Schlumberger had been contracted to carry out wireline logging on the rig when a sealed radio isotope used in a logging instrument to obtain well data was left laying on the drill floor unshielded for about four hours after an engineer failed to load it properly into the tool.
The rig was carrying out a drilling programme on Maersk Oil North Sea’s Cawdor prospect in Block30/14, about 335 kilometres east of Dundee, at the time of the incident on 4 April 2008.
The
