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92-U -238 BRC,ORNL+ EVAL-OCT04 LOPEZ-JIMENEZ, MORILLON, ROMAIN
DIST-JAN09 20090105
----JEFF-311 MATERIAL 9237
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
*************************** JEFF-3.1.1 *************************
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** Original data taken from: JEFF-3.1 **
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***************************** JEFF-3.1 *************************
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** Original data taken from: New evaluation **
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05-01 NEA/OECD (Rugama) 8 delayed neutron groups
Jefdoc-976(Spriggs,Campbel and Piksaikin,Prg Nucl Eng 41,223(2002)
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JEFF-3.1 evaluation above the unresolved resonance region
based on model calculations, from 20 keV to 30 MeV.
M-J. Lopez-Jimenez, B. Morillon, P. Romain,
E. Dupont and J-Ch. Sublet
CEA/DAM Bruyeres-le-Chatel
CEA/DEN Cadarache
MF=1 General Information
The prompt fission neutron multiplicity and spectra
are calculated using the BRC improved Los Alamos model from
Vladuca and Tudora [1]. The model parameters are slightly
different from those adopted in [1]. The prompt fission
neutron multiplicity is obtained from an energetic balance
ratio. The available energy (the average fission energy
released minus the average fission fragment kinetic energy
minus the average prompt gamma ray energy) is divided by the
energy carry away by the neutron (the average fission
fragment neutron separation energy plus the average
center-of-mass energy of the emitted neutrons). The main
improvement is the dependence of the average total
fission-fragment kinetic energy and the average gamma energy
on neutron incident energy.
MT=452 Total Nubar. Sum of MT=455 and 456
MT=455 Delayed Neutron Yields. BRC modified ENDF/B-VI r8
MT=456 Prompt Neutron Yields.
Vladuca and Tudora BRC improved Madland-Nix model
MT=458 Energy Release. BRC modified ENDF/B-VI r8
MF=2 Resonance Parameters
EVALUATION IN THE RESOLVED RESONANCE REGION 0-20 keV
H. Derrien, A. Courcelle, L. C. Leal, N. Larson (ORNL, oct 2004)
A description of the present evaluation can be found
in [2]. This evaluation was performed with the
computer code SAMMY [3] using Reich-Moore formalism.
Resonance parameters are obtained from 0 to 20 keV
1/ thermal - 1 keV
The thermal capture value has been adjusted to
sigma0 = 2.683 b (Trkov et al. [14]). The shape of the
capture cross-section in the thermal range was checked with the
capture measurements of Corvi et al. [9].
For the large s-wave 6.67 eV, 20.8 eV and 36.6 eV resonances,
the seven transmission spectra of Olsen [12] were fitted
with 4 transmission measurements of Meister et al. [7]
and the capture measurements of De-Saussure et al [11].
To get a better correction of residual errors in experimental
normalizations and backgrounds, SAMMY fits were performed
resonance by resonance up to 60 eV. The Crystal Lattice Model
of SAMMY for Doppler broadening was used to describe the shape
of the 6.67 eV resonance.
Below 102 eV, the radiative widths fitted with the present
experimental database give a slightly higher average values
( = 23.5 meV [2]) than in ENDF\B-VI [4]
( = 23.1 meV [4]). Both values are considered to be
in the uncertainty margins of the differential experiments.
Fits using fixed radiative widths from ENDF\B-VI [Mox1994]
below 102 eV give best results on thermal integral benchmarks,
(See the work of the WPEC/subgroup-22
[15]), and were consequently adopted for this evaluation
From 250 eV to 1 keV the Macklin et al. capture [6]
measurements were included in the fit. The spin of several
p-wave resonances have been changed from the original evaluation
([4]) to account for the spin measurements of Gunsing
et al. [16]. Reliable estimates of p-wave neutron widths
below 300 eV were given by Crawford et al.
[17] with very thick uranium sample transmission
measurements and were used as prior parameters in the fit.
The fission widths (below 10 keV) are taken from
ENDF\B-VI [4] and were deduced from the Measurements of
Defilippo et al. [10]
3/ 1 keV to 20 keV
The Olsen 1979 transmission data [13] were analyzed in
the energy range 1 keV to 10 keV and the Harvey transmission
data [5] in the energy range 1 keV to 20 keV.
The capture data of de Saussure[11] and Macklin[6]
were analyzed in the energy range 1 keV to 10 keV and
1 keV to 20 keV respectively. In general, the thick sample
transmissions calculated from the resonance parameters and
averaged over 1 keV energy intervals agree within 1% with
the experimental values of Harvey and within 1.5% with the
experimental values of Olsen, in agreement with the quoted
experimental errors, The fit to the capture cross sections
could not be obtained without large normalization and
background corrections.
