The Beta-M is a radioisotope thermoelectric generator (RTG) that was used in Soviet-era lighthouses and beacons.
The Beta-M[1] contains a core made up of strontium-90, which has a half-life of 28.79 years. The core is also known as radioisotope heat source 90 (RHS-90). In its initial state after manufacture, the generator is capable of generating 10 watts of electricity, almost enough to power a compact fluorescent light bulb with light output equivalent to a 60-watt bulb.[2] The generator contains the strontium-90 radioisotope, with a heating power of 250W and 1,480 TBq of radioactivity – equivalent to some 280 grams (9.9 oz) of Sr-90.[3] Mass-scale production of RTGs in the USSR was the responsibility of a plant called Baltiyets, in Narva, Estonia. The efficiency of thermal input (250 watts) to electric output (10 watts) at 4% is relatively high for an RTG of that era but low compared to larger scale thermal power conversion processes such as steam turbines which reach 30% and more efficiency.[4]
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Further information: Lia radiological accident |
Some Beta-M generators have been subject to incidents of vandalism when scavengers disassembled the units while searching for non-ferrous metals.[1][3][5] In December 2001 a radiological accident occurred when three residents of Lia, Georgia found parts of an abandoned Beta-M in the forest while collecting firewood.[3] The three suffered burns and symptoms of acute radiation syndrome as a result of their exposure to the strontium-90 contained in the Beta-M.[3] The disposal team that removed the radiation sources consisted of 25 men who were restricted to 40 seconds' worth of exposure each while transferring the canisters to lead-lined drums.[6]