Fission Product Yield Data for the Transmutation of Minor Actinide ...

s S = A f(E*)/(a a – b a Z CN 2 /A) + ca (4.5.14)
where a a , b a and c a are parameters of the systematics.
The systematics parameters from Eqs (4.5.12)–
(4.5.14) and dependences of Y S/Y a on Z CN, A and
E* for proton and neutron induced fission have
been determined by systematically fitting experimental
data from the present work and from Refs
[4.5.37–4.5.44]. One conclusion of this procedure is
that the functions Y S /Y a for protons and neutrons
differ, and the final equations are as follows:
M H,a = 28.6(A/Z CN ) + 0.708 Z CN for Z CN ≥ 92;
M H,a = 54A/Z CN for Z CN = 90, 91;
s a = (A/Z CN )(Z CN – 73)(0.074 + 0.0296(E*) 0.25 );
s S = 0.031A(E*) 0.25 /(90.54 – 1.9(Z CN 2 /A)) 0.5 + 9.64;
g 1 and g 2 from Table 4.5.9;
Y S /Y a = 1.244(E*) 0.25 (1 – exp(–0.0027(E* – 5.7) 1.5 ))
× (1 + 100/(E*) 0.5 (Z CN/A – 0.4))
for neutrons with E n = 5–200 MeV;
Y S /Y a = 1.18((E*–5.7) 0.25 (1 – exp(–0.011(E* – 5.7) 1.5 ))
– 0.101)(1 + 2500/E*(Z CN /A – 0.393))
for protons with E p = 5–200 MeV;
Y a = 200/(Y S/Y a + 2); Y S = 200 – 2Y a
Mass distributions Y(M) calculated from the
systematics are compared to the experimental data
in Figs 4.5.18–4.5.20.
These figures show that this systematics
reproduces the main features of the experimental
data and could be used as the basis for predicting
fission product yields from 5 to 200 MeV neutron
reactions of interest for the transmutation of minor
actinides.
4.5.6. PYF code
The systematics has been encompassed within
the PYF computer code [4.5.45] in order to
calculate the pre- and post-neutron emission
fragment mass yields for the fission of target nuclei
from Th to Bk in reactions with protons and
neutrons at incident energies from 5 to 200 MeV.
The numbers of emitted prompt neutrons are
206
FIG. 4.5.18. Experimental mass yields (circles) from
neutron induced fission at E n ª 5 MeV [4.5.36, 4.5.38–
4.5.41]; their systematic descriptions are also shown in
linear and logarithmic scales (lines).
FIG. 4.5.19. Experimental mass yields from neutron
induced fission at E n = 16.5 MeV [4.5.43] (circles) and their
systematic descriptions (lines) are shown in linear and
logarithmic scales.
calculated with the post-fission neutron number
systematics from Ref. [4.5.46].
Figure 4.5.21 depicts the user’s window to the
code, in which the initial input data for the desired
reaction, the calculated results and the name of the