The Energy Security Strategy, unveiled by Prime Minister Boris Johnson, sets out how Britain will speed up plans for wind, new nuclear, solar and hydrogen power.
It includes an aim to progress up to eight smaller “modular” nuclear reactors across several projects by 2030.
Mrs Mortimer described the announcement as a “huge boost” to the British nuclear industry.
The reactor at the EDF power station on Brenda Road is due to be decommissioned from 2024.
Mrs Mortimer said: “As one of eight designated nuclear sites, Hartlepool is at the front of the queue for a new reactor.
"This is a huge boost for my campaign to bring new nuclear to Hartlepool, which would secure jobs and investment for many generations to come.”
Industry representatives are invited to apply for a share of £2.5m funding to develop a UK Advanced Modular Reactor (AMR).
The reactors use novel and innovative fuels, coolants, and technologies to generate high-temperature heat for industrial applications as well as for electricity to power people’s homes.
The GMB says it has long campaigned for a new nuclear reactor in Hartlepool.
Regional secretary Hazel Nolan said: “At least the government has finally woken up to what GMB has been saying for years: new reactors are the only way we can secure the UK's energy security, and there can be no net zero without new nuclear.
“But a clear commitment by the Government to build a new nuclear reactor in Hartlepool would have been levelling up in action.”
“Instead, local workers and communities will be left facing uncertainty at a time when the country is facing a cost-of-living crisis and our energy security is a matter of national security.
“After years of dither and delay, it’s time to get on with it and put spades in the ground in the North East.”