Title: Sigma web interface for reactor data applications
ArXiv ID: 1004.5116
Date: 2010-04-28
Authors: B. Pritychenko, A. A. Sonzogni
📝 Abstract
We present Sigma Web interface which provides user-friendly access for online analysis and plotting of the evaluated and experimental nuclear reaction data stored in the ENDF-6 and EXFOR formats. The interface includes advanced browsing and search capabilities, interactive plots of cross sections, angular distributions and spectra, nubars, comparisons between evaluated and experimental data, computations for cross section data sets, pre-calculated integral quantities, neutron cross section uncertainties plots and visualization of covariance matrices. Sigma is publicly available at the National Nuclear Data Center website at http://www.nndc.bnl.gov/sigma.
💡 Deep Analysis
Deep Dive into Sigma web interface for reactor data applications.
We present Sigma Web interface which provides user-friendly access for online analysis and plotting of the evaluated and experimental nuclear reaction data stored in the ENDF-6 and EXFOR formats. The interface includes advanced browsing and search capabilities, interactive plots of cross sections, angular distributions and spectra, nubars, comparisons between evaluated and experimental data, computations for cross section data sets, pre-calculated integral quantities, neutron cross section uncertainties plots and visualization of covariance matrices. Sigma is publicly available at the National Nuclear Data Center website at http://www.nndc.bnl.gov/sigma
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📄 Full Content
Increasing energy demand, concerns over climate change and high volatility of petroleum market make a very strong case for nuclear power renaissance in the US and worldwide. New power reactor units will be built utilizing the latest technologies and their design will incorporate the best available nuclear data. It is essential, in parallel with the data developments, to produce effective data analysis and processing tools for reactor physicists and engineers utilizing the modern computer technologies.
Sigma’s Web interface was created to extend the line of NNDC products and satisfy the data needs of the broad spectrum of users, including those who are not necessarily familiar with ENDF-6 and EXFOR formats. Its design is based on the current Web (Java, Java Server Pages, JavaScript and HTML) and relational database (MySQL and Sybase) technologies. Sigma’s mission includes providing search and browsing capabilities in a transparent way for five major evaluated libraries: ENDF/B-VII.0, JEFF-3.1, JENDL-3.3, ENDF/B-VI.8 and ROSFOND [1,[3][4][5][6]. The interface also offers the raw ENDF-6 data as well as processed versions and plots. Additionally, Sigma can allow the comparison between evaluated data and experimental data from the EXFOR/CSISRS database [7], and basic mathematical operations between evaluated data sets.
Interface plotting is performed by using the Java package jplots [9]. The ENDF utility codes such as PREPRO [10] are used to process the raw ENDF data and produce a point-wise version of the libraries for plotting and further computation. MySQL database server is used to store data in Sigma; a separate EXFOR database is available if necessary [11].
Sigma’s front page includes Periodic Table and Directory Tree options for graphical navigation and search options; on top of the Periodic Table tab, there are pull-down menus to select a library and sub-library. Fig. 1 shows an example of what Sigma front page would look like after selecting ENDF/B-VII.0 library, neutron reactions, and clicking on Uranium (U, Z=92) and on A=233. The scrollable table on the right of the figure with a light green background shows all the data available for this material, which can be retrieved in the ENDF-6 format, and some of them processed in an interpreted form or in a plot. Two search capabilities have been implemented, a basic one and a more advanced one. Basic Search shields users from having to know the intricacies of the ENDF-6 format when using Sigma. However, the Advanced Search feature, would require some knowledge of the format in order to make full use of it.
It is important to select high-quality ENDF evaluations before using nuclear data for reactor physics problem. Sigma Web interface provides connection to the CSISRS/EXFOR database, which contains a wealth of experimental data that has been carefully added to the database over several decades, for experimental cross sections, angular distributions and energy spectra.
The connection is made possible by the fact that both Sigma and CSISRS/EXFOR Web applications use the same EXFOR Relational database software [11] to facilitate the data exchange. The code X4toC4 [12] is used in Sigma to process data from CSISRS/EXFOR database for plotting. Fig. 2 shows cross sections for the 233 U(n,fission) reaction from five evaluated libraries together vs. selected experimental data sets [13][14][15] in the 10 -5 eV -20 MeV neutron energy range.
ENDF evaluations contain angular distributions of emitted neutrons, photons and residual nuclei for a particular reaction channel. In general, many reaction channels are open and combined spectra are observed in experiments, creating a challenge when comparison between evaluation and experimental results need to be done. This problem was solved by the ENDVER code [16] that is integrated in Sigma as Full Spectra for d/dE and d 2 /ddE spectra.
Computations in Sigma are based on the fact that pointwise cross section values are linearized within 0.1% for a particular energy bin. This creates a possibility of calculating evaluated cross sections for any energy point within the ENDF energy range and producing a unified energy grid for neutron evaluations. The success of nuclear astrophysics calculations using ENDF libraries [17] has provided the necessary validation for this approach.
Beta version of mathematical operations in Sigma has been implemented in December of 2007. The Web application stores cross section data from the File 3 together with cross sections derived from the resonance parameters in File 2 that have been Doppler broadened to 300 0 K and linearized using PREPRO [10]. These data can be plotted simultaneously in Sigma for a variety of different reactions (MT values) using the Plot Cart feature. The Plot Cart is made up of different sets of (x,y) data points. Almost any mathematical equation can be easily typed in using the Computations options and a new set of (x,y) points resulting from such a mathematical
