posted by mysterychicken .
Need help anwering this:
43. Explain how the fission can be slowed in the nuclear reactor.
The rate of fission depends on the abundance of neutrons at the right speed. So, you can absorb neutrons to reduce the number, or reduce the moderator to cut down on the population at the right speed. In practice, "control" rods do both, with emphasis on "absorption" of the neutrons in the right velocity range.