94-Pu-241
94-Pu-241 JAERI Eval-Feb00 Y.Nakajima, T.Kawano
DIST-MAR02 Rev4-Mar00 20020214
----JENDL-3.3 MATERIAL 9443
-----INCIDENT NEUTRON DATA
------ENDF-6 FORMAT
HISTORY
79-10 New evaluation was made by Y.Kikuchi (JAERI) and N.Sekine
(HEC) /1/. Data of JENDL-1 /2/ were superseded.
79-12 Files 2, 3 and 4 were released as JENDL-2B /3/.
87-03 The fission cross section was revised by adopting results of
simultaneous evaluation /4/ for JENDL-3.
89-02 FP Yields were added.
90-07 FP yield data were modified.
93-05 JENDL-3.2.
Resolved resonance parameters evaluated by Derrien and
de Saussure/5/ (adopted in ENDF/B-VI) were modified by
H.Derrien (JAERI)/6/.
Compiled by T.Nakagawa (NDC/JAERI)
***** Modified parts for JENDL-3.2 ********************
(2,151) Resolved resonance parameters up to 300 eV
***********************************************************
00-03 JENDL-3.3
Evaluation was made by Y.Nakajima(RIST) and T.Kawano(Kyushu
Univ.) and compiled by O. Iwamoto (NDC/JAERI)
***** Modified parts for JENDL-3.3 ********************
(3,2), (3,18), (3,102)
(5,16), (5,17), (5,91), (5,455)
***********************************************************
02-01 Covariances were taken from JENDL-3.2 covariance file except
for MF/MT=33/18.
MF=1 General Information
MT=451 Comment and dictionary
MT=452 Number of neutrons per fission
Sum of Nu-p (MT=456) and Nu-d (MT=455).
MT=455 Delayed neutron data
Data of Benedetti+ /7/
MT=456 Number of prompt neutrons per fission
Data of Boldeman and Frehaut /8/ for thermal fission were
adopted at low energies by assuming Nu-p(Cf-252 spontaneous
fission) = 3.753 for JENDL-2. For JENDL-3, data were
increased by a factor of 3.756/3.753. An energy dependent
term was based on Frehaut+ /9/
MF=2,MT=151 Resonance Parameters
Resolved resonances : 1.0E-5 - 300 eV (Reich-Moore formula)
Parameters were evaluated by Derrien and de Saussure/5/,
and modified by Derrien /6/. Details of the modification
are given in Appendix.
Unresolved resonances : 300 eV - 30 keV
Obtained by fitting evaluated fission and capture cross
sections.
Energy dependent parameters : So, S1 and Gam-f.
Fixed parameters : R=9.8 fm , Gam-g = 0.040 eV,
D-obs = 0.85 eV
2200-m/sec cross sections and calculated resonance integrals.
2200 m/sec Res. Integ.
total 1384.9 b -
elastic 11.35 b -
fission 1012.0 b 572.6 b
capture 361.53 b 179.9 b
MF=3 Neutron Cross Sections
Above 300 eV, smooth cross sections were given as follows.
Between 300 eV and 30 keV, cross sections were represented with
the unresolved resonance parametes.
MT=1, 2, 4, 51-61, 91, 251 : Total, elastic, inelastic
scattering cross sections and mu-bar
Calculated with optical and statistical models. Optical
potential parameters used were obtained from systematics/10/
V = 40.25 - 0.05*En , Ws = 6.5 , Vso = 7.0 (MeV)
r = rso = 1.32 , rs = 1.38 (fm)
a = b = aso = 0.47 (fm)
Statistical model calculation was performed with CASTHY code
/11/. Competing processes (fission, (n,2n), (n,3n), (n,4n))
and level fluctuation were taken into the calculation. The
level scheme taken from Ref./12/.
No Energy(keV) Spin-Parity
g.s. 0 5/2 +
1 41.8 7/2 +
2 94.0 9/2 +
3 161.5 1/2 +
4 170.8 3/2 +
5 223.1 5/2 +
6 230.0 9/2 +
7 242.7 7/2 +
8 300 11/2 +
9 335 9/2 +
10 368 13/2 +
11 445 11/2 -
Continuum levels assumed above 490 keV.
The level density parameters: Gilbert and Cameron /13/.
MT=16, 17, 37 (n,2n), (n,3n), (n,4n)
Calculated with evaporation model.
MT=18 Fission
Below 30 keV: Taken from JENDL-3.2
Above 30 keV: Results of recent simultaneous evaluation
of fission cross sections /14/ were adopted.
