Document: NRC Regulatory Guide
Document ID: 377c2606-4b7c-4c7f-997d-37aed1680452
Document Type: regulatory_guide
Title: Performance, Testing, and Procedural Specifications for Thermoluminescence Dosimetry: Environmental Applications + HISTORY - HISTORY 10/2018 – DG-4019 , Proposed Revision 2 11/2014 – Periodic Review of Revision 1 – Revise (Rev. 2)
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML1808/ML18087A169.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-4.13
CFR Part: 
CFR Title: 

Content:
). Note that, if the baseline background dose rates are determined after facility operations have begun, a professional health physics staff’s evaluation and judgment will be needed to determine the baseline background dose rates. 2. For each location, calculate the standard deviation of the historical baseline background dose data. Select the standard deviation at the location that has the 90th-percentile highest standard deviation. The systemwide environmental dosimetry MDD is established as equal to 3 standard deviations (3σ) above the baseline background dose rate (at that 90th-percentile location). Note that use of a 3σ value increases the MDD by approximately 1 mrem (0.01 mSv) but helps to avoid false positives because of the relatively large number (approximately 40) of dosimeters deployed in a typical environmental monitoring program. b. Analyze current monitoring period (e.g., quarter) gross field dosimeter readings. 1. Perform a qualitative review of the field dosimeter results to identify and remove any obvious data outliers and investigate any apparent discrepancies. DG-4019, Appendix A, Page A-2 Note that the review is performed before removal of extraneous dose from the field dosimeter readings. The extraneous dose is the additional dose accumulated on a dosimeter other than the dose received at the field monitoring location (e.g., before or after field deployment). The method used to determine the extraneous dose has been the least understood process over historical environmental measurements. The extraneous dose is not simply the average dose on control dosimeters stored in a lead vault. American National Standards Institute (ANSI)/Health Physics Society (HPS) N13.37-2014, “Environmental Dosimetry—Criteria for System Design and Implementation,” describes, in detail, proper methods for determining extraneous dose. 2. Calculate the average field dosimeter reading at each monitored location (assuming that two or more dosimeters were used at