ISO/TC 85/SC 5/WG 5 - Characterisation and waste management

This document is the first of a series of seven documents which outlines the general principles to manage the various type of radioactive waste, and provides guidance for the practical implementation of those principles. The purpose of this document is to address the following: a) principles, objectives and practical approaches for radioactive waste management; b) outline of the structure of series from ISO 24389-1 through ISO 24389-7.

ISO 19017:2015 is applicable to gamma radiation measurements on radioactive waste. Radioactive waste can be found in different forms and exhibit a wide range of characteristics, including the following: - raw or unconditioned waste, including process waste (filters, resins, control rods, scrap, etc.) and waste from dismantling or decommissioning; - conditioned waste in various forms and matrices (bitumen, cement, hydraulic binder, etc.); - very low level (VLLW), low level (LLW), intermediate level (ILW) and high level radioactive waste (HLW); - different package shapes: cylinders, cubes, parallelepipeds, etc. Guidance is provided in respect of implementation, calibration, and quality control. The diversity of applications and system realizations (ranging from research to industrial systems, from very low level to high level radioactive waste, from small to large volume packages with different shapes, with different performance requirements and allowable measuring time) renders it impossible to provide specific guidance for all instances; the objective of this International Standard is, therefore, to establish a set of guiding principles. Ultimately, implementation is to be performed by suitably qualified and experienced persons and based on a thorough understanding of the influencing factors, contributing variables and performance requirements of the specific measurement application. This International Standard assumes that the need for the provision of such a system will have been adequately considered and that its application and performance requirements will have been adequately defined through the use of a structured requirements capture process, such as data quality objectives (DQO). It is noted that, while outside the scope of this International Standard, many of the principles, measurement methods, and recommended practices discussed here are also equally applicable to gamma measurements of items other than radioactive waste (e.g. bulk food, water, free-standing piles of materials) or to measurements made on radioactive materials contained within non-traditional packages (e.g. in transport containers).

ISO 16966:2013 gives guidelines for a common basic theoretical methodology to evaluate the activity of radionuclides in activated waste generated at nuclear reactors using neutron activation calculations.

ISO 21238:2007 gives guidelines for the common basic methodology of empirically determining scaling factors to evaluate the radioactivity of difficult-to-measure nuclides in low- and intermediate-level radioactive waste packages. ISO 21238:2007 gives common guidelines for the scaling factors used in the characterization of contaminated wastes produced in nuclear power plants with water-cooled reactor. ISO 21238:2007 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 ISO 21238:2007.

ISO 6962:2004 specifies a method designed to check the long-term stability of a solid to alpha disintegration by detection of all modifications in the properties of an irradiated sample. The material favoured hitherto is a borosilicate glass, but possible alternatives include ceramics, glass-ceramics or other glass compositions.

ISO 16797:2004 describes the Soxhlet-mode parameter test to assess the chemical durability of materials by measuring the initial dissolution rate in pure water. The measurement is performed at the boiling point of water, at which the dissolution rate is considerably higher than at room temperature. In most cases, the alteration phenomena are therefore significantly accelerated. The test is applicable to vitrified matrixes for high-level redioactive waste. The test described in ISO 16797:2004 is intended to measure the initial dissolution rate; it is thus applicable only to nonporous materials (or materials with small, closed porosity) for which the primary alteration phenomenon is a surface reaction mechanism (diffusion mechanisms are involved in the dissolution of porous media). The test results can therefore be compared only with findings obtained for nonporous materials if serious errors of interpretation are to be avoided. The resulting "initial dissolution rate in pure boiling water at atmospheric pressure" can be used to compare materials of the same type (e.g. oxides), provided their initial dissolution is governed by the same mechanism (e.g. surface reactions). This parameter test cannot be used to assess the long-term behaviour of a material, which generally requires several tests, modelling and validation, as described, for example, in Standard ENV 12920. This test is applicable to any glass, vitrified material (i.e. material resulting from a vitrification process) or nonporous oxide material with a morphology that allows the preparation of monolithic test coupons of known surface area. It determines the initial dissolution rate of the material in deionized water at the boiling point (approximately 100 °C) by analysis of the leaching solution and by measurement of the specimen mass loss.

ISO 14850:2004 describes a procedure for measurements of gamma-emitting radionuclide activity in homogeneous objects such as unconditioned waste (including process waste, dismantling waste, etc.), waste conditioned in various matrices (bitumen, hydraulic binder, thermosetting resins, etc.), notably in the form of 100 L, 200 L, 400 L or 800 L drums, and test specimens or samples, (vitrified waste), and waste packaged in a container, notably technological waste. It also specifies the calibration of the gamma spectrometry chain. The gamma energies used generally range from 0,05 MeV to 3 MeV.

Provided to measure the resistance to leaching of the solidified materials: glass, glass-ceramics, ceramics, bitumen, cement, concrete, plastics, the test being aimed at the comparison of different kinds or compositions, intercomparison between test results from different laboratories on one product or on products of different processes. It is not required to carry out tests in all possible combinations of variables but one appropriate set of standard conditions should be met.

Specifies a method designed to check the long-term stability of a solid to alpha disintegration by detection of all modifications in the properties of an irradiated sample. The solid is borosilicate glass or, as an alternative, ceramics or glass-ceramics and a two-phase mixture of glass beads dispersed in a metal matrix, made from adequate (stable) fission product elements spiked with appropriate tracers.