he says the procudures do not match what they are publicly saying. He does not disagree with what you said though. He says he doesn't know what they were experiencing but even at 3 mile island they did not vent it went out the stack. But then again they weren't hit by a tsunami.
OK, I think that I may have sorted some of this out. If you want, run this by your friend and s if it makes sense.
In a loss of coolant situation, the reactor vessel is either receiving no recirculating coolant or too little. In this case, the water level in the reactor vessel begins to drop. In the event that this occurs, an emergency procedure can be carried out where the reactor vessel is vented to the primary containment. Steam that has been in contact with the reactor core then flows into the primary containment.
The primary containment is comprised of two components: the dry well and the wet well. The wet well is a torus-shaped reservoir that sits under the reactor vessel. The reservoir is filled with a very large mass of water. In the event of an emergency, the reactor vessel is vented through pipes than run down into the wet well. Thus, the reactor's gas is vented through this water, where it then percolates up, exchanging heat with the torus' water reservoir. This is probably what your friend was referring to - in the vent of an emergency with insufficient coolant, they would vent to the primary containment.
The large mass of water in the wet well of the primary containment can condense a lot of steam before its temperature climbs to high temperatures. This buys the reactor operators time to establish backup cooling. However, if this doesn't happen or if the coolant supply rate is insufficient, then reactor coolant continues to flash into the dry well, where it is fed to the wet well through standpipes, continuing to heat the water in the wet well. Eventually, this will get so hot that it will begin to boil, pressurizing the primary containment structure.
In the original Mark I design, this was it. If the accident continued, then there was a roughly 90% chance that the primary containment structure would over-pressure and fail.
Some years ago, this was recognized, and Harold Denton (director of the NRC office of nuclear regulation at the time) campaigned for modifications to the Mark I design. The primary modification was the addition of an emergency vent system that would allow the primary containment vessel, if dangerously over-pressured, to be vented to the secondary containment housing. Here, it can be filtered to remove any radioactivity and vented to the atmosphere. There is even (at least usually) a hydrogen removal device that is basically a hot electrical filament that will ignite any hydrogen in the feed and convert it to water. However, if electrical power is spotty due to the accident, this might not work. It was likely at this point that hydrogen began to build in the secondary containment structure...this ultimately led to the explosion.
All of this isn't so bad as long as the water level in the reactor continues to cover the fuel rods. However, when the rods are uncovered, they hat and melt (not a meltdown) and release some radioactive material that builds up between the fuel pellets that are encased in the (now melted) fuel rods. This material, such as cesium, can then be vented in the primary containment, and ultimately the secondary containment, if pressures get too high. This is what happened in Japan in reactors 1 and 3.
If you have the time, see if this makes sense to him....
What has happened in reactor 2 could be worse. This part is speculation on my part at the moment, but what may have happened is that the pressure could not be relieved and thus the protective measure that Denton had pushed for was no longer operable. If this happened, then it is possible that the pressure built to a point that either the reactor vessel or primary containment failed due to over-pressure. Hopefully as more information comes out, my reasoning will prove to be incorrect on this last point.
