Fuel debris removal attempt halted at Fukushima Daiichi.

[NNadir]

7. In theory, I don't think it would have made much difference to have done it that way, evaporation, but...

...the rate would have probably been much slower.

It is also possible that the public perception, as silly as it is, would have been worse, since the concentration of tritium in the atmosphere would have been somewhat higher. Rapid diffusion in seawater quickly leads to dilution to even more trivial concentrations.

It has not proved possible to detect tritium in seawater outside the Fukushima reactor since the concentration is very near background.

The water being released at Fukushima is passed through ion exchange resins to remove any other radioactive components, soluble fission products like cesium radioisotopes that may be in the water, again for public perception purposes, as the ocean is way more radioactive naturally than anything Fukushima can do, largely because a naturally occurring isotope of potassium ⁴⁰K is present in vast quantities. It is also in all living things, as potassium is an essential element to life.