The £1.99 household product Cillit Bang is being used to help clean plutonium stains at the defunct Dounreay nuclear power plant in Caithness.
Dounreay Site Restoration Limited (DSRL) said it would help reduce the £2.6bn cost of dismantling the site.
The cleaner's use has also drawn interest from operators of other nuclear sites in the UK.
A different domestic product has already been applied in the cleaning of contaminated glass tubes.
Randall Bargelt, of the Nuclear Decommissioning Authority, which owns Dounreay, said such innovative thinking would save taxpayers, who are funding the cost of the dismantling project.
Staff at Sellafield in Cumbria were among those monitoring the use of Cillit Bang in Dounreay's experimental chemical plant.
One of the clean-up team suggested trying the product after the fluid normally used was deemed to be slowing down the operation.
The cleaner was found to markedly reduce levels of radioactive contamination.
Project manager David Manson said: "The normal decontamination agents we would use on steel and glass need time to dry and this slowed us down.
"The acids that had been used years ago also created problems. It meant we had to think carefully about the most effective way to wipe the plutonium from the steelwork before we could cut it up."
He added: "It was at one of our regular toolbox talks that one of the guys suggested Cillit Bang.
"He remembered seeing it dissolve the grime on a 2p coin in an advert on TV and thought it was worth looking at. I'm very glad we did. We tested it and found it to be very effective."
The 15-strong clean-up team wear whole-body plastic suits with their own oxygen supply and often need four or five layers of gloves to protect them from radiation.
Previously, Mr Muscle has been used along with a glass cleaning agent to decontaminate glass columns at the plant's reprocessing laboratory.