If these graphs are trustworthy, then there are two still-developing situations, although both are moving slowly, and neither looks like an emergent problem in the short term. But in dealing with previously damaged systems, all bets are off.
The pressure in the core of Fukushima Daiichi number one continues to rise, while the drywell pressure falls. The rising pressure is disturbing even though it is just approaching 1,000 kPa, which is about ten atmospheres. We have seen these vessels performing well in excess of 6,000 kPa, and at the rate the pressure is rising, that would be weeks from now even if it continued in a linear fashion, which is unlikely. So as a raw amount of pressure, it is not alarming, but the fact that it is rising at all is a problem which will have to be solved somehow.
The silver lining in this case is that at least we may presume that the core vessel remains intact. Hard to contain ten atmospheres in a cracked vessel.
This brings us to the other developing situation. Reactors two and three are both utterly flatlined at one atmosphere, drywell and core. This implies that like a flat tire, it won’t hold any pressure because its insides are said to be “communicating” with what’s outside. The fact that the drywell and core in number two have reached the same pressure suggests that no isolation is possible or at least currently in place between the two formerly separate environments. The fact that they have converged at zero difference compared to the outside world strongly suggests that there is no containment anywhere in reactor two, and that the same hold for reactor three, which has the same readings.
On the other hand, it could well be that some of the sensors are unreliable. There’s a great technical term referring to measuring equipment which is no longer trustworthy due to likely damage: deranged. I suppose this means that the equipments reading can no longer be reliably plotted against a known range, as the calibration is suspect. But the other connotations of “deranged” work just as well here. One imagines a little meter staggering around the reactor trying to shake it off after an explosion.
For example, the torus pressure sensor in number two has no readings plotted after the explosion for that reactor (each one has exploded, for those keeping score at home). This is consistent with the widely-held suspicion that the explosions was in the torus. This is thought to have caused direct leakage of highly radioactive water and to have preserved the upperworks of the building, which were destroyed by explosions higher up in numbers one and three. I suspect a similar but limited effect at work in number three, where despite the core and drywell having converged and flatlined at one atmoshpere, the torus for some reason seems to have flatlined at nearly two atmospheres.
I find this unlikely, albeit without any real technical knowledge, and I posit that the sensor in that torus is reading high. I believe it is right in there with the others at zero difference from the outside world. Another possibility is that one way or another that sensor is now underwater and is reporting the added weight of water as pressure. Since water pressure (in sea water, which we will assume to make this easy) increases by one atmosphere for each added 10 meters of depth, and the drywell pressure reading is 180 kPa (a.8 atmospheres), I feel reasonably confident that if it’s due to water, it’s because the water level is now eight meter above the torus pressure sensor. Assuming that the sensor is in the torus but at the top, that would put the water level at just about the bottom of the core vessel. Implications there I don’t know.
So the pressure is rising in the number one core vessel, but falling in the drywell, and the second and third reactor have become one with the atmosphere. Two is putting radioactive water into the ground, while three seems to hold its water.
None of that addresses that spent fuel pools, which I believe is where all the airborne particulates have come from. Not sure.
Finally, I cannot describe my admiration for those brave men who are fighting fire, flooding, earthquakes, radiation, hunger, darkness, fatigue, thirst, and despair.
