# The Naked Scientists Forum

### Author Topic: Nuclear Power Calculations  (Read 3132 times)

#### Zoltan

• First timers
• Posts: 3
##### Nuclear Power Calculations
« on: 15/05/2007 06:33:13 »
Sorry if this ia a bit out of date but I've only recently found out about the Naked Scientists and have been playing catch-up with the podcasts.

However, the Nuclear Power episode on 11th February got me thinking. If some of the elements in the spent fuel is dangerously radioactive for around 300,000 years and we currently don't have a permanent way of disposing it, would the energy used in continually repackaging and storing it eventually exceed the amount of energy produced by the power stations during its active life?

Although it's possible that something will be developed in the future that will deal with this satisfactorily, if we make a pessimistic assumption and assume that what we have now is as good as it gets, how much energy would be consumed by reprocessing, repackaging and guarding all this material for 300,000 years?

#### Batroost

• Sr. Member
• Posts: 276
• There's no such thing as a dirty atom!
##### Nuclear Power Calculations
« Reply #1 on: 15/05/2007 17:53:26 »
Quote
how much energy would be consumed by reprocessing, repackaging and guarding all this material for 300,000 years?

Perfectly reasonable question - to which the answer is "very little". Bear in mind that you get 100,000 times as much energy from 1 kg of low-enriched Uranium as you get from one kg of coal. The energy spent in mining and preparing the uranium is higher than for coal - but not that much higher! - and if we adopt a direct geological disposal of used fuel then there is very little energy expended in transport and storage.

I'd be surprised if it totalled more than a couple of percent of the energy you get from the fuel.

Have a look at:

http://www.british-energy.com/pagetemplate.php?pid=251

which looks at the subject in terms of CO2 emissions, and you'll see what I mean.

Note that this is a bigger issue for some other forms of generation e.g. photovoltaics that take (possibly?) 15 years to pay-back the energy used in manufacture and biomass where you have to take into account bulk transport emissions.

Cheers,

Batroost

#### Zoltan

• First timers
• Posts: 3
##### Nuclear Power Calculations
« Reply #2 on: 16/05/2007 00:58:30 »
I have no doubt that if we disposed of NW in a geological deposit, very little energy would be consumed. However, my question, perhaps hypothetical, is that if we continued to store it in the same manner as we do now, what would be the total energy consumption of doing so. Some elements of the NW are dangerously radioactive for only a short time whereas others are dangerously radioactive for many thousands of years, with Pu239 at around 300,000 years. How do we store Pu239 now? Is it kept in drums in some kind of warehouse awaiting the time it can be stored safely underground?

#### The Naked Scientists Forum

##### Nuclear Power Calculations
« Reply #2 on: 16/05/2007 00:58:30 »