Fukushima disaster: Robot finds possible melted nuclear fuel | Hacker News Reader

Fukushima disaster: Robot finds possible melted nuclear fuel

bbc.co.uk

63 pointslouthy31 comments

It is great to see this issue (which is a pet one of mine) given fair context. I'm really glad to see someone juxtaposing:

- "...the most serious nuclear accident since Chernobyl..."

- "More than 18,500 people were killed ... when an earthquake triggered the massive tsunami ..."

- "No-one died directly in the Fukushima disaster."

Not that it isn't a disaster; just that the disaster, in context, wasn't the biggest deal that day.

18,500 dead for a single weather event is a disaster by any measure.

Additionally the 2011 Fukushima reactor failure is the worst nuclear accident since Chernobyl which means it is the second (or third) worst nuclear accident in history. [0]

What do you mean by "the disaster, in context, wasn't the biggest deal that day"?

I'm not trolling. I honestly cannot understand what you are trying to communicate.

Are you diminishing the magnitude of the disaster? If so, you haven't yet presented anything to warrant the designification of the tsunami and subsequent Fukushima reactor failure.

[0] http://www.ucsusa.org/nuclear-power/nuclear-power-accidents/...

EDIT: Add link and parenthetical "(or third)".

I think roenxi is referring to how the Fukisima nuclear accident wasn't the biggest deal that day, as the tsunami had a far greater impact (0 vs 18 500 direct casualties, respectively).

No worries. I see two separate disasters here, both linked. The first an absolutely devastating weather event that killed more people than live in my home town in it's entirety + caused massive damage, and secondly the Fukushima nuclear disaster (which seems to be treated separately in many cases, which the article is about and which my comment was directed at).

In my experience, many people & journalists hold Fukushima up as a really bad disaster. I'm trying to communicate that I don't think that Fukushima was a disaster that warranted international coverage - the weather was.

At an international scale, I don't think Fukushima is much worse than a near miss. I would be really interested to get an expert academic order of magnitude on how many people died in the evacuation due to the Fukushima disaster vs. the theoretical number of deaths if they had evacuated more slowly (say over 12 months). It frustrates me that the cost-benefits of the evacuation aren't a more prominent point of discussion.

EDIT: Just for fun; I can't pretend I know anything about radiation or what the Japanese are up to; but on wiki I see things like "absolute increase in the risk of cancer(of all types) during their lifetime, of approximately 1% due to the accident" [1], " Life expectancy of the evacuees dropped from 65 to 58 years ... because of depression, alcoholism, and suicide" [2]. I'd like to know who I can turn to for an honest rundown of the risks, because the radiation doesn't seem that terrible.

[1] https://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disa...

[2] https://en.wikipedia.org/wiki/Japanese_reaction_to_Fukushima...

From wikipedia:

"but 34 people died as a result of the evacuation" [1].

I'm not sure I can agree that Fukushima isn't an internationally noteworthy incident. It's even one that really requires long term monitoring of radiation levels (locally only of course).

Many mistakes were made in the handling of the Fukushima reactor and accident. Radiation accidents have the potential of be massive disasters. It's important to learn from Fukushima, and not just treat it as an "acceptable cost".

[1] https://en.wikipedia.org/wiki/Fukushima_Daiichi_nuclear_disa...

I don't think they said it wasn't noteworthy.

Didn't they thought?

I'm trying to communicate that I don't think that Fukushima was a disaster that warranted international coverage - the weather was.

I guess you could draw a distinction between the terminology each post used, but it reads the same to me.

> At an international scale, I don't think Fukushima is much worse than a near miss.

The International Atomic Energy Agency (IAEA) seems to disagree. They have a very particular rating system for nuclear incidents, and rated Fukushima at highest level 7 ("Major accident"), much above "accident with local consequences" (level 4) or "anomaly" (level 1).

As Fukushima could have been avoided with more careful engineering and caused long-lasting damage to property and the environment on a wide area, I think it's good that nuclear experts take it seriously enough.

I appreciate your reply and your explanation of assessing the human casualties due to the tsunami separately from the deaths due to the reactor failure. Thank you.

Comparing the Fukushima reactor failure (due to the tsunami) to deaths from the tsunami and concluding the reactor failure was "not the biggest deal that day" seems somewhat of a non sequitur.

That is, the tsunami had two immediate effects and many people feel both are worthy of international attention and historical comparisons.

To my mind, the loss of life does not make the nuclear reactor failure relatively inconsequential. For me, they multiply the crises caused by the tsunami.

I understand how you can arrive at your assessment, but I believe that assessment is based on a comparison that compartmentalizes events a bit too rigidly.

EDIT: remove extraneous word.

What weather event are you two talking about?

> I don't think that Fukushima was a disaster that warranted international coverage - the weather was.

Be reminded that this was a geological, not meteorological, event.

I believe roenxi meant, "the [nuclear] disaster, in context, wasn't the biggest deal that day"

They're referring to the fact that the reactor meltdown at Fukushima is the newest addition to the list of incidents that 'prove' that nuclear fission energy is bad and should be banned. They're glad that the reactor meltdown is juxtaposed to the real disaster (in terms of human life lost) namely the earthquake and the tsunami itself. So that people place the reactor meltdown in the correct category: 'bad, but not a terrible earth-shattering disaster of epic proportions'.

Hopefully the poster will reply themselves but...

I think they mean that the nuclear accident, wasn't the biggest disaster that happened that day. It is pretty amazing, that a nuclear accident, that's the biggest accident since Chernobyl, wasn't the biggest disaster that was cause by the tsunami.

