Operating Under Pressure

It appears from the latest report from Fukushima that the people trying to recover from the accident are operating under tremendous pressure while several of the reactor vessels are not according to the IAEA. This is not good news.

The numbers are given in metric but I will translate them to English. First a little explanation is in order: Gauge pressure and absolute pressure. Absolute pressure is just what it sounds like. The reference pressure is zero. Which is to say a vacuum. Gauge pressure ignores (an offset actually) atmospheric pressure. Suppose you are putting air in your bicycle tire. What matters is how much more pressure than atmospheric is in the tire not the absolute pressure. So that is why you have absolute and gauge pressure. Gauge pressures can be negative (below atmospheric) absolute pressures are always zero or positive.

The chart linked above gives two readings (A) and (B). I'm not sure why. I'm going to give just the highest one since it will provide enough information for my purposes. I have rounded the psi numbers for convenience since order of magnitude is sufficient.

Reactor 1 .491 MPaG 71 psi above atmospheric
Reactor 2 -.023 MPaG 3 psi below atmospheric
Reactor 3 .018 MPaG 3 psi above atmospheric

So how do you get a negative pressure? It could be instrument error (including errors caused by cross flows). It could be wind blowing across a hole (like a perfume atomizer). Or it could be things have gone cold and steam is condensing (not a chance in hell unless the core has moved on and that still leaves you with a big hole in the bottom of your tea kettle).

Reactor vessels 2 & 3 are breached. This is confirmation of a report I provided: Still I Look To Find The Reason Why .

How about the containment vessels?

Atmospheric pressure is exactly: .101325 MPaabs or 14.6959 psiabs

Containment 1 .230 MPaabs    33.4 psia
Containment 2 .100 MPaabs    14.5 psia
Containment 3 .1064 MPaabs   15.4 psia

Which says that containment 2 and 3 are breached as well.