Neutron Inelastic Cross Section Measurements for Sodium

C. Rouki,S. Kopecky,N. Nankov,A. J. M. Plompen,M. Stanoiu 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Inelastic scattering cross sections for sodium are of interest to the development of sodium cooled fast reactors. A recent OECD-NEA subgroup analysed the sensitivity of reactor parameters to cross sections and accordingly determined target uncertainties for the nuclear data. Comparing these target uncertainties with the current status of nuclear data uncertainties and covariance data resulted in a list of target priorities. Among these features sodium inelastic scattering for which a target uncertainty of about 5% was established, approximately two to three times as good as the uncertainty for current evaluated data les for this isotope (see OECD-NEA High Priority Request List, http://www.nea.fr/html/dbdata/hprl/hprlview.pl?ID=448). At IRMM, the GAINS gammaarray for inelastic neutron scattering was developed with the purpose of measuring cross sections with uncertainties at or below the target uncertainties for nuclides like ²³Na using the (n, n´γ)-technique. Measurements were performed at the GELINA facility at a 200 m flight path with eight high purity germanium detectors. The sample was an 80 mm diameter metallic disk prepared at IRMM by cutting, pressing, rolling and punching. For the experimental work, a careful review was made of the gamma-efficiency calibrations and the flux normalization in order to investigate in detail the corrections and the nal uncertainties that may realistically be achieved. An elaborate account will be presented of the data analysis and checks that have been made and implications for earlier work by our group will be discussed. First results will be shown for the gamma-production cross sections of the main transitions in the energy range from threshold to 10 MeV.

Transmission and Capture Measurements for ^(241)Am at GELINA

C. Lampoudis,S. Kopecky,A. Plompen,P. Schillebeeckx,P. Siegler 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The precise knowledge of cross sections for neutron induced reactions of major and minor actinides is essential for the design of advanced reactors. Furthermore, the present evaluated data files disagree with the results of some recent measurements. Therefore it was decided to perform new transmission and capture measurements for ^(241)Am at GELINA aiming to improve the evaluations. For the measurements a novel sample preparation method has been employed, for ensuring the homogeneity of the samples. The first results of capture and transmission measurements are consistent with each other, and with recent experimental values, but seem to be inconsistent with the evaluated data files. Before the final results can be reported, a careful characterisation of the americium sample is required.

Recent Progress in Neutron-, Proton- and Deuteron-induced Reaction Nuclear Data for EAF-2010 and the European Activation System

L. W. Packer,J. -Ch. Sublet,J. Kopecky,R. A. Forrest 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The European Activation System (EASY) has been continuously developed and improved formore than 20 years. Its primary purpose is to carry out neutron- proton- and deuteron-induced activation calculations in support of nuclear technology, particularly for nuclear material selection, design and optimization. It comprises the EAF nuclear data libraries and the FISPACT inventory code. For fusion applications, materials used for the construction of ITER, particularly plasma facing components, will be submitted to intense neutron irradiation. These materials may be evaluated using EASY for their nuclide inventory, He gas production and decay heat production over time, for example. EASY includes data to 60 MeV, making it also relevant for IFMIF analysis, and now covers 66,256 reactions. Such large libraries require an extensive validation process, which includes the statistical analysis of cross sections (SACS) and comparisons with differential and integral data. The suite of these methods has now been extended to evaluate the next library release, EAF-2010. Furthermore, significant attention has been focused on improving the uncertainty file, a unique feature of EAF libraries. In this work we discuss recent data improvements to be included in EAF-2010 and extensions to the treatment of uncertainties both in EAF and within EASY.

Database for Time-of-flight Spectra Including Covariances

N. Otuka,A. Borella,S. Kopecky,C. Lampoudis,P. Schillebeeckx 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

A data format for time-of-flight spectra (transmission, reaction andself-indication yields) and their covariance matrices based on the AGS(Analysis of Geel Spectra) format is discussed in collaboration betweenEC-JRC IRMM and IAEA-NDS for the EXFOR library. Experimentalists areencouraged to consider the uncertainty propagation following the AGSprinciple and submission of their data to the International Networks NuclearReaction Data Centres (NRDC) for EXFOR compilation using a proposedtemplate.