*) JENDL-3.2
Above 70 keV, simultaneous evaluation with U-235, U-238,
Pu-240, Pu-241 /4/ were adopted. The experimental data
taken into account are those by Szabo+ /15,16/, Carlson+
/17,18/, Fursov+ /19/and Keappeler+ /20/. Below 45
keV, JENDL-2 was adopted. These two sets of data were
connected smoothly between 45 and 70 keV.
MT=102 Capture
Direct/semi-direct capture component was added to the
cross section of JENDL-3.2.
*) JENDL-3.2
Based on the data of Alpha by Weston+ /21/ up to 250 keV.
Calculated with CASTHY above 250 keV. The gamma-ray
strength function was determined so that the capture cross
section was 269 mb at 250 keV.
MF=4 Angular Distributions of Secondary Neutrons
MT=2, 51-61 : Calculated with CASTHY.
MT=16,17,18,37,91 : Isotropic in the laboratory system.
MF=5 Energy Distributions of Secondary Neutrons
MT=16,17,91
Calculated with pre-compound and multi-step evaporation
theory code EGNASH /22,23/.
MT=18,37
Calculated with pre-equilibrium and multi-step evaporation
code PEGASUS/24/.
MT=18 Prompt fission neutron spectrum.
Determined from Z**2/A systematics by Smith et al. /25/.
MT=455 Delayed neutron spectrum.
Summation calculation made by Brady and England /26/ was
adopted.
MF=31 Covariances of Average Number of Neutrons per Fission
MT=452
Constructed from MT=455 and 456.
MT=455
Based on experimental data.
MT=456
Based on experimental data. A chi-value was 1.06.
MF=32 Covariances of Resonance Paremeters
MT=151
Resolved resonance
Based on experimental data /6/.
Unresolved resonance
The covariances were obtained by using kalman./27/
MF=33 Covariances of Cross Sections (ref.27)
MT=1
The covariances were obtained by using kalman.
MT=2
Constructed from MT=1, 4, 16, 17, 18, 37, and 102.
MT=4, 51-61, 91
The covariances were obtained by using kalman /27/.
A chi-value was 0.97.
MT=16
Systematics.
MT=17
Systematics.
MT=18
Based on simultaneous evaluation /14/.
MT=37
Systematics.
MT=102
The covariances were obtained by using kalman /27/.
A chi-value was 0.97.
MF=34 Covariances of Angular Distributions (ref.27)
MT=2
The covariances of p1 coefficients were obtained by using
kalman.
References
1) Kikuchi Y. and Sekine N.: JAERI-M 84-111 (1984).
2) Kikuchi Y.: J. Nucl. Sci. Technol., 14, 467 (1977).
3) Kikuchi Y. et al.: J. Nucl. Sci. Technol., 17, 567 (1980).
4) Kanda Y. et al.: 1985 Santa Fe, 2, 1567 (1986).
5) Derrien H. and de Saussure G.: Nucl. Sci. Eng., 106, 415
(1990).
6) Derrien H.: JAERI-M 93-251 (1994).
7) Benedetti G. et.al.: Nucl. Sci. Eng., 80, 379 (1982).
8) Boldeman J.W. and Frehaut J.: Nucl. Sci. Eng., 76, 49 (1980).
9) Frehaut J. et.al.: CEA-R-4626 (1974).
10) Matsunobu H. et.al.: 1979 Knoxville Conf., p.715, NBS Special
Publication 594 (1980).
11) Igarasi S. and Fukahori T.: JAERI 1321 (1991).
12) Lederer C.M. and Shirley V.S.: Table of Isotopes, 7th Ed.
(1978).
13) Gilbert A. and Cameron A.G.W.: Can. J. Phys., 43, 1446(1965).
14) Kawano T. et al.: JAERI-Research 2000-004 (2000).
15) Szabo I. et.al.: CONF-701002, p.257 (1971).
16) Szabo I. et.al.: 1973 Kiev Conf, Vol.3, p.27 (1973).
17) Carlson G.W. et al.: Nucl. Sci. Eng., 63, 149 (1977).
18) Carlson G.W. and Behrens J.W.: Nucl. Sci. Eng., 68, 128
(1978).
19) Fursov B.I. et.al.: Sov. At. Energy, 44, 262 (1978).
20) Kaeppeler F. and Pfletschinger E.: Nuc. Sci. Eng., 51, 124
(1973).
21) Weston L.W. and Todd J.H.: Nucl.Sci.Eng.,65,454 (1978).
22) Yamamuro N.: JAERI-M 90-006 (1990).
23) Young P.G. and Arthur E.D.: LA-6947 (1977).
24) Iijima S. et al.: JAERI-M 87-025, 337 (1987).
