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

The comparisons of our evaluated data with
ENDF/B-VI, JENDL-3, JEF-2.2 and CENDL/FY
are given in Tables 3.2.4–3.2.7 and Figs 3.2.1–3.2.5,
and show the following:
(a) General agreement with other libraries:
For most cases, differences between our
present evaluated data and others are not large.
Defining ‘discrepant’ as those data in which the
difference of our evaluated data to others exceeds
10%, or is larger than the uncertainty given by the
corresponding library, the number of such cases is
about 11% for 235 U and 238 U fission. Moreover, the
number of such cases for 235 U is approximately the
same for different libraries and different energy
points for thermal (T) and fission spectrum (F)
yields; however, this number is considerably smaller
for 14 MeV (H) in CENDL/FY than in ENDF/B-VI
and JENDL-3. The number of such ‘discrepancies’
for 238 U fission with JEF-2 and CENDL/FY is larger
than with ENDF/B-VI for fission spectrum
neutrons (but the opposite for 14 MeV neutrons
(H)). According to the above definition, the
number of discrepant cases is influenced by the
magnitude of the uncertainties assigned in the
different libraries. For example, the uncertainties in
ENDF/B-VI are reasonably small, whereas the
uncertainties in CENDL/FY are larger (see Tables
3.2.8 and 3.2.9). So when the number of discrepant
cases is the same for both libraries, the differences
in the yields when compared with CENDL/FY are
attributed to the larger uncertainties; if this number
is smaller for CENDL/FY this does not mean that
the differences in yield values are smaller. Certainly
the differences between the present evaluated
values and those in ENDF/B-VI are smaller than
with JEF-2 and CENDL/FY for 235 U fission by
thermal and fission spectrum neutrons, and for 238 U
fission by fission spectrum neutrons.
(b) Discrepant 235 U yields:
When compared with data in the other four
libraries, our recommended yields are larger by
27–62% for 91 Br(T), by 65–70% for 106 Ru(F), by 34–
44% for 115 Cd(T), by 16–35% for 115 Cd(F), by 85–
95% for 115m Cd(F) and by 19–20% for 147 Pm(H);
and smaller by 25–60% for 90 Br(T), by 10–26% for
137 151
I(T) and by 33–80% for Pm(H). Our evaluated
yields for 91 Br(T), 106 Ru(F), 115m Cd(F), 147 Pm(H)
and 151Pm(H) are not recommended because they
are based on only one set of measurements; whereas
90 115 137
those for Br(T), Cd(T, F), I(T) are
recommended — they are based on more than one
set of measurements, but the existing discrepancies
should be borne in mind. Furthermore, our values
for 111Ag(T, F, H) are also recommended, although
only some of them are in agreement with one or two
of the four libraries — they are mainly 10–30%
smaller than the equivalent data from all other
libraries. Care should be taken when using these
data because some systematic uncertainties may
exist.
(c) Discrepant 238 U yields:
Our recommended yields are larger by 20–
27% for 88 Br(H), and smaller by 9–26% for 89 Br(H),
by 8–28% 146 Nd(H), by 11–21% for 149 Sm(H) and
by 20–25% for 151Sm(H) when compared with the
other four libraries. Except for 149 Sm(H) our
evaluated data are not recommended because they
are based on only one set of measurements. There
are only two sets of measured data available for
149
Sm(H), and our evaluated data are only
recommended as reference.
The recommended yield for 85 Kr(F) is 10–15%
larger than the equivalent data in ENDF/B-VI,
JENDL-3 and CENDL/FY, but is 18% smaller than
in JEF-2, while our value for 109 Ag(H) is about 20%
larger than the data in ENDF/B-VI, JENDL-3 and
CENDL/FY, but agrees with JEF-2; our 129I(F) value is about 70% smaller than the data in ENDF/
B-VI, JENDL-3 and CENDL/FY, but agrees with
JEF-2. Our evaluation for 85Kr(F) and 109Ag(H) is
based on only one set of measured data and is
recommended only as reference. However, the
evaluated yield for 129I(F) is recommended, since
the data are based on three sets of measured data
(although the existing discrepancies should be
borne in mind).
Compared with CENDL/FY, our
recommended yield is 39% smaller for 93 Zr(H),
26% smaller for 144Pr(F) and 19% smaller for
147,149
Pm(H), although in agreement with all other
evaluations.
53