By Timothy Gardner

WASHINGTON, July 1 (Reuters) - Commonwealth Fusion Systems, a U.S. company attempting to generate electricity by replicating the process that fuels the stars, said on Wednesday it is joining a UK government program to demonstrate production of fuel for fusion reactors.

• Fusion, which is still experimental, ​generates energy by jamming light atoms together under extremely high ⁠temperatures.

• The agreement builds on momentum from King Charles' address to the U.S. Congress in April.

• Commonwealth is the first international company to participate in the UK's Atomic Energy Authority's Lithium Breeding Tritium Innovation (LIBRTI) program.

• Tritium, a form of hydrogen, is extremely rare in nature but can be produced, in a process known as breeding, in reactors by hitting a blanket lined with lithium with neutrons released from fusion reactions.

• Commonwealth, based in Massachusetts, has raised about $3 billion, more than any other company looking to build fusion plants, with investments from ​Bill Gates and ​Nvidia NVDA.O and ⁠others.

• Commonwealth believes the project will help demonstrate that its ARC power plants, the first of which it expects to start generating power in the early 2030s, will be able to generate their fuel supply.

• Amanda Quadling, the executive director of the UKAEA, told reporters that LIBRTI will enable companies like CFS to demonstrate that their breeder technology produces tritium in a controlled manner, an important milestone for investors, operators, and regulators.

• "It's a vital capability for commercializing future fusion energy, and the power plants that they can produce enough of their own fuel and potentially seed the next power plant that gets built," Quadling said.

• The UK is investing the equivalent of about $292 million in LIBRTI.