Some dairy farms in Fukushima resume milk shipment

[FBaggins]

Some dairy farms in Fukushima Prefecture have resumed shipping milk after radiation levels in the milk cleared the government's safety standards. The shipments are the first since the Japanese government lifted a ban last Friday on milk from 7 cities and towns in the prefecture.

The restriction was imposed by the health ministry last month after unsafe levels of radioactive substances were detected in milk from areas around the quake-damaged Fukushima nuclear plant.

...snip...

The prefecture will conduct follow-up radiation measurements once a week on milk shipped from the prefecture.

http://www3.nhk.or.jp/daily/english/11_18.html

How could this be true? I have it on good authority that the region will be uninhabitable for decades. They certainly won't be able to use those cows again. Oh how could the government show more clearly that all they're interested in is profits over human safety!?!? :sarcasm:

[FarPoint]

1. I am clueless as to how one cleans up radiation

but I think it takes 10-20 years to do so....not 4 weeks.

[FBaggins]

2. You don't in most cases. You wait for it to go away.

A very high percentage of the radioactive material that has been released has comparatively short half-lives.

I don't know the particulars of the area of the farms mentioned, but I'd be willing to bet that it was primarily Iodine-131, which has a half-life of a tad over a week. Most of that would have been deposited in the first week or so after the earthquake, so those initial deposits are now at about 1/8th of where they started.

There's quite a bit of variability, but that's the general principle.

In the case of some longer-lived isotopes, even 10-20 years wouldn't be enough. Most of the plutonium deposited by the Hiroshima bomb, for instance, is still there.

[FarPoint]

4. Thanks ...that helps.

Now if we get the facts honestly from Japan and the US...I can guess-a-mate the presence of radiation.

[CJvR]

3. That depends entirely...

...on what radiation we are talking about.

Shortlived isotopes like I-131 you don't need to clean up because they will effectively be gone in a few weeks. This seems to be the main radiation source released from Fukushima. Longer lived isotopes like those released from Mayak and to from Chernobyl are an entirely differnt ballgame. The best thing to do is probably to plow it under and let it decay naturally. Unfortunately there are reports of Cesium leaking from Fukushima, although this seems to be several magnitued lower than shortlived isotopes.