SAT Subject Physics Practice Question 577: Answer and Explanation
3. When U-235 is fissioned in a nuclear reactor, the nuclear reaction is maintained by
A. heat produced in the reactor.
B. the moderator rods.
C. radioactive decay products.
D. vibrations induced in the U-235.
E. neutrons produced in the reaction.
Correct Answer: E
The correct answer is (E). A chain reaction (industrial fission is a chain reaction) continues because of the neutrons that are emitted in the fissioning of each U-235 atom.