ASTM E 798 : 2024

1.1This practice covers procedures for high-intensity irradiations designed to support material damage equivalence studies using accelerator-based neutron sources. The discussion focuses on two types of sources, namely nearly monoenergetic 14-MeV neutrons from the deuterium-tritium T(d,n) interaction, and broad spectrum neutrons from stopping deuterium beams in thick beryllium or lithium targets. However, most of the recommendations also apply to other types of accelerator-based sources, including spallation neutron sources (1).2 Interest in spallation sources has increased due to the development of high-power, high-fluence rate sources for neutron scattering (2-4) and their proposed use for transmutation of fission reactor waste (5).

1.2Many of the experiments conducted using such neutron sources are intended to provide a simulation of irradiation in another neutron spectrum, for example, that from a DT fusion reaction. The word simulation is used here in a broad sense to imply an approximation of the relevant neutron irradiation environment. The degree of conformity can range from poor to nearly exact. In general, the intent of these experiments is to establish the fundamental relationships between irradiation or material parameters and the material response. The extrapolation of data from such experiments requires that the differences in neutron spectra be considered.

1.3The procedures to be considered include methods for characterizing the accelerator beam and target, the irradiated sample, and the neutron fluence rate (recommended terminology for the deprecated term “flux”) and spectrum, as well as procedures for recording and reporting irradiation data.

1.4Other experimental problems, such as temperature control, are not included.

1.5The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.7This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.