BN-1200 reactor

The BN-1200 reactor is a sodium-cooled fast breeder reactor project, under development by OKBM Afrikantov in Zarechny, Russia. The BN-1200 is based on the earlier BN-600 and especially BN-800, with which it shares a number of features. The reactor's name comes from its electrical output, nominally 1220 MWe.

Originally part of an expansion plan including as many as eight BN-Reactors starting construction in 2012, plans for the BN-1200 were repeatedly scaled back until only two were ordered. The first was to begin construction at the Beloyarsk nuclear power plant in 2015, with commissioning in 2017, followed by a second unit. A possible new station known as South Ural would host another two BN-1200s at some future point.

In 2015, after minor delays, problems at the recently completed BN-800 dictated a fuel redesign. BN-1200 construction was put on "indefinite hold", and Rosenergoatom stated that no decision to continue would be made before 2019. In January 2022, Rosatom announced that a pilot BN-1200M would be built by 2035.

Background
Fast reactors of the BN series use a core running on enriched fuels including highly (80%) or medium (20%) enriched uranium or plutonium. This design produces many neutrons that escape the core area. These neutrons create additional reactions in a "blanket" of material, normally natural or depleted uranium or thorium, where new plutonium- or, respectively, atoms are formed. These atoms have distinct chemical behavior and can be extracted from the blanket through reprocessing. The resulting plutonium metal can then be mixed with other fuels and used in conventional reactor designs.

For the breeding reaction to produce more fuel than it uses, neutrons released from the core must retain significant energy. Additionally, as the core is very compact, the heating loads are high. These requirements led to the use of a liquid sodium coolant, as this is an excellent conductor of heat, and is largely transparent to neutrons. Sodium is highly reactive, and careful design is needed to build a primary cooling loop that can operate safely. Alternate designs use lead.

Although the plutonium produced by breeders is useful for weapons, more traditional designs, notably the graphite-moderated reactor, generate plutonium more easily. However, these designs deliberately operate at low energy levels for safety reasons, and are not economic for power generation. The breeder's ability to produce more new fuel than was spent while also producing electricity makes it economically interesting (it uses 99% of uranium energy, instead of 1%). However, to date the low cost of uranium fuel has made this unattractive, as it is four times cheaper than the BN600.

Previous designs
The successive Soviet government began experimenting with breeders in the 1960s. In 1973, the first prototype of a power-producing reactor was constructed, the BN-350 reactor, which operated successfully until 1999. This reactor suffered an almost continual series of fires in its sodium coolant, but its safety features contained them. A somewhat larger design, the BN-600 reactor went into operation in 1980 and continued to run until at least 2019).

Design of a larger plant with the explicit goal of economic fuel production began in 1983 as the BN-800 reactor, and construction began in 1984. By this time the French Superphénix had begun operation. The Super Phenix had startup problems before achieving operational reliability. A slump in uranium prices added to the concerns, making the breeder concept economically infeasible. The Chernobyl disaster in 1986 ended construction until new safety systems could be added.

BN-800 underwent a major redesign in 1987, and a minor one in 1993, but construction did not restart until 2006. The reactor did not reach criticality until 2014, and further progress stopped due to problems with the fuel design. It restarted in 2015, and reached full power in August 2016, entering commercial operation in 2023.

Design concept
The BN-1200 concept is essentially a further developed BN-800 design with the twin goals of economical operation, while also meeting Generation IV reactor safety limits. It uses a simpler fueling procedure and has an extended design life of 60 years. Safety enhancements include the elimination of outer primary circuit sodium pipelines and passive emergency heat removal.

The design has a breeding ratio of 1.2 to 1.3–1.35 for mixed uranium-plutonium oxide fuel and 1.45 for nitride fuel. Boron is to be used for in-reactor shielding. Thermal power is a nominal 2900 MW with an electric output of 1220 MW. Primary coolant temperature at the intermediate heat exchanger is 550 °C and at the steam generator 527 °C. Gross efficiency is expected to be 42%, net 39%. It is intended to be a Generation IV design and produce electricity at RUR 0.65/kWh (US 2.23 cents/kWh). The design evolved to adopt a simpler fueling procedure than the BN-600 and BN-800 designs.

The World Nuclear Association lists the BN-1200 as a commercial reactor, in contrast to its predecessors.

Planned construction
OKBM initially expected to commission the first unit with MOX fuel in 2020, growing to eight (11 GWe total output) by 2030. SPb AEP also claimed design involvement. Rosenergoatom considered foreign specialists in its design, with India and China mentioned.

In early 2012, Rosatom's Science and Technology Council approved the construction of a BN-1200 reactor at the Beloyarsk Nuclear Power Station. Technical design was scheduled for completion by 2013, and manufacture of equipment was to start in 2014. Construction was to begin in 2015 with first fuel loads in 2017 and full commercial operation as early as 2020. A second unit, either a BN-1200 or BN-1600, was to follow, along with the possibility of a BREST-300 lead-cooled breeder. These plans were approved by Sverdlovsk regional government in June 2012.

Status
The construction of the BN-1200 is pending economics "comparable to VVER-1200".

Two BN-1200s remain in Russia's master plan, which includes another nine reactors of other types. This report suggests one BN-1200 in two locations, Beloyarsk and South Urals. The rest are a mix of VVER-600 and VVER-TOI.