Please look at the text in quotes and tell me what caused reactors to meltdown in Fukushima?

"On March 11, 2011, at 2:46 p.m. local time, Japan experienced a 9.1 magnitude earthquake—the biggest earthquake in the country’s recorded history—80 miles off the coast of Sendai. The shaking lasted six minutes, but the earthquake and the resulting 50-foot tsunami caused immense devastation and death, killing upwards of 20,000 people.

Twelve years later, Japan is still recovering from this historic earthquake, and nowhere can this be seen more plainly than at the Fukushima Daiichi Nuclear Power Plant. Although the plant, equipped with six nuclear reactors, terminated fission reactions automatically once it detected the earthquake, the resulting tsunami that arrived less an hour later breached the plant’s seawall and damaged the back-up generators needed to pump coolant to dissipate decay heat. This caused three of the six reactors to experience a meltdown over the next 72 hours."
system
kripaya uddharanon main paath ko dekhen or mujhe bataaen ki phukushima main riektaron ko kya kiya gaya he?

"11 march, 2011 ko, 2:46 baje, sthaneey samyaanusaar, japan ne 9.1 pariman bukamp kaa anubhav kiya - desh ke record kiye gaye itihaas main sabase bada bukamp - sendai ke tat se 80 mile dur. jhatkon chah minute tak chali, lekin bukamp or50-foot tsunami ke parinamswaroop 20,000 logon kii maut ho gai, jisase baari tabaahi or maut ho gai.

baarah saal baad, japan abhi bhi is aitihaasik bukamp se ubar rahaa he, or kahin bhi phukushima daichi parmaanu urja sanyantr kii tulana main adhik spasht rup se nahin dekha ja saktaa he.haalanki, chah parmaanu riektaron se las sanyantr, bukamp kaa pataa lagane ke baad swachaalit rup se vikhandan pratikriyaaon ko samaapt kar detaa he, jiske parinamswaroop tsunami jo ek ghante baad kam pahunchi, usne paudhe ke samudri jal ko bhang kar diya or kulent ko pump karne ke liye aavashyak back-ap janarator ko nuksaan pahunchaaya.isane chah riektaron main se teen ko agle 72 ghanton main meltdown kaa anubhav kiya. "
user
2011 main, ek bukamp ne ek tsunami ko trigar kiya, jisane phukushima daichi parmaanu urja sanyantr ke siwal ko tod diya or riektaron ko thanda karne vaale janaretaron ko nuksaan pahunchaaya.
assistant
<|system|>
</s>
<|user|>
kripaya uddharanon main paath ko dekhen or mujhe bataaen ki phukushima main riektaron ko kya kiya gaya he?

"11 march, 2011 ko, 2:46 baje, sthaneey samyaanusaar, japan ne 9.1 pariman bukamp kaa anubhav kiya - desh ke record kiye gaye itihaas main sabase bada bukamp - sendai ke tat se 80 mile dur. jhatkon chah minute tak chali, lekin bukamp or50-foot tsunami ke parinamswaroop 20,000 logon kii maut ho gai, jisase baari tabaahi or maut ho gai.

baarah saal baad, japan abhi bhi is aitihaasik bukamp se ubar rahaa he, or kahin bhi phukushima daichi parmaanu urja sanyantr kii tulana main adhik spasht rup se nahin dekha ja saktaa he.haalanki, chah parmaanu riektaron se las sanyantr, bukamp kaa pataa lagane ke baad swachaalit rup se vikhandan pratikriyaaon ko samaapt kar detaa he, jiske parinamswaroop tsunami jo ek ghante baad kam pahunchi, usne paudhe ke samudri jal ko bhang kar diya or kulent ko pump karne ke liye aavashyak back-ap janarator ko nuksaan pahunchaaya.isane chah riektaron main se teen ko agle 72 ghanton main meltdown kaa anubhav kiya. "</s>
<|assistant|>
2011 main, ek bukamp ne ek tsunami ko trigar kiya, jisane phukushima daichi parmaanu urja sanyantr ke siwal ko tod diya or riektaron ko thanda karne vaale janaretaron ko nuksaan pahunchaaya.</s>
