Nuclear decommissioner Sellafield mistakenly dumped five bin bags of low-level radioactive waste at a local landfill site on 12 April.
Although an initial analysis has found no environmental implications, as a result of the incident Sellafield has suspended the disposal of bagged process wastes until further investigations have been carried out.
According to Sellafield, the 30kg of waste were taken to Lillyhall landfill site in Cumbria instead of the low-level waste repository near Drigg because a bag monitoring machine incorrectly categorised them as not being radioactive.
The Environment Agency has launched an investigation to establish how it happened.
A statement from Sellafield said: “Our assessment has determined that the maximum potential dose to a member of staff at the Lillyhall site as a result of this would be significantly less than a member of the public would receive from normal background radiation.”
Waste Recycling Group (WRG), which runs the landfill site, explained that it is allowed to receive certain quantites of low-level radioactive waste. But the Sellafield bags of waste has “radioactivity levels higher than allowed under the exemption order that permits this kind of waste to be disposed of at this site”.
WRG added: “Owing to the method of control and traceability we implement at the site for this type of waste, the specific loads in question have been identified in the landfill, the area around them has been cordoned off and is being monitored to ensure there is no risk to WRG employees or anyone else working at the site. The waste contains only low levels of radioactivity and poses no hazard to members of the public or the environment.”