JAERI 1287 JNDC Nuclear Data Library of Fission Products Fir

JNDC Nuclear Data Library of Fission Products JAERI 1287
(b) Systematic behavior of the values of Qoo was examined for each mass region and
each even-old category, and the Qoo -value was extrapolated to each nuclide.
By use of the QOo -values determined by the above methods, Ep, ET and T,,z were calculated.
There was, however, no essential difference between the two decay power curves corresponding
to the above two methods (a) and (b). This is due to a fact that the contribution from
these nuclides is small in the calculated decay power even at very short cooling time. In practice,
we stored the Ep, Er and Tll2 data based on the method (b) in the JNDC Library.
Furthermore Ep and Er were calculated for 87 high Q-value nuclides, in the same way
as in the case 1) providing the experimental half-life and the decay scheme information.
The importance of these 87 nuclides will be described in the following section.
2.3.3 Adoption of the Theoretical Values for Ep and Er of Some Short-lived Nuclides
with Measured Data
The nuclear theories 32 ' 33 ) give the large beta strength at high excitation energy as shown
in Fig. 2.3.2. With the mitigation due to rapid decrease of the Fermi function /(£) in Eqs.
2.3.4 and 2.3.5, this decreases Ep, and increased Er. On the other hand the energy levels at
1.0 i—i—r TT"
1 I I I I I | "I 1—I I II I
•3 0.9
> 0.8
x
4-1
U
o a.
(0
0.7
0.6
0.5
% 0.4
1 0.3
0.2
• ORNL (1980)
D ORNL (1962)
o LASL (1963)
10 u
i i i i i i i i i i i i i i i
10 1
Cooling time , t (s)
Fig. 2.3.3 Effect of using theoretical values of Er on the calculated results of 235 U gamma
decay power. The solid curve with (§) corresponds to calculation after the
replacement of experimental Ep and Er values for 87 nuclides with theoretically
estimated ones. The solid curve with @) corresponds to calculation before
the replacement. The experimental data are taken from the papers by ORNL
(Ref. 3 and Perry A.M. et al. : ORNL-TM-4197 (1973)) and by LANL (Fischer
P.C. and Engle L.B. : Phys. Rev. 134, B796 (1964)).