Russian BN-800 fast breeder reactor connected to grid

Shaun Burnie (with Mycle Schneider)

Thirty-one years after construction start, the BN-800 Fast Breeder Reactor (FBR) at Zarechnyy, in the Sverdlovsk region of Russia, was connected to the grid on December 10, 2015 at 21:21 (19:21 MSK). In the beginning the reactor will be operating at about 35 percent of its power. According to the IAEA, the BN-800 has a nominal net capacity of 789 MWe. The reactor first reached criticality in June 2014.

The extremely long construction time is no exception. Russia has connected only four reactors to its power grid over the past ten years (including the BN-800) and the average construction time was just under 30 years.

The BN-800 is eventually to be fueled with surplus weapons grade plutonium manufactured into plutonium-uranium Mixed Oxide (MOX) fuel, produced at the MOX fabrication plant in Zheleznogorsk, which produced first fuel in September 2015. However, BN-800's initial core is a combination of MOX fuel with pellets supplied by the Mayak Plant, Chelyabinsk region and vibro-packed MOX from the Research Institute of Atomic Reactors (NIIAR, Dimitrovgrad, Ulyanovsk region). Of the total of 576 fuel assemblies in the initial core, 102 are fuel assemblies with high-enriched uranium.

A full MOX core with reactor-grade plutonium would contain 2,710 kg, while the use of weapons-grade plutonium would limit the quantity to 2,215 kg.

The Russian FBR program has limited experience with plutonium based MOX fuel. Due to a combination of cost and safety issues, most of the fuel used in the BN-350 and BN-600 reactors has been based on uranium with enrichment from 17% to 26%. Some experience with plutonium fuel was acquired in the experimental BOR-60 reactor and in a few experimental fuel assemblies in BN-350 and BN-600.

Under the United States-Russia Plutonium Management and Disposition Agreement (PMDA), signed in 2000, each nation agreed to dispose of at least 34 tons of surplus weapons-grade plutonium. The original plan by Russia to fabricate MOX fuel and use it in light water reactors was amended with an additional protocol to the PMDA, signed in 2010, whereby the 34 tons of plutonium would be "burned" in fast reactors. The change reflected the long-standing commitment in Russia to a nuclear power program based on "closed nuclear fuel cycle", including reprocessing and FBRs. However, earlier Russian plans in the 1980's to construct five BN-800s in the Ural region failed to materialize. Its current plans to scale up FBR deployment to 14 GWe by 2030 and 34 GWe of capacity by 2050 no not seem realistic. Plans for the next stage in fast reactor development, the BN-1200, scheduled to be operational by 2025, have been postponed due to doubts over its economic viability. As part of its "Breakthrough" program, Rosatom is also working on another FBR design, Brest-300. Preparation for the construction of the pilot unit, Brest-OD-300, are underway in Seversk (formerly Tomsk-7).

As a fast neutron reactor, the BN-800 will be capable of breeding additional plutonium, which is one reason Article VI of the PMDA Agreement imposes a ban on spent fuel and breeder blanket reprocessing during the disposition process until disposition of plutonium covered by the PMDA is complete. However, before that time, Russia can reprocess up to 30 percent of the fuel discharged by the BN-800, provided that it was made with plutonium other than disposition plutonium.