A tentative agenda is provided below. The number of attendees will be limited. A form is included on the last page of this Newsletter that can be returned to preregister for the course. Your responses on this form will be used to help formulate the final agenda and course structure.

Tentative Course Agenda

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New ENDF/B-V Libraries Available

Several spectra suitable for collapsing this fine-group library to a broad-group structure are included as part of the library. A 44-group derivative of the 238-group library, 44GROUPNDF5 (DRR 94-005), collapsed using a spectrum for a pressurized-water-reactor fuel pin, will also be included in the RSIC data package. This broad-group library has a similar group structure as that provided in the SCALE 27-group ENDF/B-IV library, except that additional groups were added to ensure more accurate treatment of the 0.3 eV resonance of Pu-239. Based on an analysis of a set of 93 thermal and fast critical experiments, the ENDF/B-V 44-group library has demonstrated markedly improved performance over similar analyses performed with the ENDF/B-IV 27-group library ( Validation of SCALE-4 Criticality Sequences Using ENDF/B-V Data, Proceedings of the Topical Meeting on Physics and Methods in Criticality Safety, Sept. 19 - 23, 1993). In addition, by comparing SAS2H/ORIGEN-S results with measured isotopic data, the library has demonstrated improved results in the prediction of spent fuel isotopics (Validation of the SCALE System for PWR Spent Fuel Isotopic Composition Analyses, ORNL/TM-12667, available December 1994).

The 238-group and 44-group libraries were originally discussed in Issue No. 7, August 1993. Testing and validation of the libraries were sponsored by the U.S. Nuclear Regulatory Commission (NRC) Office of Regulatory Research. The libraries will be released by RSIC as a data package that is separate from, but completely compatible with, the SCALE code package. Users of SCALE-4.0 or later can access the libraries by placing the desired library file on I/O unit 70 and specifying 44GROUP or 238GROUP in the CSAS input. The validation and testing documentation performed at ORNL will be provided with the data package released by RSIC. Contrary to the previous Newsletter article, these libraries will be available to foreign as well as U.S. facilities.

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In addition, this new version of NITAWL-II is able to interpolate the available thermal-scattering matrices to obtain data for the temperature requested by user input (via direct input to NITAWL-II or via the SCALE Standard Composition data). Previously, NITAWL-II had no such capability and selected the thermal- scattering data that was closest to the requested temperature. This limitation and some implications from it were discussed in Thermal-Scattering Data Limitation (Issue No. 3, July 1991). Thermal- scattering data for moderator materials, such as hydrogen and graphite, are available at many more temperatures in the new ENDF/B-V SCALE libraries than in the older ENDF/B-IV SCALE libraries. However, even with the new ENDF/B-V libraries, the interpolation should better determine the effect that a change in moderator temperature will have on the system multiplication factor.

The CSAS and SAS1 - SAS4 modules also have been modified via MIPLIB to provide two new parameters in the optional MORE DATA input (MRR 94-007):

MLV: maximum L value for which resonance calculation will be done (L = 0 is s-wave, L = 1 includes p-wave, L = 2 includes d-wave). The default value is L = 2.

MSH: maximum number of mesh points per resonance. The default value is 2001.

Note that if NITAWL-II is run stand-alone, the default values for MLV and MSH are 0 and 501, respectively.

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KENO-VI maintains all the flexibility and options of KENO-V.a plus a variety of new options. In KENO-VI, units can be constructed using both the simple geometric shapes provided and the tailored geometric shapes constructed using quadratic equations. KENO-VI should be available through RSIC some time during the fall of 1994. It will include the new 2-D color plotting capability that has been added to KENO-V.a (see Improvements to KENO-V.a Include 2-D Color Plot Capability ). At this time KENO-VI will only be able to run as a stand-alone module. Eventually KENO-VI will be included as part of the SCALE Criticality Safety Analysis Sequence.

Users should be aware that the added geometry features in KENO-VI can result in significantly longer run times than KENO-V.a. A KENO-VI problem that can also be modelled with KENO-V.a will typically run twice as long as the same problem using KENO-V.a. Thus, the new version VI should not be viewed as a replacement for the existing version V.a, but as an additional version for complex geometries that could not be modeled previously.

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Eight new problems were added to the existing 25 sample problems. Sample problems 26 through 28 are variations of sample problem 1, modeled as hemicylinders with chords and origins, and are extensions of sample problems 23 through 25, which are modeled using chords without origins. Sample problem 29 is a bare critical sphere, and sample problems 30 through 32 are the same critical system modeled using hemispheres with origins. Sample problem 33 is a critical triangular pitched array of partially flooded cylindrical annuli of low-enriched-uranium metal.

