A battery powered by nuclear waste could keep a spaceship or hospital operating for 28,000 years without needing to be recharged or replaced, its developers claim. 

The radioactive battery is 'completely safe' for humans, according to California-based Nano Diamond Battery (NDB), who say it will 'change the world'. 

The firm hopes to start selling the battery to commercial partners, including space agencies for long duration missions, within the next two years. 

NDB are also working on a consumer version that could run a smartphone or electric car for up to a decade without requiring a charge. 

No details on pricing have been revealed by the technology startup, who say it is still in development phase. 

The technology involves combining radioactive isotopes taken from nuclear waste with layers of panelled nano diamonds stacked in a battery cell.

Extremely good heat conductance of the microscopic diamonds acts to move heat away from the radioactive isotopes so quickly the transaction generates electricity.

It is based on a technology called diamond nuclear voltaic (DNV) presented by scientists in 2016 from the University of Bristol using waste graphite blocks.

This technology is best suited for devices that need a slow trickle of electricity, consistently over a long period of time due to low energy production.