The event took place on campus earlier this week
A number of high-profile staff including Miriam O'Callaghan, Bryan Dobson, David McCullagh and RTE News Managing Director Jon Williams were posing for pictures without practicing social distancing or wearing masks.
The broadcaster has said what happened was "unnecessarily risky" and says social distancing was observed throughout the so-called impromptu gathering.
The NUJ wants the state broadcaster to carry out a full investigation into its Covid-19 protocols so its staff are kept safe.
