Question

regulating fission nuclear reactions
a power plant needs to slow down the fission reactions in its nuclear reactor. in which direction should the uranium - containing rods in the diagram be moved?
left
up
right
down
neutron - absorbing material
rods containing uranium
nuclear reactor

Explanation:

Step1: Understand nuclear fission control

Nuclear fission is controlled by absorbing neutrons. More neutron - absorbing material in the reaction zone slows down the reaction.

Step2: Analyze rod movement

Moving the uranium - containing rods down will bring more neutron - absorbing material (assuming the rods are designed to absorb neutrons as they move down) into the nuclear reaction zone, thus slowing down the fission reactions.

Answer:

down