Flip on the news 8.8 quake in Japan

[Hemlawk]

The dose levels are lethal in the reactor building. Water needs to be pumped up 100' to cool the rods, that requires power. Most plants have an emergency pump that runs off gas or diesel but if that got ruined by the quake, there's nothing they can do.

Their best bet now it to dump concrete onto the rods and entomb the fuel.

Those 50 workers who stayed behind will be dead soon. :(

[2ndgenz28]

Originally Posted by Milk 1027

that's what I mean. They have to pump the water into them. I'm just trying to understand the functionality. Wouldn't it be easier to have some sort of flood gate that automatically opens when everything else fails?

If I had to bet id say its all down to money, why places like that cut corners.
And it don't happen jsut there. [our local one almost blew from cutting corners for cost[acid leak for years eatin through the dome]]

Id bet that those higher up were just ignoring everyone and was only thinking about how to salvage as much as they could, which meant not flooding anything like they could have real easy early on.

[8cd03gro]

Originally Posted by Hemlawk

The dose levels are lethal in the reactor building. Water needs to be pumped up 100' to cool the rods, that requires power. Most plants have an emergency pump that runs off gas or diesel but if that got ruined by the quake, there's nothing they can do.

Their best bet now it to dump concrete onto the rods and entomb the fuel.

Those 50 workers who stayed behind will be dead soon. :(

True heroes.

They can't just flood the facility because of the destruction it would cause to containment materials. Sea water on extremely hot metals is super corrosive. There are still daughter products decaying AKA there are still minor fission reactions happening within the reactor core. That lingering heat generation means if they flooded the chamber and it were to fall apart and drain, there would just be more problems. I really don't know all the details of the reactor, but it should only be putting out between 0.3% and 0.4% of it's full potential heat output by now from residual daughter reactions, but I guess that would be very problematic if they were to lose containment, on top of the fact that would expose more radioactive material to the atmosphere. I only have a very basic understanding of the reactor here, but that's what I'm understanding from what I've seen. Feel free to correct me if I'm wrong.

[DGthe3]

Originally Posted by Hemlawk

The dose levels are lethal in the reactor building. Water needs to be pumped up 100' to cool the rods, that requires power. Most plants have an emergency pump that runs off gas or diesel but if that got ruined by the quake, there's nothing they can do.

Their best bet now it to dump concrete onto the rods and entomb the fuel.

Those 50 workers who stayed behind will be dead soon. :(

I've wondered about an emergency system similar in concept to how fire sprinklers work. Triggers automatically to above normal heat, with its own source of water stored in an on-site tower. It would be a last-ditch system but at the very least, it should be enough to stave off disaster and buy time for emergency workers to get things under control.

[kwicslvr]

Originally Posted by Milk 1027

that's what I mean. They have to pump the water into them. I'm just trying to understand the functionality. Wouldn't it be easier to have some sort of flood gate that automatically opens when everything else fails?

Not sure how BWR's are set up in the US but all PWR's have a safety system call Safety Injection. These are essentially gigantic storage tanks located around the reactor that will dump borated water on ther reactor via gravity drain and flood the containment area and cover the core. In a case like this.

[Zabo]

Originally Posted by kwicslvr

Not sure how BWR's are set up in the US but all PWR's have a safety system call Safety Injection. These are essentially gigantic storage tanks located around the reactor that will dump borated water on ther reactor via gravity drain and flood the containment area and cover the core. In a case like this.

http://en.wikipedia.org/wiki/Pressurized_water_reactor

In a PWR the primary coolant (water) is pumped under high pressure to the reactor core where it is heated by the energy generated by the fission of atoms. The heated water then flows to a steam generator where it transfers its thermal energy to a secondary system where steam is generated and flows to turbines which, in turn, spins an electric generator. In contrast to a boiling water reactor, pressure in the primary coolant loop prevents the water from boiling within the reactor. All LWRs use ordinary light water as both coolant and neutron moderator.

http://en.wikipedia.org/wiki/Boiling_water_reactor

The BWR uses demineralized water as a coolant and neutron moderator. Heat is produced by nuclear fission in the reactor core, and this causes the cooling water to boil, producing steam. The steam is directly used to drive a turbine, after which it is cooled in a condenser and converted back to liquid water. This water is then returned to the reactor core, completing the loop. The cooling water is maintained at about 75 atm (7.6 MPa, 1000–1100 psi) so that it boils in the core at about 285 °C (550 °F). In comparison, there is no significant boiling allowed in a PWR (Pressurized Water Reactor) because of the high pressure maintained in its primary loop—approximately 158 atm (16 MPa, 2300 psi).

In the case of PWR vs BWR this could have happened to either type with the loss of coolant pumping power. We're probably also looking at some sort of inherent flaw in reactor/plant design which is why they're pushing on the idea of life limits on Nuclear Reactors.

[DGthe3]

Originally Posted by kwicslvr

Not sure how BWR's are set up in the US but all PWR's have a safety system call Safety Injection. These are essentially gigantic storage tanks located around the reactor that will dump borated water on ther reactor via gravity drain and flood the containment area and cover the core. In a case like this.

What does borated water do that normal water doesn't? Does it have a higher heat capacity? Extra neutron absorption?

[kwicslvr]

Originally Posted by DGthe3

What does borated water do that normal water doesn't? Does it have a higher heat capacity? Extra neutron absorption?

Borated water is pure water with boric acid added to it. Usually around 3000ppm boron in the water. Boron has a large cross section for absorption for neutrons. Essentially that means it is really good at absorbing the neutrons from the fissioning process. By absorbbing these neutrons they will not be able to cause another fission event with the uranium, thus ensuring the reactor stays sub critical.

[kwicslvr]

Originally Posted by Zabo

http://en.wikipedia.org/wiki/Pressurized_water_reactor



http://en.wikipedia.org/wiki/Boiling_water_reactor



In the case of PWR vs BWR this could have happened to either type with the loss of coolant pumping power. We're probably also looking at some sort of inherent flaw in reactor/plant design which is why they're pushing on the idea of life limits on Nuclear Reactors.

I know the difference between how the two different designs work. Just not sure if BWR's have the gravity drain Safety Injection system like the PWR's do.

[Camaro21]

http://www.nytimes.com/interactive/2...r-tsunami.html

[PB3]

Incredible!

[bossbunny]

Thats just crazy. It just wiped out all those houses.

[anthonyj9h]

to think i was there not to long ago

[PoorMansCamaro]

wow, the interactive maps are pretty cool. Unfortunately it's because of a disaster...