Program - Brookhaven National Laboratory

exercise, integral cross section data recently measured at the ASP 14 MeV irradiation are compared, where
data exists, with integral data from other neutron irradiation facilities (extracted from the international
EXFOR database) and with effective (collapsed) cross sections calculated from EASY-2012 cross section
data evaluations. These are shown as plots of the C/E ratio. Integral cross section data is presented for
reaction products resulting from irradiation of Nb, Cr, Au, Ag and Pb; with a focus on short-lived reaction
products of potential interest to fusion device neutron diagnostics.
This work was funded by the RCUK Energy Programme under grant EP/I501045 and the European
Communities under the contract of Association between EURATOM and CCFE. The views and opinions
expressed herein do not necessarily reflect those of the European Commission.
PR 37
Multigroup Cross Section Adjustment Based on ENDF/B-VII.0 Data
G. Palmiotti, M. Salvatores, H. Hiruta, R. D. McKnight, G. Aliberti, M.W. Herman, S. Hoblit, P. Talou,
INL, CEA, ANL, BNL, LANL.
Under the Advanced Reactor Concepts (ARC) program funded by DOE NE (Nuclear Energy) Office an
activity devoted to reduce uncertainties associated to the main neutronic parameters relevant to advanced
systems (reactors and associated fuel cycles) assessment and design has been carried out in the last few
years. The aim of this activity is to produce a set of improved nuclear data to be used both for a wide
range of validated advanced fast reactor design calculations and for the assessment of innovative fuel
cycles, and for providing guidelines for further improvements of the ENDF/B files (i.e., ENDF/B-VII.0,
and future releases). The process for producing the improved (i.e., with reduced uncertainties) nuclear
data involves several ingredients and steps: selection of a set of relevant experiments, sensitivity analysis
of selected configurations including reference design configurations, production and use of science based
covariance data for uncertainty evaluation and target accuracy assessment, analysis of experiments using the
best methodologies available, use of calculation/experiment discrepancies in a statistical data adjustment
process. The most recent adjustment performed uses a 33 group energy structure, ENDF/B-VII.0 as
starting data, COMMARA 2.0 covariance matrix, and more than 100 integral experiments. It is important
to underline that the COMMARA data file (now widely recognized internationally) has been developed in
the frame and consistently with the needs of this project. The set of integral experiments includes very
well characterized and complementary systems. Among those that have been utilized we can list: small
and very hard spectrum (e. g., GODIVA and JEZEBEL), medium and large systems (ZPR6-7, ZPPR9 and
ZPPR10), and power reactors (e. g., JOYO, PHENIX). For the purpose of the project, detailed validated
models of the experiment were used, and gathered in a unique database that allows the preservation of past
high quality experimental programs. The integral measured quantities used in the adjustment range from
critical mass to spectral indexes, from sodium void reactivity to control rod worth. Uncertainties were
also reassessed for all the experimental values, based on past information and best practices. Of particular
importance were separated isotope sample and special pin irradiation experiments (e. g., PROFIL and
TRAPU) that have allowed adjustment of minor actinide and fission product data. In the full paper results
will be presented with the most significant feedback for the ENDF/B-VII.0 provided by isotope, reaction,
and energy range. The results of the statistical data adjustment should, as much as possible, translate in
nuclear data file improvements.
PR 38
281