Question

section 24.3 continued
heat produced by nuclear fission is carried away by (24) _, which enters the core at point (25) _. it then leaves the core at point (26) _ in the diagram.
heat from the reactor core is used to boil water in the (27) _ shown at (28) _ in the diagram. steam produced here is used to generate electricity at point (29) _ in the diagram. the steam is then cooled at location (30) _ by water from an outside source.
for each statement, write true or false.

1. a nuclear reactor produces energy from fuel rods containing uranium - 238.
2. the amount of energy produced for each kilogram of uranium is about the same as the amount of energy from a kilogram of coal.
3. the only elements that can be used as fuel in a nuclear power plant are those in which a chain reaction can occur.
4. if more than a critical mass is present in a sample, that sample is said to have supercritical mass.
5. water is the most common coolant used in a nuclear reactor.
6. nuclear power plants usually produce electricity.
7. the purpose of the control rods in a nuclear reactor is to reflect neutrons back into the core.
8. the production of energy in a nuclear reactor can be stopped by pulling out all control rods.
9. a breeder reactor produces more fuel than it uses.
10. the fission products produced in nuclear power plants are not radioactive.
11. an uncontrolled chain reaction led to the nuclear accident in chernobyl, ukraine.

Explanation:

1. Nuclear reactors usually use uranium - 235, not uranium - 238 as the main fuel, so false.
2. Uranium produces much more energy per kilogram than coal, so false.
3. Only elements where a chain reaction can occur are used as nuclear fuel, so true.
4. A sample with more than critical mass is super - critical, so true.
5. Water is a common coolant in nuclear reactors, so true.
6. Nuclear power plants are mainly for electricity production, so true.
7. Control rods absorb neutrons, not reflect them, so false.
8. Pulling out control rods increases the reaction, not stops it. Inserting them stops the reaction, so false.
9. Breeder reactors produce more fuel than they use, so true.
10. Fission products in nuclear power plants are radioactive, so false.
11. An uncontrolled chain reaction caused the Chernobyl accident, so true.

Answer:

1. False
2. False
3. True
4. True
5. True
6. True
7. False
8. False
9. True
10. False
11. True