Keyword:OVER
OVER ja
This keyword enables library data to be modified for a particular case. It can be called several times during an irradiation if required. ja specifies the nuclide that is to have data changed. The identifier can be specified using the format ‘Te129m’. The OVER keyword is followed by one of four keyword options below. Note that the arrayx and collapx files are not altered, so that in subsequent runs the cross-section, half-life or error factor will revert to its original value. Note that the OVER keyword must occur after the GETXS and GETDECAY keywords that obtain the library data to be modified.
Contents
Overwriting cross sections
ACROSS jb
sig(n) n=1,ngr
jb is the daughter of the reaction and sig(n) is the new cross-section (barns) for the n-th energy group. For all existing EAF and ENDF libraries ngr = 1. (ngr is used to retain backward compatibility.) jb is specified in the same manner as ja above.
Note that if a fission reaction is required then jb' should be either Fission or 0.
Example usage for overwriting U238 one group cross section for neutron capture:
OVER U238 ACROSS U239 1.0E3
Overwriting half-lives
ALAM thalf units
thalf is the new half-life of the nuclide and units specifies the time unit using one of the allowable (and interchangeable) values:
SECS 1 seconds MINS 2 minutes HOURS 3 hours DAYS 4 days YEARS 5 years
Example usage for overwriting C14 half-life to 3000 years:
OVER C14 ALAM 3000.0 5
Overwriting cross section errors
ADCROSS jb
errfcs
jb is the daughter of the reaction and errfcx is set as the new error factor for the cross-section.
Example usage for overwriting the error factor for the C14(n,2n)C13 reaction to 1.10:
OVER C14 ADCROSS C13 1.10
Overwriting half-life errors
ADLAM dthalf
dthalf is set as the new error factor for the half-life of the nuclide.
Example usage for overwriting the error factor for the C14 half-life to 1.10:
OVER C14 ADLAM 1.10