Purposefully deactivating all security mechanisms and automatic control of a reactor in order to try and get a chain reaction going despite Xenon poisoning of the core isn't lack of luck. Removing all but 12 control-rods from a reactor that needs at least 30 to maintain a negative void coefficient (which the automatic control doesn't allow) isn't lack of luck.
Chernobyl wasn't lack of luck.
In fact, after 1986, all RBMK reactors used somewhat higher enriched fuel (2.4% or so) with absorbers included into fuel rods to permanently give the reactors a negative void coefficient. A fact that is widely ignored by the public.
Also, as the WASH-1250 report pointed out in 1975 - before TMI, Chernobyl and Fukushima - having a large containment with containment spray as was the case with all PWRs as opposed to BWRs built before the 1990ies isn't luck. But was credited back in 1975 with retaining a much larger amount of radionuclides compared to BWRs. That's because of larger retention times, as the larger volume has a much slower pressure build-up and containment spray can remove both iodine and caesium from the containment-air before venting. The accident in Fukushima proved this report to be accurate. (And unlike Japan, many European countries adopted counter-measures in the form of filtered containment vents that can remove 99.99% of Cs and 99% of iodine during venting.)
TMI wasn't luck.
As the WASH-1250 also pointed out, floods and tsunamis ('tidal waves') were known as a major risk that could lead to melt-downs and must be dealt with. Both Onagawa to the north of Fukushima and Tokai to the south of Fukushima were prepared for and hit by the tsunami, resulting in non-events, as the inlets for cooling water were sealed and no vital equipment was destroyed. Strangely enough, they were able to foresee what it takes to prepare for a tsunami, but the Fukushima power stations were not prepared.
Fukushima Daiichi and Daini weren't prepared. But out of ten reactors only five lost emergency power supply - those with Mark I Containments. All others had Mark II containments mong them only reactor #6 in Fukushima Daiichi (current generation BWRs would have a Mark IV or Mark V containment, if they hadn't stopped numbering after Mark III). Those retained at least one emergency generator. That wasn't luck either, but an advanced safety concept calling for two separate sections that could provide all functions necessary for the safety of the reactor. Including an air-cooled emergency generator. No additional air-cooled generators were supplied to any of the Mark I containments, even though the Mark II containment made it plonkingly obvious to anybody that they were needed. And those are cheap compared to a nuclear power plant.
What's worse is that the japanese regulator NISA specifically told plant operators that total station black-outs need not be included in safety drills. Personell could not properly deal with the situation, despite having the necessary equipment to mitigate it by using the firefighting equipment to pump cooling water into the reactor. Those had been equiped with the necessary joints to plug the pumps right in, as the (american) designers of the containment had the foresight to deal with this possibilty. Training would have included knowing how and when to properly vent the containment, without creating a backwash into the containment building and opening the blow-out panels to prevent hydrogen build-up in case of a meltdown - as was done in reactor #2 where no explosion occured.
Fukushima wasn't bad luck.It was lack of training, safety equipment and regulation that had been established decades ago in other countries.
Source: http://rss.slashdot.org/~r/Slashdot/slashdotScience/~3/Vagozt1RPy4/fukushima-fish-still-radioactive
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