A new material that cleans up nuclear waste

March 4th, 2008 - 2:51 pm ICT by admin  

New York, March 4 (IANS) Those opposed to nuclear power because of problems related to the disposal of radioactive waste can now breathe easy - scientists have found a substance to do the cleaning up. Chemists at Northwestern University have identified metal sulphide materials as a possible source for nuclear waste removal.

The new material is extremely successful in removing strontium from a sodium-heavy solution, with concentrations similar to those in real liquid nuclear waste.

Strontium-90, a major waste component, is one of the more dangerous radioactive fission materials created within a nuclear reactor.

By taking advantage of ion exchange, the new method captures and concentrates strontium as a solid material, leaving clean liquid behind.

In the case of actual nuclear waste remediation, the radioactive solid could then be dealt with separately - handled, moved, stored or recycled - and the liquid disposed.

Strontium is like a needle in a haystack: sodium ions outnumber strontium ions by more than a million to one.

The material developed at Northwestern - a layered metal sulphide made of potassium, manganese, tin and sulphur called KMS-1 - attracts strontium but not sodium.

“It is a very difficult job to capture strontium in vast amounts of liquid nuclear waste,” said the paper’s co-authors.

“Sodium and calcium ions, which are non-radioactive, are present in such enormous amounts compared to strontium that they can be captured instead of the radioactive material, interfering with remediation,” said co-author Mercouri G. Kanatzidis.

“The metal sulphide did much, much better than we expected at removing strontium in such an excess of sodium,” he added.

“We were really amazed at how well it discriminates against sodium and think we have something special. As far as we can tell, this is the best material out there for this kind of application.”

KMS-1 works in very basic and very acidic solutions, the conditions common in nuclear waste, and everywhere in between.

The results of the study have been published online in the Proceedings of the National Academy of Sciences.

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