TMI pressure vessel integrity.

[vanesch]

I would like to check something. If I understand well, in the TMI accident, the reactor vessel was never damaged (in the sense of: having lost major containment function) ? Can someone confirm this, or correct my understanding ?

[Astronuc]

AFAIK, the reactor pressure vessel was not perforated, but the liner and part of the carbon steel shell was damaged (partially melted or chemically reacted) from the core material that melted/interacted with the baffle and core support plate. I've seen pictures from the inside and it's a mess.

[vanesch]

Ah, was at some point the vessel completely emptied from water ? I thought it was just the upper part of the fuel elements that was out of the water and melted ?

[Astronuc]

Certainly the upper half of some of the fuel had disintegrated along with the control rod clusters (SS and Ag-In-Cd), but I also seem to remember the damage at one corner of the core.

Here is picture of the damaged TMI-2 core - http://americanhistory.si.edu/tmi/images/10.01_enlarged.jpg

and - http://americanhistory.si.edu/tmi/tmi08.htm

from - http://americanhistory.si.edu/tmi/tmi10.htm

There was some fuel particles/chunks which fell to the bottom of the RPV, and I believe they interacted with the stainless-steel liner on the bottom.

There are other pictures, but I can't seem to find them at the moment, but similar to

http://www.mpra.com/graphics/d-d_tmi2coredamage.gif

This last one shows that the one or two of the baffle plates were perforated, but the core barrel is apparently intact.