Talk:KBS-3

Comments
I had to stare at this for a long time to figure out what is meant by After 100.000 years of storage, the radioactivity level of the waste is at the same level as that of uranium ore.

I think it's probably true (allowing for the European numeral, I'd write 100,000 years), in fact I'm surprised it's such a low figure now that I think I understand it. But it's also true that after less than 3,000 years the waste will contain less radioactive material than the ore bodies did. How can these both be true?

I think the trick is that the article as it stands is talking about the level of radioactivity of encapsulated, intact PWR fuel elements, which have quite a high uranium content even allowing for the encapsulation material. These fuel elements are much smaller than the ore bodies that were mined to produce them, which are typically much less than 1% uranium (0.20% of oxide by weight is rich, 0.05% has sometimes been commercially viable depending on the market). So, by the time they have decayed to the same level as these ore bodies, there will be much less radioactive material left in them than there was in the ore bodies when they were mined.

It may even be that at the 100,000 year mark the level of radioactivity is at a minimum, and then increases for a while! That could explain why it's such a low figure. These things happen. For example if you want to dispose of an unused fuel element, its current level of radioactivity is harmless, you could stand beside it without danger. But in a few hundred years time when the U-235 decay products that were separated from the uranium in the mill and refinery have built up again, standing beside it will be very quickly fatal. (Thorium is even worse.)

I'm not quite sure how or even whether to incorporate any of this explanation into the article. As it stands I think it gives a needlessly conservative picture of the period of time for which we need to keep the waste out of the environment, although not quite as bad as some others admittedly. Andrewa 16:26, 27 Oct 2004 (UTC)

I think the 100,000 year uranium ore comparison is a bit deceptive. It doesn't count the decay products left in the ore, or the depleted uranium left in permanent storage. However, this indicates that at 100,000 years, the stuff is comparable in toxicity to many things one might find in the ground, such as uranium ore, arsenic or mercury deposits, etc.

More seriously, I believe that KBS-3 is a proposal, not a working repository. According to http://www.uic.com.au/nip39.htm, updated 2004oct, "Research at the Aspo Hard Rock Laboratory nearby is well advanced towards identifying characteristics for this final deep repository. Site selection procedures are also well advanced, and two municipalities have now voted to be candidate locations for a deep geological repository."

pstudier 01:09, 2004 Nov 30 (UTC)

BTW, I believe that they measure radioactivity in curies, or becquerels, not mass. This is approximately correlated with toxicity. pstudier 01:14, 2004 Nov 30 (UTC)

I went out on a limb and changed it to future tense until I see a reference that it is operating. The link given appears to be broken. pstudier 01:21, 2004 Nov 30 (UTC)