A UNIVERSITY lost a substance which is more than one million times more radioactive than uranium for five days, it was revealed yesterday.

The radium 226 went missing from York University after it was meant to have been transported to be disposed of.

It was supposed to be held in a lead container and sent to a specialist disposal company. But when the container arrived there was nothing inside.

A full-scale investigation was launched, but the radium - about the size of a pea - was only found five days later at a plant in South Yorkshire where it had been sent by mistake.

A university spokesman said it was "extremely unlikely that any person was exposed to any risk to their health at any time".

As part of the investigation, the university's biology department was searched, and independent agents examined local waste skips.

In the end it was traced to the stainless steel reprocessing plant.

The university spokesman said the radium 226 had now been disposed of in accordance with established procedures.

He said: "The level of radiation from the capsule is extremely low and represents little or no danger to human health.

"If crushed or broken, the capsule contents would be dangerous only if inhaled or ingested in significant quantities."

The spokesman said all relevant agencies and companies had been kept informed of developments during the investigation.

Professor Dale Sanders, head of biology, said the radium had been used to calibrate a machine in the biology department.

The machine, a RackBeta device, is used to measure radioactivity in biological materials.

It had been due for dismantling and the university had wanted to dispose of the radium 226 before disposing of the rest of the machine.

Prof Sanders said the university had swung into action as soon as it had been informed of the missing radium at 4pm on Friday, February 16.

"The relevant agencies were notified - the Health and Safety Executive (HSE), the Environment Agency and the police," he said.

He said a university inquiry was being conducted by Keith Lilley, director of facilities management, and the report would be sent to the HSE.

The inquiry would examine exactly how the substance got to the reprocessing plant.

A North Yorkshire Police spokesman confirmed the police had been informed.

A spokeswoman for the HSE said: "The HSE has been informed and will be making its own inquiries."