Nuclear power remains the leading low-carbon energy technology in Europe. The environment inside a nuclear reactor requires constant monitoring to maintain safe temperatures and control fission reactions. While the use of data acquisition systems is rapidly increasing across the nuclear industry, there are currently no suitable standards which specify the format of this list-mode data, with each instrument manufacturer providing its own format. This prevents the comparison of radioactivity measurements needed for greater confidence, transparency and harmonisation. These measurements ensure the safe and efficient operation of nuclear power plants, underpin nuclear medicine and provide nuclear security. EMRP project ENG08 presented an initial draft data format to a working group of the IEC Technical Committee on Nuclear Instrumentation, who then stated their support for a new work item proposal to produce an appropriate standard. This project successfully produced the International Standard IEC 63047 "Nuclear instrumentation – Data format for list mode digital data acquisition used in radiation detection and measurement".The International Standard enables measurements to be compared across data analysis centres, providing greater confidence in and harmonisation of radioactivity measurements, and enabling the development of improved technology for nuclear safety.