It is absolutely true, that the impact of the tsunami, and deaths it directly caused, was much bigger than the nuclear accident itself.

The nuclear accident itself caused no direct casualties. Its impact has mostly been that on the local population that was evacuated (which has of course caused much pain, and economic disruption).

I'm interested in how this robot "survived" the radiation levels that many previous robots did not [1]. I know little to nothing about radiation hardening, but this seems like an almost impossible task, considering it being exposed to more than 530 sieverts per hour [2], which is the highest radiation level ever recorded.

[1] http://gizmodo.com/excessive-radiation-inside-fukushima-frie...

[2] https://www.sciencealert.com/radiation-levels-in-the-fukushi...

Water absorbs radiation really well. https://what-if.xkcd.com/29/

It's amazing to me that we're six years in now and essentially no progress has been made on cleanup beyond simple containment and mitigation. I suppose Chernobyl isn't particularly any different in that regard either.

In March, the NYT published an article discussing the accumulation of contaminated water from the failed Fukushima reactor. [0]

At the time of writing, 400 tons per day of contaminated water were being collected and officials were concerned that storage for the water might run out.

Alarmingly, one possible contingency was to dilute the collected contaminated water and dump it in the ocean.

Excerpted from the article:

  > But the decontamination filters cannot remove all the
  > radioactive material. So for now, all this water is being
  > stored in 1,000 gray, blue and white tanks on the grounds.
  > The tanks already hold 962,000 tons of contaminated water,
  > and Tokyo Electric is installing more tanks. It is also
  > trying to slow the flow of groundwater through the reactors
  > by building an underground ice wall.
  > 
  > Within a few years, though, and no one is sure exactly when,
  > the plant may run out of room to store the contaminated
  > water. “We cannot continue to build tanks forever,” said
  > Shigenori Hata, an official at the Ministry of Economy,
  > Trade and Industry.
  > 
  > The authorities are debating whether it might be acceptable,
  > given the relatively low radioactive levels in the water, to
  > dilute the contaminated water and then dump it into the
  > ocean. But local fishermen are vehemently opposed. Many
  > people still do not trust Tokyo Electric because of its
  > bungled response to the disaster, the worst nuclear accident
  > since Chernobyl.

[0] https://mobile.nytimes.com/2017/03/11/world/asia/struggling-...

My understanding, which is limited, is that it's not as alarming as it sounds. The water is "contaminated" with tritium (really, the water is composed in part of tritium), which has low bioavailability. Much more importantly, however big a number "962,000 tons" sounds like, the ocean is vast, on a whole different scale from anything amount of water humans can manipulate directly.

If the liquid was radioactive sludge that would could settle at the seafloor or clump up and ride the top of the waves like an oil slick, dumping it would be untenable. But tritiated water is literally just water; it will quickly dilute back down to the ambient radioactivity of the ocean.

I'm not saying I approve of them dumping HTO into the ocean; I'm just saying it may not be as terrible as it sounds.

The half-life of tritium is also only 12.3 years. So you're not creating a permanent problem by dumping it, and the longer you leave it sitting around in tanks, the less the problem is when you do dump it somewhere.

Tritium is rare enough that it seems like they'd be better off trying to harvest it than dump it. You can't extract tritium form water like you can deuterium since tritium is rare in nature. Typically you need a breeder reactor (like Watts Bar Nuclear) where you bombard lithium in order to generate tritium.

I don't think there's some huge unmet industrial demand for tritium, though, and even if there were, it'd probably be more cost-effective to simply breed it out using an existing reactor in controlled circumstances than to try to distill it from millions of tonnes of radioactive wastewater.

And unlike helium, it's not worth stockpiling tritium now if you don't have immediate uses for it, as it decays in storage.

Much more importantly, however big a number "962,000 tons" sounds like, the ocean is vast, on a whole different scale from anything amount of water humans can manipulate directly.

https://en.wikipedia.org/wiki/Ocean#Physical_properties

The total mass of the hydrosphere is about 1.4 quintillion metric tons

Written out in full, that's 1,400,000,000,000,000,000. 962,000 is roughly 0.7 parts per trillion of that.

And tritium has a short half-life, too. It'd be interesting to calculate how many tonnes of tritiated water at the same concentration as Fukushima's could be dumped into the ocean per day and be diluted enough to have no meaningful biological effects. It's probably a huge number.

It's just the downside of nuclear reactors. When they go pop like this there isn't much you can do to meaningfully clean up, when everything, everywhere is filthy with radioactivity.

Chernobyl is still in use though. At least the reactors which weren't damaged. But only thing that could be done would be putting the radioactive material from one hole to another.

The last operational reactor in Chernobyl was shut down in 2000.

There were originally four reactors. It was reactor 4 that exploded; the three remaining reactors were kept operational for many years.

As far as I know, the contamination from Chernobyl has been stopped as soon as they built the first sarcophagus in November 1986 [1]. It was meant to be temporary and the new one was finished in 2016 [2]

[1] https://en.wikipedia.org/wiki/Chernobyl_Nuclear_Power_Plant_... [2] https://en.wikipedia.org/wiki/Chernobyl_New_Safe_Confinement

It hasn't been "stopped", it's simply been contained. Said containment needs ongoing monitoring and maintenance.

Have there been independent assessments of sea food safety in Japan? Not that I don't absolutely trust the government on this...

EDIT: Linked at the bottom of the article - http://www.bbc.com/news/av/world-asia-39140871/checking-radi...

Also from that video: https://blog.safecast.org

This was studied far from Japan but fish off the Oregon coast have certainly remained safe to eat.

https://whatisnuclear.com/resources/fish_from_fukushima.html

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