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

all product nuclides. The data tables were processed to
generate the data in the required format.
I.3.2.12. Laurec et al. [I.14]
Measurement type 2: The cumulative yields
from 233,235,238 U and 239 Pu fission induced by fission
spectrum and 14.7 MeV neutrons were measured by
the radiochemical method. The g ray spectra were
measured with a Ge(Li) detector and the number of
fissions was determined with a plane ionization
chamber.
The data for 239 Pu fission at 14.9 MeV were
used. Although the measured yields are cumulative,
the differences between these values and the chain
yields are all within the experimental uncertainties.
So all data were used except for 136 Xe, whose yield is
small and possibly incorrect.
I.3.2.13. Winkelmann et al. [I.15]
Measurement type 2: The cumulative yields
from 242 Pu fission induced by 15.1 MeV neutrons
were measured for 65 fission products from 85 Kr to
151 Pm. The fission product activities were measured
by direct g ray spectrometry with a Ge(Li) detector,
as well as chemical separation of the fission product
elements Pd, Ag, Cd, Sn, Sb and Ce, followed by
b counting or g ray spectrometry. The chain yields
of 43 mass chains were obtained by dividing the
measured cumulative yields by an adjustment
factor, which is the ratio of the cumulative yield of
the measured product nuclide to the corresponding
chain yield.
The data were used after the following
procedures had been applied:
(a) Some chain yields were obtained from two or
more cumulative yields — the recommended
chain yield was taken as their weighted
average.
(b) Two fission yields were not used: that of 126g Sb
because the value is an independent yield, and
that of 111m Pm because the datum is only a
partial isomeric yield.
(c) The data of product nuclides 130g Sb, 131 Sb and
131m Te were also discarded. The chain yields
deduced from the cumulative yields of these
nuclides are too small. The fractions of the
measured cumulative yields to the corresponding
chain yields are too small, which
could introduce large uncertainties into the
resulting chain yields. In addition, there are
large differences for the adjustment factors of
these nuclides between the values given in the
paper and those calculated with the data from
ENDF/B-VI.
I.4. RESULTS, RECOMMENDATIONS AND
DISCUSSION
Based on the data selected from the
available experimental data, and after their
evaluation and processing as described above, the
recommended mass distribution data for 238 U,
239,242 Pu fission are listed in Table I.1. All
recommended data are given in the annex to this
section, and plotted in Figs I.1–I.16.
As mentioned above, there are two types of
measurements for mass distributions:
(a) Data are obtained by recording prompt fission
fragments (data type 1 in Table I.1) with a
double Frisch gridded ionization chamber,
silicon PIN diode detector arrays, etc., as
described by Vivès et al., Zöller and Äystö
et al.
(b) Data are obtained by recording the radioactivity
of fission product nuclides (data type 2
in Table I.1) by means of g ray spectrometry
with a Ge(Li) or HPGe detector, either
directly from the fission sample or after radiochemical
separation, as undertaken by Nagy et
al., Chapman, Li Ze et al., Liu Conggui et al.,
Daroczy et al., Liu Yonghui et al., Gindler et
al., Ford, Laurec et al. and Winkelmann et al.
From the comparisons in Figs I.17–I.19, the data
measured by different laboratories but obtained with
the same type of method (data type 1 or 2) are
generally found to be in good agreement within the
experimental uncertainty. But there is a systematic
difference between the two types of data. The reason
lies (a) in the physical nature of the measured yield
and (b) in differences in the measurement techniques.
The essential difference between the two types of
method is that for type 2 there is some delay time
(days, hours seconds, etc.) between fragment
formation and measurement, during which the
radioactive products decay (although this effect can
be accounted for), whereas for data type 1 the
measurement is ‘prompt’. Nevertheless, even in the
type 1 method the fragments are generally measured
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