Program - Brookhaven National Laboratory

we achieve very good separation of prompt fission γ-rays from the prompt fission neutron component in
a very compact source-detector geometry, which removes a possible source of uncertainties. After about
four decades since the experiments were performed whose results are still used for current evaluations, we
present new spectral prompt fission γ-ray data from the reactions 252 Cf(SF) [5] and 235 U(nth, f). We will
also report on γ-ray data as a function of fission-fragment mass and total kinetic energy. Based on our
new findings we recommend to replace the current ENDF/B-VII evaluation for 252 Cf(SF) as well as for
238 U(n,f) and 241 Pu(n,f).
[1] G. Rimpault, in: P. Rullhusen (Ed.), Proceedings of the Workshop on Nuclear Data Needs for Generation
IV, Antwerp, Belgium, World Scientific, ISBN 981- 256-830-1, 2006, April 2005, p. 46 [2] G. Rimpault, A.
Courcelle, D. Blanchet, Comment to the HPRL:IDH.3 and H.4,
http://www.oecd-nea.org/html/dbdata/hprl/tmp/HPRLgammafission.pdf
[3] R. Billnert, S. Oberstedt, E. Andreotti, M. Hult, G. Marissens, A. Oberstedt, Nuclear Instruments and
Methods in Physics Research Section A 647, bf 94 (2011) [4] A. Oberstedt, S. Oberstedt, R. Billnert, W.
Geerts, F.-J. Hambsch, J. Karlsson, Nuclear Instruments and Methods in Physics Research Section A 668,
14 (2012) [5] R. Billnert, F.-J. Hambsch, A. Oberstedt, S. Oberstedt, submitted for publication
DE 6 5:15 PM
Validation and Testing of ENDF/B-VII Decay Data
I.C. Gauld, M.T. Pigni, G. Ilas
Oak Ridge National Laboratory
The nuclear decay library developed for the Oak Ridge Isotope Generation and Depletion (ORIGEN) code
released within the SCALE 6.1 code system [1] was upgraded from ENDF/B-VI.8 to -VII.0. Used internationally
by industry, regulatory agencies and research for design and safety studies involving irradiated
nuclear materials, ORIGEN solves for the transmutation and decay of more than 2300 nuclides. Recent
experience with ENDF/B-VII.0 library has identified a number of serious deficiencies in the evaluated
decay data files, initially identified in the 238 U decay series [2], but also found to impact fission product
decay schemes and decay energy release. To address the deficiencies in the decay data released in SCALE
6.1, Oak Ridge National Laboratory (ORNL) has developed an ORIGEN decay library based on the most
recent ENDF/B-VII.1 evaluations. This paper describes a validation and test suite developed to evaluate
decay data performance and initial results obtained using ENDF/B-VI.8, -VII.0, and -VII.1 libraries. The
tests include the thorium 4n, neptunium 4n+1, uranium 4n+2, and actinium 4n+3 decay series, as well
as experimental benchmarks including destructive isotopic assay measurements [3] and integral decay heat
measurements for full-length fuel assemblies [4]. In addition, measurements of β and γ energy release and
spectra for times of < 1 to 10 5 s after fission are applied to evaluate the fission product decay data [5].
These tests will form the basis of future performance evaluation of ENDF/B decay data at ORNL and
processing of the data for use in SCALE.
[1] RSICC Computer Code Collection, CCC-732, 2011. “SCALE: A Comprehensive Modeling and Simulation
Suite for Nuclear Safety Analysis and Design,” Technical Report ORNL/TM-2005/39, Version
6.1, Oak Ridge National Laboratory. [2] http://www.nndc.bnl.gov/exfor/endfb7.1 decay.jsp [3] G. Ilas,
I.C. Gauld, and G. Radulescu, “Validation of new depletion capabilities and ENDF/B-VII data libraries
in SCALE,” Annals of Nuclear Energy, 46, 43 (2012). [4] F. Sturek, L. Agrenius, and O. Osifo, “Measurements
of Decay Heat in Spent Nuclear Fuel at the Swedish Interim Storage Facility,” Clab, Svensk
Karnbranslehantering AB, R-05-62, December 2006. [5] “Assessment of Fission Product Decay Data for
Decay Heat Calculations, ”International Evaluation Co-operation, Volume 25, NEA/WPEC-25, Nuclear
Energy Agency (2007).
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