The owner of the Sellafield nuclear plant has been fined £700,000 after admitting sending low-level radioactive waste to a landfill site.

Sellafield Limited confessed to sending four bags, containing plastic, paper, clothing, wood and metal, from its plant to the Lillyhall landfill in Workington, in April 2010. The bags should have been sent to the Low Level Waste Repository at Drigg. According to the firm, a wrongly configured monitoring system resulted in the bags being labelled as “general waste”, making them exempt from the usual disposal treatment process.

The charges were brought to Carlisle Crown Court by the Environment Agency and the Health and Safety Executive, and included breaches of the Radioactive Substances Act 1993, the Environmental Permitting (England and Wales) Regulations SI 2010/675 and the Health and Safety at Work etc Act 1974.

Judge Peter Hughes said the mistakes were the result of “basic management failures”. He commented, “this prosecution arises out of the discovery, by chance, that bags of radioactive waste had been wrongly classified as exempt waste and allowed to leave Sellafield and to be transported to a landfill site and deposited there. That such a basic mistake could possibly occur in what needs to be an industry managed and operated with scrupulous care for public safety and the environment is bound to be a matter of grave concern.”

A statement from the company, which has held an ISO 14001 certification since 1997, said it regretted the incident and had suspended the disposal of waste from the site until it had identified and corrected the error.