How are neutrons accelerated to strike U-235 to cause nuclear fission?

Question

What is the process to produce a neutron that strikes a U-235 nuclei and produces nuclear fission?

Answer 1

Uranium 235 is radioactive, and decays spontaneously to 2 smaller elements, as well as 3 neutron particles. We can think of U235 as the fuel and each neutron as a projectile. When the neutron hits another U235 nucleus fission occurs. As the number of neutron grows with each fission event, the nuclear chain reaction is formed.

The process of fission of the Uranium nucleus itself gives off tremendous energy. It's like a mini explosion where everything just flies apart. Therefore, technically neutrons do not need to be 'accelerated' because they are already flying off in the fission event.

When someone wants to slow or stop the nuclear reaction they actually do the opposite and 'slow' the neutrons down by using control rods containing non radioactive elements to capture and absorb free neutrons. To let the reaction run again, they simply remove control rods (in nuclear plants) or put together enough fuel to form 'critical mass' (in nuclear bombs). Either of these ensure enough free neutrons are flying around to get the chain reaction occurring.

Answer 2

In a nuclear reactor, the fission process starts with a rare and spontaneous fission of a U-235 nuclei. This releases heat, plus 2 neutrons. Free neutrons are slowed by contact with hard water, the catalyst. Only a slow moving neutron can fission another U-235 nuclei. Neutrons can not be slowed by contact with other U-235 nuclei. The speed of the fission is controlled by cadmium control rods. Neutrons that strike the control rods are removed from the fission process.

Answer 3

U-235 is radioactive, meaning unstable. Any individual atom has a small chance of randomly giving off a neutron at any time. If this neutron hits another Uranium atom, it will be cut in half, releasing more neutrons and possibly causing a chain reaction. However, in normal conditions this is not likely to happen because the U-235 atoms are spaced too far apart. If, however, a lump of U-235 is compressed and made more dense, the chances of a chain reaction increase. Eventually a state density is reached where the likelihood if a chain reaction is so high that it becomes almost a certainty, this is called critical mass. Energy is released whenever a Uranium atom is split in two, if a chain reaction takes place fast enough an explosion will occur.

Answer 4

They acquire kenetic energy when released from a fission event.

Some of those fission events are spontaneous, and some are triggered from the bombardment of neutrons produced by other fission events.

If you have enough U235 that is brought together in the right shape fast enough, the spontaneously released neutrons cause an accelerating cascade chain of neutrons through
bombardment, causing a nuclear explosion

Some debunking

Clearly the fact that nuclear weapons exist demonstrates that you don't need a moderator for a spontaeneous sustained nuclear reaction

Answer 5

some isotopes can decay by spontaneous fission, it truly is an decision to the traditional alpha decay of heavy atoms. Uranium 238 and many of the plutonium isotopes are examples that could spontaneously fission. A fission chain reaction is a very not likely journey, inspite of the indisputable fact that it style of feels to have occured at Oklo. the percentage of U-235 to U-238 at Oklo is below elsewhere contained in the global, suggesting that something has used up extra of the U-235 in that deposit, this may were a organic reactor, if the ore had a extreme sufficient concentration of uranium and moisture got here upon a way into the rock the water might want to actual looking neutrons and restricted criticality might want to have occured. this may clarify the diverse proportions of uranium isotopes.

Answer 6

The neutrons actually have to be moving slowly. Fast neutrons do not cause fission, because they cannot be absorbed by U-235.

Answer 7

what the hell does that mean!!!!