Office for Nuclear Regulation

Quarterly statement of nuclear incidents at nuclear installations
2nd quarter 2007

HM Nuclear Installations Inspectorate

A statement on incidents at nuclear installations in Britain which meet Ministerial reporting criteria is reported to the Secretary of State for Business, Enterprise & Regulatory Reform and the Secretary of State for Scotland and is published every quarter by the Health and Safety Executive.

For the period 1 April 2007 to 31 July 2007 there was one incident at a nuclear licensed installation that met the reporting criteria.


On 20th May 2007 UKAEA personnel performed a radiological survey of the inside of a manhole that services an inactive drain line on the North West side of the Dounreay site. This is a part of the site where historic contamination is known to be present. A contamination smear sample from inside the manhole showed the presence of about 1.3kBq of alpha emitting radioactive material which was subsequently found to contain 60% plutonium/americium. The manhole was sealed and the area designated as radioactive contamination high. The quantity of plutonium on the smear sample was about 1000 times less than that of Column 4 of Schedule 8 of Ionising Radiations Regulations 1999.

As part of their investigation UKAEA placed a temporary enclosure over the manhole to provide an additional means of containing any plutonium present and to facilitate control over personnel entries to perform further radiological surveys. Surveys of the inside of the manhole were performed on 3rd July 2007, through the temporary enclosure by UKAEA personnel wearing air fed suits. No further alpha contamination was found inside the manhole. UKAEAs investigation is still ongoing, but is expected to conclude that there is no significant contamination inside the manhole, however the source of the plutonium contamination from the smear sample remains unknown.

The alpha contamination found on 20th June 2007 on a filter processing water from a spring just outside the site boundary, but close to the contaminated manhole was investigated in depth. The investigation indicated that the initial result was spurious.

Single copies of statements are available free from the Health and Safety Executive, Nuclear Directorate, Division 4a, Building 4 NG1, Redgrave Court, Merton Road, Bootle, L20 7HS,