Oxyhydrogen is a mixture of hydrogen (H2) and oxygen (O2) gases. ... Theoretically, a ratio of 2:1 hydrogen:oxygen is enough to achieve maximum efficiency; ... "Brown's gas" and HHO are terms for oxyhydrogen mainly encountered in fringe science. ... pseudoscientific claims have been made about Brown's gas's pretended ability to neutralize radioactive waste, help plants to germinate, etc. [17]

17. Ball, Philip (2006). "Nuclear waste gets star attention". News@nature. doi:10.1038/news060731-13. ISSN 1744-7933

Nuclear waste gets star attention | by Philip Ball | Nature News | 4 August 2006

( ... http://www.nature.com/news/2004/040913/full/040913-24.html) ... a team of researchers in Japan in 2004 trapped atoms inside electron-rich, soccer-ball-shaped cages of carbon, making it slightly more likely that an electron would find its way into the nucleus and bring about the transmutation of the radioactive element. But the team couldn't make the effect any larger; the prospect of using it ... they admitted, was "somewhat remote".

Claus Rolfs of the Ruhr University in Bochum, team leader of the latest attempt [is] more optimistic about his own findings, saying that they suggest the possibility of reducing [a] hazardous component of spent nuclear fuel, from around 1,600 years to just 1 year. "This means that nuclear waste could probably be dealt with entirely within the lifetimes of the people that produce it," Rolfs says.

His approach is somewhat similar to that of the Japanese work, placing the radioactive atoms in the electron-rich environment of a metal. The metal's 'sea' of free electrons can enhance the probability that a positively charged particle might be ejected from the nucleus ... as well as ... electron capture, Rolfs says. Lower temperatures apparently bring the free electron closer to the radioactive nuclei.

Rolfs's team and their European co-workers have ... described similar effects for heavy metals, suggesting that the technique could be viable for the elements typically found in radioactive waste — such as radium. But the [time] estimate ... is so far only theoretical.

Other nuclear scientists have said that the findings contradict earlier experiments and, more damningly, current understanding of solid-state physics.

But they are at least based on a plausible and testable theory. That's probably more than can be said for some of the 'nuclear remediation technologies' circulating on the fringes of science.

One of the favourites involves Brown's gas, a putative form of water 'discovered' by American engineer William Rhodes in the 1960s and championed subsequently by the Bulgarian-Australian physicist Yull Brown.