As of yesterday the Nuclear disaster in Japan has been upgraded to a 7/7, on par with Chernobyl. It is important to note however, that the radiation released (so far) is not believed to be even close to that of the Ukrainian disaster.
According to CNN, Chernobyl saw a release of 5,200,000 terabequerels of radioactive iodine-131. To compare, Japan has seen a release of 630,000 terabecquerels. So while the total release (so far) is much less, it does put them both at a 7/7 on the INES scale. A 7/7 is defined as:
Level 7 is: “A major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures,” according to the IAEA.
A friend of mine who did not site her source, said she read that IF there was a total meltdown, the level of radiation dumped into the ocean could render the Pacific Ocean as off limits for recreation and food for as long as 25 years. I have no idea if this is at all credible, but if I find any information for or against this statement I will post it. If any readers out there have seen this, please let me know and I will post info on it. I for one have to say I am not sure I believe it would be this severe, but who knows.