How does a chain reaction occur in nuclear fission?

Question

Accepted Answer

Welcome back, everyone select the statement that does not explain the chain reaction in nuclear fission. We've got choices A through D which contrast the mechanisms behind a chain reaction either through combining the nuclei fission causing more fission, neutron bombardment, causing splitting of nuclei or having sufficient phys material. So let's go ahead and consider first the difference between sorry between nuclear vision versus nuclear fusion. Recalled that fission involves a heavy nucleus which we call A, which is going to be split into two or more light nuclei. And we'll say that those would be A or sorry B and C, those split nuclei would be B and C for example. And this is also accompanied by the release of a massive amount of energy recall that nuclear fission is used in unnatural processes such as use in nuclear power plants or in the formation of atomic bombs. Now, we're going to define nuclear fusion and we would differentiate nuclear fusion from fission because nuclear fusion is going to involve the combination of light nuclei. We would say in this case D and E which will be combined to form a heavier nucleus, which we say is F So that is also accompanied by the release, sorry, the release of a massive amount of energy and we would observe nuclear fusion occur in natural processes such as in the sun and stars which undergo nuclear fusion. Let's consider our answer choices now that we understand a bit about fission choice. A states that the chain in nuclear fission occurs when two nuclei combine. And based on what we outlined choice, a certainly aligns with the definition for nuclear fission. I'm sorry, actually, that certainly aligns with what we determined for nuclear fusion. So we do put a check mark by choice. A because it is a untrue statement or false statement about nuclear fission, which as we stated, takes a heavy nucleus and splits it into lighter nuclei does not combine two nuclei. So this is describing fusion, not fission. So it is false. Choice. A looks like a good answer. Choice for that reason. Now we've got choice B which states that the chain reaction occurs when the fission of a nucleus causes additional fission. And we would recognize Choice B to be a true statement about nuclear fission because additional fission brought on by the abundance of high energy neutrons and fissionable material to keep the nuclear fission going until there's nothing left to react is necessary to occur. Because otherwise the chain reaction would be controlled by using rods to absorb the neutrons. So we would rule out choice B since it is a true statement about nuclear fission. Now, we've got to c which states that a chain reaction happens when neutron bombardment of the nucleus causes the nucleus to split into smaller nuclei, releasing high energy neutrons that strike other nuclei as well. We would also recognize choice C as a true statement describing fission. So we would rule it out as an answer. Choice since we only want to describe what is not true about fission. And then we've got choice D which states that chain reaction proceeds when there is enough fissile material. So we called that for fissile material, that would be something like uranium 2 35 which is capable of sustaining a nuclear fission chain reaction. And so choice D is also a true and correct statement because the chain reaction will only be sustained if a sufficient quantity of fissionable material is brought together. So we can rule out choice D because it correctly describes nuclear fission. And so that leaves us with choice A as the only correct answer choice, which does not describe fission, but rather describes a process in fusion where the chain reaction in nuclear fusion. Sorry, in nuclear fusion, we would correct it to say occurs when two nuclei combine. So our final answer is choice. A I hope this made sense. And let us know if you have any questions.

How does a chain reaction occur in nuclear fission?

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Key Concepts

Nuclear Fission

Chain Reaction

Critical Mass