JAERI 1287 JNDC Nuclear Data Library of Fission Products Fir

22 JNDC Nuclear Data Library of Fission Products JAERI 1287
and A are given as neutron spectral data in Groups 26 and 27, respectively. The thermal
neutron flux 0,* in Eq. (2.6.1) is given as the integral of the neutron flux below 0.5 eV.
4>ih= 4>{E)dE. (2.6.4)
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2.7 Nuclear Data Tables
The evaluated nuclear data of fission products in the present JNDC FP Nuclear Data
Library are tabulated in this section.
The decay data and fission yield data are given in Table 2.7.1 for each mass number.
The decay chain diagram is shown graphically for each mass number. The branching ratios
are given in the decay chain diagram if more than one decay modes exist for some fission
product nuclides in the decay chain. The feeding mode through neutron capture is designated
by (n,r) and the one through the delayed neutron emission by(d n)in the diagram. When
there are the ground and isomeric states in a neutron captured nuclide, the capture cross section
must be divided among them. However, there is not enough information about partial
capture cross sections. The fractions in the diagram are taken from the ratios of the thermal
neutron capture cross sections, which were taken from Table of Isotopes or BNL-325 57 ^.
The decay constant {A), Q-value and the average decay energies of beta-rays (Ep), gammarays
(Er) and internal conversion electrons (ECE) are given for each nuclide as the decay data in
Table 2.7.1 in addition to the decay chain diagram. If there are more than one decay modes
for some nuclide, Q-value is averaged with the weight of branching ratio. The average energies
Ep, Er and ECE were calculated by the PROFP code 28) using the intensity and energy data.
For the nuclide with no or with incomplete experimental data, the necessary decay data had
been estimated with the gross theory of beta decay as described in Sec. 2.3.
The most of the independent fission yield data have been taken from the compilation
by Rider and Meek 41) and supplemented by the present authors for the additional nuclides
and isomeric states. Independent yield values are normalized so that the sum of yields is
200% per fission. Then, the cumulative yields have been calculated from the independent
yields using the branching ratios in this library as described in Sec. 2.4. Ten sets of different
independent and cumulative yields are given in the table for six fissionable nuclides and three
neutron energies. The ten sets are:
(1) 235 U , t ; t = thermal neutron fission
(2) 235 235 TJ
> ^
235 U u ,/'•/ , / = fission spectrum neutron fission
235TJ
(3) 235Tj , ^ h \ h = 14 MeV neutron fission
(4)
(5)
(6)
(7)
(8)
(9)
(10)
238TJ
238TJ
239pu
239 Pu
241 pu
233 ij
, f
, t
, f
, t
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Twenty-seven group neutron capture cross sections are given for 80 nuclides in Table
2.7.2. Groups 1 to 25 shown in Table 2.6.1 are for fast reactor calculations. Groups 26 and
27 are for thermal reactor calculations; the resonance integral and the thermal neutron capture
cross section for 2200 m/s-neutrons, respectively (cf. Sec. 2.6). The calculation of fission
yields, the data edition, the tabulation and the graphical representation of decay-chain diagram
have been performed by a computer code PROFP-Y 58) .