Extension and maintenance of evaluated decay data files UKPADD-6

The recommended decay data for two specified sets of radionuclides have been prepared by assembling and assessing the relevant literature, evaluating or calculating the desired data, and preparing computer-based files in ENDF-6 format. Twenty-seven thermal fission products (plus short-lived daughters and related metastable/ground states) were judged to have inadequate decay-data files in the JEF2.2 library (OECD-NEA Data Bank), although important in fuel reprocessing, for adoption as monitoring standards or because they undergo significant delayed-neutron emission. Decay data for a further thirty-five short-lived fission products were also considered, despite the total lack of measured data; theoretical data were adopted from various sources. Both sets of decay data now form part of the UKPADD-6 library, which contains decay data for 452 radionuclides. Details of the evaluation procedures are given within Sections 2 and 3 of this report, although the reader is referred to the specific data files in UKPADD-6 for the complete sets of recommended data and listings of the supportive references. (author)