92-U -236

 92-U -236 TIM        Eval-Mar88 T.Yoshida                        
                      DIST-MAR02 REV3-MAR00            20000728   
----JENDL-3.3         MATERIAL 9231                               
-----INCIDENT NEUTRON DATA                                        
------ENDF-6 FORMAT                                               
                                                                  
HISTORY                                                           
79-03 New evaluation for JENDL-2 was made by T.Yoshida(NAIG).     
86-12 JENDL-2 data were critically reviewed.                      
88-03 JENDL-2 data were revised to make JENDL-3 on the basis of   
      the 86-12 review.  New Russian measurements (1982- 1986)    
      were fully adopted, resultantly leading to a nearly 30      
      per-cent reduction of capture cross-section above 1.5 keV.  
      Sub-threshold fission curve was introduced between 1.5 keV  
      and 700 keV.  Unknown gamma-f was assumed to be 0.354       
      milli-eV.                                                   
  Data were compiled by T.Nakagawa (JAERI).                       
90-07 FP yield data were modified.                                
90-10 MF=5, MT=16,17,91: Spectra at threshold energies were       
      modified.                                                   
93-12 JENDL-3.2.                                                  
      Modified by T.Nakagawa (NDC/JAERI)                          
00-03 JENDL-3.3.                                                  
      Modified by T.Yoshida (Tech. Inst. Musashi) and compiled by 
      T.Nakagawa (NDC/JAERI).                                     
                                                                  
     *****   Modified parts from JENDL-3.2  ********************  
      (1,455) decay constants                                     
      (3,2), (3,102) Direct/Semi-direct process included.         
      (5,16), (5,17), (5,91), (5,455)                             
     ***********************************************************  
                                                                  
                                                                  
MF=1  General Information                                         
  MT=451  Descriptive data and dictionary                         
  MT=452  Number of neutrons per fission                          
     Sum of MT's 455 and 456.                                     
  MT=455  Delayed neutrons per fission                            
     Six group decay constants were adopted from Brady and England
     /1/. Nu-d below 6 MeV was adopted from Gudkov et al./2/, and 
     that above 7 MeV from Bobkov et al./3/, respectively.        
  MT=456  Prompt neutrons per fission                             
     Taken from Malinovskii's paper /4/.  Above 5.9 MeV, their    
     recommendation was extrapolated.                             
                                                                  
MF=2 MT=151 Resonance parameters                                  
  Resolved resonances for MLBW formula : 1.0E-5 eV to 1.5 keV     
     Res. energies and Gam-n(for Gam-n greater than 0.1*Gam-g)    
                                              : Carraro /5/       
     Gam-n (for Gam-n smaller than 0.1*Gam-g) : Mewissen /6/      
     Gam-g : Mewissen /6/, when not given, mean value was taken.  
     Gam-f : Theobald /7/.                                        
        Average Gam-g = 23.0 milli-eV                             
        Average Gam-f = 0.354 milli-eV                            
     A negative resonance was introduced to reproduce the 2200-   
     m/s capture cross section of (5.11+-0.21) barns recommended  
     in BNL-325 4th edition.                                      
  Unresolved resonances : 1.5 keV to 40 keV                       
     Parameters were determined to reproduce total and capture    
     cross sections calculated with CASTHY and evaluated fission  
     cross section. Obtained parameters are:                      
        S0 = 0.906E-4, S1 = energy dependent (1.8E-4 - 2.7E-4)    
        Gam-g = 0.023 eV, Gam-f = energy dependent                
        R = 9.36 fm, D-obs = energy dependent (14.66 - 13.57 eV)  
                                                                  
     Calculated 2200-m/s cross sections and res. integrals        
                     2200-m/sec      Res. Integ.                  
         total       13.69   b          -                         
         elastic      8.337  b          -                         
         fission      0.0613 b         7.77 b                     
         capture      5.295  b       346.   b                     
                                                                  
MF=3  Neutron Cross Sections                                      
  Below 1.5 keV, all background cross sections are zero.          
  In the energy range from 1.5 to 40 keV, unresolved resonance    
  parameters were evaluated and background cross section was given
  to elastic scattering.                                          
  Above 40 keV, data were evaluated as follow:                    
                                                                  
  MT=1,2,4,51-79,91,102  Sig-t,Sig-el,Sig-in,Sig-c                
     Coupled channel and statistical model calculations were made 
     with ECIS /8/ and CASTHY codes /9/, respectively.            
     The deformed optical potential parameters after Haouat and   
     Lagrange /10/:                                               
        Vr =49.8 - 16*sy - 0.3*En                   (MeV),        
        Ws = 5.3 -  8*sy + 0.4*En  (En .LT. 10 MeV) (MeV),        
           = 9.3 -  8*sy           (En .GE. 10 MeV) (MeV),        
        Vso= 6.2                                    (MeV),        
             where sy=(N-Z)/A                                     
        r=1.26, rs=1.26, rso=1.12                   (fm),         
        a=0.63, as=0.52, aso=0.47                   (fm).         
                                                                  