Neutron Resonance Parameters of ^(197)Au from Transmission, Capture, and Self-Indication Measurements at GELINA

C. Massimi,A. Borella,S. Kopecky,C. Lampoudis,P. Schillebeeckx,M. C. Moxon,G. Vannini 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

Transmission, capture and self-indication measurements on^(197)Au have been performed at the neutron time-of-flightfacility GELINA, operated by the European Commission, at EU-JRC-IRMM inBelgium. Part of this work was performed within the framework of the EFNUDATproject, with the objective to improve resonance parameters for the ^(197)Au(n, γ) cross section. Resonance parameters, i.e.,energy, spin, parity, neutron and radiation width, have been deduced in theenergy domain up to 200 eV. A comparison with results of measurementsperformed at RPI and at n_TOF shows a good agreement betweenthe data sets. In particular the nuclear resonance parameters, of the firsts-wave resonance at 4.9 eV, extracted at RPI are in very good agreement withthe results of the present work.

Neutron Resonance Spectroscopy at GELINA

P. Schillebeeckx,A. Borella,S. Kopecky,C. Lampoudis,C. Massimi,M. Moxon 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The neutron time-of-flight facility GELINA installed at the JRC-IRMM Geel (B) has been designed to produce cross section data for neutron induced reactions in the resonance region. It is a multi-user facility, providing a pulsed white neutron source, with a neutron energy range between 10 meV and 20 MeV and a time resolution of 1 ns. The research program concentrates on cross section data needs for nuclear energy applications. In this contribution efforts to improve the quality of cross section data in the resonance region are discussed. These efforts include the implementation of self-indication measurements and improved data reduction and resonance analysis procedures. Due to these efforts accurate neutron-induced cross section data and resonance parameters together with their covariance information can be obtained from thermal up to the unresolved resonance region.

Evaluation of cross sections for neutron interactions with 238U in the energy region between 5 keV and 150 keV

Sirakov, I.,Capote, R.,Gritzay, O.,Kim, H. I.,Kopecky, S.,Kos, B.,Paradela, C.,Pronyaev, V. G.,Schillebeeckx, P.,Trkov, A. Springer 2017 European Physical Journal A Vol.53 No.10

<P>Cross sections for neutron interactions with U-238 in the energy region from 5 keV to 150 keV have been evaluated. Average total and capture cross sections have been derived from a least squares analysis using experimental data reported in the literature. The resulting cross sections have been parameterised in terms of average resonance parameters maintaining full consistency with results of optical model calculations by using a dispersive coupled channel optical model potential. The average compound partial cross sections have been expressed in terms of transmission coefficients by applying the Hauser-Feshbach statistical reaction theory including width-fluctuations. A generalized single-level representation compatible with the energy-dependent options of the ENDF-6 format has been applied using standard boundary conditions. The results have been transferred into a full ENDF-6 compatible data file.</P>

Evaluation of Neutron Cross Sections for Hafnium in the Resolved Resonance Range

T. Ware,D. Weaver,M. Moxon,C. Dean,R. Hiles,P. Schillebeeckx,S. Kopecky 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23

The international High Priority Request list notes: - "In the nuclear industry hafnium is used as neutron absorbing material to regulate the fission process. Interpretation of critical experiments with UOx fuel conducted by CEA in the AZUR zero-power reactors has shown systematic underestimation of the reactivity worth that may be attributed to an overestimated natural hafnium capture cross section in the epi-thermal energy range"To service the request for improved resonance data a PhD project has:-a) Improved REFIT R-matrix evaluation code.b) Obtained hafnium oxide samples enriched in Hf176, 177, 178, 179 isotopes.c) Gained support from NUDAME and EUFRAT projects.d) Prepared enriched and natural Hf samples.e) Performed capture and transmission Time of Flight measurements at the GELINA linear accelerator.f) Analysed the capture counts to generate yields using AGS and AGL codes.g) Used REFIT to perform least squares analysis of GELINA measurements.(Included previous ORNL, Harwell and RPI transmissions and capture yields.)h) Submitted results to EXFOR.i) Included resolved resonance parameters in JEFF evaluations taking the resolved range to over 1keV. j) Tested evaluations with suitable benchmarks.k) Passed resolved resonance data to CEA Cadarache for unresolved analysis.Resultant Hf evaluations will be included in JEFF3.2.