The Experimental Data Covariance Evaluation Handler Development And ~ (58,60,61,62,64, Nat) ~ Of Ni Neutron Covariance Data Evaluation

The study and evaluation of covariance data are a part of the project "Nuclear Data Measurement, Evaluation and the Technique of Setting up Library for Military Applications". The project is one of the defense pre-research programs in high priority of the PLA General Equipment Department in the "Tenth-Five" plan period. The evaluation of covariance data for structural materials is a composition part of the project, and was assigned to Zhengzhou University by the General Nuclear Industry Company of China and the Chinese Nuclear Data Center. The task includes five parts:1. Experimental data retrieval from EXFOR Experimental Nuclear Data Library;2. Experimental data evaluation;2. Theory calculations based on the experimental data;4. Evaluated data comprehensive adjustment for making consistent;5. Development of the covariance data evaluation and processing program. The first ,second and last parts were studied in this work.Mastering the output format of covariance of neutron cross section in ENDF/B-6 evaluated nuclear data Library, clearly understanding the meaning of each physical quantity, grasping the mathematical methods pf covariance for experimental nuclear data and evaluated nuclear data, a set of evaluation processing method was deduced from the meaning of cross sections and errors. And then a program was developed for evaluating and processing the covariance matrix of experimental data, which are output in the ENDF/B-6 format. The program can be used directly for the covariance data evaluation of experimental data, and also can be taken as output code of the covariance file for Chinese Evaluation Nuclear Data Library (CENDL).Experimental data of Natural Ni and its five isotopes 58Ni, 60Ni, 61Ni, 62Niand 64Ni were retrieved from the EXFOR Experimental Nuclear Data Library and the corresponding evaluated nuclear data for reference were retrieved from the Evaluated Nuclear Data File(ENDF/B-6). Analyzing and evaluating the experimental method, the data were decided if they are accepted or rejected and made necessary correction. For the data accepted, thesources, values and the reasonability of the errors were analyzed and made adjusted when it is necessary. Ensuring the short-range, medium-range and long-range errors, using the covariance evaluation and processing program for experimental data, the covariance matrices were constructed for each set of experimental data. The cross section data were fitted and the covariance data were combined for each reaction channel by using the spline fitting program (SPC) developed at CNDC. Adjusted the input parameters, a set of optimal data and covariance matrices were obtained in the statistical meaning. Correlative coefficients of the cross sections were plotted in three dimension pictures with Origin program. In this way, the physical meaning of the covariance matrices and the correlation between the cross section data at each energy points are displayed visually.The evaluated data will be taken into Chinese Evaluation Nuclear Data Library (CENDL) and served as the basis of theoretical calculations. These data are of great economical and societal significance for designing nuclear weapon, "No Violating the Treaty" nuclear test and developing military nuclear power submarine.