APR: your source for nuclear news and analysis since April 16, 2010

Tuesday, March 15, 2011

Fukushima Daiichi No. 4 fuel pool

Just heard a really credible source indicating that there is NO .. repeat NO new or fresh fuel in plant No. 4 fuel storage pool... only spent fuel.

8:45 PM Eastern Tuesday 3/15



  1. What is the difference between used and fresh fuel, what is better to have in the pool if a fire breaks out?

  2. Spent fuel has been used up in the reactor and has far less Uranium present, so is less reactive and develops less heat than brand new fuel. However it may also be more delicate physically because of the amount of irradiation damage to the metal.

  3. You have it bassakwards. New fuel does not need to be in a fuel pool or containment vessel. It comes in to the plant on a fal bed semi trailer and wou can climb up on the truck and sit on the fuel bundles. They are only slightly radioactive as they are only uranium 238 and 3% U235. I know this as I am the one who sat on them. Spent fuel is full of highly activ fission products witch decay and produce heat. They call this decay heat. The fuel in a fuel pool cannot fission, this only happens in the reactor vessel. The fuel in unit 4 pool was just removed from the reactor in Dec 2010 and thus still has lots of decay heat potenial. The rods became exposed to the air and got very hot with now water to carry away heat. Hot enough to oxidze the zirconim fuel cladding an start it on fire. Metal fires burn very hot, in fact hot enough to start reacting with water or steam. This is what happened at unit 4.

  4. These fuel elements aren't highly enriched Uranium, which ours were.... so thanks for the clarification! Other than that I'm aware of all of what you said.