Posts by EducationOperation

Facts Instead of Scare

Yesterday, somebdoy posted a very useful URL:

http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html

What you can see in the 3D-diagram is the reactor and the building around it. The brown "pill" vertically in the center is the reactor vessel containing many bundles of fuel "pipes". In each pipe, there are many fuel "pills", where the fission reaction takes place. The fuel pipes are cooled by water, which doubles as a moderator to slow down the neutrons so that fission is possible.

https://secure.wikimedia.org/wikipedia/en/wiki/Nuclear_reactor_technology

The problem is when the cooling water flow ceases, the water heats and at one point begins to boil. This builds up pressure, which must be vented to protect the reactor vessel at some point. Heat is even generated, even when the control rods (neutron absorbers) are fully pushed into the reactor. This is because fission creates a chain of after-products which are not stable atom kernels, but after some time emit radioactive particles and/or break into even smaller nuclei. This process will continue for weeks and generate between 300MW (immediately after shutdown) down to 1MW(weeks after) of power.

What happened in Japan is that the cooling system (for yet unexplained reasons) failed and the water essentially cooked off. This means dozens of MWs are now at work melting the fuel pipes (aka "fuel rods"). At this extreme temperatures (up to 2500K), water and the metal present generates Hydrogen. When the reactor vessel is vented for protection, this hydrogen gets into the top part of the building (which is structually not more than a tent), where a nice big hydrogen explosion occurs. This blows off this weak structure, but the reactor vessel and the protective Concrete-Steel Containment around the reactor vessel stay intact !

This is what we saw - not a Czernobyl-type explosion/graphite burn of the reactor itself. Czernobyl didn't have a Concrete-Steel Containment at all ! The USSR was too busy building weapons for their Panzer Troops in Germany to afford that.

Bottom line: All the Nasty Stuff is contained, as in Harrisburg. Cooling of the Containment and Reactor Vessel by Sea water is performed. Expected Effects: As in Harrisburg, no significant health effects expected.