94-Pu-237 JAERI EVAL-MAR95 T.Nakagawa, V.A.Konshin
JAERI-Research 95-067 DIST-MAR02 20001004
----JENDL-3.3 MATERIAL 9431
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
HISTORY
95-02 New evaluation was made by Nakagawa and Konshin /Na95/.
00-10 Compiled by T.Nakagawa.
The following quantities are re-evaluated after JAERI-
Research 95-067:
MF=3 MT=102
MF=5 MT=16, 17, 18, 19
MF=1 General information
MT=451 Descriptive data
MT=452 Number of neutrons per fission
Sum of MT=455 and 456.
MT=455 Delayed neutrons per fission
Determined from the systematics of Manero and Konshin /Ma72/.
MT=456 Prompt neutrons per fission
Determined from the data for Pu-239.
MF=2 Resonance parameters
MT=151
No resonance parameters were given.
Thermal cross sections and resonance integral (barns)
0.0253 eV resonance int.
Total 2966.5 -
Elastic 11.5 -
Fission 2455.0 816
Capture 500 142
MF=3 Neutron cross sections
Below 1.0 eV
The fission cross section at the thermal energy was based on
the recommended value of Mughabghab /Mu84/ based on
experimental data. The ratio of capture to fission cross
sections was assumed to be the same as that in the keV region
(about 1/5).The 1/v shape was assumed to the fission and
capture cross sections. The elastic scattering cross setion
of 11.5 b was calculated with CASTHY /Ig91/.
Above 1.0 eV
Three codes of CASTHY/Ig91/, ECIS/Ra00/ and STAPRE/Uh76/
were used.
Parameters (MeV, fm) of deformed potential/Ko93/ for ECIS:
V = 46.2 - 0.3*E
W-d = 3.05 + 0.4*E 0 =< E =< 10 MeV
= 7.05 - 0.082*(E-10) 10 < E <=20 MeV
W-v = 8.0/(1+exp(-(E-50)/10))
V-so= 6.2
r-r = 1.26 a-r = 0.63
r-d = 1.26 a-d = 0.52
r-so= 1.12 a-so= 0.47
beta-2 = 0.220 beta-4 =0.07
The spherical potential parameters/Ig85/ used in CASTHY:
V = 44.7 - 0.3*E, r-r = 1.256, a-r = 0.626
W-d = 4.115 + 0.4*E, r-d = 1.260, a-d = 0.555+0.0045*E
V-so= 7.5, r-so= 1.256, a-so= 0.626
V was modified so as to reproduce the total cross section
of Pu-239 in the keV region.
Level density parameters used in CASTHY:
a(1/MeV) T(MeV) delta(MeV) E-x(MeV) spin-cutoff
Pu-237 30.94 0.389 0.779 4.2131 31.10
Pu-238 31.68 0.394 1.556 5.1959 31.56
STAPRE calculation is described in Ref. /Ko95/. Fission
barrier parameters used are as follows:
Ef-A(MeV) Ef-B(MeV)
Pu238 5.60 5.10
Pu237 6.00 5.80
Pu236 5.30 4.70
Pu235 5.60 5.10
MT=1 Total
1 eV - 400 keV: calculated with CASTHY.
Above 400 keV : calculated with ECIS.
MT=2 Elastic scattering
Below 1 keV: a constant value of 11.5 b was assumed.
Above 1 keV: Calculated as the (total) - (sum of partial)
cross sections.
MT=4, 51-91 Inelastic scattering
Compound process was calculated with CASTHY, and direct one
with ECIS.
Level scheme/Ak95/:
Energy (keV) Spin-parity direct-component
g.s. 0.0 7/2 -
1 47.71 9/2 - *
2 106.0 11/2 - *
3 145.54 1/2 +
4 155.45 3/2 +
5 175.0 13/2 - *
6 201.18 5/2 +
7 224.25 7/2 +
8 257.0 15/2 - *
9 280.22 5/2 +
10 304.0 9/2 +
11 320.97 7/2 +
12 370.4 3/2 +
13 371.0 9/2 +
14 404.19 5/2 +
15 407.83 5/2 +
16 438.41 7/2 +
17 453.2 7/2 +
18 473.5 7/2 +
19 486.0 9/2 +
20 513.0 9/2 +
21 545.0 1/2 -
22 582.0 5/2 -
23 591.0 3/2 -
Levels above 655 keV were assumed to be overlapping.
The direct process was calculated with ECIS for the levels
marked with *.
MT=16,17 (n,2n) and (n,3n) reactions
Calculated with STAPRE. The results were reported in Ref.
/Ko95/.
MT=18 Fission
Above 1 MeV, the cross section /Ko95/ calculated with STAPRE
was adopted. In the region 0.1 - 1 MeV, assumed to have
almost same shape as Pu-239. Below 100 keV, the reaction cross
section * 0.85 was assumed.
MT=102 capture
Calculated with CASTHY. The average capture width of 0.047 eV
and the level spacing of 0.233 eV were assumed. The direct
and semi-direct cross section was calculated with DSD /Ka99/.
MF=4 Angular distributions of secondary neutrons
MT=2 Elastic scattering
Above 400 keV: calculated with ECIS.
Below 400 keV: calculated with CASTHY.
MT=16,17, 18 (n,2n), (n,3n) and Fission
Assumed to be isotropic in the laboratory system.
MT=51-91 Inelastic scattering
Calculated with CASTHY and ECIS.
MF=5 Energy distributions of secondary neutrons
MT=16, 17, 91
Calculated with EGNASH/Ya90/.
MT=18
Evaporation spectrum with nuclear temperature obtained from
the systematics of Smith et al. /Sm79/ and Howerton-Doyas
/Ho71/. The ratios of multi-chance fission to total were
estimated from the STAPRE calculation/Ko95/.
References
Ak95) Y.A. Akovali: Nucl. Data Sheets, 74, 461 (1995).
Ho71) R.J. Howerton and R.J. Doyas: Nucl. Sci. Eng., 46, 414
(1971).
Ig85) A.V. Ignatyuk, et al.: Sov. J. Nucl. Phys. 42, 360 (1985).
Ig91) S. Igarasi and T. Fukahori: JAERI 1321 (1991).
Ka99) T. Kawano: private communication (1999).
Ko93) V.A. Konshin, et al.: Proc. Workshop on Computation and
Analysis of Nuclear Data Relevant to Nuclear Energy and
Safety, Trieste, Italy, 10 Feb. - 13 Mar 1992, World
Scientific, p.775 (1993).
Ko95) V.A. Konshin: JAERI-Research 95-010 (1995).
Ma72) F. Manero, V.A. Konshin: At. Energy Review, 10, 637 (1972).
Mu84) S.F. Mughabghab: "Neutron Cross Sections, Vol.1, Part B,"
Acadenic Press (1984)
Na95) T. Nakagawa and V.A. Konshin: JAERI-Research 95-067 (1995).
Ra00) J. Raynal: unpublished.
Sm79) A. Smith, et al.: ANL/NDM-50 (1979).
Uh76) M. Uhl and B. Stromaier: IRK-76/10 (1976).
Ya90) N. Yamamuro: JAERI-M 90-006 (1990).