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

cross-section data has been achieved for three
different nuclei, 235,238 U and 237 Np.
(b) Reasonable values have been derived for the
outer barrier heights and the corresponding
curvatures of each mode.
(c) Symmetric and asymmetric fission can be
explained by penetration through different
outer barriers. At sub-barrier neutron incident
energies, the least asymmetric mode S1 is
dominant, while above the fission threshold
the most asymmetric mode S2 becomes
dominant in fission. This behaviour has consequences
for the observed fission fragment
properties, e.g. fragment mass distribution.
(d) Within the concept of multi-modal fission, the
calculations of fission fragment mass distributions,
the prompt fission neutron multiplicity
and neutron energy spectrum for each mode
are feasible from the measured fission crosssections
only.
116
REFERENCES TO SECTION 4.1
[4.1.1] BROSA, U., et al., Nuclear scission, Phys. Rep.
197 (1990) 167–262.
[4.1.2] TURKEVICH, A., NIDAY, J.B., Radiochemical
studies on the fission of Th-232 with pile
neutrons, Phys. Rev. 84 (1951) 52–60.
[4.1.3] BRITT, H.C., et al., Energetics of charged
particle-induced fission reactions, Phys. Rev. 129
(1963) 2239–2252.
[4.1.4] HAMBSCH, F.-J., et al., “ 252 Cf(sf): fission modes
and far asymmetric mass yields”, Nuclear Data
Science Technology (Proc. Int. Conf.. Trieste,
1997) (REFFO, G., et al., Eds), Vol. 59, Part II,
SIF, Bologna (1997) 1239–1241.
[4.1.5] SIEGLER, P., et al., et al., Fission modes in the
compound nucleus 238 Np, Nucl. Phys. A 594
(1995) 45–56.
[4.1.6] OBERSTEDT, S., et al., Fission-mode calculations
for 239 U, a revision of the multi-modal
random neck-rupture model, Nucl. Phys. A 644
(1998) 289–305.
[4.1.7] McLANE et al. (Eds), ENDF/B-VI, ZA93237,
MF=3, MT=2, 4, 18, 19, 20, 102; ENDF/B-VI
Summary Documentation, Rep. BNL-NCS-
17541, 4th Edn, Suppl. 1, Brookhaven National
Laboratory (1996).
[4.1.8] VLADUCA, G., et al., Neutron cross-sections of
238 U in the energy range 0.01–5.5 MeV, Ann.
Nucl. Energy 27 (2000) 995–1010.
[4.1.9] VLADUCA, G., et al., Fission cross-section
evaluations in the frame of the multi-modal
fission model for 237 Np(n,f), Nucl. Phys. A 707
(2002) 32–46.
[4.1.10] RAYNAL, J., Notes on ECIS94, CEA-N-2772
(1994).
[4.1.11] VLADUCA, G., et al., Evaluation of the fission
cross-section within the multi-modal fission
approach for 235 U(n,f), Nucl. Phys. A 720 (2003)
274–292.
[4.1.12] EXFOR Nuclear Data Library (2000), nucleus
ZA93237, quantities CS, reactions (n,tot) (n,f)
and (n,g).
[4.1.13] STRAEDE, C., et al., 235 U(n,f) fragment mass-,
kinetic energy- and angular distributions for
incident neutron energies between thermal and
6 MeV, Nucl. Phys. A 462 (1987) 85–108.
[4.1.14] HAMBSCH, F.-J., Institute for Reference
Materials and Measurements, EC Joint
Research Centre, unpublished studies, 2002.
[4.1.15] VIVÈS, F., et al., Investigation of the fission
fragment properties of the reaction 238 U(n,f) at
incident neutron energies up to 5.8 MeV, Nucl.
Phys. A 662 (2000) 63–92.
[4.1.16] SHPAK, D.L., Angular anisotropy of fragments
from fission of 238 U by 0.85–6.28 MeV neutrons,
Sov. J. Nucl. Phys. 50 (1989) 574–577.
[4.1.17] GOVERDOVSKII, A.A., ICTP lecture notes,
Nuclear Reaction Data and Nuclear Reactors:
Physics, Design and Safety (Proc. Workshop
Trieste, 2002), Abdus Salam International
Centre for Theoretical Physics, Trieste (2002).