Well, this is one way for humanity to learn...
This photo of two of the six crippled nuclear power reactors was shared by a Tokyo Electric Power Company (TEPCO) executive, shortly after the announcement that the remaining 50 workers at the Fukushima Dai-Ichi nuclear power plant on the east coast of Japan had been evacuated, due to "spiking" radiation levels. [LATER: Workers are being "allowed" back into the site now.]
Among the six reactors, TEPCO remains unable to maintain coolant levels in most of the reactor vessels, and in some the spent fuel storage vessels (located in the "attics" of the reactor containment buildings).
There have been fires and explosions and some of the reactor vessels are assumed by TEPCO to be breached. Cesium-137 and Iodine-131 have been detected in the surrounding atmosphere, supporting the breach assumption.
The roofs of several of the buildings have been blown off, leaving the spent fuel storage vessels exposed to the environment. Spent fuel rods, and fuel rods contained within the reactors, have been left uncovered by coolant and exposed to air for varying periods on the order of hours to days. Temperatures of the fuel, spent and otherwise, is climbing, and at least several of the reactors are assumed by TEPCO to be have already begun experiencing "partial melt-downs."
The Prime Minister of Japan has stated that radiation is leaking from four of the six reactors. An area of roughly 250 square miles (area within 20 km radius, halved) with about 140,000 inhabitants according to NHK-TV has been evacuated, and an additional 300 square miles (the band between 20 and 30 km from the plant, halved) has been issued a shelter-in-place order.
Most nuclear agencies regard the evolving situation as the worst nuclear accident since Chernobyl, a Level 6 incident (with Three Mile Island being a 5 and Chernobyl being a 7) and expect it to worsen. Major aftershocks continue to be experienced throughout Japan, both on- and offshore (the second variety making another tsunami possible).
Nuclear engineer Arnie Gundersen said on CNN today that TEPCO has been trying to deal with decay heat of the spent fuel rods, but that without a supply of cooling water, the spent fuel pool could go into a criticality, a chain reaction, making the situation far worse. "It can boil dry in a day." Then "the fuel catches fire, the steel--the zirc-alloy--begins to burn and the [radioactive fuel within] volatilizes and becomes an aerosol, becomes airborne."
One source said that there are 600,000 pounds of spent fuel rods at the Fukushima Dai-Ichi power station, and another report stated that some or all of the buildings are too radioactive for people to enter.
The workers at this site deserve medals, but I have little confidence that they will accomplish their goal of stabilizing the situation. This may well turn into an all-new nuclear "experiment," the likes of which we've never before seen, or even imagined. The stuff of nightmares.