What happened

A catastrophic boiler-side failure at the Feroze Gandhi Unchahar Thermal Power Station's newly commissioned 500 MW Unit 6 released high-velocity hot flue gases, steam and ash into work areas. Early reports gave lower and changing casualty totals, but NTPC's later internal review recorded 45 workers killed and more than 100 injured, many with severe burns. Operators knew that ash had accumulated inside the boiler and reduced the unit to approximately 300 MW while workers attempted to clear deposits from the furnace bottom. The later internal findings, reported by Reuters, said experienced plant managers made an error in judgment by keeping the boiler online rather than shutting it down before the clearing work. Ash buildup contributed to a steam-tube leak and rising pressure; the unit then tripped and expelled hot ash and gases at high speed. The Indian Ministry of Power constituted a statutory committee to investigate causes, responsibility and prevention measures. This entry uses the final 45-death figure rather than the preliminary totals of 29 to 38 that circulated while victims remained hospitalized.

When cited sources give different casualty, damage or spill figures for this event, they’re reported side by side above rather than merged into one number. See how confidence levels work.