During the second and third decades of the program, experience was acquired in the use of fast-reactor technology.

In 1961, the critical assembly BFS-1 started operation at IPPE. It allowed researchers to simulate fast-reactor core volumes of up to 3 m3 with cores fueled by different mixtures of plutonium and uranium of varying enrichments, and different configurations of control and safety rods. It also allowed studies of the effects of sodium voids on reactivity and other physical effects. BFS-2, which started operating at IPPE at the end of the 1960s, could simulate cores with volumes up to 10 m3.

A higher power special fuel-testing reactor, the BOR-60, was designed and constructed in the Institute of Atomic Reactors (Dimitrovgrad) in five years and began operating in 1969. Vibro-packed fuel was tested in this reactor. It is still operational.

Between 1962-1964, the future direction of Soviet nuclear energy development was studied. A main concern was conservation of uranium resources. The study concluded that a "promising perspective is expansion of nuclear energy using fast breeder reactors starting with enriched uranium fuel and step-by-step replacement with plutonium fuel."

A demonstration project was initiated even before the BR-5 began operating. Initially the demonstration reactor was named BN-50 (50 MWt) but later the power was increased to 1000 MWt. The reactor came to be called BN-350 for its equivalent electrical output.9 The design of the demonstration BN-350 and a significant number of experiments at the BFS-1 critical assembly were completed before construction started in 1964.10 The Minister of Atomic Energy, Yefim P. Slavsky, decided to build the reactor on the Mangyshlak peninsula on the Caspian Sea. The heat was used for desalination as well as electricity generation. It was fueled with uranium enriched up to 20-25 percent uranium-235 and with mixed — oxide uranium-plutonium (MOX) test fuel assemblies. It began operations in 1972.

A year later, in late 1973, the BN-350 experienced a major sodium fire due to the failure of one of the steam generators. The BN-350 steam generators were designed and built without sufficient experimental study. Additionally, welding quality control on the first set of steam generators was inadequate. The reactor was shut down for repair for approximately four months and then continued operations until it was shut down permanently in April 1999.

Even before the BN-350 began operating, the Government decided to start a second fast-neutron reactor with a still higher power as a step toward fast-neutron reactor commercialization. The project was called BN-600 (600 megawatt electric). Experience acquired during the initial period of BN-350 operation was used to make changes to the BN-600 design.

The reactor was designed with a secondary sodium circuit between the radioactive primary sodium and the steam generator. It is a pool-type design with the heat exchangers between the primary and secondary sodium loops within the reactor vessel. There is no containment structure. The reactor was the third unit of the Beloyarskaya nuclear power plant in the Ural region and is still operating.

As of 1997, there were 27 sodium leaks in the BN-600, 14 of which resulted in sodium fires. The largest leak was 1000 liters.11 The fires were extinguished without casualties, however, and plant personnel repaired the damage. The steam generators are separated in modules so they can be repaired without shutting down the reactor.

No irresolvable problems were encountered during construction of the BN-350 and BN-600 reactors. The pumps, vessel, piping, cover of the reactor with its movable port for locating the refueling machine over a specific fuel assembly, and steam generators were produced at Soviet manufacturing plants, and all mechanical equipment was tested prior to final installation. Standard turbines were used.12

During 1970-80, IPPE launched the designs of two new fast-neutron reactors, the BN-800 (figure 5.1) and BN-1600. The BN-800 (800 MWe), which is again under construction (as of 2009), will be a modernized version of the BN-600 to match a standard turbine.13 The BN-1600 will be a commercial nuclear power plant. In the early 1980s the Government planned to build five BN-800s in the Ural region. After the Chernobyl accident in 1986, however, the Soviet nuclear energy program was cut back (table 5.1).Russia’s economy was not able to support substantial investments in new nuclear power plants during the 1990s. In addition, fast-neutron reactors were not economically competitive with Russia’s light-water and graphite-moderated thermal-neutron reactors and estimates of available high-grade uranium increased sharply as a result of the discovery of large uranium deposits in Kazakhstan in the 1960s and 1970s.

Core fragments trap

Figure 5.1 Artist’s Rendition of the BN-800 reactor now under construction (2009).

Source: Institute of Physics and Power Engineering.

In 2000, however, in a speech at the U. N. Millennium General Conference, President Putin unveiled a new program for expansion of Russia’s nuclear capacity. This expansion program, while focused primarily on light-water reactors, includes fast-neutron reactors. The first step towards commercialization will be the construction of a few replicas of the BN-800 and completion of the design of a commercial prototype of the BN-1600.14

The fast-neutron reactor program has several goals:

1. Develop a closed uranium-plutonium fuel cycle;

2. Produce chain-reacting uranium-233 from neutron capture in thorium blankets as a potential fuel for thermal-neutron reactors;

3. Fission the minor transuranics, neptunium, americium and curium; and,

4. Significantly reduce highly radioactive waste volume for a final geological repository.

It is difficult to estimate the cumulative investment in the fast-neutron reactor program. One estimate offered in 2004, by F. M. Mitenkov of the Afrikantov Experimental Machine Building Design Bureau, is approximately $12 billion, which included construction of the BN-600 and design of the BN-800.15