[Enthalpy]

Hello you all!

At Fukushima dai-ichi, where they used huge amounts of water to cool the reactors, first sea water in open-loop, presently sweet water in closed loop, they have "filters" to remove the radio-caesium from the contaminated water stored on the site, but have left the radio-strontium in this waste water.

Why?

Removing strontium as well would have obvious advantages, since radio-iodine (already decayed), -caesium and -strontium make nearly all the radioactivity in the day-to-millenium time span. Presently the site is filled with tall tanks for this water, which leak in the soil and probably in the Ocean: 300t few days ago, brutally radioactive.

Is strontium any difficult to remove from water? Radio- plus natural together.

Or is it because the operation would remove also other ions like calcium, of which (sea) water would contribute excessive amounts?

And if you see a process usable for thousands of tonnes of water, it should be useful!
A crown-something?
Precipitate the calcium first? In a fractional process if selectivity needs it.

Concentrating this amount of waste water to brine must be possible by reverse osmosis, if it helps.
Removing all or part of the (bi) carbonate, as well.

Thank you!

[Enthalpy]

Crown ethers are well-knwon to remove radio-strontium:
http://www.radioaktivitaet.uni-bremen.de/downloads/Sr90corr.pdf
http://www.google.com/patents/EP0216473A1?cl=en

One 1000t tank with 80 million Bq/L contains 0.18mol of ⁹⁰Sr (30 years half-life).
Some C₂₈H₅₂O₈ variation of 18-crown-6 weighs 516g/mol.
That would need 100g per tank - there are hundred plus tanks.

What is difficult in that?
Non-scalable additional hardware?
Insufficent selectivity saturates the ether with calcium?

[Enthalpy]

Since March 2013, a water cleaner was installed at Dai-ichi - I had missed that. It's not the imported initial one that removed mainly caesium from the water, but one produced in Japan that is to remove everything but tritium (difficult to separate from stable hydrogen).

This cleaner called ALPS is presently out of order for some time but is meant as the answer to accumulated waste water, and several more units are expected. Search for:
"Overview of the Multi-nuclide Removal Equipment (ALPS) at Fukushima Daiichi Nuclear Power Station"