INTRODUCTION

BRIEF REVIEW OF THE NUCLEAR COMPLEX OF EX-USSR

Historically the nuclear complex in Soviet Union was created to provide production of nuclear and thermonuclear weapons. After 1954 (start up of the world's first nuclear power plant in Obninsk) active use of nuclear energy began in the country for power production as well as for ship propulsion (in both nuclear submarines and on-surface ships, including icebreakers). Later underground nuclear explosions were used to solve various national economy tasks.

On the whole the structure of the nuclear complex of ex-USSR included:

• the nuclear weapon production line - plutonium and tritium production reactors, nuclear fuel manufacturing for the reactors, highly enriched uranium (HEU) production, the production reactors spent nuclear fuel reprocessing aimed at plutonium recovery, nuclear weapon components production from metallic HEU and plutonium, and plants and institutions engaged in design and manufacturing of nuclear warheads and related devices. The production works on manufacturing of nuclear fuel for Naval ship reactors and plants for their spent nuclear fuel reprocessing may be also attributed to this line;

• the nuclear power production line - nuclear power plants, research reactors, civil nuclear ship propulsion facilities, nuclear fuel manufacturing plants and spent reactor fuel reprocessing plants, facilities for production of radioactive isotopes and ionizing radiation sources to be used in the national economy, and enterprises for non-reactor radioactive wastes processing and disposal ("Radon" type enterprises).

The production of primary nuclear materials to be used both in defense and civil purposes as well as spent nuclear materials reprocessing (uranium ore mining and enrichment, uranium isotopic enrichment and UF₆ conversion, nuclear fuel manufacturing and radiochemical reprocessing of spent nuclear fuel, radioactive wastes processing) were conducted, as a rule, on common industrial sites, but in different process facilities.

These special industrial sites were chosen for interconnected production works because of their geographical situation, availability of power, water and manpower resources. On the basis of that principle such well known enterprises as the Industrial Association "Mayak" (Chelyabinsk Region), the Siberian Chemical Combine (Tomsk Region), the Mining & Chemical Combine (Krasnoyarsk Land) have been created.

As a rule, the enterprises have complete technological cycle and include production nuclear reactors, the reactors spent nuclear fuel reprocessing plants, facilities for manufacturing of necessary articles from weapon grade uranium and plutonium, facilities for processing of all types of radioactive wastes, and the auxiliary production complexes.

Later new production works were created at the enterprises: storage and reprocessing of spent nuclear fuel of civilian nuclear power plants (the Mining & Chemical Combine, the Industrial Association "Mayak"), and the production of radioactive isotopes and ionizing radiation sources to be used in the national economy (the Industrial Association "Mayak", the Siberian Chemical Combine). In such a way the enterprises were transformed into powerful industrial complexes with personnel numbering several tens of thousand people.

The nuclear complex of ex-USSR integrated everything that was necessary for its functioning, was produced either at enterprises and in organizations, situated in different republics of the USSR and belonging to the system of the Ministry of Medium Machinebuilding of the USSR (its assignee now in Russia is the Ministry of Russian Federation on Atomic Energy) or in cooperation with enterprises and organizations of other ministries.

In Table 1 the distribution of the nuclear industrial potential of the former USSR over new independent states of the CIS and Baltia, formed after the USSR disintegration in 1991, is presented. It is seen from the Table that more than 80 % of the nuclear industrial potential of the ex-USSR have stayed on the territory of Russia. In 1996 removing of nuclear weapons from Ukraine, Byelorussia and Kazakhstan was completed. At present, all the nuclear weapons of ex-USSR are accomodated in Russia only.

Besides that, in the time period following the USSR disintegration, the construction of the 4-th power unit at the Balakovo NPP (Nuclear Power Plant) in Russia and the 3-d power unit at the South-Ukrainian NPP in Ukraine was completed. Data on accomodation of the ex-USSR nuclear complex infrastructure in the subjects of Russian Federation are presented in Table 2, and similar data for other states, formed as a result of the USSR disintegration, are presented in Table 3. Data in both tables show that all the production of nuclear fissile materials for military and civil purposes in the former USSR was concentrated on the territory of Russia. On the negative side, the production works are the main source of radioactive wastes generation and accumulation at the country's territory.

In Table 4 data on total amounts of radioactive wastes and spent nuclear fuel accumulated in Russia are presented, as of 01.01.96. It follows from the data that for the whole time period of the ex-USSR nuclear complex activities more than 500 million cubic meters of radioactive wastes with ~ 1.5 billion Ci total activity and 8700 tons of spent nuclear fuel with ~ 5 billion Ci total activity have been accumulated on the territory of Russia.

All the radioactive wastes and spent nuclear fuel are accomodated in special structures (steel reservoirs, concrete and reinforced concrete storage facilities, etc.) and are put under constant guard and control.

In Fig. 1 structure of the State administration in the field of radioactive waste management in Russia is presented, as of 01.01.96.

The former USSR nuclear complex formation and development, especially at the initial period, was accompanied by negative effect on the environment due to production activities resulted in the discharges of liquid radioactive wastes into the Techa River and later on - into the Karachai Lake and other open water reservoirs at the Industrial Association "Mayak", Chelyabinsk Region; releases of cooling waters of plutonium production reactors into the Yenisei River at the Mining & Chemical Combine near Krasnoyarsk and into the Tom" River at the Siberian Chemical Combine near Tomsk, and as a result of accidents including the explosion of a tank with liquid radioactive wastes in 1957 and the wind-borne scattering of radioactive dust from the Karachai Lake banks in 1962 at the IA "Mayak", Chelyabinsk Region; the Chernobyl NPP accident in 1986, and atmospheric nuclear weapons tests and some civil underground nuclear explosions. The incidents have led to radioactive contamination of large areas.

In the following chapters an analytical overview of the detailed data on the radiation legacy of the former USSR are presented for every sector of its nuclear complex.

Table 1

The distribution of the ex-USSR nuclear potential over new independent states, formed as a result of the USSR disintegration

Table 2

The ex-USSR nuclear complex infrastructure accomodation in the subjects of Russian Federation

Table 4

The amounts of accumulated radioactive wastes (RW) and spent nuclear fuel (SNF) in Russian Federation

Figure 1

Structure of State administration of radwaste management