It should greatly dissipate and "one" of the radioactive iodides has a half life of only 8 days.
It'll be weeks and months of continuous movement, if the source isn't stopped, that may some cause problems.
0355: Pressure is rising again at Reactor 3, the power station operator says - Reuters. That reactor includes plutonium and uranium in its fuel mix.
0352: The temperature of Reactor 5 is now a growing cause for concern, a Japanese official reports. “The level of water in the reactor is lowering and the pressure is rising,” he says.
http://www.bbc.co.uk/news/world-middle-east-12307698