Office for Nuclear Regulation

Statement of nuclear incidents at nuclear installations

A statement of nuclear incidents at nuclear installations in Britain during the fourth quarter of 2001 is published today by the Health and Safety Executive. It covers the period 1 October to 31 December 2001. There is one installation mentioned in the statement: Sellafield (British Nuclear Fuels plc).

The statement is published under arrangements that came into effect from the first quarter of 1993, derived from the Health and Safety Commission's powers under section 11 of the Health and Safety at Work, etc. Act 1974.

Notes to Editors

1. The arrangements for reporting incidents were announced to Parliament by the Parliamentary Under Secretary of State for Energy on 30 April 1987 (Hansard col. 203-204). A minor modification to arrangements for reporting on nuclear incidents was announced in HSE press notice E108:93 of 30 June 1993.

2. Normally each incident mentioned in HSE's Quarterly Incident Statements will already have been made public by the licensee or site operator either through a press statement or by inclusion in the newsletter for the site concerned.

Statement of Nuclear Incidents at Nuclear Installations: Fourth Quarter 2001 - single copies of each free from the Information Centre, Health and Safety Executive, Room 004, St Peter's House, Stanley Precinct, Bootle L20 3LZ.


The Health and Safety Executive presents the attached statement of nuclear incidents at nuclear installations published under the Health and Safety Commission's powers derived from section 11 of the Health and Safety at Work, etc. Act 1974.

INCIDENT 01/4/1 SELLAFIELD (British Nuclear Fuels plc)

British Nuclear Fuels reported the detection of Tc99 in groundwater taken from a borehole on its Sellafield site close to the Main Gate. This was the result for the first analysis of groundwater from this borehole for this isotope. The incident report noted that the sample may have been a false analysis. Subsequent analyses have confirmed Tc99 in this borehole and, at lesser concentration, in others in the same area. Activity has also been detected beyond the site boundary but at much lower concentrations.

The Health and Safety Executive's Nuclear Installations Inspectorate (NII) has asked BNFL to determine the source of the activity and to report the work the company is undertaking to prevent further leakage from the plant and to prevent activity leaving the site.

The company has confirmed that the probable source of activity in the ground is the sludge storage tanks in Building B241. These old tanks have been suspected to be leaking for some years and recent modifications have been made to address this. The recent detection appears to be confirmation that leaked material has reached the groundwater on the site. The fall off of activity concentration in boreholes away from the plant is consistent with B241 being the source of the activity.

To remove the potential for leakage from this old facility, BNFL is proposing to commence emptying the storage tanks in 2002. The NII is currently considering the safety case for BNFL's plans to do this. The Inspectorate has requested BNFL's proposals for control of the radioactive material that has entered the ground and expects to receive this soon.

In respect of the activity detected off the site, the Environment Agency has stated that it is satisfied that the reported concentration of Tc99 is radiologically insignificant. However, until the source of the activity is known, the Agency has regulatory concern. It also has requested BNFL to undertake monitoring to confirm the point of leakage, and will work with NII to consider any regulatory action.

The incident has been classified as Level 0 on the International Nuclear Event Scale (INES).