Sellafield has admitted failings in its system after a worker suffered chemical burns at the nuclear plant.

In December a fitter was taken to hospital after suffering chemical burns to his arms and hands, after coming into contact with an acid/water mixture while carrying out routine work in the Magnox reprocessing site.

Now a report carried out by Sellafield’s independent investigator has revealed a series of failings.

A Sellafield Ltd spokesman said: “Safety and security are our overriding priorities.

“We take incidents of this kind extremely seriously. That’s why we immediately launched a thorough and rigorous investigation.

“The results will help us understand why this happened and how we can avoid a similar incident happening in future.”

The incident happened when the fitter was carrying out some maintenance work on a system which has two pipes: one for water and one for chemical substances.

He was replacing a spade, similar to a stopcock, in the water pipe.

However the valve further up the system had not been isolated, resulting in the chemicals dripping onto his hands.

The worker was wearing minimum protective equipment – gloves and a face visor.

The report said he initially thought this was water, and it wasn’t until he felt a “tingling sensation to his forearms” that he realised he was suffering from acid burns.

The investigator said: “The root cause of this event is the failure, over a significant period of time, of the organisation to identify that a hazard from acid was present when carrying out intrusive maintenance on the system.”

The report added several opportunities existed to identify the risk.

Workers and managers should have checked and challenged whether the isolation of the valve carrying the chemical substance had been carried out effectively.

Investigators also said there was a culture of “lack of detail when filling in plant record documents”.

Staff were told to be more descriptive when filling in forms for jobs to be carried out.

The report states drawings of the system were outdated and should be updated to reflect its real configuration.

The report recommends a series of actions.

It will be sent to to the Office for Nuclear Regulation and will go through a peer-review process.

The incident was reported to the Health and Safety Executive as a “dangerous occurrence”.