A DEFECTIVE pipe caused an acid leak at Bradwell nuclear power station sparking an investigation at the plant.
In late September a "small quantity" of acid escaped from a pipe with all of the fluid contained at the site, on the banks of the River Blackwater.
A Magnox spokesman said: "During ongoing decommissioning work of a new water treatment plant, a defect was located within a pipe that allowed a small quantity of acid to escape into a further containment hold.
"This pipe is not used to discharge liquid from the site. All of the material has been contained on the site, there has been no release of radioactivity and no impact on the environment.
"Regulators have been informed and an investigation is underway to ensure we can learn any lessons from the event."
Magnox has spent £100m on decommissioning the old power station in the last year with the estimated revenue for the local economy annually estimated to be £19m.
All of the 850 contractors are on course to finish their decommissioning work, which began in 2002, by next autumn.
The plant will then be placed in the "care and maintenance stage" for between 85 and 105 years.
In August the Chronicle revealed how Chinese corporations are understood to have chosen the Dengie, from a shortlist of locations, for a 3,000-megawatt station sitting beside the partly-decommissioned Magnox plant.
