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91-Pa-232 ORNL,TIT EVAL-DEC99 R. Q. WRIGHT, N. TAKAGI
DIST-JAN09 20090105
----JEFF-311 MATERIAL 9134
-----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: ENDF/B-VI.8 **
** **
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ENDF/B-VI MOD 2 Revision, December 1999, R.Q. Wright (ORNL)
The JENDL-3.2 evaluation was adopted and updated as follows:
MF=1,
MT=456 NUMBER OF PROMPT NEUTRONS
Changed from LNU=1, polynomial representation to LNU=2,
tabulated representation. MT=452, 455, and 456 are now
represented as tabulated functions.
MF=2 RESONANCE PARAMETERS-- MLBW FORMALISM USED.
The resolved resonance parameter evaluation is based on
the measurements of Danon [Da1996]. Preliminary results were
given in the paper by Moore et al. [Mo1994].
For the levels below 5 eV, the parameters from Table 1
of Moore et al. were used. The 2nd column of Table 1 of that
reference is actually g*Gamma-n0, not 2g*Gamma-n0 as
indicated.
For the 5 to 10 eV range, the parameters from Table 1 of
Danon are used. In this table, Column 2 should be
2g*Gamma-n0, not 2g*Gamma-n as indicated. In the current
evaluation the neutron widths for the 6.44 and 8.85 eV
resonances were both increased slightly.
The resulting parameters give a very good fit to the
fission cross section for the energy range below 10 eV.
2200-m/s cross sections and resonance integrals
2200 m/s value Res. Int.
Total 1762.19 b -
Elastic 32.75 b -
Fission 1517.34 b 868 b
Capture 212.10 b 146 b
MF=3 NEUTRON CROSS SECTIONS
MT=1 TOTAL CROSS SECTION
For the energy range 10 eV to 35 keV, the total cross
section is calculated as sum of MT = 2, 18 and 102, using
the revised values of MT = 2, 18, and 102. above 35 keV
The cross section is 133.35 barns at 10 eV. The revised
total is about the same as the JENDL-3.2 evaluation; it is
slightly higher below 4 eV and slightly lower between 4 eV
and 3 keV.
MT=2 ELASTIC SCATTERING CROSS SECTION
The elastic cross section is revised below 100 eV to join
smoothly with the resolved resonance range; it is unchanged
above 100 eV. The elastic cross section is 17.6 barns at 10
eV, and is slightly higher between 10 and 100 eV.
MT=18 FISSION CROSS SECTION
The fission cross section is revised below 35 keV to join
smoothly with the resolved resonance range; it is unchanged
above 35 keV. The cross section at 10 eV (100.0 barns) is
based on the average fission from 2 to 10 eV, as caluclated
from the resolved resonance parameters.
The average fission cross section = 108.4 barns for the
energy range 5.5 to 10 eV. For the energy range 100 ev to
30 keV, the revised cross section is very close to the
ENDF/B-VI 235U fission cross section.
MT=102 CAPTURE CROSS SECTION
The capture cross section is revised below 35 keV to join
smoothly with the resolved resonance range. It is unchanged
above 35 keV.
The cross section at 10 eV (15.75 barns) is based on the
average capture from 2 to 10 eV (resolved resonance range).
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REFERENCES
Da1996 Y. Danon, M.S. Moore, P.E. Koehler et al. Nucl.Sci.Eng.
124, 482 (1996).
Mo1994 M.S. Moore, P.E. Koehler, P.E. Littleton et al., Int.
Conference on Nuclear Data for Science and Technology,
Gatlinburg, Tennessee, May 9-13, 1994 (American Nuclear
Society, 1994) Vol. 2, p. 1075.
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JENDL-3.2 COMMENTS FOLLOW--
HISTORY
88-08 NEW EVALUATION WAS MADE BY N. TAKAGI (TOKYO INSTITUTE OF
TECHNOLOGY, TIT) /1/.
94-06 JENDL-3.2.
NU-P, NU-D AND NU-TOTAL WERE MODIFIED.
COMPILED BY T.NAKAGAWA (NDC/JAERI)
***** MODIFIED PARTS FOR JENDL-3.2 ********************
(1,452), (1,455), (1,456)
***********************************************************
MF=1 GENERAL INFORMATION
MT=451 COMMENT AND DICTIONARY
MT=452 NUMBER OF NEUTRONS PER FISSION
SUM OF NU-P NAD NU-D.
MT=455 DELAYED NEUTRONS PER FISSION
AVERAGE VALUES OF SYSTEMATICS BY TUTTLE/2/, BENEDETTI ET
AL./3/ AND WALDO ET AL./4/ DECAY CONSTANTS WERE ADOPTED
FROM THE EVALUATION BY BRADY AND ENGLAND/5/.
MT=456 PROMPT NEUTRONS PER FISSION
BASED ON SYSTEMATICS BY MANERO AND KONSHIN/6/, AND BY
HOWERTON/7/.
MF=2 RESONANCE PARAMETERS
MT=151 RESONANCE PARAMETERS
NO RESONANCE PARAMETERS WERE GIVEN.
