The market resolves as YES if a nuclear power plant used primarily for electricity production has at least a partial meltdown (as in Three Miles Island) before the end of 2030. The meltdown should be bad enough to require the shutdown of the reactor. It would not necessarily lead to the release of radioactive material (the meltdown could be fully contained). The market resolves as NO if no such accident occured.

Voluntary meltdown of fuel assemblies for research purposes in small research facilities are excluded. Only power plants are considered, submarine/ship reactors are excluded.