Buck, R.

Cullen, D.

Heinrichs, D.

Krass, A.

Lee, C.

Lee, M.

Lent, E.

UNT Digital Library

LLNL-CONF-492113COG11 - Available Now toCriticality Safety PractitionersR. Buck, D. Cullen, D. Heinrichs, C. Lee, E. Lent,A. Krass, M. LeeAugust 8, 2011International Conference on Nuclear CriticalityEdinburgh, United KingdomSeptember 19, 2011 through September 23, 2011Disclaimer  This document was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor Lawrence Livermore National Security, LLC, nor any of their employees makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or Lawrence Livermore National Security, LLC. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or Lawrence Livermore National Security, LLC, and shall not be used for advertising or product endorsement purposes.  LLNL-CONF-492113  Page 1 of 4  COG11 – AVAILABLE NOW TO CRITICALITY SAFETY PRACTITIONERS   R. Buck, D. Cullen, D. Heinrichs, C. Lee and E. Lent∗ Lawrence Livermore National Laboratory 7000 East Avenue, P.O. Box 808, L-198, Livermore, California, 94551, USA buck2@llnl.gov; cullen1@llnl.gov; heinrichs1@llnl.gov; lee12@llnl.gov; lent1@llnl.gov  A. Krass C.S. Engineering 702 Foxfield Lane, Knoxville, Tennessee, 37922, USA krassaw@y12.doe.gov  M. Lee United States Department of Energy National Nuclear Security Agency, Livermore Site Office 7000 East Avenue, P.O. Box 808, L-293, Livermore, California, 94551, USA mark.lee@oak.doe.gov  ABSTRACT This paper describes new features and capabilities of the COG11 code and future code development activities.  COG11 is available from the Radiation Shielding Information Computer Center and Nuclear Energy Agency Data Bank. Key Words: code, COG, criticality, Monte Carlo, transport  1 INTRODUCTION COG is a modern, general purpose, high fidelity, multi-particle, Monte Carlo transport code developed at the Lawrence Livermore National Laboratory.  A general description of the features and capabilities of the first external release of the COG code – COG version 10, or COG10 – was previously published for ICNC 2007 [1].  A recent paper describes specific COG10 features of interest to criticality safety practitioners [2].  This paper describes new features and capabilities included in the latest version of the COG code – COG version 11, or COG11 – available from the Radiation Shielding Information Computer Center1 at Oak Ridge National Laboratory and the Organization for Economic Co-operation and Development Nuclear Energy Agency Data Bank2.   1.1 Machine Requirements COG11 is available from the Radiation Shielding Information Computer Center and the Nuclear Energy Data Bank for use on personal computers running Windows or Linux operating systems utilizing serial or parallel processing.   At the request of our internal photonics science users and external criticality safety users, additional special, limited distribution, versions have been provided for use on Apple Macintosh personal computers using Intel x86 processors running MAC OS 10.5; Hewlett-Packard machines                                                  1 http://www-rsicc.ornl.gov/codes/ccc/ccc7/ccc-777.html  2 http://www.oecd-nea.org/tools/abstract/detail/CCC-0777  Page 2 of 4  with Intel Itanium processors running Redhat Linux 5.5; and personal computers running SuSE 11.2. COG11, and subsequent versions, may be developed for other hardware-software machine platforms upon request from our users. 1.2 New Code Features Significant COG11 code features include new nuclear data libraries, interactive graphics, LATTICE geometry, a NOT operator, parallel processing, and user-specified detectors and sources, which were implemented in response to requests from our users. 1.2.1 New Nuclear Data Libraries In addition to the data libraries previously distributed, COG11 includes the most recent Evaluated Nuclear Data Files, Version 7, Release 0 (ENDF/B-VII.0), from the United States National Nuclear Data Center (NNDC): ENDFB7R0  point-wise continuous cross-sections PT.ENDFB7R0.BNL unresolved resonance region probability tables T.ENDFB7R0  thermal scattering laws Supplemental libraries distributed with COG11 include ENDFB6R8, ENDL99, ENDL2008, JEF2.2, JEFF3.1, JEFF3.1.1, and JENDL3.3; as well as MCNP.50c, MCNP.66c, and MCNP.70c originally developed at Los Alamos for use with the MCNP code3. 1.2.2 Interactive graphics Interactive graphics allow users to run interactive jobs (in the foreground) and easily modify the graphical display of the problem geometry using a simple command to launch a user-friendly graphical user interface. This feature is useful in developing problems with complex geometry or debugging user geometry errors. 1.2.3 LATTICE feature The LATTICE feature allows the user to easily specify a regular array of identical units where the unit may have an arbitrarily complex structure.  