In reply to <[email protected]>'s message of Thu, 26 Jan 2017 19:07:40 -0800: Hi Bob,
Regular reactors use Uranium enriched to some extent, except CANDU AFAIK. Without the enrichment they don't achieve criticality. Reactors usually run "on a knife edge", IOW they produce and consume neutrons at the same rate. However an average fission reaction requires 1 neutron, but produces about 2. That means that in order to run normally the excess neutron needs to be trapped/redirected. Some go into converting U238 eventually into Pu239 which is also fissile, and some of that gets burned up too. Some are fast enough to directly fission U238, but only a small percentage, and not enough to keep the reaction going. Others get absorbed by fission daughter products, but I would guess that most are absorbed by the control rods. That means that if the control rods malfunction in some way, then it's possible for the production/consumption ratio (k) to exceed one. I'm guessing that that is the sort of accident you are referring to. >Criticality based on fast neutrons in regular fission reactors is a bad >accident, and it has happened many times—killing workers in some cases. > >I would guess that any fission reaction could release fast neutrons. However, >I may be wrong and would like to review the data on fission cross sections for >the actinides we are talking about. A reference would be desirable. > >Bob Cook > >Sent from Mail for Windows 10 [snip] Regards, Robin van Spaandonk http://rvanspaa.freehostia.com/project.html
