Information Notice No. 81-26, Part 3, Supplement No. 1: Clarification of Placement of Personnel Monitoring Devices for External Radiation
SSINS No.: 6835 IN 81-26, Part 3, Sup. No. 1 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 July 19, 1982 Information Notice No. 81-26, PART 3, SUPPLEMENT NO. 1: CLARIFICATION OF PLACEMENT OF PERSONNEL MONITORING DEVICES FOR EXTERNAL RADIATION Addressees: All nuclear power reactor facilities holding an operating license (OL) or construction permit (CP), research and test reactors, fuel facilities, and Priority I material licensees. Purpose: This information notice is a supplement to Information Notice No. 81-26, Part 3: Placement of Personnel Monitoring Devices for External Radiation Exposure, issued in August 1981. Guidance provided in August 1981 concerning dosimeter placement for determining whole body doses in situations where the principal source of radiation is from underfoot was overly conservative. Discussion: The earlier guidance was, "If the principal source of radiation is from underfoot, the appropriate location for the dosimeter might be on the lower leg just above the ankle, since the long bones of the lower leg contain active blood-forming marrow." As defined in 10 CFR 20.101(b)(3), "'dose to the whole body' shall be deemed to include any dose to the whole body, gonads, active blood-forming organs, head and trunk, or lens of eye." According to the International Commission on Radiological Protection (ICRP) publication No. 23, "Report of the Task Group on Reference Man," an adult's long bones of the lower leg contain essentially no blood-forming red bone marrow. Red marrow has been replaced by yellow marrow after the 18th year; yellow marrow performs no blood-forming function and is mainly fatty tissue. ICRP-23 shows for the reference man's femur (thigh bone) a steeply declining red marrow content until the early to middle twenties when no red marrow is evident in the femur shaft. However, in discussing red and yellow marrow distributions, ICRP-23 states, "...it must be pointed out that there is much variation, and exceptions should not be regarded as unusual." In the woman, ...the red marrow may occupy up to one-half to two-thirds of the shaft of the femur. . . . " Another factor is the body's ability to physically replace the yellow with active, red marrow in periods of stress, such as anoxemia, blood loss, anemia, etc. The time frame for the red for yellow marrow replacement was not known when ICRP-23 was published. 8204210395 . IN 81-26, Part 3, Sup. No. 1 July 19, 1982 Page 2 of 2 Guidance: To monitor an adult for whole body doses when the principal source of radiation is from underfoot, a reasonable placement for a whole body dosimeter would be just above the knee. Any further generalization for whole body dosimeter placement could be non-conservative, considering reported variability because of age, race, sex, and state of general health. Note that extremity monitoring requirements may dictate the placement of additional dosimeters in the feet and ankle area. No written response to this information is required. If you need additional information regarding this matter, please contact the Regional Administrator of the appropriate NRC Regional Office. Edward L. Jordan, Director Division of Engineering and Quality Assurance Technical Contact: J. E. Wigginton 301-492-4967 Attachment: List of Recently Issued IE Information Notices
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Page Last Reviewed/Updated Tuesday, March 09, 2021