Re: New fusion power system test creates 300,000 degrees C plasma

On 1/12/2024 1:57 pm, john larkin wrote:

On Sat, 30 Nov 2024 23:54:54 +0100, Jeroen Belleman
<jeroen@nospam.please> wrote:
 

On 11/30/24 22:59, john larkin wrote:

On Sat, 30 Nov 2024 21:12:23 +0100, Jeroen Belleman
<jeroen@nospam.please> wrote:
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On 11/30/24 18:19, john larkin wrote:

On Sat, 30 Nov 2024 11:57:50 +0100, Jeroen Belleman
<jeroen@nospam.please> wrote:
>

On 11/30/24 10:34, Liz Tuddenham wrote:

Jeroen Belleman <jeroen@nospam.please> wrote:
>

On 11/29/24 23:03, Liz Tuddenham wrote:

Jeroen Belleman <jeroen@nospam.please> wrote:
>

On 11/29/24 21:04, Liz Tuddenham wrote:

Jeroen Belleman <jeroen@nospam.please> wrote:

 Googling has many references and some papers, all around 10 Kg
unshielded, half that with a good neutron reflector.
 I suppose something that doesn't normally emit neutrons can still
fission, from a cosmic ray or something.
 All 5 plutonium isotopes have a critical mass, at which point I assume
that Something Bad happens.

You don't have to assume anything. Critical mass is the point where some neutron showing up anywhere in the critical mass is likely to hit another atom and produce enough neutron that one of them will hit another atom somewhere in the mass before it escapes.
If the atom it hits immediately produces a batch of prompt neutrons, you may get a lot of energy released before the critical mass melts and dribble away.
Nuclear reactors are controllable because U-235 doesn't seem to emit all it's neutrons all at once and the ones that show up late give you time to push in the control rods before the process runs away.
--
Bill Sloman, Sydney