MrEmjoy

Some of the idiotic comments from youtube and Facebook are amazing:

Michael

I doubt that. You can't just open the doors of the containment vessel and run a fire hose. If they did, all the gases from the reactor would escape to the environment and the containment vessel would be rendered useless. I wonder if that emergency capability was already built into the plant.

Apparently the way the reactor is normally cooled is that water is pumped through a closed loop through the reactor inside the containment vessel and that water is cooled by ocean water which is circulated from and to the ocean. Even this I don't quite understand since it would seem that the circulation of ocean water would make the containment vessel vulnerable since there would be pipes that pass through the containment vessel reducing the integrity of the containment vessel.

paddingtongreen

The containment is a building or chamber and must have pipes passing through it since the reactor vessel is inside the drywell. The instrumentation passes through to the habitable part of the building for monitoring and control.
This may give you a better look.

The first nuke that I worked on was one of these BWRs, in North Carolina.

Michael

I understand that water pipes have to run through the containment wall but I don't understand how the containment wall can prevent leakage if a meltdown occurs with a massive pipe is running through the wall. It would seem that the pipe would be the weak link in the wall and wouldn't be able to withstand the pressures and heat generated during a meltdown.

Do they have a way of sealing off the pipes with a massive value if a meltdown occurs? It would seem that the value would need to be as thick as the containment wall and have the same melting point of the wall to not compromise the integrity of the containment vessel.

MrEmjoy

Pile all that on a surface that can turn into jelly at the tip of a hat and it's all suddenly, not so safe anymore.

paddingtongreen

This may explain the system better. The pipes are very strong for their size, they do not have to be as thick and strong as the containment to survive.

From: http://www.world-nuclear.org/info/inf32.html

The pressurizer works like an expansion tank, it is from there that they release pressure in the reactor when it is in trouble.

dinosaur

This and this from the Register seem to provide some insight.

Michael

Not much in the link to describe the detail but just an overview. Even the containment vessel does not seem to have a high enough melting point if a total meltdown occurs. According to the link, the containment vessel is made of steel which typically has a melting point of between 2600-2800 F and other links indicate temperatures in the core can reach 3400 F during a core meltdown. Maybe there is some steel alloy that has a melting point above 3400 F or they are now using radioactive materials that won't reach those temperatures.

I suspect that during a total core meltdown, pressures are probably not a major problem since there isn't any water in the vessel to produce pressure. Now they have to release that built up pressure since steam is being produced that can't be condensed.

Those links describes the current situation in Japan which are probably currently level 4 failures. Three mile island was a level 5 failure which had major core damage but didn't result in a complete core meltdown and had a limited lrelease of radio active material. Until there is a complete core meltdown that remains at a level 5 failure, we won't know if the containment vessel can contain the meltdown. If it hits a level 6 (Kyshtym) or level 7 (Chernobyl), that means the containment vessel was breached.

Scouse Express

One questions the wisdom of building so many Nuclear Facilities in area prone to big Earthquakes and Tsunamis.

What the F*** were they thinking?


Jim.

SultanOfSwing

Very well balanced and informative articles you posted there. These should be required reading for everybody so they can educate themselves about the engineering and physics principles at work here and ignore the scaremongering by the largely uneducated denizens of the news media.

In fact the only sensible thing I heard regarding the news about this was from a weatherman who stated that this was 'not going to be another Chernobyl'. Of course, being a scientist, you'd not expect any less

Instead of crediting the Japanese people for their resilience in the face of disaster, and their ability to handle the situation and keep things under control during what must be unmeasurably stressful times, they concentrate on the usual scaremongering and crying wolf. I'm sorry but I find that to be inexcusable, and another reason why once the weather and the traffic report is done, I ignore the news and go do other things.

My hat is off to Japan on this one - they are handling this so much better than a lot of other countries would IMHO. There were terrible losses of course, but it could have been so much worse.

N1cky

Agree with you here Sultan, the situation is horrendous and they seem to be dealing with things the best they can, alot better than most countries would.

Hubby has just sent me an email saying his company have made a $2.5m donation and will match employee donations up to another $1m. It's a nice gesture, but its like a drop in the ocean really isn't it.

SultanOfSwing

True, but at least they are doing what they can to help.

dinosaur

Unfortunately, it's their job - let's be honest, "Nuke power plants safety mechanisms on the whole working" isn't going to sell as many ads as "Meltdown Catastrophe May Be Underway".

Sally Redux

They take a gamble.

SultanOfSwing

Aye, such is life I suppose. Wasn't always that way - I was watching on YouTube last night a video of when they landed a 727 at Meigs Field in Chicago so it coule be put on display at the Museum of Science and Industry (needless to say the short runway at Meigs made for a tricky landing). The pilot on the day had put together various news clips from local Chicago stations and they reported the event with the right mix of info and enthusiasm.

Something tells me if it was done this year (and let's assume that numpty Daly hadn't closed Meigs Field in the meantime) that they would have done something more like "Passenger jet narrowly misses Hancock building and rush hour traffic on Lake Shore Drive for emergency landing on private airfield. Latest reports say health care reform and stem cell research is to blame. More at 10."

[/sarcasm]