[1][2] For three decades he worked commissioning and operating nuclear reactors in the UK for British Energy (formerly the Central Electricity Generating Board).
He emigrated to Australia in 1999 and took a position with the Australian Nuclear Science and Technology Organisation (ANSTO), where he remained for ten years.
Irwin chairs the Nuclear Engineering Panel of Engineers Australia and lectures at the Australian National University[3] and University of Sydney on nuclear science.
Irwin is an advocate for nuclear power in Australia and has recommended the deployment of small modular reactors, provided that legislation can be changed to allow for it.
[5] In 2014 he told the media:"Small modular reactors with their natural safety based on passive safety systems using gravity, natural circulation and pressurised tanks, represent a game-changer that is particularly suitable for Australian conditions.