It's a huge mission, Diablo Canyon is supplying something critical to help the Japanese cool down its crippled nuclear reactors.

The nuclear power plant is sending tons of boric acid. The boric acid will be used at the Fukushima Daiichi Power Plant. It absorbs free neutrons and will be used to cool down the damaged reactors in Japan.

It was transported to Vandenberg Air Force Base Wednesday night and the boric acid was loaded up on Thursday to be flown to Japan. Boric acid is used in nuclear power plants as a neutron poison to slow down the rate at which fission is occurring. Fission chain reactions are generally driven by the amount of neutrons present (as products from previous fissions). Natural boron is 20% boron-10 and about 80% boron-11. Boron-10 has a high cross-section for absorption of low energy (thermal) neutrons. By adding more boric acid to the reactor coolant which circulates through the reactor, the probability that a neutron can survive to cause fission is reduced. Therefore, changes in boric acid concentration effectively regulate the rate of fission taking place in the reactor. This method is only used in pressurized water reactors (PWRs). Boron is also dissolved into the spent fuel pools containing used uranium rods. The concentration is high enough to keep neutron multiplication at a minimum.