A privatised atomic energy company has been fined £250,000 after their 'cavalier attitude' exposed the public to potentially lethal levels of radiation.

A toxic beam was emitted from a van as it drove 130 miles across the country through Aireborough, Otley, Ilkley and Addingham along the A65 after blundering workers failed to put a plug in a safety container.

AEA Technology admitted the dangerous lapse in safety as they took source material from a radiotherapy machine to be decommissoned.

The company, whose Safeguard division specialised in the safe disposal of nuclear waste, admitted six charges of breaching safety rules at Leeds Crown Court this week.

In addition to the fine they were ordered to pay £151,323 costs, bringing the total penalty to over £400,000.

The Recorder of Leeds, Judge Norman Jones, slammed the "careless" nuclear giant for the potentially deadly mistake.

"Anyone operating in the field of the disposal of highly toxic waste materials has to be meticulously careful to ensure they do not escape and injure the public," the judge said.

"There is no field where this necessity is more important than in the disposal of nuclear waste.

"There is no room for carelessness, or the making of assumptions, or the avoidance of regulations and procedures designed to protect the safety of fellow workers and the public at large

"In this case, the defendants fell well below the required standards."

The court heard that the radioactive material was taken from Cookridge Hospital, in Leeds, to the Windscale decommissioning plant on the Sellafield site, in Cumbria, on March 11, 2002.

The highly-dangerous Cobalt-60 source was put in a safety flask inside a specially built two and half tonne container for the three and a half hour journey from Leeds and through the Yorkshire Dales to the Cumbrian coast

But a plug designed to prevent radiation leaks was missing and the dangerous beam escaped through the gap.

Two workers at AEA failed to notice the missing shield plug before the trip. They did not complete full safety checks but still ticked a check-list to claim they were done.

The package was scanned for radiation before departure, but the bottom was not checked, allowing their mistake to go unnoticed.

The long-serving employees, who have since resigned, were slammed by the judge for their "cavalier" attitude.

Judge Jones also criticised the "poor management" of AEA for allowing the local managers to operate unchecked in such a dangerous industry

"I am satisfied that they made assumptions in relation to the packaging that they were wholly unjustified in making," he said

"In doing so they behaved in a cavalier and somewhat indifferent manner to their duties.

"They demonstrated a degree of arrogance in their approach to their duties. I am satisfied that the risk that ensued were considerable."

The court heard that the levels of radiation measured when the leak was discovered were up to 1,000 times over what would be considered a very high dose

Employees standing one metre away from the beam would have received a dose greater than the legal limit in only 40 seconds. Members of the public would have been over-exposed in just eight seconds.

But the court heard because the 8mm wide beam was pointing downwards, through the van and onto the road, no one came into direct contact with it.

"It is good luck that no one was injured or worse," Judge Jones added.

"It is a matter of deep concern that if there had been any event during the transportation of the packaging that caused its reorientation then there is a grave risk that injury could have resulted.

"This is not a case of the carriage of a source emitting a beam of deadly radiation at all and sundry who came in range as it was carried for three and a half hours across the English countryside

"Had it been so then any fine would have been measured in millions of pounds."

The court heard that the load was part of a £245,244 contract won by AEA to dispose of eight loads of radioactive material from Leeds Teaching Hospitals NHS Trust.

The company hired a specialist sub-contractor haulier for the trip and stressed their expertise and ability to eliminate health and safety risks during the work

But they have now admitted six breaches of the health and safety act, ionising radiations regulations and the regulation of radioactive material regulations.

The leak was only found when a background radiation check found high radiation levels near the truck when it arrived at Windscale.

Checks on the base of the flask showed a dose of 3.5 sieverts per hour, compared to the permitted maximum amount of one per hour.

The court heard that had the package been turned the beam would have projected up to 300 metres from the side of the truck, endangering more people.

John Hand QC, mitigating, said that after the blunder the former state-run company closed down the division responsible for a year, at a loss of £1million.

It was then restructured with new staff before being sold off last year.

He told the court the company had an excellent safety record before the incident and were sorry that mistakes had been made.

"This is not an attempt to diminish the seriousness of the matter," Mr Hand said.

"The public must have confidence in the safe disposal of this material, and the defendant realises that what happened at Cookridge dents that confidence."

He added that although the mistakes were grave, there had fortunately been no injuries caused.

The court heard that although AEA Technology has a turnover of 157 million pounds it is not currently making large profits.

Mr Hand added that they were able to pay a fine but urged the judge to limit the amount imposed.

But Judge Jones said a substantial fine must be given to such a large company and ordered it to be paid within 14 days.

After the hearing the firm's spokesman Matthew Moth said: "AEA pleaded guilty to a number of charges.

"Lessons were learnt from this and steps taken to replace or retrain the management and staff and to introduce improved procedures to ensure that this sort of incident could not happen again."

James Taylor, from the Health and Safety Executive, said: "This case should serve as a reminder that radiation protection should never be taken for granted and that management must understand the principles, not least of which is the

need to supervise their staff properly.

"I am pleased that the court clearly saw this as a serious matter. While there is no evidence that anyone received a significant exposure during the preparation and transport of this material, there was clearly the potential for an extremely serious incident

"Anyone exposed to the beam coming from the container could have exceeded the legal dose limit within seconds and suffered radiation burns within minutes."