I live in JP too. This is what the government website is telling me about radioctivity in my area 211km away from the Fukushima power plant as the crow flies in Saitama Prefecture. These readings appear to be supported by many independent sources too. While readings peaked for two 2hr periods at 1.2uSv/h on March 15th, they've remained relatively low. From what I gather; the United states has up to twice this level of environmental radioactivity with apparently no harm. While I'd prefer to see no I-131 and C-137 detectable in my tap water, these levels are obviously not harmful and in fact I-137 peaked at 37 Bq/kg, so the trend is encouraging (nothing like an 8 day half life!). Anyway; I think this may have already been posted on slashdot and while not fully reliable, might help to at least give some perspective on the level of contamination at this stage.
However; in the immediate area (i.e. 30-40km radius from the plant), obviously things are different and it is most likely going to be many years before life is returned to normal - that much is undeniable. Fortunately unlike Chernobyl the reactors have an extra protective casing and have only experienced damage to fuel as opposed to a full meltdown at this stage, but the situation is obviously critical. Although they've restored electricity, highly radioactive water used to cool spent fuel rod pools and reactors has found it's way into turbine rooms where many controls are located meaning they are unable to test what equipment still works. Worse still, this water has also been leaking into the ocean. At least they have changed water used to cool reactors etc from sea water to fresh water, which eliminates corrosion fears, but even this problem will crop up again once they start using boric acid to absorb neutrons.
So basically it's a critical juggling act of keep the spent fuel rod pools and reactors cool, while diverting water from control/turbine rooms & the ocean, all while trying fix/restart in particular cooling systems. Furthermore; trace samples of plutonium were discovered in the immediate location suggesting leakage from reactor 3, which was using MOX fuel.
Even with all that in mind, I'd struggle to see how travelers to China could bring in enough radiation to be harmful unless they'd ignored the 30km exclusion zone and spent a day or two in the affected area before boarding their flight... I also have to wonder how they destroyed their luggage... boric acid bath? It would have knocked any insects they'd inadvertently brought in!
Anyway; I feel our immediate concerns should really be directed toward communities of north-eastern Japan devastated by the massive post-quake tsunamis...
FORTUNE'S FUN FACTS TO KNOW AND TELL: A guinea pig is not from Guinea but a rodent from South America.