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

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The uncertainty was processed as follows:
(a) Adjustment for standard fission yield:
2 2
( 0 S S0)
DY¢ = DY¢ + DY¢ - DY¢
or for fission cross-section:
DY¢ = DY0¢ + Ds S¢ - Ds
S¢
(3.2.4)
(3.2.5)
where ΔY¢ is the relative uncertainty of the
data Y: ΔY¢= ΔY/Y. However, ΔY¢ S0 (uncertainty
of the old standard) may not be
included in Y 0 (total uncertainty of the data
given by the author); under such circumstances,
ΔY¢ S0 should be taken to be zero.
(b) Gamma ray intensity adjustment: The ΔY
uncertainty was not changed, because this
adjustment is usually not large and the
uncertainty of the gamma ray intensity is not
given.
(c) Calculate the yield from ratio R 0
(d) Calculate the ratio R 0 from R value R v :
(3.2.6)
(3.2.7)
where ΔY¢ mxw and ΔY¢ Smxww are the uncertainties
of the measured and standard
nuclides, respectively.
(e) Calculate ratio R 0 from fission yield: since this
evaluation is for reference fission yield data,
only ratios for measured relative data were
used, if the details of the standards are given
(otherwise the data were discarded). Under
these circumstances:
(3.2.8)
If ΔY′ s is not included in the total ΔY given by
the author, ΔY′ s is assigned a value of 0.
The processing of the data and their uncertainties
for each sub-entry in a paper are given in
the corresponding tables of Refs [3.2.2–3.2.8].
3.2.2.4. Data processing
2 1 2
2 2
( 0 )
( )
2 2 1 2
DY¢ = DR0¢ + DYS¢
DR¢ = DR¢ + DY¢ + DY¢
0
2 1 2
2 2 2
( n mxw Smxw )
( )
2 2 1 2
DR0¢ = DY¢ + DYS¢
The collected and adjusted data with their
(re-)evaluated uncertainties were processed with
weighted averages, and simultaneously evaluated.
1 2
(a) Data average: Data measured at the same
energy points for the same fissioning nuclide
were averaged using the AVERAG code. The
recommended weighted mean and external
uncertainty were calculated. Tables 3.2.2 and
3.2.3: Data for which averages have been
calculated are marked ‘A’ in the column
headed ‘PROC’, and the number of data
points is given in the column headed ‘POINT’;
averages have been taken in most cases.
(b) Simultaneous evaluation: Data for which
absolute yields and their ratios had been
measured were simultaneously evaluated by
using the ZOTT code [3.2.11]. Simultaneously
evaluated data are marked ‘S’ in Tables 3.2.2
and 3.2.3. There are two kinds of correlated
measurements: different energy points for the
same nuclide, and different nuclides at the
same energy point.
3.2.2.5. Evaluation system FYDES
All data retrievals, adjustments, modifications to
quoted uncertainties and data processing were
performed with the fission yield data evaluation system
FYDES which has been developed to assist in the
evaluation of fission yield data. The following specific
characteristics of these data and the FYDES system
make them distinct from other data types (like crosssection
data) and corresponding evaluation systems:
(a) Data in the EXFOR file can also be given
under the heading ‘ELEM/MASS’ (see
below);
(b) More fission yield data are measured on a
relative basis as ratios or R values;
(c) Many data need to be adjusted for the
standard yield, gamma ray intensity and
fission cross-section and have to be recalculated
from ratios or R values;
(d) The dependence of yields on neutron energy
appears to be linear for most cases.
The fission yield data can be retrieved from
the EXFOR database by target, or by incident
neutron energy, or by product (if given in
REACTION), using the EXFOR retrieval system.
But when in an EXFOR entry the ‘variable product’
formalism is used, ‘ELEM/MASS’ is given in
REACTION, and the product occurs under the
heading ‘ELEM/MASS’ of the DATA table and
cannot be retrieved this way. Some supplementary
programs were developed to solve this problem,