A SENIOR firefighter has reassured the public over the scale of a fire at Sizewell B nuclear power station.Although about 50 firefighters were at the scene for seven hours after fire broke out in a charcoal filter on Friday night, Kevin Burton said their presence was mainly precautionary.

A SENIOR firefighter has reassured the public over the scale of a fire at Sizewell B nuclear power station.

Although about 50 firefighters were at the scene for seven hours after fire broke out in a charcoal filter on Friday night, Kevin Burton said their presence was mainly precautionary.

Mr Burton, an area manager for Suffolk Fire and Rescue Service who was in charge of the incident, said the heat generated by the small blaze was less than that of a lit cigarette.

The fire began just before 8.45pm in a cabinet measuring about 10 cubic metres. The heavy steel construction had a door on either side with a filter containing fresh charcoal taking up about a third of the space inside the cabinet.

Mr Burton said the duct system had not been used for about 18 months.

In the air flow of the cabinet, there was a heater to ensure no moisture got into the charcoal.

It is believed a component of the heater was faulty, causing it to malfunction and the charcoal to burn.

A little flame was seen coming from the filter as it began smouldering.

About 45 firefighters were sent to the power station, including retained crews from the surrounding areas.

However, Mr Burton said the incident was dealt with by two crews employed at Sizewell B.

Water was put through pipes to extinguish the blaze, but initially it did not seem to make any difference.

Mr Burton said thermal imaging cameras were used to check on the heat and the temperature of the fire was just above 200C. He added a lit cigarette burned at 300C.

The effort to put the fire out and cool down the charcoal was hampered as engineers were needed to clamp the cabinet doors shut as the water was pumped in.

Mr Burton said: 'The crews carrying out the work were from Sizewell. Our role was providing advice, support and direction for what they were doing.'

He said one of the first officers on the scene had taken the precaution of calling in more firefighters in case the incident spread.

'If the fire had got outside the cabinet and duct work, then we could have been dealing with a bigger incident.

'However, it was only a small fire and not a fast-burning one. There was no radioactive material involved whatsoever.'

Jim Crawford, Sizewell B's station director, said: 'At no time was there any risk to the public.'

Sizewell B has been shut down since the end of March and is not expected to be in operation until the third quarter of 2010.