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The card-image decay library file END6DEC in SCALE-4.2 contains erroneous data for the half-life (HALFL), recoverable energy (Q), and fraction of recoverable energy from gammas (FG) for Br-86m (nuclide ID 350861). The erroneous values were inadvertently introduced during the last decay data update, but produce only a negligible effect for reactor problems. This error will be corrected in the next SCALE release. The current (i.e., erroneous) and the correct values are:

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In addition to the 2-D color plots, some of the other enhancements made to KENO-V.a include: (1) Fractional values are now valid for the lpi= parameter in the plot data to make it easier to print round circles on laser printers. (2) The system total fissions and absorptions by region can be calculated, and a parameter to suppress printing fissions and absorptions by region for each group has been added. Set gas=yes to print only the system totals by group. (3) MT 1452 is used in calculating nu*Sigma-t only if MT 18 and 452 do not exist. (4) The mixing table edit has been changed to print mixture density, nuclide, number density, weight fraction, ZA number, atomic weight and nuclide title; sorted first by mixture, then by ZA. (5) The total mass of each mixture in the problem can be calculated and printed.

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HEATING7.2: A coding flaw was found and corrected in HEATING that prevented the proper application of the unit system conversion factors for the material properties database. This option allows the user to select a material from the database and convert the property values to the user's unit system. Due to the flaw, the material property values were not converted and values were used in the calculations that were not correct for the unit system. This flaw would effect only HEATING or HTAS1 problems that specify unit conversion factors for the material properties database (MRR 94-005).

HTAS1: A coding flaw was found and corrected in HTAS1 that prevented the building and the use of enclosure radiation connectors for models that replace the material in the neutron shield with a void (no material). A normal (and the default) analysis would replace the material in the neutron shield with air. Any other material or a void can be placed in the neutron shield volume. As long as any type of material (not a void) is in the neutron shield then the thermal radiation connectors are built in OCULAR and the analysis procedures correctly. However, if a void volume is modeled in HTAS1 then the flaw prevented the building and use of the connectors. Thus, no heat would be transferred across the neutron shield, which could significantly and potentially nonconservatively alter the thermal history of the shipping cask (MRR 94-012).

All Cross-Section Libraries: The atomic masses of nuclides were modified to all be in terms of neutron mass for consistency (DRR 94-006).

KENO-V.a: (1) Corrected error that sometimes occurred when the boundary of a HOLE touched another HOLE or adjacent geometry region. The error can produce erroneous results, either conservative or nonconservative, without triggering warning or error messages. The effect on keff can be very significant in some cases (~ 1%). SCALE users were notified about this problem in the article Don t Let Your Holes Touch in KENO-V.a Geometry (Issue No. 7 of the SCALE Newsletter, August 1993). (MRR 94-003). (2) Fixed to allow more than 13 scattering angles. Although the parameter sct= was limited to 13, no check was made to avoid overstoring data. (3) Corrected error causing core dump on some workstations when a global unit wasn't explicitly defined (MRR 94-009).

NITAWL: Corrected the grayness correction to self-shielding in annular regions (MRR 94-008).

MIPLIB: (1) Added checks to avoid the use of negative number densities when solutions with physically unrealistic parameters are entered. (2) Corrected an error that caused CSAS to loop if the collapse option was specified and an input nuclide ID was not found in the cross-section library (MRR 94-007).

Standard Composition Library: (1) Revised the resonance energy scattering and/or total cross sections for 197 materials based on the 44-group ENDF/B-V cross-section library. Consistent values were specified for both the natural element and individual isotopes B, Zr, Eu, Hf, and W. (2) Turned off resonance processing flags for NISS, NIINCONEL, NI-ESIGT, CRSS, CRINCONEL, CR-ESIGT, MNSS, FESS, FEINCONEL, and FE-ESIGT. These flags only affect ENDF/B-V cross-section libraries (DRR 94-007). (3) Added new composition ZIRC2 for Zircaloy-2 when using ENDF/B-V cross-section libraries (DRR 94-001).

XSDRNPM/SAS4: Adjoint calculation in XSDRNPM for SAS4 was corrected. Only affects fixed-source calculations with upscatter on machines whose single and double precision formats are different (includes IBM workstations). Any such calculations should be re-run to determine impact of correction (MRR 94-014).

BONAMI: (1) Restored Bondarenko factor printout that was inadvertently deleted in July 1990 modification. Results were not impacted (MRR 94-006). (2) Corrected so that calculations with more than one nuclide specified with a zero number density will run (MRR 94-004).

SAS1: Corrected setting of termination flag so that SCALE driver can run other modules when cases are stacked in an input file (MRR 94-001).

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Words to the Wise...

Checking Input for User Errors

Be Case Conscious on UNIX machines

ENDF/B-VI Isotopic Specifications Not Consistent with Standard Composition Library

Updated SCALE-4.2 Installation Instructions for Sun, DEC, and HP

SCALE Help As Close as Your E-mail

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