There is no such thing as a Chernobyl solution.
There can't be, because the two situations are nothing alike.
Chernobyl was one massive explosion, resulting from a complete meltdown of the core and explosion of the fissionable gases which has no containment vessel to retain them. Exacerbating the problem was the fact that the casing of the fuel rods which housed the enriched uranium pellets were made of graphite. The graphite gave a fuel source for a long burning radioactive fire which spread the residual disintegrated uranium fuel in it's smoke plume. However, most of the radioactive material from the single exploded Chernobyl reactor was spread in the initial explosion. Borax and sand were dumped on top to stymie the radioactive fire.
Fukushima is a meltdown in slow-motion. The ability to cool the ever-trying-to-heat-themselves fuel rods was lost after primary and backup cooling systems went down. The ability to respond to the situation was hindered by the magnitude of the disastrous 9.0 earthquake (Designed for 7.1) and 17m tsunami (designed for 8m). The Japanese firm in charge, TEPCO, also downplayed the potential severity of the incident and responded to the situation with the same nonchalance as the initial press releases, spurning international offers of assistance in the days following the incident.
At this point a few things really set Fukushima apart from Chernobyl. Fuku has 4 reactors in trouble. Plutonium, with a half-life of 24,000 years is in their fuel rods. The plant is on a tiny, highly populated island.
And now as the most dramatic portions of the crisis appear to have passed the focus turns from acute emergency to long-term monitoring and control.
Concrete will not work. There isn't enough, you can't move enough fast enough and place it well enough. There isn't really any reason for it... the rods are going to continue to heat and heat and heat until they melt melt melt. What's the point of the concrete itself? It'll crack, can't cure. Now, I have no idea what this means for melting core material as it reaches thousands of degrees, moving through it's containment (Which they say might have happened due to the presence of plutonium in soil samples, but if it'd really gone down I feel like we'd have seen something more as far as a physical reaction. I think water may be escaping the vessel which is contaminated with plutonium.) and on down... how the corium will interact with soil, concrete... it definitely would react strongly with water, which there seems to be a lot of.
So, let's take the idea behind the concrete solution and blow it the fuck up. Dirt. As much dirt as you can move in as few days as you can move it. The biggest dumptrucks on the island. Build a ramp/mountain around each reactor building, saturate the building wtih borax, and dump and dump and dump that soil. Entire mountains. D-12's. Push the entire nearby landscape right over it.
The worst-case scenario, and it is the worst case until the rods are fully contained/cooled, is a large explosion which ejects the fallout material high into the atmosphere, spreading fallout dust. The massive weight of that soil would suppress any such explosions and any fallout dust would be kept local.
Concrete is not the solution. The most elegant solution is often the most simple. Use the most plentiful and effective material around... soil. A sand fill in the reactor buildings would provide shielding as well as high hydraulic conductivity to keep water moving past the reactors.
Drill rigs should be drilling horizontally under the plant and installing two level of wells: a shallow set to recapture water that moves through the soil and sand topside containment and a deeper set to drop the groundwater table and isolate the groundwater/marine transition from the source of the contamination. If the contaminated topside plume and the GW can be pumped independently (the deep GW wouldn't even have to be stored, simply pumped into the ocean) the dissolved isotopes that are currently seeping into the coastal water can be stopped.