25) Smith A. et al.: ANL/NDM-50 (1979).
26) Brady M.C. and England T.R.: Nucl. Sci. Eng., 103, 129(1989).
27) Shibata K. et al.: JAERI-Research 98-045 (1998).
=================================================================
Appendix REVISED RESONANCE DATA ,JAERI MAY 1993
=================================================================
Revision of the 241Pu Reich-Moore resonance parameters
by comparison with recent fission cross section measurements.
Herve Derrien
Japanese Atomic Energy Research Institute
I-INTRODUCTION.
The resonance parameters of the neutron cross sections of
241Pu were obtained by Derrien and de Saussure/1/ in the energy
range from thermal to 300 eV by a Bayesian fit of selected
experimental effective total cross sections, fission and capture
cross sections by using the Reich-Moore fitting code SAMMY/2/.
The results of this work were used in the ENDF/B-VI evaluated data
file. Some difficulties were encountered in the normalization of
the experimental fission cross sections due to the discrepancies
in the shape of the available experimental data both in thermal
and high energy ranges. The consistency among the experimental
data base could not be obtained without large renormalization and
background correction parameters in the SAMMY fits. Particularly,
it was shown that the discrepancy between the fission cross
sections in the thermal energy range was due to a deviation from
the 1/v shape below about 0.05 eV.
New fission cross section measurements were recently
performed by Wagemans et al./3,4/ in the energy range from 0.002
eV to 20 eV in order to check the shape of the cross section in
the thermal energy range. They showed that the shape of the
fission cross section was clearly compatible with the 1/v law, in
contradiction to all the previous measurements reported in the
litterature. Consequently, the normalization of all the previous
results using the low energy region could be erroneous.
Particularly, the discrepancy observed in the average fission
cross section over the 0.26 eV resonance could be due to the
errors of normalization in the thermal region. Wagemans et al.
compared the ENDF/B-VI data to their new results and concluded
that the evaluated data files using the evaluation of Derrien and
de Saussure should be revised in the energy range up to 300 eV.
II-COMMENTS ON ENDF/B-VI EVALUATION.
In the energy range from 0.01 eV to 3 eV the new data of
Wagemans et al. are on average 2.2 % smaller than ENDF/B-VI. This
difference is mainly due a difference of 3% between the 1976 data
of Wagemans et al./5/ and the new values of Wagemans et al. The
1976 data of Wagemans et al. were used in the evaluation of
Derrien and de Saussure in the low energy region.
In the intermediate energy range from 3 eV to 12 eV, the
average fission of ENDF/B-VI is in excellent agreement with the
new data of Wagemans et al. In this energy range, the SAMMY fits
of Derrien and de Saussure were performed on the fission cross
section of Weston and Todd/6/, of Blons/7/ and of Migneco et
al./8/ with an adjustment of the normalization factor and of the
background correction parameters of all the experimental data; the
agreement between the new data of Wagemans et al. and ENDF/B-VI
shows that, at least in this energy range, SAMMY performed on the
data of Weston and Todd a renormalization equivalent to that
recommended by Wagemans et al./4/.
In the higher range up to 300 eV, the SAMMY fits relied
mainly on the high resolution measurements of Blons and of Migneco
et al. for the accurate determination of the resonance parameters.
Quite large normalization coefficients and background correction
parameters were also needed in this energy range to obtain the
consistency between the calculated cross sections and the
experimental data. However, the result of the fits was in quite
good agreement with the data of Weston and Todd normalized to the
1976 data of Wagemans et al. in the low energy region,which is
also equivalent to the normalization to the 1983 data of Wagemans
et al./9/. Since the earlier data of Wagemans et al. should
decrease by 3% to be consistent with the new data, it is likely
that the ENDF/B-VI fission cross section could be too large by
about 3% in the energy range above 12 eV.
III-REVISION OF THE RESONANCE PARAMETERS.
An accurate up-dating of the 241Pu resonance parameters could
be obtained by renormalizing the fission experimental data base
according to the new data of Wagemans et al. and by restarting the
SAMMY fits of the new experimental data base, including the high
resolution transmission data of Harvey and Simpson/10/. Due to
lack of time a new SAMMY analysis was performed only in the energy
range from 0.002 eV to 3 eV. In the energy range above 3 eV the
up-dating was performed by applying some small corrections to the
resonance parameters.
