, affected by the discharges of the Hanford reactors). That time the content of ^Sr in the Waters near Japan (from the Pacific Ocean side) was about 6 Bq/m3 [ 2 ]. From the beginning of 70s Roshydromet started with investigations of the impact of dumping into Far Eastern waters of radioactive wastes on radioactive contamination of sea water and bottom sediments. For example, in 1980 SPA "Typhoon" during expedition survey of radioactive contamination of the North West Pacific Ocean carried out investigations of the dumping areas in the Japan Sea and near the Kamchatka Peninsula shore. The content of radionuclides in the Japan Sea dumping areas was about 5 Bq/m3137Cs and 4 Bq/m3 ^Sr in the surface waters; at the depth 2500 m about 1 Bq/m3 of each radionuclide. These levels corresponds to the levels formed by the global source. Primorsky regional Roshydromet department undertook in 1990 the investigation of radioactive contamination of bottom sediments in the Chazhma Bay, where the accident at nuclear submarine occured in 1985. It was found that radioactive contamination of bottom sediments was formed by 60Co mainly (up to 850 Bq/kg). In 1988 and 1993 Roshydromet specialists carried out the radioactive contamination investigations. In 1993 the content of 137Cs in the water layer 0-200 m varied from 1.5 to 3.6 Bq/m and the content of Sr in surface sea water varied from 1.0 to 2.6 Bq/m3.

710 In general, it was possible to charactirize the radiation situation in the Far Eastern sea regions covered by Roshydromet monitoring system ( excluding the of accident in the Chazhma Bay) as well-being. The measured levels of radioactive contamination corresponded to levels caused by the global source of contamination. However, in connection with publication of the information on long term practice of radioactive waste dumping into the Far Eastern Seas [ 3 ], the attention of public to the situation with marine environment radioactive contamination become strained. That is why in 1994-1995 in accordance with agreement on governmental level, the joint Russian-Japanese-Korean expedition on board research vessel "Ocean" belonging to FEHRI of Roshydromet was carried out to investigate the marine environment radioactive contamination immediately in the former USSR, Russia, Japan and Republic of regions of radioactive waste dumping. The international investigations conducted also do not reveal any signs of impact of radioactive waste dumping in the Far Eastern Seas on marine environment radioactive contamination in the sea regions studied.

References

[ 1 ] V.B.Chumichev. The strontium-90 content in the Pacific Ocean waters in 1962 and 1964. USSR Academy of Sciences, Transactions of the Institute of Oceanology, 1966, v.82, pp.20-23.

[ 2 ] S.MVakulovsky, Al.Vorontsov, I.Yu.Katrich, I.AKoloskov, E.I.Rosly, V.B.Chumichev. Strontium-90 and tritium in the surface waters of the North Pacific Ocean in 1974. -Oceanologia, v.18, issue 2, 1978, pp. 244-247.

[ 3 ] White Book (1993) Yablokov, A.V. et al. Facts and problems related to radioactive waste disposal in seas adjacent to the territory of the Russian Federation. Office of the President of the Russian Federation, Moscow.

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