Calculating U-235 Requirements for a 707 MW Nuclear Fission Reactor

In summary, the question asks for the amount of kilograms of U-235 needed to run a 707 MW reactor for 1 year, assuming only U-235 is used and the reactor operates at 30% efficiency. With this information, and given the energy released per fission event of U-235 and the number of reactions per year, the amount of energy needed can be calculated and converted to kilograms of U-235.
  • #1
haxxorboi
24
0

Homework Statement


How many kilograms of U-235 would be needed to run a 707 MW reactor for 1 year?


Homework Equations


183.9 MeV released per reaction
7.57E26 reactions per year
(These numbers are from the prior problems)

The Attempt at a Solution


I thought maybe half life, but you'd never get 0kg for the final answer with that.

I can't seem to wrap my mind around this one, I've gotten the other parts but this one is throwing me...

Any help is appreciated
 
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  • #2
haxxorboi said:

Homework Statement


How many kilograms of U-235 would be needed to run a 707 MW reactor for 1 year?
This is a complicated question to answer if you are working from first principles. I think you should make it simple and assume that the reactor fissions only U235 (no PU239), that it operates at a set efficiency (say 30%) and that the reactor produces 707 MW of electricity for one year. Also assume that the question is really asking how much U235 is consumed.

Set out your information and assumptions:

Total heat energy needed to produce 707 MW of electricity for one year (in Joules).
Heat Energy released in one fission event of U235 (in eV converted to Joules)
No. of U235 atoms in 1 Kg
Total energy released per kg. (in Joules)

You get the idea.

AM
 
  • #3
haxxorboi said:
How many kilograms of U-235 would be needed to run a 707 MW reactor for 1 year?

183.9 MeV released per reaction
7.57E26 reactions per year
(These numbers are from the prior problems)

I can't seem to wrap my mind around this one, I've gotten the other parts but this one is throwing me...

Hi haxxorboi! :smile:

Hint: how much energy is 707 MW for 1 year? :wink:
 
  • #4
Holy crap, THANK YOU!

22.29595E15 joules heat energy per year at 707 MW

2.9464E-11 Joules per event

2.5617E24 atoms per kg

75.478E12 Joules per kg

and then obviously divide to get final answer of kg.

That one was killing me, thanks so much both of you.
 

1. What is a nuclear fission reactor?

A nuclear fission reactor is a type of power plant that uses the process of nuclear fission to generate electricity. It involves splitting atoms of uranium or other radioactive elements, which releases a large amount of energy that is used to heat water and create steam to power turbines.

2. How does a nuclear fission reactor work?

A nuclear fission reactor works by controlling the process of nuclear fission. In the reactor core, uranium fuel is bombarded with neutrons, causing the atoms to split and release energy. This energy is used to heat water, which produces steam to turn turbines and generate electricity. The reactor is carefully designed to maintain a controlled chain reaction and prevent overheating.

3. What are the benefits of nuclear fission reactors?

Nuclear fission reactors have several benefits, including the production of large amounts of electricity without emitting greenhouse gases or other pollutants. They also have a low fuel cost and can operate for long periods of time without needing to refuel. Additionally, nuclear power is considered a reliable and stable source of energy.

4. What are the risks associated with nuclear fission reactors?

The main risk of nuclear fission reactors is the potential for accidents or malfunctions that can release harmful radiation. However, modern reactors have multiple safety features in place to prevent such incidents. The disposal of radioactive waste is also a concern, as it can remain dangerous for thousands of years. However, advancements in technology have allowed for safer and more efficient disposal methods.

5. Are there alternatives to nuclear fission reactors?

Yes, there are alternative sources of energy such as solar, wind, and hydro power. However, these sources may not be able to meet the high demand for electricity in the same way that nuclear power can. Additionally, some argue that nuclear power is a necessary alternative to fossil fuels in order to combat climate change. Research and development of new technologies, including fusion reactors, are ongoing to potentially provide even more sustainable alternatives in the future.

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