RE: Graphite Quiz: Re: Chapelcross -(2)

["Dukelow, James S Jr" <jim.dukelow@PNL.GOV>]

Emil Murat wrote:

-----Original Message-----

From: Emil Murat [mailto:kerrembaev@YAHOO.COM]

Sent: Wednesday, July 11, 2001 9:12 AM

To: radsafe@list.vanderbilt.edu

Subject: Graphite Quiz: Re: Chapelcross -(2)



	<snip>



3.1



Here comes the quiz: Reactor Designers.





 Why did they/he/she choose those materials?  



a) Magnesium has a pretty look :-) 

b) It is slim = has light weight. :-) 

c) Both graphite and magnesium are flammables = 

   temperature + free oxygen.

d) In Great Britain: Zirconium is an import product, 

   Magnesium is an export product.

e) The reactor designer wanted to be a plane engineer 

   rather than a nuclear.

f) A, B and E

g) C and D





Good luck, fellas!





Emil.



==================



My guess is that the answer is:



h)  the Magnox alloy has a very low thermal neutron absorption coefficient,

about a third that of zirconium.  This permitted a graphite moderated reactor

using natural uranium or only slightly enriched uranium fuel.  As I noted in an

earlier message, various constraints required that this fuel be metallic uranium

and limited the thermal efficiency of the reactor to around 30%.  The set of

properties was attractive for economic reasons in a country that did not, to the

best of my knowledge, have large uranium enrichment facilities.



Best regards.



Jim Dukelow

Pacific Northwest National Laboratory

Richland, WA, USA

jim.dukelow@pnl.gov



These comments are mine and have not been reviewed and/or approved by my

management or by the U.S. Department of Energy.

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