Correction to the Be Cross-Section Data 
              in the 238- and 44-Group ENDF/B-V Libraries
                         May 29, 2002

Introduction
------------
A very significant error in the beryllium metal cross-section data
contained in the 238- and 44-Group ENDF/B-V libraries was recently
discovered by SCALE users at ORNL. Several critical experiments that
involved beryllium metal as the reflector were found to have > 1%
difference in calculated k-eff values between different versions of
SCALE (4.3 vs. 4.4a).

Explanation
-----------
An update to the Be-9 cross-section data is documented in the
January 1998 SCALE Newsletter:

   238- and 44-group cross-section libraries:
   Corrected negative scattering and total cross sections
   for minor actinides, fission products, and beryllium
   metal. Also corrected thermal Bondarenko factors for potassium.
   Only significant impact should be on cases where potassium is
   important in the thermal range. (DRRs 97-014 and 97-015)

This update was included in SCALE 4.4 and 4.4a. Unfortunately, when
these minor corrections were made, a factor of 2 scaling
error in the Be thermal scattering transfer arrays was introduced. 
This error can result in non-conservative errors in calculated k-eff
values of greater than 1%. This error is NOT present in SCALE 4.3.

SCALE 4.4 and 4.4a users should update the Be metal data (nuclide ID
4309) in the 238- and 44-group cross-section library using the update
file available on the SCALE Download web page. The update file is a
SCALE input file containing input to the following modules:
1. AIM - Corrected 238-group Be metal data in ASCII format
2. AJAX - Copies the new Be metal data and the rest of 238-group 
   library to a new library on unit 64 (ft64f001).
3. AIM - Corrected 44-group Be metal data in ASCII format
4. AJAX - Copies the new Be metal data and the rest of 44-group 
   library to a new library on unit 63 (ft63f001).
5. SHELL - Unix or DOS commands to copy new 238- and 44-group libraries
   to the SCALE data subdirectory to replace the existing libraries.
   
Instructions to perform update
------------------------------
1. Download be-metal_update.zip for PC or be-metal_update.tar.gz for Unix.
   Note that Internet Explorer may rename the Unix file be-metal_update.tar.tar.
   If so, rename it be-metal_update.tar.gz before proceeding to the next step.

2. Unzip the file on PC or gunzip the Unix file.

3. Edit the input file be-metal_update.input
   
   IMPORTANT: THE DOS OR UNIX COMMANDS IN THE SHELL INPUT MUST BE MODIFIED
   BY THE USER TO COPY THE NEW LIBRARIES TO THE CORRECT LOCATION. 

   For example, if SCALE 4.4a is installed on the C: drive of a PC, the copy
   commands in the SHELL input would be:

       copy ft63f001 C:\scale4.4a\data\ft83f001
       copy ft64f001 C:\scale4.4a\data\ft84f001

   For SCALE 4.4 installed on a Unix system in /scale4.4, the commands would be:
       cp ft63f001 /scale4.4/data/scale.revxx.xn44
       cp ft64f001 /scale4.4/data/scale.revxx.xn238
   where "xx" is the appropriate revision number for the 44- and 238-group
   libraries. Check the names of your current files first.

4. If you want to keep a copy of the original libraries, copy them
   (do NOT rename them - this will cause the update to fail).

5. Change to the directory where the file be-metal_update.input is located, 
   and run SCALE to execute the update:
       scale44 be-metal_update

6. Check the output file to see if everything executed normally.

7. Check the date/time and size of the 238- and 44-group libraries in the
   SCALE data subdirectory to make sure that the updated files are there.

8. Rerun your Be validation cases.