How much matter gets converted to energy in power plants?

[chcarnage]

In nuclear power plants, matter gets converted to energy. I'm curious how much matter gets lost per year. Miligrams, grams or more? According to wikipedia, there are about 440 active plants worldwide.

In Switzerland there are 4 plants. The three smaller ones have a power output of 300 Megawatt each, the biggest one delivers 900 MW, if I remember correctly. We could estimate how much mass gets lost, if we knew how much energy is in one gram of matter (I guess it doesn't matter of which kind the mass is). I know it equals a huge quantity of power (e=m*c^2), but I've no idea how to further calculate it.

Back to one of the smaller Swiss power plants:
300MW electrical output / 0,4 estimated degree of efficiency = 750MW thermal output
750MW * (365*24*60*60 seconds in a year) = 23'652 mil. Megajoule thermal output/year

Now how much matter equals that? Ideas anyone?

 

[chcarnage]

Found something... In the German version of wikipedia: The sun loses 4 mil. Tons of mass per second and produces 3,7*10^26 Watt.

Let's say the average power production of a nuclear power plant is 750 MW:
750MW * 440 = 330'000 MW=3,3*10^11 Watt

That's approximately 10^15 times less than the sun.

4*10^12 g / 10^15 = 4*10^(-3) g = 4 Milligrams of mass per second

0,004 g * (365*24*60*60) = 131'400 g

So we're converting roughly 130 kg mass to energy per year... Impressive. I may be fatally wrong however.

 

[f95toli]

E=mc^2 as you have already written
The total energy generated by one power plant is 23'652 mil. Megajoule=2.3e16 Joule

c=3e8 m/s

hence,
m=E/c^2=2.3e16/(3e8)^2=0.256 kg

Now, if there are 440 active plants and I believe they are on average is slightly bigger than 750 MW so lets set m=0.5 kg for simplicity, the total consumption should then be around 200 kg.