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

AI Thread Summary
To determine the kilograms of U-235 required to operate a 707 MW nuclear reactor for one year, the total heat energy needed is calculated to be approximately 22.3 trillion joules. Each fission event of U-235 releases about 2.95E-11 joules, and there are roughly 2.56E24 atoms in one kilogram of U-235. The total energy released per kilogram of U-235 is around 75.5 trillion joules. By dividing the total energy requirement by the energy produced per kilogram, the final amount of U-235 needed can be calculated. This approach simplifies the problem by assuming the reactor only uses U-235 and operates at a set efficiency.
haxxorboi
Messages
24
Reaction score
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
 
Physics news on Phys.org
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
 
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:
 
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.
 

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Calculation on spontaneous fission and effect from alpha decay
Replies
23
Views
2K
Struggling with Uranium-235 Nuclear Fission
Replies
5
Views
2K
I understanding this nuclear fission process
Replies
1
Views
2K
U-235 Fission in Nuclear Reactor: Calculating Atom & Kg Usage/sec
Replies
3
Views
2K
Nuclear physics: critical state and fission
Replies
2
Views
2K
Calculating the Rate of Nuclear Fission with 1000 kW Power and 200 MeV Energy
Replies
3
Views
3K
When do fission products get cooler than fuel?
Replies
6
Views
2K
Reactor fuel and waste: fission/fusion problem
Replies
2
Views
3K
Calculating Fission Energy from Uranium Fuel
Replies
7
Views
4K
Calculating Energy Released by Fission of 1g of U-235
Replies
2
Views
2K

Hot Threads

Recent Insights

Back
Top