This presentation discusses the health, safety and environmental risks associated with the deployment of nuclear logging services while drilling (LWD). During these operations, radioactive sources are inserted into logging tools which are run in hole as part of the drill string bottom-hole assembly. This paper summarizes the key radiation safety and environmental protection aspects of a 'secure source' logging system, designed to deliver the highest possible standard of protection to the logging sources during drilling operations. The risks associated with various critical scenarios are assessed and compared. The discussion includes a summary of the procedures followed when stuck nuclear logging tools are required to be abandoned in hole and the importance of avoiding loss of the sources at an unknown location in the well. The conclusions are presented within the context of an ongoing debate on the relative merits of 'secure' logging sources and alternative 'retrievable' systems, involving sources which may be able to be returned to the surface if the bottom-hole assembly gets stuck in hole.
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