Effects of cross sections tables generation and optimization on rod ejection transient analyses

Best estimate analysis of rod ejection transients requires 3D kinetics core simulators. If they use cross sections libraries compiled in multidimensional tables,interpolation errors – originated when the core simulator computes the cross sections from the table values – are a source of uncertainty in k-effective calculations that should be accounted for. Those errors depend on the grid covering the domain of state variables and can be easily reduced, in contrast with other sources of uncertainties such as the ones due to nuclear data, by choosing an optimized grid distribution. The present paper assesses the impact of the grid structure on a PWR rod ejection transient analysis using the coupled neutron-kinetics/thermal-hydraulicsCOBAYA3/COBRA-TF system. Forthispurpose, the OECD/NEA PWR MOX/UO2 core transient benchmark has been chosen, as material compositions and geometries are available, allowing the use of lattice codes to generate libraries with different grid structures. Since a complete nodal cross-section library is also provided as part of the benchmark specifications, the effects of the library generation on transient behavior are also analyzed.Results showed large discrepancies when using the benchmark library and own-generated libraries when compared with benchmark participants’ solutions. The origin of the discrepancies was found to lie in the nodal cross sections provided in the benchmark.

Harriet Robinson

Born on September 10, 1917, in Jefferson City, Harriet Robinson is a child of two Lincoln University alumni. Robinson and her siblings also attended Lincoln Laboratory School and the University, but she was unable to finish her degree due to the Depression. Robinson worked in retail until she entered a federal re-training program. In 1969 she was hired at Lincoln University as a switchboard operator, and later worked as a library assistant at Page Library. For twenty-three years, Robinson helped students and faculty with their research, retiring in 1992. While at Page Library, she also had other responsibilities, such as keeping the Lincoln Collection. She recognized the historical importance of objects, salvaging things such as the “Blue Tiger” Café Window. Robinson has assisted people working on graduate and doctoral degrees, and several books have been dedicated to her. Her knowledge of Lincoln University is extensive, and many are fortunate that she has always shared her passion for history.

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18th President 1st Female President 2005-2012 Dr. Carolyn R. Mahoney earned her B.S. degree in Mathematics from Siena College; M.S. and PhD. Degree in Mathematics from the Ohio State University. On February 1, 2005, Dr. Mahoney became the 18th president of Lincoln University of Missouri.