Chernobyl accident which took place in the night since 25 till 26, April is the most considerable nuclear accident of our days. It affected million of people living not only in Russia, Ukraine and Byelorussia, but in Europe also.

It will be enough to say that only in Russian Federation common area of contamination reached almost 60 thousand km2. 3 million people lived on these territories. Altogether contaminated territories are in 16 regions of Russia and in 3 republics (Moldova, Tatarstan and Chuvashia).

Ecological influence of Chernobyl accident made USSR solve very difficult new problems affected almost all spheres of social life, many aspects of science, production and moral.

In June, 1986 works in 30-km zone of Chernobyl accident were started. During these works on the research of the accident a special division “Ecology” was formed. The Government charged to carry out these works to Russian Academy of Sciences. Later the division “Ecology"” was transformed into the independent Complex program “Influence of radioecological contamination on flora and fauna” during 1986-1990 years. The scientific leader of this program became academician-secretary of Common Biology Department of RAS director of Institute of evolution morphology of animals RAS academician V.E. Sokolov. The head of the Expedition – head of laboratory I.N. Ryabov, deputy head – I.A. Ryabtsev.

In May, 1987 according to the order of Presidium of RAS (13100/800 from 22.05.87) on the base of Chernobyl Expedition Complex Radioecological Expedition RAS was formed. It still continues radioecological and genetic researching in Russia, Byelorussia and Ukraine.

Researches were carried out in following directions:

1. radioecological monitoring on the territory of Chernobyl Atomic Station
2. landscape radioecology
3. radioecological research of flora and fauna
4. genetic influence of the accident

Different collectives from 28 institutes worked in the Complex Radioecological expedition for these years. It is necessary to mention collaborators from such institutes as Institute of Common Genetic - head is V.A. Shevchenko, Laboratory of Forest Research – head is U.D. Abaturov, Laboratory of Gelmentology – head is A.A. Pelgunov. Institute of chemical physics head is I.I. Pelevin, Institute of physical chemistry – head is B.F. Gulyaev and also other leading scientific institutions of different departments (Moscow Physics Institute – head is V.N. Lystsov, Soil Faculty of MSU – head is F.A. Tichomirov, Biological Faculty of MSU – heads are N.V. Belova, U.B. Kudryashov, A.S. Severtsov).

Except receiving scientific data it was necessary to organize scientific exchange of received information. With this purpose in 1990 the 1 International conference on Radioecology and Biological influence of the accident was organized. In next years collaborators of the expeditions started to take part in the international Chernobyl projects, for example “Inko-Kopernicus”, etc. It is important to mention that scientific contacts with Ukrainian and Byelorussian colleagues are continued.

In different years more than 300 scientific collaborators, drivers, technicians worked in the expedition. Only in Institute of Evolutional morphology of Animals (now A.N. Severtsov Institute of Ecology and Evolution) 52 collaborators in 1986-1990 became liquidators.

After the accident 1 million 800 thousand people are living in the zone of radioactive contamination.

In 10th anniversary of the accident the country remembered those people who were first there. Order “The Hero of Russia” was handed to V.E. Sokolov and 16 collaborators of the Institute were rewarded by government.

In 1998 the scientific leader of Complex Radioecology Expedition academician V.I. Sokolov died. Also passed away the head of expeditional detachment U.D. Abaturov, collaborators of the A.N. Severtsov Institute of Ecology and Evolution – A.A. Gostev, P.V. Bogatyrev, E.K. Musaev, K.P. Markov; collaborator of the ichthyology chain of MSU B.V. Verigin; drivers A.I. Filimonov, K.M. Solovych, A.M. Pankratov.