The average value of the capture cross section calculated with
the resonance parameters is 2.4% larger than ENDF/B-VI
in the energy range 1 keV to 10 keV, and 4.5% smaller in the
energy range 10 keV to 20 keV (unresolved range evaluation of
Froehner [24]).
The value of the effective scattering radius, R'=9.45 fm, and of
the external resonance parameters, were obtained by assuming that
the normalization coefficients in Harvey and Olsen experimental
transmission were accurate within 1.0-1.5%.
4/ The resonance parameters
The fit to the experimental data was obtained by using
898 s-wave, 849 p1/2 and 1565 p3/2 resonances with a level
density nearly constant over the entire energy range.
In addition to the resonances needed for an accurate
representation of the shape of the experimental data
another type of resonances was added: those of very small neutron
width values not seen in the experimental data; these resonances
could have a small contribution in the average capture
cross section.
The statistical properties of the resonance parameters were
checked against the Wigner distribution of the level spacing
and the Porter-Thomas distribution of the reduced neutron widths.
It is likely that about 20 % of the p-wave resonances are still
missing corresponding to very small values of the neutron widths,
particularly in the high energy part of the data.
This evaluation assumes that the contribution of direct capture
is small in the range thermal - 20 keV but this needs to be
checked
Unresolved Resonance Range 20 keV to 300 keV
JEF-2.2 data, F.H. Froehner [18]
LSSF=1, MF-3 contains dilute cross-section for the URR. MF-2
is to be used solely for the calculation of self-shielding
factors
MF=3 Reaction Cross-sections
From the energy of 1 keV up to 200 MeV, nineteen states [19]
Coupled Channel Calculations are performed using the ECIS95[20]
code which also provides compound nucleus cross sections and
transmission coefficients used in pre-equilibrium/evaporation
emission treated in the exciton and Hauser-Feshbach models
implemented in the Bruyeres-le-Chatel modified version of the
GNASH code[21]. This reaction code has been modified to include
width fluctuation factors, relativistic kinematics, and a more
realistic treatment of the fission process. A new fission [22]
penetrability model taking into account Triple Humped Fission
Barrier (THFB) has been developed, explicitly coupling class
I, II and III states while damping those of class II and III.
Emission of light hadrons up to He4 are explicitly treated in
the model calculations. Fission decay of associated residual
nuclei is also treated. However, none of these emissions and
fission cross-sections, are yet explicitly provided in this
file.
The Resolved Resonance Range, ending now at 20 KeV, the
model calculations data are implemented from this energy.
MT=1 calculation from BRC deformed optical potential
over the whole energy range 1 keV-200 MeV.
the results have been validated with existing
experimental neutron reaction cross section data.
MT=2 calculation from BRC deformed optical potential
MT=3 calculation from BRC deformed optical potential
MT=4 calculation from BRC deformed optical potential
sum of mt=51-91.
MT=16 (n,2n) cross section
the results of GNASH have been validated with the
experimental (n,2n) cross section of Frehaut,
re-normalized by a factor 1.10.
MT=17 (n,3n) cross section
MT=18 (n,F) calculation with BRC modified GNASH code, with
a triple humped fission barrier penetration model
MT=19-21(n,f),(n,nf),(n,2nf) calculation with BRC modified
GNASH code, with a triple humped fission barrier
penetration model.
MT=37 (n,4n) cross-section
MT=38 (n,3nf)calculation with BRC modified GNASH code,
with a triple humped fission barrier penetration
model. In fact this cross section include more
complex processes thus as : (n,4nf),(n,pf),(n,df),
(n,tf),(n,He-3f),(n,He-4f),(n,pnf), ...
MT=51-78(n,n') cross-section for 1st-28th excited states
MT=79-90(n,n') cross-section for 29th-40th excited states
These discrete states are embedded im the contiunuum.
The corresponding cross section are originated from
pre-ENDF/B-VII (u238la8j) evaluation. The chosen
states, for this present evaluation, result from
adjustment by trial and error to best accomodate the
14-MeV Baba's data [23].
MT=91 (n,n') continuum cross-section
MT=102 (n,g) cross-section
MF=4 Angular Distributions of Secondary Particles
MT=2 elastic angular distribution, given up to 30 MeV
MT=18 fission given up to 30 MeV (assumed isotropic)
MT=51-78 inelastic levels, 1st-28th excited states
With a uniform number of angular points (91), equal values
of the tabulated probability distributions may occur.
