Fort Calhoun had some questions about the use of extremity dosimetry. Some of this has been asked before but not as detailed. Would appreciate your answers to as many questions as possible, or the contact info of someone that I could talk with directly that would have detailed knowledge.
1) What are you using for an extremity admin limit (same as federal of 50 Rem, or some percentage of the 50 Rem limit)? 2) When you consider whether extremity or whole body dose is limiting, are you looking at it based on the yearly federal limits (50 Rem vs 5 Rem - 10X), the yearly admin limits (for us - 50 Rem vs 1 Rem - 50X) or just the extremity vs whole body dose expected for the particular job (say expected dose is 2 Rem extremity and 400 mrem whole body - 5X). 3) Are you using extremity monitoring criteria that is different from INPO (more than 500 mrem to the extremity and 2 times the whole body dose or worker may exceed 10% of the federal extremity limit (5 rem) for the year)? 4) Do you use a secondary dosimeter when monitoring extremity locations or just a TLD? 5) Do you have an extremity dose threshold above which you would require use a secondary dosimeter or below which you would just use an extremity TLD only? 6) Do you use single element TLDs (finger rings), multi-element TLDs (like a normal whole body TLD), or an extremity TLD with more than one element (chip)? 7) What kind of secondary dosimeter do you use (PIC - pocket ion chamber, EAD - electronic alarming dosimeter, etc) 8) If you use an EAD as the secondary dosimeter, do you use it like an electronic PIC (indication of dose and dose rate only, no alarm functionality active and dose / doserate setpoints not needed) or do you use the alarm functions for dose and doserate? 9) If you don't use alarm functionality, how do you address it (procedure, white paper, analysis, etc) so it is not questioned by regulators? 10) If the alarms are turned on, what criteria do you use to set the dose rate alarm (same INPO criteria that is used for whole body dose rate alarms, 2x max work area contact dose rate, 10x whole body doserate setpoint, etc)? 11) Do you wear the TLD and secondary dosimeter in the same location on the extremity (say both at the wrist or at the ankle)? 12) Do you use correction factors to account for the difference in placement of the TLD and secondary dosimeter (say tld on finger while EAD on wrist)? 13) How do you determine the extremity EAD dose setpoint when a correction factor is used (expected dose / correction factor = dose setting)? 14) Do you allow extremity EADs to have different dose settings due to applying correction factors (say you estimate the worker will get 4 rem extremity, and have determined the correction factor for hands is 2 and the feet are 4, so the dose setpoint for the hands is 4 rem/2 = 2 rem, and the feet are 4 rem / 4 = 1 rem) Thanks, Dohn Dohn Little Radiation Health Specialist - Dosimetry [email protected] - (402) 533-7162 Omaha Public Power District Fort Calhoun Station - Admin Building FC 2-1 9610 Power Lane Blair, Ne. 68008 [Description: cid:[email protected]] ---------------------------------------------------------------------- This e-mail contains Omaha Public Power District's confidential and proprietary information and is for use only by the intended recipient. Unless explicitly stated otherwise, this e-mail is not a contract offer, amendment, or acceptance. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited.
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