THE MOST SIGNIFICANT PUBLICATIONS

1. Ryabov I.N., Belova N.V. The results of radioecological researches of water ecosystems after the Chernobyl accident (1986-1995)// Thesises of the 5 International Conference “Chernobyl-96”, “The results of 10-year work on liquidation of the influence of the Chernobyl accident”, Zelenyi Mys, 1996, pp. 337-338
2. Nasvit O., Ryabov I.N., Romanenko V.D., Hadderingh R., Carriero C. Processes and parameters govering accumulation and elimination of radiocaesium by fish.// The radioecological consequences of the Chernobyl accident, Proceedings of the fish international conference, Minsk, Belarus, 18-22 Martch 1996, p. 137-146.
3. Ryabov I.N., Polyakova N.I., Belova N.V. Field studies on Seasonal and age changes in Fish Dict. Modelling and Study of the Mechanisms of the Transfer of Radioactive Material from the Terrestrial Ecosystems to and in Water Bodies Around Chernobyl V. II 2.2.3., ECR-3, EUR 16529 EN, 1996, p. 95-100.
4. Verigin B.V., Belova N.V., Makeyeva A.P., Emelyanova N.G., Vybornov A.A.,Ryabov I.N. Artificial reproduction of silver carp from cooling-pond of Chernobyl.// In: Abstracts book “Fish reproduction 96”, Czech republic, 9-12 September 1996, p. 50
5. Ryabov I.N., Belova N.V., Polyakova N.I. Evolution of the contamination for radiocaesium in fish after Chernobyl.// The 9th international congress of European ichthyologists “Fish biodiversity”, Italia, 24-30 August 1997.
6. Bessonov A.A., Nitsche H., Nebelung C., Ryabov I.N. Determination of actinides in fish samples from the river Irtysh and the Kojanovskoe Lake.// Annual report 1996, Institute of radiochemistry, Forschungszentrum Rosserdorf , May 1997, p.34
7. Hadderingh R., van Aerssen G., Ryabov I.N., Koulikov A.O., Belova N.V. Contamination of the fish with 137Cs in Kiev reservoir and old river bed of Pripyat near Chernobyl.// Freshwater and estuarine radioecology, Elsevier science B.V., 1997, p. 339-353.
8. Ryabov I.N. Radioecological research of natural ecosystems in contaminated regions.// Book II “Moscow-Chernobyl”, Moscow, 1998, p. 226-236
9. Belova N.V., Emelyanova N.G., Makeeva A.P., Ryabov I.N. Unique phenomenon of dwarf species of Hypophtalmichthys molitrix.// Questions of ichthyology, 1998, v. 38, ¹6À p. 839-843.
10. Smith J.T., Kudelsky A.V., Ryabov I.N., Hadderingh R.H. Radioceaesium concentration factors of Chernobyl-contaminated fish: a study of the influence of potassium, and “blind” testing of a previously developed model. Journal of Environmental Radioactivity 48, 2000, p. 359.
11. Taskaev A.I., Shevchenko V.A., Popova O.N. Ecological and genetic influence of the Chernobyl accident for flora.// Preprints “Scientific reports”. Komi Scientific Center. Syktyvkar, 1998, p. 60
12. Frolova N.P., Popova O.N., Taskaev A.I., Frolov U.M. Monitoring of natural population Plantago Langeolata L. In the 30-km zone of the Chernobyl accident.// Preprints “Scientific reports”. Komi Scientific Centre. Syktyvkar, 1989, p. 49.
13. Igor Ryabtsev, Tetsuji Imanaka Legislation and research activity in Russia about the Radiological consequences of the Chernobyl accident.//Research activities about the Radioecological consequences of the Chernobyl NPS Accident and social activities yo assist the suffers by the accident. Research Reactor institute, Kyoto University, March 1998, p. 40-51
14. I.N. Ryabov Long-term observation of radioactivity contamination in fish around Chernobyl.// Research activities about the Radioecological consequences of the Chernobyl NPS Accident and social activities yo assist the suffers by the accident. Research Reactor institute, Kyoto University, March 1998, p. 112-113.

Picture 1. Scientific leader of Complex Radioecological Expedition academician V.E. Sokolov, head of expedition I.N. Ryabov, dbs N.V. Kulikov (Chernobyl, 1987)
	Picture 2. Leaders of ecpeditional detachments on the meeting with academician V.E. Sokolov (Oranoe, 1988).
Picture 3. Head of Complex Radioecological Expedition I.N. Ryabov and famous radiobiologist Zh.A.. Medvedev on the conference.
	Picture 4. Collaborator of the expedition P.B. Bogatyrev (Chernobyl, 1988).
Picture 5. Collaborators of ichthyological detachment of MSU A.P. Makeev, N.V. Belova, B.V. Verigin, N.G. Emelyanova (Chernobyl, 1989).
	Picture 6. Laboratory
Picture 7. Kitchen
	Picture 8. The Teterev river.