Office for Nuclear Regulation

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Third quarterly statement of nuclear incidents at nuclear installations

A statement on incidents at nuclear installations in Britain which meet Ministerial Reporting Criteria (MRC) is reported to the Secretary of State for the Department of Energy and Climate Change and the Secretary of State for Scotland and is published every quarter by the Health & Safety Executive.

For the period 1 July 2010 to 30 September 2010 there were no incidents at licensed nuclear installations that met the reporting criteria. However there are two events that occurred in this quarter that may be reportable. Should further investigations into this event identify that it meets the criteria an update will be provided in the next report.

For the period 1 April 2010 to 30 June 2010 we said there was one incident that may meet the reporting criteria. The incident, which occurred at the Sellafield site, is considered to meet the MRC and an update is provided below.

Sellafield-Calder Hall

On 19 April 2010, Sellafield Ltd (SL) sent a routine consignment of exempt waste to the Lillyhall landfill site in Workington, Cumbria. Exempt waste is defined as material with an activity level of less than 0.4 becquerel/gram ie a very low level. This consignment included four bags of material that SL subsequently identified as being above the exemption threshold. This became apparent when SL identified another bag of waste having activity levels above the threshold for exempting waste, however this bag had also been categorised as exempt. The bag was quarantined and operations in the waste sentencing facility at SL were suspended. The Health and Safety Executive (HSE) was notified of the incident on 21 April 2010.

The four bags of waste were safely recovered by SL from the Lillyhall landfill site over the period 22 to 28 April 2010. One bag had been punctured resulting in minor land pollution. This was remediated with confirmatory monitoring detecting only background activity levels. SL has reported that no other bags of waste with activity levels exceeding the exemption level have been sent to the Lillyhall site. The health and safety of persons was unaffected by either the incident or subsequent recovery activities.

A detailed investigation by SL identified the main cause of the incident to be incorrect loading of software in the waste sentencing equipment for one of the activity detection instruments together with shortfalls in the commissioning procedure for this system.

This incident is being investigated by the Environment Agency (EA) in respect to breaches of the Environmental Permitting Regulations 2010. This is on the basis that SL did not have a permit to dispose of waste with activity levels greater than those specified for exempt waste to the Lillyhall landfill site.

On 16 July 2010 the Department for Transport issued an Improvement Notice in relation to this incident due to concerns over SLs arrangements for discharging its obligations under Transport Regulations.

HSE has taken no formal enforcement action in relation to this incident on the grounds that there have been no related health and safety effects on the public or workforce and no significant breaches in Health and Safety law. HSE is however supporting the EA investigation.

Single copies of statements are available free from the Health and Safety Executive, Nuclear Directorate, Division 3, Building 4.N2, Redgrave Court, Merton Road, Bootle, L20 7HS,