New KENO Weights Library

Download Updates from SCALE Web Page

Final SCALE-4.3 Manual Released

The PDF format allows the user to view the documents using Adobe Acrobat Reader, a free program, in a high-quality format that is nearly identical to the printed manual. In addition, Acrobat Reader has the capability to search the manual and to print selected pages.

KENO Default Number of Histories Increased

SCALE-4.3 Minor Modifications

KENO V.a: KENO V.a has been updated to correct an error in the k_eff calculation that caused a doubling of k_eff when using an ICE mixed AMPX format working library. This error was introduced in SCALE-4.3. This discrepancy has been reported in a previous issue of the SCALE Newsletter. If your work requires the use of ICE and KENO V.a, please contact the SCALE staff for the correction. (MRR 95-073)

MIPLIB: (1) Updated to allow moderator mixture in a lattice cell to be used in the gap and to add the ability to specify the inner radius to the resonance data. (2) Updated to allow a control program to suppress certain output by setting flags. Added input options to MORE DATA to allow specifying an XSDRNPM adjoint solution, a criticality search in XSDRNPM using the zone width search option, a unit number for the balance table file, and suppressing the cross section weighting. (MRRs 96-035 and 96-049)

KENO-VI: (1) The code was updated to correct a problem that could cause cases containing arrays with complex boundaries to incorrectly calculate k_eff. (2) Corrected a discrepancy that caused the code to go into an infinite loop when boundaries consisted of a body with multiple sets of paired planes. (3) Corrected an error that prevented a restart problem from producing a readable file if it stored data in the generation before the code entered the infinite loop. (4) Corrected a problem involving nested arrays and hexprisms that sometimes caused the code to go into an infinite loop if a collision occurred very near a boundary. (5) Corrected a problem that occurred when a particle crossed a boundary and immediately had a collision that reversed its direction without traveling any distance. The particle sometimes got lost and entered an infinite loop. (6) Subroutine TRACK was modified to correct a problem that occurred when an array shared a boundary with a hole that contained the array. If the distance to cross out of the array is less than EPS, the particle now exits the array instead of crossing from one unit to another within the array. (MRRs 96-033, 96-034, 96-040 and 96-046, 96-051)

Standard Composition Library: Mass of copper was corrected (it was in atomic mass units instead of C-12 mass units). Density of c-graphite was changed from 1.0 to 2.3 g/cc. The following compositions were added: graphite, kerosene, kero(h2o), norpar13, norpar(h2o), polyvinylcl, pvc, pvc(h2o), tbp, tbp(h2o). (DRR 96-006)

XSDRNPM: Updated to correct the value of productions/absorptions when a direct buckling search is done. (MRR 96-045)

KENO V.a: Updated to allow printing the frequency distributions for 1-group problems.(MRR 96-039)

MORSE Sample Problem 8: The 10** array was modified by adding a 22r0.0 at the end.(DRR 95-020)

H7TECPLOT and H7MONITOR: Outdated comment lines in the BLOCK DATA subroutine that are used to activate or deactivate computer-system-dependent blocks of code resulted in memory not being allocated for variably-dimensioned arrays. An additional correction was made in H7TECPLOT, where the x and y axes were reversed when a translation was done from spherical to Cartesian coordinates. (MRR 96-053)

SUBLIB: Subroutine DREAD was modified to correctly process data following the second digit of an exponent when called by the array reading subroutine YREAD. Previously, exponents of 10 or greater sometimes caused errors in the reading of FIDO-type input arrays. This discrepancy was discovered in an ORIGEN-S case. (MRR 96-060)

Words to the Wise...

Dancoff Factor Discrepancy for Moderator in Fuel Rod Gap

This discrepancy potentially could impact previous analyses where the fuel rod gap was assumed to be flooded with water. The discrepancy occurs in the calculation of the Dancoff factor, which is the probability that a neutron emitted from the surface of one fuel rod will pass through the gap, clad, and moderator and into another fuel rod. The significance of the discrepancy depends upon whether the mixture number of the material in the gap region is identical to the mixture number in the moderator region. If the mixture numbers are different for the gap and moderator regions, the impact on the calculated k_eff value is conservative and typically very small for a thin gap region (e.g., < 0.1% for a typical light water reactor fuel rod cell). In this case, the moderating medium in the gap is ignored in the Dancoff calculation, and the probability of a neutron passing from one rod to another is overestimated, resulting in a conservative value of k_eff. The error will increase with increasing gap region thickness.

If the same mixture numbers were used to define the materials in both the gap and moderator regions, the impact on the calculated k_eff value is non-conservative and can be much more significant. In this case, the density of the moderating medium (e.g., water) is accounted for twice in the calculation of the total cross section of the moderator, which is used in the Dancoff factor calculation. The error effectively doubles the amount of moderator that the neutron must pass through between fuel rods, thus reducing the probability of a neutron passing from one rod to another. The smaller Dancoff factor results in a non-conservative calculated k_eff value. For example, for a typical light water reactor fuel rod cell in a one-dimensional XSDRNPM model, the result was approximately 1% low. For the same fuel in a three-dimensional KENO V.a conceptual cask model, the result was approximately 0.7% low.

