Lessons learned from this event included :
• The importance of effective characterisation of plant contamination , including the impact of hard-to-detect radionuclides and the use of available information to inform risk assessments
• The risk of embedded alpha contamination in reactor primary coolant systems , especially significant when conducting aggressive work that all the required information has been obtained before work is resumed
• The need to ensure the protection of workers not performing the work . In this case , none of the workers who were performing the work activity had intakes , as they were wearing respiratory protection ; only those working in the containment surrounding the work had been exposed
• The need for adequate bioassay arrangements to be made in advance , as part of contingency planning .
These lessons were embedded into the revised EPRI guidance and have since become standard practices used across the nuclear power industry in North America and internationally .
• The need to adequately assess unusual conditions once detected , to ensure
28 Radiation Protection Today www . srp-rpt . uk