JAEA-Data/Code 2007-004 - Welcome to Research Group for ...

Then, using the homogeneous spectrum obtained and assuming the flat flux, the effective cross-section
of each material is calculated by
where
Σ , = γ Σ − ∑ Σ → Φ / Φ
(7.2-11)
tr g,
M g t,
g,
M
s1,
g ' g,
M 1, g'
1,
g
g '
γ = 1
for P1 approximation (7.2-12a)
g
g
g
{ 1 − ( tan α ) α }
−1 α g / 3
−1
γ = α tan
/ for B1 approx.
g
g
{ 1 − ( tanh α ) α }
−1 α g / 3
−1
γ = α tanh
/ for B1 approx. with
g
g
g
g
2
2
2
with α g = B / Σ , if B 2 t , g >0 (7.2-12b)
2
2
2
with α g = −B / Σ , if B 2 t , g