The objective of the Digital System Reliability Failure Mode Taxonomy (DIGREL) task group, formed under the OECD/NEA Working Group on Risk Assessment (WGRISK), has been to develop a taxonomy of failure modes of digital components for the purposes of probabilistic risk analysis (PRA). An activity focused on the development of a common taxonomy of failure modes is seen as an important step towards standardised digital instrumentation and control (I&C) reliability assessment techniques for PRA. Needs from PRA has guided the work, meaning, e.g. that the I&C system and its failures are studied from the point of view of their functional significance point of view. The taxonomy will be the basis of future modelling and quantification efforts. It will also help to define a structure for data collection and to review PRA studies. This report can be seen as a step towards more harmonised approach to analyse and model digital I&C in PRA.