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Comment by beaner | Hacker News Reader

Couple naive questions:

1. How does a piece of spent fuel end up in a "grassy bit of ground" outside the reactor? Thought it would have all melted in one big clump in the same spot?

2. Why is Chernobyl still so dangerous if literally ingesting the spent fuel isn't super bad? Or is Chernobyl no longer dangerous?

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For #1, about 5% of the reactor core was spread outside the building through a series of explosions. (which is a large part of why reactors in the western world all have containment structures) So while most of the core is in a couple of mounds within the reactor building, quite a bit got spread around.

Regarding #2, this is a very small fragment, and there are a lot of them around. Eating this wouldn't do much to you, but 10x a day for a year? Hello cancer.

Who would be eating that much of it 10 times a day for a year?

If you were living in that area and eating local food, such levels wouldn't be impossible to hit - especially if you account for the fact that 'grain of sand sized solid chunk' is pretty close to minimally bioavailable, and so you could hit equivalent dosages with significantly less material.

1. There was an explosion (edit: two explosions) that began the incident which destroyed the reactor and ejected matter a significant distance.

2. Chernobyl, IIRC, isn't really so dangerous to visit but you should avoid eating or drinking anything in the exclusion zone. Cesium-137 and Strontium-90 will poison you from the inside out. The latter ends up bio-accumulating in bone.

IIRC the uptake rate of Cs-137 is about 10%. Meaning you only store about 10% of what you ingest. Also, we are SUPER safe when it comes to radiation. No chances. No ifs ands or buts. When it comes to dosage, rad workers already have several safety factors from what we can detect an increase risk of cancer, as it should be.

The sensitivity of our tools for detecting radiation never ceases to amaze me. In some ways it's a problem because most people don't understand just how good we are at detecting radiation. Like, not only can we find it in old bits of wood, we can find it so well that we can tell you whether that old bit of wood stopped gathering radioactive carbon from the atmosphere in 10,000 BCE or 10,300 BCE. We can measure how much radiation you get from the sun precisely enough to tell whether you're living on the first story or the second story of your apartment building. But we still get people freaking out about any headline with the word radiation in it. It's crazy.

I think part of it is that a lot of people just don't know the history or the uses of radiation.

For example the history we wanted to find when other nations were testing weapons. We didn't have satellites (or many) so we had to detect from beyond borders. But radiation doesn't travel very far. Solution? REALLY REALLY sensitive detectors.

Most people also don't know uses for radiation outside cancer therapy. I'd bet you most people don't understand that a PET, CAT, or CT scan is radiation. Let alone that we irradiate food to make it safer. I doubt people know how regulated anything dealing with radiation is, or how many factors of safety are added.

Wouldn’t that also apply to all the wildlife in the area? Are there no animals inside the exclusion zone? I get that cancer rates and birth defects would go up, but that’s a bit different from being poisoned, the implication a lack of survivability.

The exclusion zone is actually resembles a wildlife refuge these days. From reports of the numbers of animals present it seems like human populations are much worse for wildlife than low levels of ionizing radiation and other contaminants from the disaster.

The animals’ populations have rebounded, especially those, like wolves and foxes, who’s habitats are least compatible with humans. Still, mean lifetimes, fertility rates and mean body mass are down, while illness are up. This also applies to some plant species. In no way was Chernobyl a strictly good event for wildlife, just that removing humans took away a very strongly negative factor.

The radionuclides I described won't kill you quickly, but over a period of decades, and, well, it's more of a stochastic death as opposed to a definite one.

It may be that shorter lifespan wildlife just aren't as significantly affected, but I've no idea to be honest.

If a biological process concentrates a radioisotope in something humans consume (let's say a deer), and you eat that deer, you might get a much higher committed dose and a resultant materially higher probability of developing cancer.

1. There were two explosions - the second of which destroyed the reactor core and distributed parts of the reactor structure (including fuel) over the area.

2. That speck of spent fuel is still radioactive enough after 30 years to push most nuclear industry workers over their annual permissable dosage. Chernobyl itself is still phenomenally radioactive - but is far less so than it was immediately after the accident.

Given that half time is 50000 years for some of its content its is not a big surprise.

The dangerous part, and the part that is discussed in the article, is CS-137, which has a half-life of about 30 years. The longer the half-life of something the less radioactive it is.

>>> That speck of spent fuel is still radioactive enough after 30 years to push most nuclear industry workers over their annual permissable dosage. Chernobyl itself is still phenomenally radioactive - but is far less so than it was immediately after the accident.

I was refelcting on this, not the original article and not on CS-137.

I assume the answer to #2 is that there is quite a lot of waste around. Gamma and beta sources are dangerous just being near you — you don’t need to eat them to have a problem.

> How does a piece of spent fuel end up in a "grassy bit of ground" outside the reactor?

There was a pretty huge steam-based explosion, blowing the top off the reactor building and scattering fuel and various debris quite far & wide.

There is a possibility that the first explosion (there were several) was nuclear-based and not steam-based [1] and produced radioactive plasma, but the plasma jets cut through both the bottom and top of the reactor.

[1] https://www.tandfonline.com/doi/full/10.1080/00295450.2017.1...

There was an explosion.

It's not that dangerous. There are people living nearby, it just increases the risk of cancer and other random mutations.

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