Except the plant did withstand the earthquake just fine and if the upper management had listened to earlier multiple critiques the disaster most likely wouldn't have happened (it should be noted that even with TEPCO's bungling, the other nuclear plant number two underwent safe shutdown). Even with the occurrence if the management hadn't bungled things so badly the problem wouldn't be as large as it is and fallout would have been a lot smaller (it's worth noting that the management really sucks, they've been found falsifying safety records in face of criticism and even having experienced flooding of the emergency generators made no changes). Most people have never even heard of Onagawa Nuclear Plant which is an example of a nuclear plant done right. It lies even closer to the epicenter of the quake (and so the tsunami) and the town it's in was mostly destroyed but the seawall did its job and took the tsunami and so the plant shut down as per procedure. In fact some townspeople took shelter at the nuclear power plant because it was the safest gathering point for them.
I specifically said that people go on unnecessarily about the incident because for the most part the loudest ones don't seem to understand the topic at hand. Statements like "radioactive isotopes are one of the most dangerous thing on earth" only prove to further illustrate that point. Standard fossil fuel burning plants (and even hydro electric dams) do damage the environment simply by existing (and can further damage them on serious incident) and nuclear accidents don't necessarily "give everything alive gene damage" (eg, there are lots of nuclear accidents that have had negligible consequences even to the workers on site). This too furthers the idea that you don't understand the topic at hand.
We can in a lot of cases actually point to radiation as a cause of premature death. An earlier statement I made is an example; radon accumulation (source of alpha particles) in the USA is estimated to cause 21,000 lung cancer deaths per year (USEPA estimate, consistent with independent study) and is said to be the second most frequent cause of lung cancer after cigarette smoking and the sixth leading cause of cancer death overall in the USA. This is backed by investigations and studies.
I'd like to see any credible studies that claim that deaths will occur as a result of this. The only one I've seen was undertaken in 2012 and criticised for extrapolating from extremely small values and a more recent, very comprehensive study by the World Health Organisation claims that increased risk of complications (including cancer) is small and that there are likely to be no related deaths beyond regular background noise. Any claims at shortened lifespan I find laughable especially coming from someone who apparently doesn't understand radiation as a hazard, especially when they say it's "for sure." As of earlier this year there isn't a single complication linked to the accident and incidences of possible complications are consistent with the rest of the nation. For many people living in "affected" zones, they're still not receiving a significantly
The ecosystem despite contamination is by all reports holding up fine. I question your claim that marine life is "more fragile" and studies show that despite unsafe levels present in various creatures they don't seem to be showing any signs of long term harm (this is ignoring that the basic oceanic organisms are constantly mutating all the time). I haven't read any credible reports of "deformed" life showing up, there is a report of mutated insects but the mutations are suggested to be hereditary and so non-harmful. I also question that there's a "there is a huge patch of dead reefs somewhere under the ocean" as a result of this. The already existing environmental hazards for coral reefs have already killed off a large amount and continue to do so.
But it did not withstand the earthquake just fine, or we wouldn't be talking about this, again their own report found that the plant had inadequate protection against earthquakes, true the seismic shocks itself did not do much damage ( though that could be debated as there are concerns that the tunnels underneath the plant was damaged), but the tsunamis and coastal earthquakes go hand in hand, and as i mentioned before earthquake can cause very unpredictable things.
The other nuclear power plant you were talking about, Fukushima Daini, Barely avoided a meltdown, of the 4 reactors in the power plant, 3 of them's cooling system failed, and it was classified as a level 5, "accident with wider consequences" on the international nuclear event scale (Fukushima Daiichi got a 7, the highest possible) , infact if it weren't for the quick thinking and extraordinary action by the plant workers, it would had been just as bad as the Fukushima Daiichi incident. And an emergency shutdown is by no means a "safe shutdown", the reactors still have to be constantly cooled and any damage to the cooling systems or the reactor itself can still make it meltdown or explode , only when the reactors reached a state of cold shutdown, which can take up to several month, can it be considered "safe". as for the Onagawa nuclear plant, i do admit it withstood the earthquake and tsunami wonderfully well. it was a built many years later that Fukushima plants and rather well designed, but like i said before, as long as there is any chance of natural disaster happening near an nuclear reactor with so much population, it's better to be safe than sorry.
