[Petrochemicals]

want to get them inside you or be near them.
I understand what you are saying viz a vi's zapping radiation but it is usually if you injest these particles

I'm pretty sure they are not the ones that are mentioned in the "radioactive for thousands of years" phrase.  Neptunium is another problematic component of nuclear waste and amongst the longest lived. I am not sure of the amount of these transuranic metals dispersed but I think it was quite low due to their characteristics.

https://en.m.wikipedia.org/wiki/Isotopes_of_neptunium

[Bored chemist]

Biological half lives are interesting in their way (it is for example interesting that, though the chemistry of uranium and plutonium are quite similar, their biological half lives are very different.)

Which isotopes in reactor waste are "worst" depends on what you plan to do with them.
It's generally a bad idea to ingest them..

Since they do get produced by reactors, you have to workout what to do with them.
It's obviously bad if they are set free by a melt down.
On that basis radioactive iodine is a big problem. the yield is relatively high, it's trapped rather well in the body- specifically in the thyroid and the half lives of the various isotopes are such that they do a lot of damage.
Equally importantly, it's easy to form volatile and/ or soluble compounds of iodine so it's likely to escape.

By the time you notice that you have a meltdown it's a bit late to do much about it.
A proper containment vessel would be a good idea.
Assuming it survives whatever cause the meltdown, you can then "simply" bury it in concrete.

Then you run into the other problem; the mausoleum.
We simply have no experience of how to build a structure that will last until the long lived isotopes decay.
We can build something which will stand for 300 years- by which time the things that we normally worry about- notably strontium and caesium - will decay.
And we don't need to worry much about things with million year half lives because  their specific activity will be low.

But there's a bunch of isotopes- 239Pu  is usually cited as the example- which will be dangerous over a period much longer than we can plan for (roughly quarter of a million years).

So, it's not so much a matter of "We don't know how to solve the problem" it's a matter of "There are lots of problems and we don't know how to solve any of them."

[evan_au]

radioactive iodine is a big problem. the yield is relatively high, it's trapped rather well in the body-

I have heard that some countries have a stockpile of potassium iodide.
- If you know there is a radioactive release impending (and are prepared to admit it to the population...)
- You can dispense potassium iodide tablets (especially to growing children)
- Apparently, the thyroid, after being given a high does of iodine goes quiescent for a while, and reduces iodine uptake from the diet
See: https://en.wikipedia.org/wiki/Iodine-131#Treatment_and_prevention

Evacuation is another important public health tool to reduce exposure...
- But if you aren't prepared to admit that anything is wrong until the radioactive plume is detected 3 countries away, it is a bit late!

[alancalverd]

Evacuation is not necessarily the best option.

There were several deaths caused by traffic chaos during the voluntary evacuation at Three Mile Island, and none attributable to the meltdown itself. In comparison, the controlled and orderly evacuation of the Chernobyl region did not add to the death toll despite the far more serious nature of the explosion.

The emergency stockpile is usually potassium iodate rather than iodide because it has a longer shelf life.

[Bored chemist]

The emergency stockpile is usually potassium iodate rather than iodide because it has a longer shelf life.

Which is odd- because both are perfectly stable in dry conditions, and you would expect to keep them in closed containers.

[Bored chemist]

- Apparently, the thyroid, after being given a high does of iodine goes quiescent for a while, and reduces iodine uptake from the diet

To a good approximation, it's simpler tan that.
You can easily give someone a gram of iodide.
They will pee most of it out.
If they also inhale a picogram of radioactive  iodide that will mix with the ingested stuff from the tablets.
And, in the same way, they will pee most of it out.

Once the thyroid's  need for iodide is sated it doesn't bother to trap it.

[alancalverd]

The emergency stockpile is usually potassium iodate rather than iodide because it has a longer shelf life.

Which is odd- because both are perfectly stable in dry conditions, and you would expect to keep them in closed containers.

Two conditions that, as we saw with COVID PPE, our wondrous government is unable to guarantee. I recall a happy evening spent with the Home Office Civil Protection scheme where "new" personal dose rate meters were handed out. Half of them did not work, mainly due to contact corrosion. The problem with "emergency-only" stock is that you either have to inspect it every couple of years (expensive, but essential for life rafts and other obviously perishable kit) or ensure that it is indefinitely stable in an affordable and easily useable package (cunning chemistry). Hence KIO3 which should last 100 years or so in a leaky hangar or soggy cave (read "secure emergency store"). 

Sealed polyethylene bag technology is surprisingly modern - the patents are dated from 1965 and vacuum sealing somewhat later - and not all polyethylene grades are longterm compatible with KI in the presence of moisture -  but emergency KIO3 stocks may date from 1957 (Windscale) in "medical" pill tubs. 

[Bored chemist]

Two conditions that, as we saw with COVID PPE, our wondrous government is unable to guarantee.

For the record, our government made the decision not to replace the stock when it went out of date. That's separate bit of  negligence.
There's a point where environmentally controlled rooms to stock rubber gloves cost more than just regularly buying new ones (and dumping the old ones on the surplus market) .
Our government chose to do neither and just cross their fingers.
They call this "doing all they could".

Potassium iodide melts at 681 degrees C; that's fairly stable.
It's on the WHO list of essential medicines.


This option may be useful in emergency situations.
https://en.wikipedia.org/wiki/Portable_water_purification#Iodine

[alancalverd]

Potassium iodide melts at 681 degrees C; that's fairly stable.

Indeed, but it is also deliquescent (guess who spent the sober hours of his youth studying the response of alkali halides to radiation?) which makes longterm storage a bit problematic. 

At the risk of offending the Official Secrets Acts, I can however reveal that HM Government used to keep 5 years' worth of "toilet paper, hard, military and government service for the use of"  in a hangar at RAF Staverton. But that's another story. 

[Petrochemicals]

Potassium iodide melts at 681 degrees C; that's fairly stable.

Indeed, but it is also deliquescent (guess who spent the sober hours of his youth studying the response of alkali halides to radiation?) which makes longterm storage a bit problematic. 

At the risk of offending the Official Secrets Acts, I can however reveal that HM Government used to keep 5 years' worth of "toilet paper, hard, military and government service for the use of"  in a hangar at RAF Staverton. But that's another story. 

In these times of bog roll shortages Alan you run the risk of being hung as a traitor if a sudden looting should happen on HMs W. C. supplies.

[alancalverd]

Not a problem. Each sheet was labelled "official use only", if I recall correctly, so nobody would have dared steal it. And Staverton is now a civilian airport.

[SeanB]

Funny enough about 3 months before Fukushima made KI unobtanium, I bought a 500g bottle of analytic grade KI, as I wanted a coolant system antibacterial that would stop the annoying growth of biofilm that would clog the system of a machine cooler. 50g into the water, and it never developed any biofilm after that, while before the water would, despite the tank being bare brass sheet, and thus dumping prolific amounts of copper in the system, tend to develop a thick biofilm after around 6 months, the film living on the plastic piping and the other plastic parts. Cleaning would mean stripping, and replace all plastic polyurethane piping, and scrubbing all parts in the tank, and then the biofilm would return, even with nearly a kilogram of (expired) methyl paraben as preservative. Yes preservatives with a shelf life.....

After the incident, you could not buy KI for months, all stocks having been bought up by all and sundry, and prices skyrocketed to insane levels. Still got the bottle, though by now it is half empty, the rest having evaporated with time.