A friend in Japan raised questions about the feasibility of underground concrete entrenchment (360-degree entombment) of the damaged reactors at Fukushima No.1 nuclear plant. This fellow pointed out that a concrete seal was successfully built at Chernobyl, even if hundreds of laborers who worked underground later died from radiation exposure. My response was skeptical since Chernobyl's concrete sarcophagus is now cracking apart due to soil settling and internal heat build-up. There is also major differences in soil structure between Chernobyl and Fukushima. Ukraine is a semi-arid steppe with a water table at considerable depth below the reactor. Fukushima No.1 rests on landfill comprising loose rock and sand over the natural seabed and is positioned only a couple of meters above the high tide mark. Water seepage and earthquake-caused liquefaction have seriously disturbed this rather weak soil structure. The carbon reactor at Chernobyl caught fire as the uranium rods melted down, creating a molten lava flow. At Fukushima, however, the quake damage and loss of water from inside the reactors caused many fuel rods to shatter. Broken pieces of uranium fell to the bottom of the reactor cores and melted through their shrouds into the containment chambers. The chemical evidence of slaked lime (calcium hydrate) in the air indicates the rod fragments then seared past the containment shields and burned through the reactor buildings' concrete footing.The continuous release of iodine-131 for more than 4 months in both air and sea water samples also indicates nonstop nuclear fission. Due to the intense heat underground, any concrete poured below the reactors will probably be unable to harden uniformly. Therefore the current strategy being considered by Tepco engineers is to pump polymer resin under the reactors to prevent the inflow of sea water and ground water. Unfortunately a watertight seal is practically impossible to achieve since the rod fragments will melt though this bubble as well. A shocking discovery at Fukushima was that zirconium (used as a "transparent" - allowing passage of neutrons - protective cladding around the fuel rods) when superheated can become a catalyst for an esoteric type of nuclear fission. At extreme temperatures, zirconium ignites even the tiniest quantities of airborne nuclear isotopes, releasing "blue lightning". This means that zirconium catalysis could also be occurring underground, triggering mini-fission events. This sort of nuclear reaction is terra incognita, a yet unexplored frontier of physics, the joker in the deck. Much of the danger comes from simpler processes. Extremely hot magma, consisting of nuclear residues mixed with soil minerals, will boil any sea water seeping underground, creating pressurized steam.Think of oatmeal cooking in a pot and how bubbles create blow holes. The same is happening inside the landfill. The steam-created tubes harden when they cool, leaving lines of structural weakness. Eventually, these air pockets will collapse, and the massive weight of the water-filled reactors, piles of spent rods and their supporting structures will drop into deep sinkholes. If the magma tubes become filled with sea water, the landfill will resemble a gigantic sponge, prone to liquefaction and collapse under earthquake motion. Even the resonance vibrations from large machines could trigger the sudden opening of new sinkholes. Water holds other dangers as well, since it is a better medium for nuclear fission than the mix of stones, dirt and concrete now under the reactors. Once sea water seeps into the newly opened underground channels, the fissile particles will become free-floating and fire neutrons into bits of uranium, plutonium and other isotopes, triggering cascades of fission. The resulting steam pressure is volcanic, bursting out of the ground and spewing vast amounts of radioactive material into the atmosphere. The oatmeal spatters across the stove top. The problem with concrete is that it not only keeps sea water out but also traps any liquid inside the seal. A concrete sarcophagus then becomes a witches' brew of nuclear fission. Entombment of a reactor built on landfill over the seabed is therefore practically impossible. After the reactors drop into sinkholes, the meltdowns could go on for decades. The one possible solution to this apocalyptic scenario is the stuff that propelled Ronald Reagan into nationwide fame as host of GE Family Theater: borax. The alkali salt used in laundry powder consists of about 15 percent boron-10, the neutron-absorbing mineral used in control rods inside nuclear reactors. Boron intercepts neutrons, thereby reducing the number of fission events and thus cooling the loose uranium. Borax dissolves in water, meaning it can be poured into the water seeping underground through turbine rooms and the maze of broken pipes. Around the hot spots, the mineral salt will turn solid, trapping and separating uranium particles. The crystalized borax will fill the steam-created gaps in the soil, strengthening the overall weight-bearing structure. The hard angular crystals can also resist seismic movement, reducing the problem of liquefaction. Borax can be poured into water seeping through the turbine rooms and damaged pipes or inserted through bore holes drilled at an angle under the reactor. This mineral salt as low toxicity, making it safe for the workers, and is harmless if it leaks into the sea. Cheap, abundant and mined in the western USA, borax is the solution for cleaning up an awful mess. If Reagan endorsed it, borax might actually work.