Why the World Shouldn't Worry About the Damaged Nuclear Reactors in Japan

This post was written by a nuclear scientist so he probably knows more than some talking head on CNN or Fox News.

Since the reactor’s cooling capability was limited, and the water inventory in the reactor was decreasing, engineers decided to inject sea water (mixed with boric acid – a neutron absorber) to ensure the rods remain covered with water.  Although the reactor had been shut down, boric acid is added as a conservative measure to ensure the reactor stays shut down.  Boric acid is also capable of trapping some of the remaining iodine in the water so that it cannot escape, however this trapping is not the primary function of the boric acid.

The water used in the cooling system is purified, demineralized water. The reason to use pure water is to limit the corrosion potential of the coolant water during normal operation. Injecting seawater will require more cleanup after the event, but provided cooling at the time.

This process decreased the temperature of the fuel rods to a non-damaging level. Because the reactor had been shut down a long time ago, the decay heat had decreased to a significantly lower level, so the pressure in the plant stabilized, and venting was no longer required.

 
From what I read sea water and boric acid mixed together will pretty much end the usefulness of the reactor.  It is the last resort to prevent the the reactor core from heating up and eventually melting down. Since there won't be a meltdown as long as they are pumping this mixture into the core the danger level has kind of passed.  Eventually the core will cool off enough so that they can pull out the Uranium fuel rods so that the reactor can be shut down permanently.

Also the hydrogen venting they talk about is what caused the explosions we saw in the last few days. They were the results of hydrogen buildup mixing with oxygen and reacting combustively.  While Chernobyl blew up due to a similar buildup of hydrogen that power plant had no hermetically sealed containment structure like these Japanese plants have.

So at Chernobyl when that hydrogen blew up it didn't just blow off parts of the extraneous outer buildings like it did in Japan it blew up everything including the core, the cooling material and the contents of the reactor. That just can't happen in Japan because the containment structure will keep the material inside of the plant and as long as the core is given enough time to cool.

Too bad more lay people don't know this stuff because I think this disaster might set nuclear power back yet another 20 years.