# Homework Help: Nuclear physics

1. Jun 9, 2009

### roshan2004

A reactor is producing nuclear energy at the rate of 30000KW.How many atoms of U-235 undergo fission per second?How many kg of U-235 would be used up in 1000 hr of operation.Assume an energy of 200 Mev is released per fission.(Avogadro number=6*10^26 atom/kg)

2. Jun 9, 2009

### fatra2

Hi there,

It all depends on what you consider as nuclear energy. If you mean the amount of energy (thermal power) freed from the fission process, then the calculation is quite simple. Otherwise, you could also mean the net electrical output of the power plant, which there you would have to go for the effeciency of the power plant.

No matter which process you mean, the number of atoms that fission to create nuclear power is very little (everything in a relative sense), knowing that each fission liberates $$\sim 200MeV$$ of energy.

Now to give you a real answer to your question. In Europe (and I believe it's the same in America), the goal of a nuclear power plant is to produce a maximum of $$50\frac{m^3}{yr}$$ of radioactive waste for every $$1000kW$$ of net electrical power output.

3. Jun 9, 2009

### vanesch

Staff Emeritus
Moved this here because it sounds too much like a homework. Homework rules apply. Show your work.

4. Jun 9, 2009

### Andrew Mason

Note: Avogadro's number is 6*10^26 atom/Mole. Work out the total energy (in Joules) produced in one second. How much energy (in J.) released from one U235 fission? Once you get that, the second part is straightforward.

AM