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Comment by CydeWeys | Hacker News Reader

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.

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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.

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.

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.

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.

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