Program - Brookhaven National Laboratory

Manturov, M.N. Nikolaev, A.M. Tsiboulia, “ABBN-93 Group Data Library. Part 1: Nuclear Data for the
Calculations of Neutron and Photon Radiation Fields.” INDC (CCP)-409/L, IAEA, p. 65 (1997). 7.V.M.
Poplavsky et al. “Core Design and Fuel Cycle of Advanced Fast Reactor with Sodium Coolant.” Int. Conf.
on Fast Reactors and Related Fuel Cycles: Challenges and Opportunities (FR09), Kyoto, Japan, December
7-11, 2009.
PR 132
Propagating Correlated Uncertainties in the Prompt Fission Neutron Spectra
M.E. Rising, A.K. Prinja, Chemical and Nuclear Engineering Department, University of New Mexico,
USA. P. Talou, Theoretical Division, Los Alamos National Laboratory, USA.
The most modern nuclear data libraries, including the ENDF/B-VII.1 library in the US [1], have recently
focussed much of the evaluation efforts not only on obtaining the best possible mean values for important
nuclear reactions but also the uncertainties associated with the mean values [2]. With many of the
neutron-induced reaction uncertainties becoming available to the nuclear applications community, there is
a large need to propagate the evaluated uncertainties through neutron transport calculations to better understand
the effect on the integral quantities computed in the neutron transport simulations and observed
in selected experiments. Recently, the prompt fission neutron spectrum (PFNS) uncertainties have been
systematically quantified across a suite of isotopes [3] using a Kalman filter and a modified version of the
Los Alamos model [4]. A covariance matrix with cross-isotope correlations describing the PFNS uncertainties
resulted along with new evaluated PFNS mean values across each suite of isotopes. The benefit of
the systematic approach to evaluating the PFNS in this manner is that the minor actinides, which have
extremely scarce differential experimental measurements, have now been evaluated using the differential
experimental measurements available for the major actinides in an indirect but very reasonable and coherent
fashion. First, we propose to use the newly evaluated PFNS mean values in some selected transport
benchmarks and compare the integral quantities obtained against the integral quantities computed using
the ENDF/B-VII.1 data library [1]. To obtain the uncertainties associated with the computed integral
quantities of the transport benchmarks, several uncertainty propagation methods are explored, including
the first-order “sandwich” rule, brute force Monte Carlo and polynomial chaos expansion methods. Finally,
the impact the cross-isotope correlations have on the selected transport benchmarks are studied by comparing
the differences when propagating the PFNS uncertainties through the transport solution separately
(assuming no cross-isotope correlation exists) and propagating the correlated PFNS uncertainties.
[1] M.B. CHADWICK, M. HERMAN, P. OBLOZINSKY et al., “ENDF/B-VII.1 Nuclear Data for Science
and Technology: Cross Sections, Covariances, Fission Product Yields and Decay Data,” Nuclear Data
Sheets, 112, 2887 (2011). [2] P. TALOU, P.G. YOUNG, T. KAWANO, M. RISING and M.B. CHADWICK,
“Quantification of Uncertainties for Evaluated Neutron-Induced Reactions on Actinides in the Fast Energy
Range,” Nuclear Data Sheets, 112, 3054 (2011). [3] M.E. RISING, P. TALOU, T. KAWANO and
A.K. PRINJA, “Systematic Uncertainty Quantification of Prompt Fission Neutron Spectra,” (submitted
to Nucl. Sci. Eng. May 2012). [4] D.G. MADLAND and J.R. NIX, “New Calculation of Prompt Fission
Neutron Spectra and Average Prompt Neutron Multiplicities,” Nucl. Sci. Eng., 81, 213 (1982).
PR 133
Evaluation of the Covariance Matrix of Estimated Resonance Parameters
Bjorn Becker, Stefan Kopecky, Peter Schillebeeckx, Konstantin Volev, EC-JRC-IRMM, Retieseweg 111,
B-2440 Geel, Belgium. Ivan Sirakov, INRNE, Sofia, Bulgaria. Cristian Massimi, INFN, Bologna, Italy.
330