He will take up the role at the trade body for the civil nuclear industry on Monday (1 February).
Utility Week columnist Greatrex has previously been Labour’s lead spokesman on nuclear energy as well as a member of the energy select committee.
He said: “I am delighted to be joining the Nuclear Industry Association at such an exciting time. Nuclear power is an integral part of a secure low carbon energy mix and, as the COP21 negotiations in Paris demonstrated, will have a key part to play in reducing global carbon emissions in the future.
“Providing thousands of high quality, skilled jobs in all parts of the country and with internationally recognised industrial and academic expertise, there are significant opportunities for our civil nuclear industry in the UK and around the world.”
Greatrex succeeds long standing chief executive Keith Parker, who said: “This is an exciting time to join the nuclear sector, as the new build programme moves forward at pace, the current fleet see life extensions and decommissioning reaches key milestones.
“The NIA, as the voice of the sector, needs robust and effective leadership to represent the interests of its member companies and argue the case for nuclear as an essential part of the UK’s low-carbon mix.”