What type of reactor is the Chernobyl design?

(Created prior to 1993)
  
Question: Texts say Chernobyl was a high-pressure water reactor, navy 
nuclear expert says it used sodium.  Does anybody know and can suggest 
references?
---------------------------------------
Here are the facts.  The RBMK-1000 is water cooled.  The water is 
under pressure.  The moderator was graphite which did not have a separate 
cooling system so when the primary cooling system (the only one) was shut 
down, the moderator got very hot and being graphite could actually burn in 
oxygen.  It contained 115 Kg of uranium in fuel assemblies that each contained 
18, 13.6mm diameter rods of Uranium.  The water was not deuterium oxide, but 
regular water.  The confinement system was not complete and that is why it 
went up.  We have a lecture that was given here at Argonne by a safety 
engineer and if you are interested we could send you a copy.  It is very 
technical.  IF you would write a letter to  S. Bowen, DEP, ANL, Argonne, IL 
60439, I would pass the request for references on to our local expert.  The 
moderator is graphite.  You are right.  The collisions are to be elastic.  
There are some small inelastic energy transfers to vibrations in the 
moderator.  In practice there will be both types of collisions with the 
moderator.  The inelastic collisions will cool the neutrons and the elastic 
will rearrange the momentum distributions.

Sam Bowen
====================================================================