RE: CANDU Chain Reaction

["Franta, Jaroslav" <frantaj@aecl.ca>]

Ron L. Kathren wrote:

While there is some fast fission of U-238 in CANDU reactors, just as there
is in
ordinary light water reactors whose fuel is more than 95% by weight U-238,
the amount of fast fission is insufficient to achieve a self-sustaining
chain reaction and actually competes with the fissile U-235 for neutrons.
Note that it is the U-235 that is fissile and not the U-238.  U-238 is
fissionable but not fissile (ie capable of sustaining a chain reaction).
<><><><><><><><>

I just checked with a colleague, who confirmed that "The fast fission factor
in CANDU due to U-238 is 2-3%."
In other words, the (almost) only way in which U238 contributes to fission
in the reactor is by first converting to Pu by radiative capture (thanks
Miro for introducing the correct terminology !).

Jaro
frantaj@aecl.ca
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