The SAMMY analysis of the new Wagemans et al. data was
performed along with the total cross section of Young and
Smith/11/ in the energy range from 0.002 eV to 3 eV, by starting
with the ENDF/B-VI resonance parameters. Only the parameters of
the 3+ resonances at -0.122 eV and at 0.265 eV were adjusted in
this energy range. The values of the cross sections calculated at
0.0253 eV are compared to the standard data/12/ in Table 1. The
average total, fission and capture cross sections calculated with
the new resonance parameters are displayed on Tables 2, 3 and 4
with the corresponding experimental data and the values obtained
from ENDF/B-VI. One should point out that an energy shift of
dE/E=+0.00384 was applied to the data of Young and Smith in order
to achieve a good consistency with the energy scale of the fission
data of Wagemans et al. over the resonance at 0.0265 eV.
In the energy range above 3 eV the small corrections applied
to the resonance parameters result in a decrease of the average
fission cross section and in an increase of the average capture
cross section, with a variation of the average total cross section
smaller than the errors of the experimental data of Harvey and
Simpson. The average values of the fission and capture cross
sections calculated with the new resonance parameters are shown in
Table 5 and 6 along with the renormalized fission cross section of
Weston and Todd and the values calculated from ENDF/B-VI.
IV-CONCLUSION.
The results of the recent measurement of the 241Pu fission
cross section in the energy range from 0.002 eV to 4 eV of
Wagemans et al. were used in a new evaluation of the resonance
parameters. The accuracy of the calculated cross sections was
greatly improved in the resonance at 0.265 eV. The cross sections
averaged over this resonance should have the same accuracy than
the standard values at 0.0253 eV. In the high energy region up to
300 eV the SAMMY analysis of the new experimental data base
obtained by the renormalization of the experimental data is
recommended in order to improve the corrections to the resonance
parameters performed in the present work.
Table 1 Cross sections at 0.0253 eV
-------------------------------------------------------------
Present results ENDF/B-VI Standard/12/
-------------------------------------------------------------
Fission 1012.50(-0.0%) 1012.68+-6.58
Capture 361.52(+0.1%) 361.29+-4.95
Scattering 11.36(-7.1%) 12.17+-2.62
Total 1385.38(-0.1%) 1386.14+-8.64
-------------------------------------------------------------
Table 2 The total cross section integral in the energy range
from 0.0021 eV to 3 eV.
------------------------------------------------------------------
Energy range Present work ENDF/B-VI Young and Smith/11/
(eV) (b*eV) (b*eV) (b*eV)
------------------------------------------------------------------
0.0021-0.020 43.54 43.09(-1.0%) 43.25(-0.7%)
0.0200-0.030 14.03 14.02(-0.1%) 14.01(-0.1%)
0.0300-0.100 65.09 66.17(+1.7%) 64.99(-0.1%)
0.1000-0.500 378.38 385.27(+1.8%) 380.10(+0.4%)
0.5000-1.000 29.74 29.41(-1.1%) 31.19(+4.4%)
1.0000-3.000 83.36 83.92(+0.7%) 82.50(-1.0%)
------------------------------------------------------------------
0.0021-3.000 614.14 621.88(+1.3%) 616.04(+0.3%)
------------------------------------------------------------------
Table 3 The fission cross section integral in the energy
range from 0.0021 eV to 3 eV.
------------------------------------------------------------------
Energy range This work ENDF/B-VI Wagemans et al. Weston and Todd
(eV) (b*eV) (b*eV) (b*eV)/4/ (b*eV)/6/
------------------------------------------------------------------
0.0021-0.020 31.06 30.61(-1.5%) 31.09(+0.1%)
0.0200-0.030 10.24 10.22(-0.2%) 10.24( 0.0%)
0.0300-0.100 49.02 50.02(+2.0%) 48.70(-0.6%)
0.1000-0.500 262.76 270.84(+3.1%) 264.58(+0.7%) 262.53(-0.1%)
0.5000-1.000 17.93 17.64(-1.6%) 17.60(-1.8%) 17.67(-1.4%)
1.0000-3.000 54.88 55.62(+1.3%) 54.40(-0.9%) 55.06(+0.3%)
------------------------------------------------------------------
0.0021-3.000 425.89 434.95(+2.1%) 426.61(+0.2%)
------------------------------------------------------------------
0.1000-3.000 335.57 344.10(+2.5%) 336.58(+0.3%) 335.26(-0.1%)
------------------------------------------------------------------
Weston and Todd experimental data were normalized to Wagemans et
al./4/ in the energy range from 0.1 eV to 12 eV (original EXFOR
data multiplied by 0.952).
Table 4 The capture cross section integral in the energy range
from 0.0021 eV to 3 eV.
