Posted by MoparNorm on Friday, March 26, 2004 at 8:03PM :
In Reply to: Re: Our reactors,.... posted by Bob Thompson on Friday, March 26, 2004 at 6:16PM :
From the TMI Breifing papers;
"The Hydrogen Bubble
When the reactor's core was uncovered, on the morning of 28 March, a high-temperature chemical reaction between water and the zircaloy metal tubes holding the nuclear fuel pellets had created hydrogen gas. In the afternoon of 28 March, a sudden rise in reactor building pressure shown by the control room instruments indicated a hydrogen burn had occurred. Hydrogen gas also gathered at the top of the reactor vessel.
From 30 March through 1 April operators removed this hydrogen gas "bubble" by periodically opening the vent valve on the reactor cooling system pressurizer. For a time, regulatory (NRC) officials believed the hydrogen bubble could explode. However, such an explosion was never possible since there was not enough oxygen in the system. "