E006:07 23 February 2007

HSE publishes THORP leak report

Operational Note

The Health and Safety Executive (HSE) has today published a report on its investigation into a leak of radioactive liquid within the Thermal Oxide Reprocessing Plant facility, part of the Sellafield nuclear reprocessing plant.  The investigation, carried out by HSE's Nuclear Installations Inspectorate (NII), culminated in a prosecution of the site licensee, British Nuclear Group Sellafield Ltd (BNGSL), which concluded in October 2006.  The report is on HSE’s website at: www.hse.gov.uk/nuclear/thorp.htm

The report describes in detail how the leak occurred, how it was discovered and why it was not detected earlier, together with background information on the plant.  It outlines 55 recommendations and actions arising from the investigation and discusses lessons for BNGSL and the wider nuclear industry.

Also available on HSE’s website is a report describing NII's assessment of BNGSL's application for consent to restart THORP, which includes consideration of BNGSL’s response to the 55 recommendations.  The decision to grant consent (announced on 9 January 2007) was made once BNGSL had satisfactorily addressed all the recommendations from HSE’s investigation and completed modifications necessary to ensure safety.

Background

• The Thermal Oxide Reprocessing Plant (THORP) at Sellafield reprocesses nuclear fuel from overseas and UK second-generation commercial reactors.
• On 20 April 2005, BNGSL discovered a leak from a pipe supplying highly radioactive liquid to a tank inside a shielded cell within THORP.
• Following a detailed investigation by NII, HSE brought a prosecution against BNGSL.  On 8 June 2006, BNGSL pleaded guilty before Whitehaven Magistrates to charges of breaching three conditions attached to the Sellafield site licence granted under the Nuclear Installations Act 1965 (as amended).  On 16 October 2006, BNGSL was fined £500,000 plus costs of over £67,000 at Carlisle Crown Court (see HSE news release at www.hse.gov.uk/press/2006/e06103.htm)
• The Nuclear Installations Act 1965 provides for the licensing and inspection of sites used for operating nuclear reactors; manufacturing, storing and reprocessing fuel and related activities. No site may be used for operating a nuclear installation without a licence granted by HSE.
• The licence for each site contains a standard set of 36 conditions, dealing with a variety of safety requirements. Contravention of any condition constitutes an offence under the Act.

• BNGSL shut down THORP in April 2005, when the leak was discovered and reported to HSE. Following the shutdown, HSE undertook a substantial amount of assessment and inspection work before issuing consent to allow the safe restart of the plant in January2007 (see HSE news release at www.hse.gov.uk/press/2007/e07001.htm).
• The actual date for restart of reprocessing new fuel at THORP is a matter for BNGSL.

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