--------------------------------------------------------------
Energy range Present work ENDF/B-VI Weston and Todd/6/
(eV) (b*eV) (b*eV) (b*eV)
--------------------------------------------------------------
0.0021-0.020 12.25 12.28(+0.2%)
0.0200-0.030 3.67 3.68(+0.3%)
0.0300-0.100 15.28 15.39(+0.7%) 15.27(-0.1%)
0.1000-0.500 110.58 109.47(-1.0%) 110.49(-0.1%)
0.5000-1.000 5.90 5.87(-0.5%) 6.51
1.0000-3.000 7.30 7.14(-2.2%) 8.96
--------------------------------------------------------------
0.0021-3.000 154.98 153.83(-0.7%)
--------------------------------------------------------------
0.0300-3.000 139.06 137.87(-0.9%) 141.29(+1.6%)
--------------------------------------------------------------
Weston and Todd experimental data were normalized to the cal-
culated average capture cross section over the resonance at
0.264 eV(original EXFOR data multiplied by 0.914); in the energy
range from 0.5 eV to 3 eV the experimental data are not accurate
due to large corrections for the impurities.
Table 5 The fission cross section integral in the energy range
from 3 eV to 300 eV.
------------------------------------------------------------------
Energy range Present work ENDF/B-VI Weston and Todd/6/
(eV) (b*eV) (b*eV) (b*eV)
------------------------------------------------------------------
3- 20 3038.63 3066.37(+0.9%) 3036.23(-0.1%)
20- 50 1683.69 1739.68(+3.3%) 1705.50(+1.3%)
50-100 1971.15 2030.10(+3.0%) 1931.50(-2.0%)
100-200 2554.85 2628.39(+2.9%) 2531.00(-0.9%)
200-300 2741.23 2820.75(+2.9%) 2747.00(+0.2%)
------------------------------------------------------------------
3-300 11989.55 12285.29(+2.5%) 11951.23(-0.3%)
------------------------------------------------------------------
Weston and Todd experimental data were normalized to Wagemans et
al./4/ in the energy range from 0.1 eV to 12 eV (original EXFOR
data multiplied by 0.952).
Table 6 The capture cross section integral in the energy range
from 3 eV to 300 eV.
------------------------------------------------------------------
Energy range Present work ENDF/B-VI Weston and Todd/6/
(eV) (b*eV) (b*eV) (b*eV)
------------------------------------------------------------------
3- 20 1213.07 1138.52(-6.5%) 1192.90(-1.7%)
20- 50 330.34 307.48(-7.5%) 338.09(+2.3%)
50-100 605.40 585.88(-3.2%) 594.83(-1.8%)
100-200 609.83 581.77(-4.8%) 652.68(+7.0%)
200-300 684.97 661.12(-3.6%) 700.53(+2.3%)
------------------------------------------------------------------
3-300 3443.36 3274.77(-5.1%) 3479.04(+1.0%)
------------------------------------------------------------------
Weston and Todd experimental data normalized to the calculated
average capture cross section over the resonance at 0.265 eV
(original EXFOR data multiplied by 0.914).
References of Appendix
1) DERRIEN,H. and de SAUSSURE,G.:Nuc. Sci. Eng. 106, 415(1990).
2) LARSON,N.M. and PEREY,F.G.:ORNL/TM-9719(1985).
3) WAGEMANS,C., SCHILLEBEECKX,P., DERUYTTER,A. and BARTHELEMY,R.:
Proc. Int. Conf., PHYSOR 90, Marseille, France, Vol.1,
III-9(1990).
4) WAGEMANS,C., SCHILLEBEECKX,P., DERUYTTER,A. and BARTHELEMY,R.:
Proc. Conf. on Nuclear Data for Science and Technology, Juelich
13-17 May 1991, p.35(1991).
5) WAGEMANS,C. and DERUYTTER,A.: Nucl. Sci. Eng. 60, 44(1976).
6) WESTON,L.W. and TODD,J.H.: Nucl. Sci. Eng. 65, 454(1978).
7) BLONS,J.: Nucl. Sci. Eng. 51, 130(1973).
8) MIGNECO,E., THEOBALD,J.P. and WARTENA,J.A.: Proc. Conf. Nucl.
Data for Reactors, Helsinki, Finland, June 15-19, 1970, Vol.I,
p.437, IAEA(1970).
9) WAGEMANS,C. and DERUYTTER,A.: Proc. Conf. on Nuclear Data for
Science and Technology, Antwerp, Belgium, 69(1983).
10) HARVEY,J.A. and SIMPSON,O.D.: Oak-Ridge National
Laboratory(1973), unpublished.
11) YOUNG,T.B. and SMITH,J.R.: WASH-1093, p.60(1968).
12) CARLSON,A. et al.: ENDF/B-VI standard evaluation, private
communication from PEELLE,R.W.(1987).