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Comment by jedsmith | Hacker News Reader

Multiple nuclear engineers on Hacker News have written that the situation is, effectively, far less dire than Three Mile Island. All of them have said there are still options and time before core damage is even on the radar. You're scaring a lot of people for no reason.

I trust Bob the self-proclaimed nuclear engineer on HN more than CNN, anyway, even though I have no idea Bob is who he says he is.

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My post was before the nuclear engineer appeared on this thread and my sources were the publicly available ones, which portrayed things rather grim.

Maybe i was not very subtle, but you must understand that i too am scared, having experienced the Chernobyl events and the aftermath (European here). But most of the downvoters don't even know what that feels like. Did i over exaggerate my worries? Perhaps. I'm not known to be an overly optimistic person.

Thanks for giving me the chance to reply.

Chernobyl was a result of Soviet disregard for safety and human lives, not nuclear power.

Chernobyl was the result of a systemic failure too complex to sum up in one sentence.

The downvotes are undoubtedly because there is far too much FUD around nuclear reactors, and detractors invariably point to Chernobyl and suggest that it's the inevitable consequence of using nuclear power. In fact, the nuclear reactors in use nowadays are very different from that one in ways that effectively prevent another disaster of that type.

Basically, it's a huge shame that such a useful technology is demonized due to the Soviets' shoddy workmanship, so supporters of nuclear power respond very harshly to things perceived as fearmogering.

One of the fundamental reasons that Chernobyl occurred lies in how that reactor was designed. Russian nuclear reactors were designed to be over-moderated, while modern power reactors are under-moderated.

The moderator is the substance which slows down the neutrons to a speed where they're likely to fission with the Uranium-235 in the fuel. This is typically water. Water can also absorb neutrons, so it has a poison effect as well. When the moderating effect of the water dominates its poison effects, the reactor is said to be under-moderated. When the moderator is reduced (for example, when it boils away), the reactor becomes less efficient, so it reduces power. This is called a negative temperature coefficient.

The Soviets, however, designed their reactors to be over-moderated, for efficiency. Thus, when the water heated up, and started boiling away, the net result was to increase the efficiency of the reactor (a positive temperature coefficient), since the water was more of a poison than a moderator. Because the reactor is now more efficient, it got even hotter, and boiled more water away. You know the rest.

We've learned a lot about designing safe reactors since Chernobyl, and it's extremely unlikely that an accident on the scale of Chernobyl will happen again (not only because of the moderation issue).

I hope this helps to alleviate your concerns. If you have any further questions, please feel free to ask me.

What was so bad aboout Chernobyl?

Just for comparison:

According to Wikipedia (http://en.wikipedia.org/wiki/Chernobyl_disaster): "It is estimated that there may ultimately be a total of 4,000 deaths attributable to the accident, due to increased cancer risk."

According to http://nextbigfuture.com/2008/03/deaths-per-twh-for-all-ener...: In the USA about 30,000 deaths/year from coal pollution from 2000 TWh.

So in the USA each year 7.5 times more people die due to the use of coal energy, than all of the people who died due to Chernobyl.

Unfortunately there is a irrational fear of nuclear power in most European states (and also the rest of the world). It seems that most people would prefer climate-damaging coal energy with a higher fatality-rate per year, compared to relatively safe nuclear energy with an extremly low fatality rate per year (even if you count in the accidents that happen every now and then).

And let's face it: If Japan would replace nuclear energy with other energy types, then a large percentage of those replacements would be coal (as it impossible to obtain all the required energy from renewable sources with today's technology).

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