feature request: average Q value of plasma, average neutron emission per reaction

[shimwell]

thinking about how to use this code with openmc and I often have the situation where the fusion reactor is quotes as 1GW fusion power and then there is a need to find number of fusion reactions from this power.

most neutronics analysis is done assuming 1GW / 17.6MeV to find the number of fusion reactions and then 1 neutron per fusion reaction is assumed.

However with the four reactions covered in nest (DD, DD, TT, DT) there is a different average Q value of the plasma and we should something different to 17.6MeV.

There is also a different number of neutrons released as TT reaction makes 2 neutrons.

So it might be useful to know the real average Q value and the average neutron emission per reaction to help normalize neutronics results

[aidancrilly]

Unless the fuel fraction is far from 50/50, the correction to average Q from other primary reactions than DT is gonna be at the % level. Perhaps this level of accuracy is important but I'd imagine not?

That said I think a useful helper function might just be to convert a spectrum to a power? This would include all primary reactions as well as the effect of scattering - which will be a large effect in ICF.

EDIT: see simple utility function here for spectrum to power
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