Vitamin B12 is entirely able to be sourced from a plant based diet. In fact, it has been stated by professional nutritional doctors that it is entirely incorrect to state that meat eaters are more able to typically source B12 than plant eaters - this is partially due to high levels of antibiotics typically found in commercial meat which affects the bacteria involved.
B12 is present in soil and on the surface of plants that have not been commercially processed.
You can claim that you don't need dietary fiber, that's fine - but the science disagree with you.
Yes, B12 can be found in plants, but not in those normally found in a western diet. That is why for example the Vegan society tells you to take supplements.
Again the japanese have it good here: nori algea have a lot of B12. shiitake a bit. So eat sushi ;) nori is really good stuff.
Unfortuantely, the ongoing fukushima disaster means that it is wise to avoid ingesting things from the ocean, particularly from asia.
The hypocrates institute in America runs nutritional education courses and make clear that the main issue for us is not so much in sourcing B12, but in absorbing and using it. That process is one which requires adequate amounts of other nutrients that many are lacking. Other doctors I have listened to have said that the idea that vegans cannot source B12 is based on old data which has been shown to be inaccurate with more modern scientific methods and equipment. None the less, we only need a tiny amount in a lifetime anyway, so a good vegan B12 supplement is simple enough to use and access. That said, there are several forms of B12 supplement and to my understanding, only one of them is actually beneficial - the ones typically found in supermarkets and other shops are not particularly effective and may even be counter productive.
As an aside, the only person I know that has been prescribed a B12 supplement is my dad and he is a meat eater who avoids fruits/vegetables.
Yes, the B12 absorption is problematic. Still it are 75% of vegans that have B12 problems, not 75% of meat eaters ;)
Regarding Fukushima I am not so sure. It depends wher the stuff gets transported and you get the nori from.
For the average ocean the bomb tests on the bikini islands etc. should provide more radiation then Fukushima.
btw. here in Germany it is still warned to eat more then once per week of fungi you got out from the woods. Some of them are still XX times more radioactive then the max. allowed (for stores) amount because of Chernobyl.
I don't know how good nori is in absorbing radioactive materials, but the shiitake are probably more dangerous.
Any figures produced for B12 need to be carefully sourced because, as stated, there is disagreement and claims being made by qualified individuals that measurements from older date is flawed. Here's a page that contradicts totally the 'accepted wisdom': http://www.vibrancyuk.com/B12.html
I don't know enough about the radiation figures involved to compare fukushima to any other event, I just know that given a choice of eating radioactive things or not - I will choose not!