The output of Pin Powers Distribution using 'set cpd' is too small.

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Thamer
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The output of Pin Powers Distribution using 'set cpd' is too small.

Post by Thamer » Fri Jun 18, 2021 6:52 pm

Hi there,

I am trying to calculate the pin power distribution for a full core using the 'set cpd' option. However, the output for the axial pin power distribution which is 'Distribution at level 2 (axial)' in the output file (core0.m) are too small values (i.e. 10^-20). I have 7.4 cm grids and 50 levels; and when I manually calculated the power of one pin I expected a value of ~1.36 KW but Serpent is printing a value of ~E-20 which is very small.

Are there any other pre-steps that should be done before using the 'set cpd' option? and what are the units of the power in the output file (core0.m) of 'set cpd' option?

Thank you very much,

Ana Jambrina
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Re: The output of Pin Powers Distribution using 'set cpd' is too small.

Post by Ana Jambrina » Fri Jun 18, 2021 7:15 pm

Have you checked the normalization? Neutron transport simulations are by default normalized to unit total loss rate. If you want to normalize the estimates at a given power level, see: 'set power' or 'set powdens' (check the Wiki for other normalization options available).

Note:
- The ‘Normalized total reaction rates (neutrons)’ section in ‘_res.m’ lists the normalized total reaction rates.
- The ‘cpd’ option outputs the power distributions in units of Watts (analogously to mt = -8 detector response).
- A more general-purpose and flexible (in terms of geometry) approach is to use detectors instead of the ‘cpd’ option.
- Ana

Thamer
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Re: The output of Pin Powers Distribution using 'set cpd' is too small.

Post by Thamer » Fri Jun 25, 2021 3:51 pm

Thank you, Ana.

Can I do unequal-sized axial bins for the power calculations?

Regards,

Ana Jambrina
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Re: The output of Pin Powers Distribution using 'set cpd' is too small.

Post by Ana Jambrina » Fri Jun 25, 2021 3:57 pm

The ‘cpd’ option sets evenly-spaced axial bins. As mentioned before, the use of detectors allows a more flexible geometry: user-defined bins.
- Ana

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