Burial disposal of low- and intermediate-level radioactive waste has been practiced in several countries. Before disposal, the radioactivity of specific nuclides in waste packages have to be declared in accordance with limits and criteria derived from safety assessment of the disposal facility. Some of these nuclides are difficult to measure from the outside of the waste packages, because they are beta or alpha emitting nuclides.
There are a number of activity determination methods. The scaling-factor method is widely applied in order to evaluate these difficult-to-measure nuclides. The scaling-factor method is based on a correlation between easily measurable gamma emitting nuclides and difficult-to-measure nuclides.
BS ISO 21238 is the international standard that gives guidelines for the common basic methodology of empirically determining scaling factors to evaluate the radioactivity of a nuclear power plant’s low and intermediate level waste. It covers, specifically, the difficult-to-measure nuclides in low- and intermediate-level radioactive waste packages.
This standard gives common guidelines for the scaling factors used in the characterization of contaminated wastes produced in nuclear power plants with water-cooled reactor. It is also relevant to other reactor types, such as gas-cooled reactors. Methodologies for determining scaling factors based on theoretical considerations (i.e. not based on experimental measurement) are not covered by BS ISO 21238.