2200-M/S CROSS SECTIONS AND RESONANCE INTEGRALS
2200 M/S VALUE RES. INT.
TOTAL 1176.23 B -
ELASTIC 12.23 B -
FISSION 700.00 B 313 B
CAPTURE 464.00 B 309 B
MF=3 NEUTRON CROSS SECTIONS
MT=1 TOTAL CROSS SECTION
BELOW 1 EV, CALCULATED AS SUM OF MT'S = 2, 18 AND 102.
ABOVE 1 EV, OPTICAL MODEL CALCULATION WAS MADE WITH
CASTHY/8/. THE POTENTIAL PARAMETERS/9/ USED ARE AS
FOLLOWS,
V = 41.0 - 0.05*EN (MEV)
WS= 6.4 - 0.15*SQRT(EN) (MEV)
WV= 0 , VSO = 7.0 (MEV)
R = RSO = 1.31 , RS = 1.38 (FM)
A = ASO = 0.47 , B = 0.47 (FM)
MT=2 ELASTIC SCATTERING CROSS SECTION
BELOW 1 EV, ASSUMED TO BE THE SAME AS SHAPE ELASTIC
SCATTERING CROSS SECTION CALCULATED WITH THE OPTICAL
MODEL. ABOVE 1 EV, OPTICAL MODEL CALCULATION WAS
ADOPTED.
MT=4, 91 INELASTIC SCATTERING CROSS SECTIONS.
OPTICAL AND STATISTICAL MODEL CALCULATION WAS MADE WITH
CASTHY/8/. NO EXCITED LEVELS WERE RECOMMENDED IN
REF./10/.
NO ENERGY(KEV) SPIN-PARITY
G.S. 0.0 2 -
LEVELS ABOVE 50 KEV WERE ASSUMED TO BE OVERLAPPING.
THE LEVEL DENSITY PARAMETERS WERE TAKEN FROM REF./11/.
MT=16,17,37 (N,2N), (N,3N) AND (N,4N) REACTION CROSS SECTIONS
CALCULATED WITH EVAPORATION MODEL.
MT=18 FISSION CROSS SECTION
MEASURED THERMAL CROSS SECTION OF 700 BARNS WAS TAKEN FROM
REF./12/, AND 1/V FORM WAS ASSUMED BELOW 1 EV. FOR
ENERGIES ABOVE 1 EV, THE SHAPE WAS ASSUMED TO BE THE SAME
AS U-233 FISSION CROSS SECTION AND NORMALIZED TO THE
SYSTEMATICS BY BEHRENS AND HOWERTON/13/.
MT=102 CAPTURE CROSS SECTION
MEASURED THERMAL CROSS SECTION OF 464 BARNS WAS TAKEN FROM
REF./12/, AND 1/V FORM WAS ASSUMED BELOW 1 EV. THE CROSS
SECTION SHAPE NEAR 1 EV WAS ADJUSTED SO AS TO REPRODUCE
THE RESONANCE INTEGRAL/12/. ABOVE 1 EV, CALCULATED WITH
CASTHY. THE GAMMA-RAY STRENGTH FUNCTION WAS ESTIMATED FROM
GAMMA-GAMMA = 0.040 EV AND LEVEL SPACING = 0.417 EV.
MT=251 MU-L
CALCULATED WITH CASTHY.
MF=4 ANGULAR DISTRIBUTIONS OF SECONDARY NEUTRONS
MT=2,91 CALCULATED WITH OPTICAL MODEL.
MT=16,17,18,37 ISOTROPIC IN THE LAB SYSTEM.
MF=5 ENERGY DISTRIBUTIONS OF SECONDARY NEUTRONS
MT=16,17,37,91 EVAPORATION SPECTRA
OBTAINED FROM LEVEL DENSITY PARAMETERS.
MT=18 MAXWELLIAN FISSION SPECTRUM.
TEMPERATURE WAS ESTIMATED FROM Z**2/A DEPENDENCE/14/.
REFERENCES
1) TAKAGI N. ET AL.: J. NUCL. SCI. TECHNOL., 27, 853 (1990).
2) TUTTLE R.J.: INDC(NDS)-107/G+SPECIAL, P.29 (1979),
3) BENEDETTI G. ET AL.: NUCL. SCI. ENG., 80, 379 (1982).
4) WALDO R. ET AL.: PHYS. REV., C23, 1113 (1981).
5) BRADY M.C. AND ENGLAND T.R.: NUCL. SCI. ENG., 103, 129(1989).
6) MANERO F. AND KONSHIN V.A.: AT. ENERGY REV.,10, 637 (1972).
7) HOWERTON R.J.: NUCL. SCI. ENG., 62, 438 (1977).
8) IGARASI S. AND FUKAHORI T.: JAERI 1321 (1991).
9) OHSAWA T., OHTA M.: J. NUCL. SCI. TECHNOL., 18, 408 (1981).
10) SCHMORAX M.R.: NUCL. DATA SHEETS, 36, 367 (1982).
11) GILBERT A., CAMERON A.G.W.: CAN. J. PHYS., 43, 1446 (1965).
12) MUGHABGHAB S.F.: "NEUTRON CROSS SECTIONS, VOL.1, NEUTRON
RESONANCE PARAMETERS AND THERMAL CROSS SECTIONS , PART B,
Z=61-100", ACADEMIC PRESS (1984).
13) BEHRENS J.W., HOWERTON R.J: NUCL. SCI. ENG., 65, 464, (1978).
14) SMITH A.B. ET AL.: ANL/NDM-50 (1979).
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