     The spherical optical potential parameters for the statisti- 
     cal model calculation with CASTHY:                           
        Vr =40.8 - 0.05*En                        (MeV),          
        Ws = 6.5 + 0.15*En                        (MeV),          
        Vso= 7.0                                  (MeV),          
        r=1.32, rs=1.38, rso=1.32                  (fm),          
        a=0.47, as=0.47, aso=0.47                  (fm).          
     Competing processes : fission, (n,2n) and (n,3n)             
     Level fluctuation was considered.                            
                                                                  
     The gamma-ray strength function was determined so that the   
     calculated capture cross section reproduced the measured     
     value of 0.85 barns /11/ around 10 keV.  The direct and      
     semi-direct capture cross section was calculated with DSD    
     code /12/ and added to the capture cross section calculated  
     with CASTHY code.                                            
                                                                  
     The level scheme taken from Ref. /13/.                       
        No. Energy(MeV)  J-Parity   No. Energy(MeV)  J-Parity     
        gs   0.0          0 +        1   0.04524      2 +         
         2   0.14948      4 +        3   0.30979      6 +         
         4   0.52225      8 +        5   0.68757      1 -         
         6   0.7442       3 -        7   0.7828      10 +         
         8   0.8476       5 -        9   0.91916      0 +         
        10   0.9581       2 +       11   0.9604       2 +         
        12   0.9670       1 -       13   0.9880       2 -         
        14   1.0014       3 +       15   1.0020       7 -         
        16   1.0356       3 -       17   1.0512       4 +         
        18   1.0529       4 -       19   1.0587       4 +         
        20   1.0661       3 +       21   1.0700       4 -         
        22   1.0862      12 +       23   1.0938       2 +         
        24   1.1044       5 -       25   1.1110       2 -         
        26   1.1267       5 +       27   1.1470       3 +         
        28   1.1494       3 -       29   1.1640       6 -         
        Continuum levels assumed above 1.17 MeV.                  
     The ground state, 1-st and 2-nd excited levels were coupled  
     in the ECIS calculation.                                     
                                                                  
  MT=16,17  (n,2n) and (n,3n)                                     
     Calculated with the PEGASUS code /14/.                       
                                                                  
  MT=18   Fission                                                 
     Evaluated on the basis of measured data of U-236/U-235       
     /15,16/.  To get absolute value Matsunobu's evaluation /17/  
     for U-235(n,f) was employed.                                 
                                                                  
MF=4  Angular Distributions of Secondary Neutrons                 
  MT=2,51,52                                                      
     Calculated with ECIS and CASTHY                              
  MT=53-79,91                                                     
     Calculated with CASTHY.                                      
  MT=16,17,18                                                     
     Isotropic distribution in the lab. system.                   
                                                                  
MF=5  Energy Distributions of Secondary Neutrons                  
  MT=16,17,91                                                     
     Calculated with EGNASH /18/.                                 
  MT=18                                                           
     Maxwellian fission spectrum.  Temperature was estimated from 
     Z**2/A values /19/.                                          
  MT=455                                                          
     Summation calculation made by Brady and England /1/ was      
     adopted.                                                     
                                                                  
References                                                        
 1) M.C. Brady and T.R. England: Nucl. Sci. Eng., 103 (1989) 129. 
 2) A.N. Gudkov et al.: Atomnaya Energiya, 66 (1989) 100.         
 3) E.Yu. Bobkov et al.: Atomnaya Energiya, 67 (1989) 408.        
 4) V.V. Malinovskii et al.: Atomnaya Energiya, 53 (1982) 83.     
 5) G. Carraro, et al.: Nucl. Phys., A275 (1976) 333.             
 6) L. Mewissen, et al.: 1975 Washington, 729 (1975).             
 7) J.P. Theobald: Nucl. Phys.,181 (1972) 637.                    
 8) J. Raynal: IAEA SMR-9/8 (1970).                               
 9) S. Igarasi and T. Fukahori: JAERI 1321(1991).                 
10) cited by P.G. Young in Proc. Specialists' Mtg on Use of       
    Optical Model, Paris, NEANDC - 222 U (1986)                   
11) A.A. Bergman: Atomnaya Energiya, 52 (1982) 409.               
    O.T. Grudzevich et al.: IAEA INDC(CCP)-220/L (1984)           
    A.N. Gudkov:  Atomnaya Energiya, 61 (1986) 379                
12) T. Kawano: private communication (1999).                      
13) M.R. Schmorak: Nucl. Data Sheets, 20 (1977) 192.              
14) S. Iijima et al.: JAERI-M 87-025, 337 (1987).                 
    T. Nakagawa et al.: JAERI-Data/Code 99-031 (1999).            
15) J.W. Behrens and C.W. Carlson: Nucl. Sci. Eng., 63 (1977) 250.
16) J.W. Meadows: Nucl. Sci. Eng., 65 (1978) 171.                 
17) H. Matsunobu: evaluation for JENDL-3 (MAT=3924).              
18) N. Yamamuro: JAERI-M 90-006 (1990).                           
   P.G. Young and E.D. Arthur: LA-6947 (1977).                    
19) A.B. Smith et al.: ANL/NDM-50 (1979).