ABSTRACT
Monitoring, training and program support was provided for a turnaround to remove naturally occurring radioactive materials (NORM) that had accumulated within several offshore and onshore vessels of an oil production operation. Exposure and program guidelines vere based on previously developed internal company criteria for NORM-related activities. In addition, detailed turnaround planning was conducted to ensure a healthy and safe operation. Monitoring included radiation dosimetry for employees, air samples for particulates, wipe samples for removable surface contamination and dose rate measurements in work areas. The maximum allowed whole body exposure dose was established at 200 mRem for the 5-day turnaround. This was set assuming worker exposure for the rest of the year would not exceed 90% of the International Commission on Radiological Protection (ICRP) guide of 2000 mRem/year.
Dosimetry and air sampling results were at least one order of magnitude below the 200 mRem exposure criteria. The wipe sample and dose rate measurement results were used to determine the degree of equipment contamination and thus the level of worker protection needed, particularly for those activities requiring vessel opening and entry.
"Lessons-learned" from this work that will be applied to existing operations and future projects include:
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increasing supervisory personnel to ensure compliance with the above
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having dedicated decontamination personnel, who may also conduct surface activity measurements but are not responsible for cleaning/repair operations.
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organizing proper work flow for contamination control and establishing a work site decontamination facility and procedures
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conducting dose rate and surface activity measurements on all equipment before repair; ideally arranging for a dedicated NORM repair/cleaning area
