Which element has the smaller critical mass; U-235 that releases 2.5 neutrons per fission, or PU 239 that releases 2.7 neutrons per fission?
a. U-235
b. Pu-235
c. both would have the same critical mass
2006-07-19 06:34:59 · 8 answers · asked by statistics graduate 1 in Science & Mathematics ➔ Physics
The correct answer is B. due to the higher number of average neutrons released per fission you have a higher percentage chance of creating a second fusion just by having another shot.
Also you can vary the critical mass of either fissile material by adding moderators (high Hydrogen content molecules that slow down neutrons) or poisons (elements that absorb neutrons).
By slowing down a neutron it enables the neutron to enter into a decaying orbit around a fissile atom. Once the neutron lands fission occurs. This enables fission to occur without a direct hit on the nucleus of the second atom.
By absorbing neutrons there are far less free neutrons that can initiate a second fission.
2006-07-19 06:52:05 · answer #1 · answered by sprcpt 6 · 0⤊ 0⤋
Pu-239
2006-07-19 06:45:42 · answer #2 · answered by jdomanico 4 · 0⤊ 0⤋
Pu-239 has the smaller critical mass. 239 / 2.7 < 235 / 2.5
2006-07-19 06:41:46 · answer #3 · answered by OccumsRevelation 2 · 0⤊ 0⤋
Never heard of Pu235
But Pu 239 would be the answer
2006-07-19 06:48:18 · answer #4 · answered by SteveA8 6 · 0⤊ 0⤋
Plutonium, the nuclear reaction requires neutrons to run, so the element whose reaction releases the most would need lower mass total...idk if that makes sense, but it's Plutonium.
2006-07-19 06:45:03 · answer #5 · answered by Safari Man 2 · 0⤊ 0⤋
b ) Pu-239
2006-07-19 06:41:49 · answer #6 · answered by gjmb1960 7 · 0⤊ 0⤋
i don't know. how does it release part of a neutron?? that's impossible.
2006-07-19 06:39:25 · answer #7 · answered by bogoyatoo 3 · 0⤊ 0⤋
c
2006-07-19 06:40:36 · answer #8 · answered by aala 1 · 0⤊ 0⤋