SCALE 5.1 ORIGEN-S Libraries Update                  December 12, 2007
                                                
Description 
------------ 

This update contains changes in the ORIGEN card-image cross-section
library to correct cross section values obtained from the FENDL-2.0
evaluated nuclear data library. Only FENDL data were updated. The
updated library origen.rev03.pwrlib.data replaces the previous version
origen.rev02.pwrlib.data. As a result of these changes to the card-image
library, the binary library PWR33GWD was updated to
origen.rev04.pwr33gwd. This update supercedes the previous update to
origen.rev03.pwr33gwd posted on August 7, 2007. The impact of this
update is that results for some activation product (i.e.
light element) nuclides are corrected. Actinide and fission product 
inventories are largely unchanged.

Large differences were reported in comparisons of the calculated
isotopic activities obtained using the card-image library (with typical
values of the flux weighted factors) and activities calculated using the
one of the new ORIGEN-ARP binary cross section library. Evaluation of
the discrepancies revealed that differences were caused by incorrect
FENDL-2.0 based cross sections.

A systematic error occurred during processing of the FENDL data due to a
non-standard format used to represent reaction transitions to metastable
product states. The FENDL library contains partial cross sections for
each reaction channel to different product states. For example, capture
reactions to the ground state are stored as MT=102, to the first
metastable state as MT=402, and second metastable state as MT=702. Only
the MT=102 transitions to ground state levels were recognized and
included in the total capture cross section during processing.
Therefore, cross sections for isotopes with a significant branching
fraction leading to metastable states were systematically
underestimated. 

The FENDL data discrepancies in the card-image library do not apply to
the binary libraries for most isotopes because problem-dependent data
from ENDF/B-V evaluations are used to update the card-image data.
However, some FENDL data are retained when ENDF/B-V cross sections are
not available.

It was also observed that several high energy threshold reaction cross
sections changed for transitions that do not have metastable product
states. Further analysis found the cause to be associated with
temperature broadening of the pointwise FENDL data by an AMPX routine
that incorrectly shifted the cross section data by one energy grid
point. For threshold reactions with relative coarse energy grid points
and peak reaction rates occurring near the threshold energy, this shift
caused significant changes in the group cross section values. The
updated data were generated without temperature broadening.

Changes were made to the library data processing routines to include all
branching transitions in calculating the cross sections required by
ORIGEN and the library was regenerated. The number of cross section
changes is extensive. A summary of all cross section values that changed
by more than 1% is listed in a separate file:
www.ornl.gov/sci/scale/downloads/origen-libraries-update-details.txt.
These changes will result in minor changes in some of the SCALE sample
problems that depend on ORIGEN-S or ORIGEN-S data (e.g., ORIGEN-S, OPUS, 
TRITON, SAS1, SAS2)


Installation instructions 
------------------------- 

Windows: 
--------
          
Windows users can download and install the self-extracting WinZip file
origen-libraries-update.exe file. This update installs the following files:

\scale5.1\data\origen_data\origen.rev03.pwrlib.data
\scale5.1\data\origen.rev04.pwr33gwd
\scale5.1\cmds\scale5.bat
\scale5.1\test\drr08003origen.input
\scale5.1\output\drr08003origen.out

Run the test case named drr08003origen.input that is installed to \scale5.1\test.
You can use the command line "batch5 -m drr08003origen.input" or you can 
drag-and-drop the input file on the "Run SCALE5.1" icon.

Compare the output file drr08003origen.out to the ORNL version in \scale5.1\output.


Unix/Linux:
-----------

Download origen-libraries-update.tar.gz. Unzip and untar in the directory
above the head scale5.1 directory. This update installs the following files:

/scale5.1/data/origen_data/origen.rev03.pwrlib.data
/scale5.1/data/origen.rev04.pwr33gwd
/scale5.1/test/d08003_origen.input
/scale5.1/output/d08003_origen.linux.output
/scale5.1/output/d08003_origen.unix.output

Run the test case d08003_origen.input and compare the output file with
the ORNL output file for your operating system (unix or linux).