Abstract
In the present work the new data on correlation and covariance matrices have been calculated for all recommended data on temporal parameters of delayed neutrons in 6- and 8-group models. The method for producing the correlation and covariance data for the temporal DN parameters is described. The table of changes is listed in the text. Some examples of the data generated on basis of experimental DN decay curves (for IPPE data) and data generated on the basis of decay curves restored using temporal parameters (for works of another authors) are listed too.
Highlights
Following Tuttle’s evaluation of delayed neutron (DN) data in 1979 [1], OECD/NEA WPEC Subgroup (SG) 6 performed an evaluation with the aim of improving the macroscopic DN data for the major actinide nuclides 235U, 238U and 239Pu, which are of primary interest for reactor technology [2]
In 2013 the Nuclear Data Section of the IAEA initiated a Coordinated Research Project (CRP) with the purpose to create a Reference Database for both microscopic and macroscopic DN databased on the latest experimental efforts [4]
The purpose of this work is threefold: (1) to develop an approach for calculation of the correlation and the covariance data for the temporal DN parameters both in the 6- and the 8-group models; (2) to calculate the correlation and the covariance matrices for all nuclides included in the recommended IAEA/CRP database [5]; (3) to provide this data in a suitable form for easy inclusion in the online IAEA/NDS beta-delayed neutron database
Summary
Following Tuttle’s evaluation of delayed neutron (DN) data in 1979 [1], OECD/NEA WPEC Subgroup (SG) 6 performed an evaluation with the aim of improving the macroscopic DN data for the major actinide nuclides 235U, 238U and 239Pu, which are of primary interest for reactor technology [2]. Recommended data were provided for the total DN yields for the above three nuclides, and for the temporal DN parameters in the 6and 8-group models for the whole set of nuclides [3] included in Tuttle’s evaluation [1]. SG 6 had no intention to elaborate an approach for calculating the correlation and the covariance data for DN temporal parameters. Among the numerous new DN data developed in the frame of this project, are the revised recommended temporal DN parameters for both the 6- and 8-group models. The revised DN group-parameters database contained information on correlations and covariances only for a few nuclides, and mainly for the 6-group model which were obtained on the basis of the IPPE data. Taking into account up-to-date requirements from the reactor community, there is a need to extend such
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