The Jet experiment in Oxfordshire was opened in 1984 to understand fusion – the process that powers the Sun.
Prof Steve Cowley told the BBC a go-ahead to run Jet at maximum power would allow scientists to try for the record by the end of the decade.
This could bring Jet up to the coveted goal of "breakeven" where fusion yields as much energy as it consumes.
Fusion is markedly different from current nuclear power, which operates through splitting atoms – fission – rather than squashing them together as occurs in fusion.
"We’re hoping to repeat our world record shots and extend them," Prof Cowley, who is director of the Culham Centre for Fusion Energy – which hosts Jet, told BBC News.
"Our world record was from 1997, we think we can improve on it quite considerably and get some really spectacular results. We’re winding up to that and by the end of the decade we’ll be doing it."
Read more on BBC News website