The impact of this discrepancy in previous calculations should only be a concern if the user modeled the gap and moderator regions with identical mixture numbers.

SCALE-PC Runs in Windows NT 4.0

New freeware versions of the conversion routines that generate the color GIF files are available for Windows NT. To generate GIF files using these routines requires changing one line in SCALE95.BAT

from

if exist _plt*.bat for %%f in (_plt*.bat) do call fixplt95 %%f

to

if exist _plt*.bat for %%f in (_plt*.bat) do call %%f

The updated conversion routines and BAT files will be posted on the SCALE and RSICC Web sites for SCALE users to download.

Further development of SCALE-PC is underway. We plan to release a new version optimized for Windows 95 / Windows NT Pentium and Pentium Pro PCs by the end of this year.

How to Make and Install Part of the Workstation Version of SCALE

make SUBDIRS="sublib unixlib miplib \
driver bonami nitawl xsdrn ice kenova csas modify mal wgt"

make SUBDIRS="sublib unixlib miplib driver \
bonami nitawl xsdrn ice kenova csas modify mal wgt" install

make data (This will make the standard composition and cross section
libraries, then fail at the origen libraries)

make SMPL="bonami nitawl xsdrn ice kenova csas" smplprbs

Reflecting Hexprisms in KENO-VI

=csas6
black absorber example
44groupndf5 infhommedium
uranium      1          end
1/vabsorber  2  1.0e10  end
end comp
read geom
global unit 1
hexprism   10  11.0  10.0  -10.0
hexprism   20  11.0  11.0  -11.0
media   1   1   10
media   2   1   20   -10
boundary  20
end geom
read bounds   all=mirror   end bounds
end data 
end

ORIGEN-S Integral Option

SAS1X Criticality / Shielding Dose Calculations with Cylindrical or Slab Geometry

This option is discussed in Sect. S1.2.3 in the SCALE manual. The equations given there explain how to calculate a dose in rem from the dose rate printed in the SAS1X output and the total fissions. These equations are based on a unit volume. In the case of spherical geometry, the volume of the source is known; the equation yields a dose in rem. However, if a cylindrical or slab geometry is used, one or more of the source dimensions is unknown; the unit volume is per cm height of a cylinder or per sq cm of a slab. In these cases, the total fissions in the equation must be per unit of height or area, respectively, to obtain a dose in rem.

Path Length Stretching in MORSE-SGC Is Incorrect with Array Geometry

A SCALE V&V package is being prepared for release through RSICC. To make the package as comprehensive as possible, it will contain the input files for the V&V cases from the above reports; the cases from the HEATING verification report, K/CSD/TM-61, originally produced for HEATING6; the Fortran utility codes listed in the appendices of the reports; and the updated output files for all cases from SCALE-4.3. Copies of the reports cited above also will be included in the package.

The input files, the Fortran utilities, and the updated summary tables of results from some of the reports will be available to download from the SCALE Web page by April 4.

SCALE KENO-VI Training Course Agenda

CSAS6 Input Data - SCALE/CSAS/MIP
Unit Cell Types and More Data
Standard Compositions, Arbitrary Materials
KENO-VI Data blocks and Parameters
Simple KENO-VI Geometry
Problem Session I

Tuesday, May 20
Review of Problem Session I
Resonance Self-Shielding
Plots
Arrays
Chords and Origins
Rotations
Problem Session II

Wednesday, May 21
Review of Problem Session II
Holes
Start Data, Bias Data, Boundary Data
Mixing Table
Cell Weighting
Problem Session 3

Thursday, May 22
Review of Problem Session III
KENO-VI Output
Monte Carlo Uncertainties
Validation Issues
Problem Session IV - Bring your own problems

SCALE KENO-VI Training Course
c/o Steve Bowman
Oak Ridge National Laboratory
P.O. Box 2008, MS 6370
Oak Ridge, Tennessee 37831-6370

NOTE: Course attendance is limited. PLEASE REGISTER EARLY!

Hotel Registration Form

Please reserve a room in my name in the block of rooms available for the SCALE KENO-VI Training Course.

Block room rate: $63 per night including tax.

Deadline for reserving a room at this special rate is April 27.

Airline Reservations Information

Delta Air Lines is offering special discounted fares for the SCALE KENO-VI Course. Some restrictions apply and seats are limited. To obtain these special fares, follow these steps:

1. Call 1-800-241-6760 any day between 8:00 am and 11:00 pm Eastern Time.

2. Refer to File Number Y2463.

SCALE Newsletter is published twice a year by Oak Ridge National Laboratory and sponsored by the Spent Fuel Project Office of the U.S. Nuclear Regulatory Commission and by the Office of Transportation, Emergency Management, and Analytical Services of the U.S. Department of Energy.

Address all correspondence (including address additions or changes) to: