The Fukushima Daiichi nuclear power plant pictured in March 2011 (top) and March 2014 (bottom).
Tokyo Electric Power Company (TEPCO) admitted last week that they should have declared a meltdown within days of the March 11th earthquake and tsunami that crippled the Fukushima Daiichi nuclear power plant, instead of delaying the public announcement for months.
“We apologize for the great inconvenience and worry the delay caused”, a representative for TEPCO said this week. The utility has also said it will investigate why the word “meltdown” was not used for months after the crisis began.
A meltdown is recognized by the public as severe damage to the core of a nuclear reactor with the potential for widespread radiation release. Once the core is damaged, radioactive materials escape from the fuel rods into the coolant, make their way outside of the reactor vessel into the reactor building. The reactor building is the last barrier between the radioactive materials and the environment. The consequences and clean-up of a full-core meltdown are obviously more complicated and dangerous than a partial-meltdown like Three Mile Island – where only a portion of the core debris was damaged and all the fuel remained in the containment structure.
The word “meltdown” was so explosive, that TEPCO, the nuclear industry, and the Japanese government were loath to apply it until it could no longer be ignored. The word has been so powerful, that it has crossed over into other fields – like personal meltdowns, financial meltdowns, political meltdowns, etc.
Within the first 24 hours, after the Unit 1 reactor building exploded on the morning of March 12th, TEPCO was aware that at least 50% of one of three cores at the Fukushima Daiichi nuclear power plant was damaged within hours of the accident and notified the government of the ongoing meltdown – but did not acknowledge that a meltdown had occurred to the public until May 2011, long after the melted nuclear fuel escaped from the damaged reactors into the containment vessels.
Tokyo Electric’s internal regulations stated that the utility should declare a meltdown if more than 5% of the reactor core was damaged. TEPCO has since admitted that the reactor pressure vessel of the Unit 1 reactor was damaged within the first 12 hours of the accident. This means that a meltdown should’ve been declared within a few hours of the onset of the accident, around the time that water levels in the reactor were falling and TEPCO began hinting at the possibility of venting operations.
Any member of the nuclear industry knew the severity of the accident must be critical if the utility was considering the manual release of radioactive materials into the environment, but the utility, regulators, and elected officials paraded in front of the media and downplayed the consequences of the venting operations to the public – further complicating an already very fast-moving and complex accident.
For months operators were unable to control the temperature and pressure levels in the reactors. They …read more