Xenon oscillations of large graphite-moderated reactors have been analyzed by a multi-group diffusion code with two- and three-dimensional core models to study the effects of the geometric core models and the neutron energy group structures on the evaluation of the Xe oscillation behavior.The study clarified the following. It is important for accurate Xe oscillation simulations to use the neutron energy group structure that describes well the large change in the absorption cross section of Xe in the thermal energy range of 0.1 approximately 0.65 eV, because the energy structure in this energy range has significant influences on the amplitude and the period of oscillations in power distributions. Two-dimensional R-Z models can be used instead of three-dimensional R-theta-Z models for evaluation of the threshold power of Xe oscillation, but two-dimensional R-theta models cannot be used for evaluation of the threshold power. Although the threshold power evaluated with the R-theta-Z models coincides with that of the R-Z models, it does not coincide with that of the R-theta models.

article Free Access Share on A performance comparison of four supercomputers Authors: Margaret L. Simmons Los Alamos National Lab, Los Alamos, NM Los Alamos National Lab, Los Alamos, NMView Profile , Harvey J. Wasserman Los Alamos National Lab, Los Alamos, NM Los Alamos National Lab, Los Alamos, NMView Profile , Olaf M. Lubeck Los Alamos National Lab, Los Alamos, NM Los Alamos National Lab, Los Alamos, NMView Profile , Christopher Eoyang INSEAD, Paris, France INSEAD, Paris, FranceView Profile , Raul Mendez Institute for Supercomputing Research, Tokyo, Japan Institute for Supercomputing Research, Tokyo, JapanView Profile , Hiroo Harada Japan Atomic Energy Research Institute, Ibaraki, Japan Japan Atomic Energy Research Institute, Ibaraki, JapanView Profile , Misako Ishiguro Japan Atomic Energy Research Institute, Ibaraki, Japan Japan Atomic Energy Research Institute, Ibaraki, JapanView Profile Authors Info & Claims Communications of the ACMVolume 35Issue 8Aug. 1992 pp 116–124https://doi.org/10.1145/135226.135234Published:01 August 1992Publication History 14citation541DownloadsMetricsTotal Citations14Total Downloads541Last 12 Months57Last 6 weeks6 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

Article Free Access Share on A performance comparison of three supercomputers: Fujitsu VP-2600, NEC SX-3, and CRAY Y-MP Authors: Margaret L. Simmons Computing and Communications Division, Los Alamos National Laboratory, Los Alamos, New Mexico Computing and Communications Division, Los Alamos National Laboratory, Los Alamos, New MexicoView Profile , Harvey J. Wasserman Computing and Communications Division, Los Alamos National Laboratory, Los Alamos, New Mexico Computing and Communications Division, Los Alamos National Laboratory, Los Alamos, New MexicoView Profile , Olaf M. Lubeck Computing and Communications Division, Los Alamos National Laboratory, Los Alamos, New Mexico Computing and Communications Division, Los Alamos National Laboratory, Los Alamos, New MexicoView Profile , Christopher Eoyang Eoyang Institute for Supercomputing Research, 1-13-1 Kachidoki, Chuo-ku, Tokyo 104, Japan Institute for Supercomputing Research, 1-13-1 Kachidoki, Chuo-ku, Tokyo 104, JapanView Profile , Raul Mendez Institute for Supercomputing Research, 1-13-1 Kachidoki, Chuo-ku, Tokyo 104, Japan Institute for Supercomputing Research, 1-13-1 Kachidoki, Chuo-ku, Tokyo 104, JapanView Profile , Hirro Harada Japan Atomic Energy Research Institute, Tokai-Mura, Maka-Gun, Ibaraki, 319-11, Japan Japan Atomic Energy Research Institute, Tokai-Mura, Maka-Gun, Ibaraki, 319-11, JapanView Profile , Misako Ishiguro Japan Atomic Energy Research Institute, Tokai-Mura, Maka-Gun, Ibaraki, 319-11, Japan Japan Atomic Energy Research Institute, Tokai-Mura, Maka-Gun, Ibaraki, 319-11, JapanView Profile Authors Info & Claims Supercomputing '91: Proceedings of the 1991 ACM/IEEE conference on SupercomputingAugust 1991 Pages 150–157https://doi.org/10.1145/125826.125924Online:01 August 1991Publication History 0citation328DownloadsMetricsTotal Citations0Total Downloads328Last 12 Months6Last 6 weeks2 Get Citation AlertsNew Citation Alert added!This alert has been successfully added and will be sent to:You will be notified whenever a record that you have chosen has been cited.To manage your alert preferences, click on the button below.Manage my AlertsNew Citation Alert!Please log in to your account Save to BinderSave to BinderCreate a New BinderNameCancelCreateExport CitationPublisher SiteeReaderPDF

Three-dimensional multi-group neutron diffusion code CITATION has been widely used for reactor criticality calculations. The code is expected to be run at a high speed by using recent vector supercomputers, when it is appropriately vectorized. In this paper, vectorization methods and their effects are described for the CITATION code. Especially, calculation algorithms suited for vectorization of the inner-outer iterative calculations which spend most of the computing time are discussed. The SLOR method, which is used in the original CITATION code, and the SOR method, which is adopted in the revised code, are vectorized by odd-even mesh ordering.The vectorized CITATION code is executed on the FACOM VP-100 and VP-200 computers, and is found to run over six times faster than the original code for a practical-scale problem. The initlal value of the relaxation factor and the number of inner-iterations given as input data are also investigated since the computing time depends on these values.

Several sm-polyfluorodiaminobiphenyls were prepared in order to obtain colnponents for her: mostable fluoroaromatic polyamides. With mixed acld 2, 2, 6, 6-(1)and 4, 4, 6, 6 -tetra uorobiphenyl(4)and 2, 2, 4, 4, 6, 6, -hexafluorobiphenyl(7)were: nitrated to the corresponding 3, 3-dinitro derivatives in good yields. Reduction of these dinitro compounds gave tetra-and hexa uoro-3, 3 -diaminobiphenyls, (3), (6)and(9).By reductive rearrangement of 2, 2, , 6, 6(10)and 2, 2, 5, 5, -tetrafluoroazobe: nzene(12), 3, 3, 5, 5-(11)and 2, 2, 5, 5 tetra uorobenzidin, e(13)were obtained respectively. Tetrafluoroazobenzene (10)was prepared from, 2, 6-di uorolithiobenzene and 2, 6-di orobenzenediazonium tetrafluoroborate, while(12)was obtained by a1: kaline reductionof 2, 5--difluoro: nitrobenzene in dioxane, The reduction of 2, 5-difluoronitrobenze: ne in ethanol gave 2, 2 -diethoxy-5, 5, -di oroazobenze ne(14), which was rearranged to 5, 5-diethoxy-2, 2 -di orobenzidine(15).