Prompt neutrons producing fissions over total number of neutrons

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1

Hello everyone,

I need to calculate the ratio of Prompt neutrons producing fissions over Total number of neutrons (ratio unitless).

The numerator should be determined by starting running a specific calculation with settings.create_delayed_neutrons = False for getting the Total fission reaction rate (score “fission”) [reactions/source - prompt neutron]. I guess the scores “prompt-nu-fission” and “nu-fission” should then be used as well as, for the total number of neutrons, the score “heating” along with the total reactor power, all of this for normalization and ending with a unitless value of the sought ratio.

Nevertheless, even with all these terms, I cannot get any satisfying formulas.

Could anyone please help me?

Thank you in advance.
Best regards,
Dimitrius

2

For getting this ratio, should it be fine to consider the equivalent in reaction rates, ie Total fission reaction rate (“fission”) normalized with The recoverable fission energy production rate (“fission-q-recoverable”) and Power, over the Total reaction rate (“total”) normalized with the Total nuclear heating (“heating”) and Power?

I do not know MCNP, but I have been told the “neutrons loss to fissions” (the sought ratio of this topic) is a “natural” output of this code. Does someone know much more?

Best

3

@paulromano

Dear Paul,

The ratio determined only by fission-q-recoverable (eV/source-prompt-neutron, with settings.create_delayed_neutrons = False) over heating (eV/source-neutron) would be sufficient?

Would you have any clues for me regarding all of that?

Deep thanks in advance.