Hey all,
I’m trying to compute the physical surface current for a very simple model, and would like a reality check on how I am doing the computation.
The “reactor” is just two ZCylinder surfaces. (inner moderator and outer annular fuel region). No bounds are defined in the z-direction, so my understanding is this is effectively a “2D” calcualtion. The outer ring is a vacuum boundary. eigenvalue run mode.
- I have a surface
currenttally defined on the outer fuel surface. (lets call this tally J) - and
kappa-fissiontally over all regions (lets call this tally H)
I am computing the flux normalization factor according to the docs.
So I have
H' = 1.602 \times 10^{-19} \left[ \frac{\text{J}}{\text{eV}} \right] \cdot H \left[ \frac{\text{eV}}{\text{source}}\right]
and
f = \frac{P}{H'}
And this all feels right.
To compute a physical current (lets call it J') then, what I think I should do for this is
J' = \frac{fJ}{2\pi r_o}
where r_o is the radius of the outer boundary. Essentially, divide by the perimeter of the cylinder.
This approach however implies that the J is current over a normalized unit height (e.g., 1 cm), so in a “2D” model this means the current tally units are \left[ \frac{\text{particles}}{\text{source-cm}} \right], and the units on J' are \left[ \frac{\text{n}}{\text{cm}^2\text{-s}} \right].
Is this interpretation correct?