MF=5 Energy Distributions of Secondary Particles
MT=18 Vladuca and Tudora BRC improved Madland-Nix model
MT=455 extended ENDF/B-VI r8 data
MF=6 Products Energy-angle Distributions
MT-16 pre-ENDF/B-VII (U238o)
MT=17 pre-ENDF/B-VII
MT=37 pre-ENDF/B-VII
MT=91 pre-ENDF/B-VII
MF=12 Photon Production Multiplicities
MT=18 pre-ENDF/B-VII
MT=102 pre-ENDF/B-VII
MF=13 Photon Production Cross-section
MT=3 pre-ENDF/B-VII
MF=14 Photon Angular Distribution
MT=3 pre-ENDF/B-VII
MT=18 pre-ENDF/B-VII
MT=102 pre-ENDF/B-VII
MF=15 Continuous Photon Energy Spectra
MT=3 pre-ENDF/B-VII
MT=18 pre-ENDF/B-VII
MT=102 pre-ENDF/B-VII
2200 m/s values and resonance integrals given by evaluation
NJOY-99.90
2200m/s values Resonance Integral
(barns) (barns)
Total 12.17 592.62
Elastic 9.49 317.74
Fission 1.89E-05 3.35E-02
Capture 2.67 274.66
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References
[1] G. Vladuca and A. Tudora, Ann. Nuc. Energy. 28, 689 (2001).
[2] H. Derrien, A. Courcelle, L. C. Leal, A.Santamarina
Proc. Int. Conf. on Nuc. Data for Sci. and Tech.,
Santa-Fe, USA (2004).
[3] N. Larson, ORNL/TM-9179/R6 ENDF-364
[4] M. Moxon and M. Sowerby, NEA-OECD report (1994)}
[5] Harvey J. A., Hill N. W., Perey F. G., Tweed G. L.
and Leal L. C, Proc. Int. Conf. on nuclear data for
Science and Technology, Mito, Japan (1988)
[6] Macklin Roger L., Perez R. B., De Saussure G.
and Ingle R. W., Proc. Int. Conf. on nuclear data for
Science and Technology, Mito, Japan (1988)}
[7] A. Meister et al.,
Proc. Conf. Nuc. Data, Long Island, October 5-8, (1998)
[8] W. P. Poenitz, L.R. Fawcett Jr and D.L. Smith,
Nucl. Sci. Eng., 78, (1981) 239-247}
[9] F. Corvi, G. Fioni,
Proc. Conf. Nuc. Data for Sci. and Tech., Mito, Japan, (1988)
[10] F.C. Difilippo et al, Phys. Rev.C 21, 1400 (1980)
[11] G. De Saussure, E. G. Silver, R. B. Perez ,R. Ingle
and H. Weaver, Nucl. Sci. and Eng., 5, 385 (1973)
[12] D.K. Olsen, G. De Saussure, R.B. Perez, F.C. Difilippo,
R.W. Ingle, and H. Weaver, Nucl. Sci. and Eng., 62, 479(1977)
[13] D. K. Olsen, G. De Saussure, R.B. Perez,
F.C. Difilippo, R.W. Ingle, and H. Weaver,
Nucl. Sci. and Eng., 69, 202-222 (1979)
[14] A. Trkov et al., personal communication,
submitted to Nucl. Sci. Eng.
[15] A. Courcelle et al., Summary report of the
WPEC/Subgroup-22, NEA report to be published
[16] F. Gunsing, K. Athanassopulos, and F. Corvi,
Phys. Rev. C, 56, Num 3 (1997)
[17] B. E. Crawford et al., Phys. Rev. C, 58, Num 2 (1998)
[18] F.H. Froehner,"Evaluation of the Unresolved Resonance Range
of 238U + n, Part II: Differential Data tests",
NSE: 111, 404-414, (1992).
[19] A.J. Koning, M.C. Duijvestijn and M-J. Lopez-Jimenez, "Data
Evaluation up to 200 MeV for Fe, Pb and U", NRG Report,
20567/03.56876/P, (2003).
[20] J. Raynal, "Code ECIS95" CEA report N-2772, (1994).
[21] P.G. Young, E.D. Arthur and M. B. Chadwick, Workshop on
Nuclear Reaction Data and Nuclear Reactors, Trieste,
Italy (1996).
[22] M-J. Lopez-Jimenez, B. Morillon and P. Romain "Triple humped
fission barrier model for a new 238U neutron cross-section
evaluation and first validation with TRIPOLI code", to be
published, ANE, (2004).
[23] M. Baba, H. Wakabayashi, N. Itoh, K. Maeda, and N. Hirakawa,
Measurements of Prompt Fission Neutron Spectra and Double-
Differential Neutron Inelastic Scattering Cross Sections for
238-U and 232-Th, IAEA Int. Nuc. Data report INDC(JPN)-129
(1989).
[24] F. H. Frohner, Nucl. Sci. and Eng.,103 (1988)
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