Statements like "radioactive isotopes are one of the most dangerous thing on earth", and "give everything alive gene damage" have everything to do with the topic, unless Fukushima was somehow a hydro solar-wind farm without me realizing it. anyways, those two statement essentially refer to the same thing, radioactive material is very dangerous, fossil fuel power plants polluting environment is a completely different type of danger than the one i am talking about, i could publish a 30 page paper comparing the ionizing radiation effect to living organisms of caesium-137 to say, petroleum, actually it would be very short, but lets just save time and say "give everything alive gene damage".
obviously not every accident that happen will causes the reactor to meltdown, breaches the the containment shield and releases radioactive particles into the atmosphere. if it did we would be doing something seriously wrong, but while major incidents are very few, the ones that did happen are devastating and are still in effect today. so since i am trying to point out why japan shouldn't be building nuclear power plants in areas with increased risks, and near the ocean, reminding people that radioactive materials is dangerous is an pretty obvious thing to do.
The only time we can say with absolute certainty that radiation was the the cause of death is when a person dies by radiation poisoning, or have spent a large amount of time in near a radioactive material without protection, death resulted from complication of long term radon exposure fall into the latter category. But nuclear accidents are entirely different things, the particles are released into the air, water, soil, it becomes ubiquitous . and complications from high amount of background radiation generally doesn't come to effect for years, or even decades, by then there are so many other factors that it becomes almost impossible to single out radiation as the cause of it. only studies ten, twenty years later can give us an clear idea of it's true damage and even then, it's still just an estimate. that's why no studies right now can claim that this incident will cause death, much less giving it a number. but at the same time no studies can claim there there won't any death related to the incident either. and that why i said "i" believe that death related to the incident will be not be none. Shortened life spans, again there are no way to directly link any complications to the incident, but i can say for sure, because i also read the the WHO report you mentioned, while it did not directly link any cases of death to the incident, it indicated an increase in cancer risks
All solid cancers - around 4% in females exposed as infants;
Breast cancer - around 6% in females exposed as infants;
Leukaemia - around 7% in males exposed as infants;
Thyroid cancer - up to 70% in females exposed as infants (the normally expected risk of thyroid cancer in females over lifetime is 0.75% and the additional lifetime risk assessed for females exposed as infants in the most affected location is 0.50%).
while those numbers are quite small, when you consider the amount of people affected, it will add up. and that directly correlates to some people having shorter life spans. And again this is only an estimate and it doesn't take into account many factors unique to this incident, also remember only 19% of the radiation active particles went on land, the rest went into the ocean.
As for marine life being more fragile, i don't think i need to pull up some scientific paper to explain that, anyone who studied biology will tell you the same thing. but i question about the "all reports" that said the ecosystems are holding up fine you were talking about, because there simply hasn't been many reports on the effect of the incident to the local ecosystem and a comprehensive study is still ongoing , since we were all so focused on humans. but all the preliminary analysis i have seen suggest that this incident's effect to the ecosystems is very serious. but also stated that like to humans, the full effect will not now be shown till years later. i mentioned coral reefs and deformed animal to emphasize my previous point, and it has been proven that some deformities/gene damage and mutations were found in local animals and will be inherited. see Dr. Timothy Mousseau's presentation below.
A finally, all this is just talking about the environmental effect of the incident, we are not even talking the financial, economic or psychological effects right now. so once again, building a nuclear power plant in that location, terrible idea.
and since you did ask, here are some articles you might want to read:
http://e360.yale.edu/feature/radioactivity_in_the_ocean_diluted_but_far_from_harmless/2391/
http://news.discovery.com/earth/oceans/will-fukushima-mutate-sea-life-130828.htm
http://www.livescience.com/22353-mutant-butterflies-japan-fukushima-disaster.html
and if you have time, please watch those videos,
http://www.psr.org/news-events/events/symposium-fukushima.html
they are really informative
and i would like to especially point out
Chernobyl, Fukushima and Other Hot Places: Biological Implication by Dr. Timothy Mousseau
and
The Implications of Massive Radiation Contamination of Japan with Radioactive Cesium by Dr. Steven Starr
Under day 1, Session Two: The Medical And Ecological Consequences of the video.