This feature is an extension of the UNIT feature. 1.2.4 NOT operator The NOT (exclusion) operator may be used to describe a sector as a volume that excludes another specified volume (or volumes) and may be defined explicitly – in terms of its bounding surfaces – or implicitly – in terms of other previously defined sectors. 1.2.5 Parallel processing To speed up calculations, a message passing interface (MPI) feature allows COG to run in parallel on a multiprocessor machine.  Inter-process communications are designed to achieve performance increases that are nearly linear in the number of processors.  1.2.6 User-specified detectors and sources COG offers the advanced user unusual flexibility in handling complex sources and detectors by providing for arbitrary user-specified detectors and sources.  The user writes and compiles his user subroutines into a user library.  At run time, COG links in the user routines and passes data to and from these routines via a formal interface.  This feature has been used to simulate count distributions as a function of the detector time gate from multiplying systems with spontaneous fission sources with excellent comparison to experimental results [4].                                                 3 http://mcnp-green.lanl.gov/  Page 3 of 4  1.3 Formal Training A formal training course [5] has been developed to enable the new user to demonstrate a basic level of competency by completing a variety of hands-on criticality safety calculations.  This training, and training in special topics, is available from the authors upon request. 1.4 Future Development Development versions of the COG11 code have implemented the JENDL-4.0 nuclear data library as well as various “beta” test versions of the Evaluated Nuclear Data Files, Version 7, Release 14.  These libraries are currently undergoing testing. New SOURCE features have been implemented in development versions of the COG11 code to allow the user to specify any number of parent isotopes and a time, or time interval, and COG will automatically calculate the photon source from alpha decay or fission product decay and then perform a standard transport calculation. State-of-the-art photonuclear nuclear resonance fluorescence (NRF) cross-sections have also been implemented and tested in development versions of COG in support of the MEGa-ray and T-REX projects at Lawrence Livermore National Laboratory [6]. ENDF, Version 7, Release 1 (ENDF/B-VII.1); JENDL-4.0; and NRF libraries; together with the new SOURCE features to simplify specification of photon emission from alpha decay and fission product decay will be included in the next external release of the COG code scheduled for distribution in 2012. 2 CONCLUSIONS  The Nuclear Criticality Safety Division of the Lawrence Livermore National Laboratory maintains COG as “safety software” for use in criticality safety applications.  Please visit our website at http://cog.llnl.gov for further details.  As criticality safety practitioners, we particularly welcome comments from the criticality safety community.  In addition to the authors’ personal addresses, we can also be reached by email at cog@llnl.gov. 3 ACKNOWLEDGMENTS This work performed under the auspices of the United States Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.  The support of the United States Department of Energy Nuclear Criticality Safety Program is gratefully acknowledged. 4 REFERENCES 1. R. Buck, et al., “COG – Publicly Available Now to Criticality Safety Practitioners,” Proceedings of the 8th International Conference on Nuclear Criticality Safety, ICNC 2007, St. Petersburg, Russia, May 28 –June 1, Vol. 1, pp.418-420 (2007). 2. R. Buck, et al., “COG – Special Features of Interest to Criticality Safety Practitioners,” Transactions of the American Nuclear Society, 102, pp.305-306 (2010).  3. R. Buck, E. Lent, COG11 Manual Supplement, LLNL-SM-461824, Lawrence Livermore National Laboratory, Livermore, California, USA (2010). 4. J. M. Verbeke et al., Neutron Correlations in Special Nuclear Materials, Experiments and Simulations, UCRL-PROC-231582, Lawrence Livermore National Laboratory, Livermore, California, USA (2007).                                                 4 http://www.nndc.bnl.gov/point2011  Page 4 of 4  5. D. Heinrichs, A. Krass, Nuclear Criticality Safety Division Training Module: COG Software, LLNL-SM-461182, Lawrence Livermore National Laboratory, Livermore, California, USA (2010). 6. C. Barty, “Going Deep with MEGa-Rays,” Science and Technology Review, UCRL-TR-52000-11-4/5, Lawrence Livermore National Laboratory, Livermore, California, USA (2011). 

COG11 - Available Now to Criticality Safety Practitioners

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COG11 - Available Now to Criticality Safety Practitioners

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