How it began
Construction of the BN-350 began in 1964 at the Mangyshlak Atomic Energy Combine near the city then called Shevchenko, now Aktau, on the Caspian shore of Kazakhstan. The reactor reached criticality in November 1972 and began commercial operation on July 16, 1973. It was built under the Soviet nuclear program. According to the Nuclear Threat Initiative, it was the first reactor to be used on an industrial scale to desalinate seawater.
How it works
The BN-350 was a fast breeder reactor cooled by liquid sodium rather than water. Its heat raised steam that was split between two jobs: driving turbines for electricity and feeding a desalination plant that turned Caspian seawater into fresh water. The plant also supplied district heating and produced plutonium. Sources give its fresh water output as roughly 100,000 to 120,000 cubic meters a day for the city.
Who pushed back
High capital costs limited wider adoption of the design. In its later years the plant faced financial difficulties, aging technology and a shortage of spare parts. After the Soviet Union ended, the plutonium-bearing spent fuel raised nonproliferation concerns, and Kazakhstan worked with the US Department of Energy to secure and store it.
What changed first
The combine gave Aktau, a city on an arid coast, a dependable supply of power, heat and drinking water from a single installation. Engineering reviews note that it demonstrated a sodium-cooled fast reactor working at commercial scale, although it suffered repeated steam generator leaks that were traced to micro cracks in weld seams and led to changes in manufacturing.
Where it stands today
The reactor was permanently shut down on April 22, 1999. It is being decommissioned in three stages over a period of about 60 years, at a projected total cost of roughly 330 million US dollars, starting with bringing the reactor to a safe state and managing its radioactive waste. The site is owned by Kazakhstan's Ministry of Energy and operated by the Mangistau Atomic Energy Complex.
