Dose Rate Survey Discrepancies Identified by Medical Isotope Shipment Recipient

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Type:  Lessons Learned

Publisher:  Brookhaven National Laboratory, Upton, NY

Published As:  Public


Topics:  Nuclear/Nuclear Safety, Transportation and Packaging, Radiation Protection

Use of different survey instrumentation results in dose rates disagreement. Brookhaven National Laboratory shipped packages containing medical isotopes to GE Health Care. BNL performed outgoing shipment surveys using a calibrated Eberline RO-20 air vented ion chamber meter. Survey results confirmed that all package contact dose rates were less than the BNL administrative limit of 180 mR/hr. GE Healthcare receipt surveys revealed all packages contact dose rates exceeded the Department of Transportation package surface dose rate limitation of 200 mR/hr. The GE Healthcare on contact receipt surveys ranged from 40% to 140% higher than the BNL shipping surveys for each package.

Lessons Learned: BNL uses an instrument for radioactive shipments (Eberline RO-20 ion chamber) which is energy independent across the entire spectrum of gamma energies encountered at BNL. GE Healthcare uses an instrument for receipt of radioactive material shipments (Eberline HP-270 energy compensated Geiger-Mueller tube attached to a digital readout) which is very energy dependent particularly at low energy <200 keV and was not fully aware of the effect differing energy levels have on the HP-270. BNL records an average dose rate based on readings identified over a 10 second interval (industry standard) this is particularly important when using digital readouts as they fluctuate dramatically ( 20%). GE Healthcare shipping and receiving staff does not average their readings; in fact they record the highest instantaneous digital reading identified.

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